fscrypt: improve file creation flow

PATCH In review Eric Biggers 2 participants 20 messages Sep 17, 2020 – Sep 22, 2020

Subsystems (5)

Memory technology devices (MTD) ext4 file system F2FS file system UBI file system (UBIFS) +1 more subsystems

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Eric Biggers

author maintainer

2020-09-17 04:13 UTC #0 lore raw

v3 cover fscrypt: improve file creation flow

Hello,

This series reworks the implementation of creating new encrypted files by introducing new helper functions that allow filesystems to set up the inodes' keys earlier, prior to taking too many filesystem locks.

This fixes deadlocks that are possible during memory reclaim because fscrypt_get_encryption_info() isn't GFP_NOFS-safe, yet it's called during an ext4 transaction or under f2fs_lock_op(). It also fixes a similar deadlock where f2fs can try to recursively lock a page when the test_dummy_encryption mount option is in use.

It also solves an ordering problem that the ceph support for fscrypt
will have. For more details about this ordering problem, see the
discussion on Jeff Layton's RFC patchsets for ceph fscrypt support
(v1: https://lkml.kernel.org/linux-fscrypt/[email protected]/T/#u
v2: https://lkml.kernel.org/linux-fscrypt/[email protected]/T/#u
v3: https://lkml.kernel.org/linux-fscrypt/[email protected]/T/#u)
Note that v3 of the ceph patchset is based on v2 of this patchset.

Patch 1 adds the above-mentioned new helper functions. Patches 2-5 convert ext4, f2fs, and ubifs to use them, and patches 6-9 clean up a few things afterwards.

Finally, patches 10-13 change the implementation of test_dummy_encryption to no longer set up an encryption key for unencrypted directories, which was confusing and was causing problems.

This patchset applies to the master branch of
https://git.kernel.org/pub/scm/fs/fscrypt/fscrypt.git.
It can also be retrieved from tag "fscrypt-file-creation-v3" of
https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git.

I'm looking to apply this for 5.10; reviews are greatly appreciated!

Changed v2 => v3:
- Added patch that changes fscrypt_set_test_dummy_encryption() to take a 'const char *'. (Needed by ceph.)
- Fixed bug where fscrypt_prepare_new_inode() succeeded even if the new inode's key couldn't be set up.
- Fixed bug where fscrypt_prepare_new_inode() wouldn't derive the dirhash key for new casefolded directories.
- Made warning messages account for i_ino possibly being 0 now.

Changed v1 => v2:
- Added mention of another deadlock this fixes.
- Added patches to improve the test_dummy_encryption implementation.
- Dropped an ext4 cleanup patch that can be done separately later.
- Lots of small cleanups, and a couple small fixes.

Eric Biggers (13):
fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context()
ext4: factor out ext4_xattr_credits_for_new_inode()
ext4: use fscrypt_prepare_new_inode() and fscrypt_set_context()
f2fs: use fscrypt_prepare_new_inode() and fscrypt_set_context()
ubifs: use fscrypt_prepare_new_inode() and fscrypt_set_context()
fscrypt: adjust logging for in-creation inodes
fscrypt: remove fscrypt_inherit_context()
fscrypt: require that fscrypt_encrypt_symlink() already has key
fscrypt: stop pretending that key setup is nofs-safe
fscrypt: make "#define fscrypt_policy" user-only
fscrypt: move fscrypt_prepare_symlink() out-of-line
fscrypt: handle test_dummy_encryption in more logical way
fscrypt: make fscrypt_set_test_dummy_encryption() take a 'const char

*'

 fs/crypto/crypto.c           |   4 +-
 fs/crypto/fname.c            |  11 +-
 fs/crypto/fscrypt_private.h  |  10 +-
 fs/crypto/hooks.c            |  65 ++++++++----
 fs/crypto/inline_crypt.c     |   7 +-
 fs/crypto/keyring.c          |   9 +-
 fs/crypto/keysetup.c         | 182 +++++++++++++++++++++++--------
 fs/crypto/keysetup_v1.c      |   8 +-
 fs/crypto/policy.c           | 200 ++++++++++++++++++++---------------
 fs/ext4/ext4.h               |   6 +-
 fs/ext4/ialloc.c             | 119 +++++++++++----------
 fs/ext4/super.c              |  17 +--
 fs/f2fs/dir.c                |   2 +-
 fs/f2fs/f2fs.h               |  25 +----
 fs/f2fs/namei.c              |   7 +-
 fs/f2fs/super.c              |  16 +--
 fs/ubifs/dir.c               |  38 +++----
 include/linux/fscrypt.h      | 120 +++++++--------------
 include/uapi/linux/fscrypt.h |   6 +-
 19 files changed, 474 insertions(+), 378 deletions(-)

base-commit: 5e895bd4d5233cb054447d0491d4e63c8496d419

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Eric Biggers

author maintainer

2020-09-17 04:13 UTC #1 lore raw

PATCH v3 1/13 fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context()

From: Eric Biggers <[email protected]>

fscrypt_get_encryption_info() is intended to be GFP_NOFS-safe. But actually it isn't, since it uses functions like crypto_alloc_skcipher() which aren't GFP_NOFS-safe, even when called under memalloc_nofs_save(). Therefore it can deadlock when called from a context that needs GFP_NOFS, e.g. during an ext4 transaction or between f2fs_lock_op() and f2fs_unlock_op(). This happens when creating a new encrypted file.

We can't fix this by just not setting up the key for new inodes right away, since new symlinks need their key to encrypt the symlink target.

So we need to set up the new inode's key before starting the transaction. But just calling fscrypt_get_encryption_info() earlier doesn't work, since it assumes the encryption context is already set, and the encryption context can't be set until the transaction.

The recently proposed fscrypt support for the ceph filesystem
(https://lkml.kernel.org/linux-fscrypt/[email protected]/T/#u)
will have this same ordering problem too, since ceph will need to encrypt new symlinks before setting their encryption context.

Finally, f2fs can deadlock when the filesystem is mounted with '-o test_dummy_encryption' and a new file is created in an existing unencrypted directory. Similarly, this is caused by holding too many locks when calling fscrypt_get_encryption_info().

To solve all these problems, add new helper functions:

- fscrypt_prepare_new_inode() sets up a new inode's encryption key (fscrypt_info), using the parent directory's encryption policy and a new random nonce. It neither reads nor writes the encryption context.

- fscrypt_set_context() persists the encryption context of a new inode, using the information from the fscrypt_info already in memory. This replaces fscrypt_inherit_context().

Temporarily keep fscrypt_inherit_context() around until all filesystems have been converted to use fscrypt_set_context().

Signed-off-by Eric Biggers <[email protected]>

---
 fs/crypto/fscrypt_private.h |   3 +
 fs/crypto/keysetup.c        | 195 +++++++++++++++++++++++++++---------
 fs/crypto/policy.c          |  62 ++++++++++--
 include/linux/fscrypt.h     |  17 ++++
 4 files changed, 223 insertions(+), 54 deletions(-)

fs/crypto/fscrypt_private.h +3 -0

index 8117a61b6f558..355f6d9377517 100644
@@ -572,6 +572,9 @@ int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key);
 int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
 			       const struct fscrypt_master_key *mk);
 
+void fscrypt_hash_inode_number(struct fscrypt_info *ci,
+			       const struct fscrypt_master_key *mk);
+
 /* keysetup_v1.c */
 
 void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);

fs/crypto/keysetup.c +150 ~~-45~~

278 lines not on this page · raw message

fs/crypto/policy.c +53 -9

117 lines not on this page · raw message

include/linux/fscrypt.h +17 -0

index eaf16eb557887..9cf7ca90f3abb 100644
@@ -158,6 +158,7 @@ int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg);
 int fscrypt_has_permitted_context(struct inode *parent, struct inode *child);
 int fscrypt_inherit_context(struct inode *parent, struct inode *child,
 			    void *fs_data, bool preload);
+int fscrypt_set_context(struct inode *inode, void *fs_data);
 
 struct fscrypt_dummy_context {
 	const union fscrypt_context *ctx;

@@ -184,6 +185,8 @@ int fscrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
 
 /* keysetup.c */
 int fscrypt_get_encryption_info(struct inode *inode);
+int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
+			      bool *encrypt_ret);
 void fscrypt_put_encryption_info(struct inode *inode);
 void fscrypt_free_inode(struct inode *inode);
 int fscrypt_drop_inode(struct inode *inode);

@@ -347,6 +350,11 @@ static inline int fscrypt_inherit_context(struct inode *parent,
 	return -EOPNOTSUPP;
 }
 
+static inline int fscrypt_set_context(struct inode *inode, void *fs_data)
+{
+	return -EOPNOTSUPP;
+}
+
 struct fscrypt_dummy_context {
 };

@@ -394,6 +402,15 @@ static inline int fscrypt_get_encryption_info(struct inode *inode)
 	return -EOPNOTSUPP;
 }
 
+static inline int fscrypt_prepare_new_inode(struct inode *dir,
+					    struct inode *inode,
+					    bool *encrypt_ret)
+{
+	if (IS_ENCRYPTED(dir))
+		return -EOPNOTSUPP;
+	return 0;
+}
+
 static inline void fscrypt_put_encryption_info(struct inode *inode)
 {
 	return;

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Eric Biggers

author maintainer

2020-09-17 04:13 UTC #2 lore raw

PATCH v3 2/13 ext4: factor out ext4_xattr_credits_for_new_inode()

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

To compute a new inode's xattr credits, we need to know whether the inode will be encrypted or not. When we switch to use the new helper function fscrypt_prepare_new_inode(), we won't find out whether the inode will be encrypted until slightly later than is currently the case. That will require moving the code block that computes the xattr credits.

To make this easier and reduce the length of __ext4_new_inode(), move this code block into a new function ext4_xattr_credits_for_new_inode().

Signed-off-by Eric Biggers <[email protected]>

---
 fs/ext4/ialloc.c | 90 +++++++++++++++++++++++++++---------------------
 1 file changed, 51 insertions(+), 39 deletions(-)

fs/ext4/ialloc.c +51 ~~-39~~

index df25d38d65393..0cc576005a923 100644
@@ -742,6 +742,53 @@ static int find_inode_bit(struct super_block *sb, ext4_group_t group,
 	return 1;
 }
 
+static int ext4_xattr_credits_for_new_inode(struct inode *dir, mode_t mode,
+					    bool encrypt)
+{
+	struct super_block *sb = dir->i_sb;
+	int nblocks = 0;
+#ifdef CONFIG_EXT4_FS_POSIX_ACL
+	struct posix_acl *p = get_acl(dir, ACL_TYPE_DEFAULT);
+
+	if (IS_ERR(p))
+		return PTR_ERR(p);
+	if (p) {
+		int acl_size = p->a_count * sizeof(ext4_acl_entry);
+
+		nblocks += (S_ISDIR(mode) ? 2 : 1) *
+			__ext4_xattr_set_credits(sb, NULL /* inode */,
+						 NULL /* block_bh */, acl_size,
+						 true /* is_create */);
+		posix_acl_release(p);
+	}
+#endif
+
+#ifdef CONFIG_SECURITY
+	{
+		int num_security_xattrs = 1;
+
+#ifdef CONFIG_INTEGRITY
+		num_security_xattrs++;
+#endif
+		/*
+		 * We assume that security xattrs are never more than 1k.
+		 * In practice they are under 128 bytes.
+		 */
+		nblocks += num_security_xattrs *
+			__ext4_xattr_set_credits(sb, NULL /* inode */,
+						 NULL /* block_bh */, 1024,
+						 true /* is_create */);
+	}
+#endif
+	if (encrypt)
+		nblocks += __ext4_xattr_set_credits(sb,
+						    NULL /* inode */,
+						    NULL /* block_bh */,
+						    FSCRYPT_SET_CONTEXT_MAX_SIZE,
+						    true /* is_create */);
+	return nblocks;
+}
+
 /*
  * There are two policies for allocating an inode.  If the new inode is
  * a directory, then a forward search is made for a block group with both

@@ -796,45 +843,10 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 	}
 
 	if (!handle && sbi->s_journal && !(i_flags & EXT4_EA_INODE_FL)) {
-#ifdef CONFIG_EXT4_FS_POSIX_ACL
-		struct posix_acl *p = get_acl(dir, ACL_TYPE_DEFAULT);
-
-		if (IS_ERR(p))
-			return ERR_CAST(p);
-		if (p) {
-			int acl_size = p->a_count * sizeof(ext4_acl_entry);
-
-			nblocks += (S_ISDIR(mode) ? 2 : 1) *
-				__ext4_xattr_set_credits(sb, NULL /* inode */,
-					NULL /* block_bh */, acl_size,
-					true /* is_create */);
-			posix_acl_release(p);
-		}
-#endif
-
-#ifdef CONFIG_SECURITY
-		{
-			int num_security_xattrs = 1;
-
-#ifdef CONFIG_INTEGRITY
-			num_security_xattrs++;
-#endif
-			/*
-			 * We assume that security xattrs are never
-			 * more than 1k.  In practice they are under
-			 * 128 bytes.
-			 */
-			nblocks += num_security_xattrs *
-				__ext4_xattr_set_credits(sb, NULL /* inode */,
-					NULL /* block_bh */, 1024,
-					true /* is_create */);
-		}
-#endif
-		if (encrypt)
-			nblocks += __ext4_xattr_set_credits(sb,
-					NULL /* inode */, NULL /* block_bh */,
-					FSCRYPT_SET_CONTEXT_MAX_SIZE,
-					true /* is_create */);
+		ret2 = ext4_xattr_credits_for_new_inode(dir, mode, encrypt);
+		if (ret2 < 0)
+			return ERR_PTR(ret2);
+		nblocks += ret2;
 	}
 
 	ngroups = ext4_get_groups_count(sb);

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Eric Biggers

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2020-09-17 04:13 UTC #3 lore raw

PATCH v3 3/13 ext4: use fscrypt_prepare_new_inode() and fscrypt_set_context()

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

Convert ext4 to use the new functions fscrypt_prepare_new_inode() and fscrypt_set_context(). This avoids calling fscrypt_get_encryption_info() from within a transaction, which can deadlock because fscrypt_get_encryption_info() isn't GFP_NOFS-safe.

For more details about this problem, see the earlier patch "fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context()".

Signed-off-by Eric Biggers <[email protected]>

---
 fs/ext4/ialloc.c | 37 +++++++++++++++++--------------------
 1 file changed, 17 insertions(+), 20 deletions(-)

fs/ext4/ialloc.c +17 ~~-20~~

index 0cc576005a923..698ca4a4db5f7 100644
@@ -819,7 +819,7 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 	ext4_group_t i;
 	ext4_group_t flex_group;
 	struct ext4_group_info *grp;
-	int encrypt = 0;
+	bool encrypt = false;
 
 	/* Cannot create files in a deleted directory */
 	if (!dir || !dir->i_nlink)

@@ -831,24 +831,6 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 	if (unlikely(ext4_forced_shutdown(sbi)))
 		return ERR_PTR(-EIO);
 
-	if ((IS_ENCRYPTED(dir) || DUMMY_ENCRYPTION_ENABLED(sbi)) &&
-	    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)) &&
-	    !(i_flags & EXT4_EA_INODE_FL)) {
-		err = fscrypt_get_encryption_info(dir);
-		if (err)
-			return ERR_PTR(err);
-		if (!fscrypt_has_encryption_key(dir))
-			return ERR_PTR(-ENOKEY);
-		encrypt = 1;
-	}
-
-	if (!handle && sbi->s_journal && !(i_flags & EXT4_EA_INODE_FL)) {
-		ret2 = ext4_xattr_credits_for_new_inode(dir, mode, encrypt);
-		if (ret2 < 0)
-			return ERR_PTR(ret2);
-		nblocks += ret2;
-	}
-
 	ngroups = ext4_get_groups_count(sb);
 	trace_ext4_request_inode(dir, mode);
 	inode = new_inode(sb);

@@ -878,10 +860,25 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 	else
 		ei->i_projid = make_kprojid(&init_user_ns, EXT4_DEF_PROJID);
 
+	if (!(i_flags & EXT4_EA_INODE_FL)) {
+		err = fscrypt_prepare_new_inode(dir, inode, &encrypt);
+		if (err)
+			goto out;
+	}
+
 	err = dquot_initialize(inode);
 	if (err)
 		goto out;
 
+	if (!handle && sbi->s_journal && !(i_flags & EXT4_EA_INODE_FL)) {
+		ret2 = ext4_xattr_credits_for_new_inode(dir, mode, encrypt);
+		if (ret2 < 0) {
+			err = ret2;
+			goto out;
+		}
+		nblocks += ret2;
+	}
+
 	if (!goal)
 		goal = sbi->s_inode_goal;

@@ -1174,7 +1171,7 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 	 * prevent its deduplication.
 	 */
 	if (encrypt) {
-		err = fscrypt_inherit_context(dir, inode, handle, true);
+		err = fscrypt_set_context(inode, handle);
 		if (err)
 			goto fail_free_drop;
 	}

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Eric Biggers

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2020-09-17 04:13 UTC #4 lore raw

PATCH v3 4/13 f2fs: use fscrypt_prepare_new_inode() and fscrypt_set_context()

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

Convert f2fs to use the new functions fscrypt_prepare_new_inode() and fscrypt_set_context(). This avoids calling fscrypt_get_encryption_info() from under f2fs_lock_op(), which can deadlock because fscrypt_get_encryption_info() isn't GFP_NOFS-safe.

For more details about this problem, see the earlier patch "fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context()".

This also fixes a f2fs-specific deadlock when the filesystem is mounted with '-o test_dummy_encryption' and a file is created in an unencrypted directory other than the root directory:

    INFO: task touch:207 blocked for more than 30 seconds.
          Not tainted 5.9.0-rc4-00099-g729e3d0919844 #2
    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
    task:touch           state:D stack:    0 pid:  207 ppid:   167 flags:0x00000000
    Call Trace:
     [...]
     lock_page include/linux/pagemap.h:548 [inline]
     pagecache_get_page+0x25e/0x310 mm/filemap.c:1682
     find_or_create_page include/linux/pagemap.h:348 [inline]
     grab_cache_page include/linux/pagemap.h:424 [inline]
     f2fs_grab_cache_page fs/f2fs/f2fs.h:2395 [inline]
     f2fs_grab_cache_page fs/f2fs/f2fs.h:2373 [inline]
     __get_node_page.part.0+0x39/0x2d0 fs/f2fs/node.c:1350
     __get_node_page fs/f2fs/node.c:35 [inline]
     f2fs_get_node_page+0x2e/0x60 fs/f2fs/node.c:1399
     read_inline_xattr+0x88/0x140 fs/f2fs/xattr.c:288
     lookup_all_xattrs+0x1f9/0x2c0 fs/f2fs/xattr.c:344
     f2fs_getxattr+0x9b/0x160 fs/f2fs/xattr.c:532
     f2fs_get_context+0x1e/0x20 fs/f2fs/super.c:2460
     fscrypt_get_encryption_info+0x9b/0x450 fs/crypto/keysetup.c:472
     fscrypt_inherit_context+0x2f/0xb0 fs/crypto/policy.c:640
     f2fs_init_inode_metadata+0xab/0x340 fs/f2fs/dir.c:540
     f2fs_add_inline_entry+0x145/0x390 fs/f2fs/inline.c:621
     f2fs_add_dentry+0x31/0x80 fs/f2fs/dir.c:757
     f2fs_do_add_link+0xcd/0x130 fs/f2fs/dir.c:798
     f2fs_add_link fs/f2fs/f2fs.h:3234 [inline]
     f2fs_create+0x104/0x290 fs/f2fs/namei.c:344
     lookup_open.isra.0+0x2de/0x500 fs/namei.c:3103
     open_last_lookups+0xa9/0x340 fs/namei.c:3177
     path_openat+0x8f/0x1b0 fs/namei.c:3365
     do_filp_open+0x87/0x130 fs/namei.c:3395
     do_sys_openat2+0x96/0x150 fs/open.c:1168
     [...]

That happened because f2fs_add_inline_entry() locks the directory inode's page in order to add the dentry, then f2fs_get_context() tries to lock it recursively in order to read the encryption xattr. This problem is specific to "test_dummy_encryption" because normally the directory's fscrypt_info would be set up prior to f2fs_add_inline_entry() in order to encrypt the new filename.

Regardless, the new design fixes this test_dummy_encryption deadlock as well as potential deadlocks with fs reclaim, by setting up any needed fscrypt_info structs prior to taking so many locks.

The test_dummy_encryption deadlock was reported by Daniel Rosenberg.

Reported-by Daniel Rosenberg <[email protected]>

Acked-by Jaegeuk Kim <[email protected]>

Signed-off-by Eric Biggers <[email protected]>

---
 fs/f2fs/dir.c   |  2 +-
 fs/f2fs/f2fs.h  | 23 -----------------------
 fs/f2fs/namei.c |  7 ++++++-
 3 files changed, 7 insertions(+), 25 deletions(-)

fs/f2fs/dir.c +1 -1

index b2530b9507bd9..414bc94fbd546 100644
@@ -537,7 +537,7 @@ struct page *f2fs_init_inode_metadata(struct inode *inode, struct inode *dir,
 			goto put_error;
 
 		if (IS_ENCRYPTED(inode)) {
-			err = fscrypt_inherit_context(dir, inode, page, false);
+			err = fscrypt_set_context(inode, page);
 			if (err)
 				goto put_error;
 		}

fs/f2fs/f2fs.h +0 ~~-23~~

index d9e52a7f3702f..0503371f88ed4 100644
@@ -1315,13 +1315,6 @@ enum fsync_mode {
 #define IS_IO_TRACED_PAGE(page) (0)
 #endif
 
-#ifdef CONFIG_FS_ENCRYPTION
-#define DUMMY_ENCRYPTION_ENABLED(sbi) \
-	(unlikely(F2FS_OPTION(sbi).dummy_enc_ctx.ctx != NULL))
-#else
-#define DUMMY_ENCRYPTION_ENABLED(sbi) (0)
-#endif
-
 /* For compression */
 enum compress_algorithm_type {
 	COMPRESS_LZO,

@@ -4022,22 +4015,6 @@ static inline bool f2fs_lfs_mode(struct f2fs_sb_info *sbi)
 	return F2FS_OPTION(sbi).fs_mode == FS_MODE_LFS;
 }
 
-static inline bool f2fs_may_encrypt(struct inode *dir, struct inode *inode)
-{
-#ifdef CONFIG_FS_ENCRYPTION
-	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
-	umode_t mode = inode->i_mode;
-
-	/*
-	 * If the directory encrypted or dummy encryption enabled,
-	 * then we should encrypt the inode.
-	 */
-	if (IS_ENCRYPTED(dir) || DUMMY_ENCRYPTION_ENABLED(sbi))
-		return (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode));
-#endif
-	return false;
-}
-
 static inline bool f2fs_may_compress(struct inode *inode)
 {
 	if (IS_SWAPFILE(inode) || f2fs_is_pinned_file(inode) ||

fs/f2fs/namei.c +6 -1

index 84e4bbc1a64de..45f324511a19e 100644
@@ -28,6 +28,7 @@ static struct inode *f2fs_new_inode(struct inode *dir, umode_t mode)
 	nid_t ino;
 	struct inode *inode;
 	bool nid_free = false;
+	bool encrypt = false;
 	int xattr_size = 0;
 	int err;

@@ -69,13 +70,17 @@ static struct inode *f2fs_new_inode(struct inode *dir, umode_t mode)
 		F2FS_I(inode)->i_projid = make_kprojid(&init_user_ns,
 							F2FS_DEF_PROJID);
 
+	err = fscrypt_prepare_new_inode(dir, inode, &encrypt);
+	if (err)
+		goto fail_drop;
+
 	err = dquot_initialize(inode);
 	if (err)
 		goto fail_drop;
 
 	set_inode_flag(inode, FI_NEW_INODE);
 
-	if (f2fs_may_encrypt(dir, inode))
+	if (encrypt)
 		f2fs_set_encrypted_inode(inode);
 
 	if (f2fs_sb_has_extra_attr(sbi)) {

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Eric Biggers

author maintainer

2020-09-17 04:13 UTC #5 lore raw

PATCH v3 5/13 ubifs: use fscrypt_prepare_new_inode() and fscrypt_set_context()

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

Convert ubifs to use the new functions fscrypt_prepare_new_inode() and fscrypt_set_context().

Unlike ext4 and f2fs, this doesn't appear to fix any deadlock bug. But it does shorten the code slightly and get all filesystems using the same helper functions, so that fscrypt_inherit_context() can be removed.

It also fixes an incorrect error code where ubifs returned EPERM instead of the expected ENOKEY.

Signed-off-by Eric Biggers <[email protected]>

---
 fs/ubifs/dir.c | 38 ++++++++++++++++----------------------
 1 file changed, 16 insertions(+), 22 deletions(-)

fs/ubifs/dir.c +16 ~~-22~~

index a9c1f5a9c9bdd..155521e51ac57 100644
@@ -81,19 +81,6 @@ struct inode *ubifs_new_inode(struct ubifs_info *c, struct inode *dir,
 	struct ubifs_inode *ui;
 	bool encrypted = false;
 
-	if (IS_ENCRYPTED(dir)) {
-		err = fscrypt_get_encryption_info(dir);
-		if (err) {
-			ubifs_err(c, "fscrypt_get_encryption_info failed: %i", err);
-			return ERR_PTR(err);
-		}
-
-		if (!fscrypt_has_encryption_key(dir))
-			return ERR_PTR(-EPERM);
-
-		encrypted = true;
-	}
-
 	inode = new_inode(c->vfs_sb);
 	ui = ubifs_inode(inode);
 	if (!inode)

@@ -112,6 +99,12 @@ struct inode *ubifs_new_inode(struct ubifs_info *c, struct inode *dir,
 			 current_time(inode);
 	inode->i_mapping->nrpages = 0;
 
+	err = fscrypt_prepare_new_inode(dir, inode, &encrypted);
+	if (err) {
+		ubifs_err(c, "fscrypt_prepare_new_inode failed: %i", err);
+		goto out_iput;
+	}
+
 	switch (mode & S_IFMT) {
 	case S_IFREG:
 		inode->i_mapping->a_ops = &ubifs_file_address_operations;

@@ -131,7 +124,6 @@ struct inode *ubifs_new_inode(struct ubifs_info *c, struct inode *dir,
 	case S_IFBLK:
 	case S_IFCHR:
 		inode->i_op  = &ubifs_file_inode_operations;
-		encrypted = false;
 		break;
 	default:
 		BUG();

@@ -151,9 +143,8 @@ struct inode *ubifs_new_inode(struct ubifs_info *c, struct inode *dir,
 		if (c->highest_inum >= INUM_WATERMARK) {
 			spin_unlock(&c->cnt_lock);
 			ubifs_err(c, "out of inode numbers");
-			make_bad_inode(inode);
-			iput(inode);
-			return ERR_PTR(-EINVAL);
+			err = -EINVAL;
+			goto out_iput;
 		}
 		ubifs_warn(c, "running out of inode numbers (current %lu, max %u)",
 			   (unsigned long)c->highest_inum, INUM_WATERMARK);

@@ -171,16 +162,19 @@ struct inode *ubifs_new_inode(struct ubifs_info *c, struct inode *dir,
 	spin_unlock(&c->cnt_lock);
 
 	if (encrypted) {
-		err = fscrypt_inherit_context(dir, inode, &encrypted, true);
+		err = fscrypt_set_context(inode, NULL);
 		if (err) {
-			ubifs_err(c, "fscrypt_inherit_context failed: %i", err);
-			make_bad_inode(inode);
-			iput(inode);
-			return ERR_PTR(err);
+			ubifs_err(c, "fscrypt_set_context failed: %i", err);
+			goto out_iput;
 		}
 	}
 
 	return inode;
+
+out_iput:
+	make_bad_inode(inode);
+	iput(inode);
+	return ERR_PTR(err);
 }
 
 static int dbg_check_name(const struct ubifs_info *c,

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Eric Biggers

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2020-09-17 04:13 UTC #6 lore raw

PATCH v3 6/13 fscrypt: adjust logging for in-creation inodes

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

Now that a fscrypt_info may be set up for inodes that are currently being created and haven't yet had an inode number assigned, avoid logging confusing messages about "inode 0".

Signed-off-by Eric Biggers <[email protected]>

---
 fs/crypto/crypto.c  | 4 +++-
 fs/crypto/keyring.c | 9 +++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

fs/crypto/crypto.c +3 -1

index 9212325763b0f..4ef3f714046aa 100644
@@ -343,9 +343,11 @@ void fscrypt_msg(const struct inode *inode, const char *level,
 	va_start(args, fmt);
 	vaf.fmt = fmt;
 	vaf.va = &args;
-	if (inode)
+	if (inode && inode->i_ino)
 		printk("%sfscrypt (%s, inode %lu): %pV\n",
 		       level, inode->i_sb->s_id, inode->i_ino, &vaf);
+	else if (inode)
+		printk("%sfscrypt (%s): %pV\n", level, inode->i_sb->s_id, &vaf);
 	else
 		printk("%sfscrypt: %pV\n", level, &vaf);
 	va_end(args);

fs/crypto/keyring.c +7 -2

index e74f239c44280..53cc552a7b8fd 100644
@@ -817,6 +817,7 @@ static int check_for_busy_inodes(struct super_block *sb,
 	struct list_head *pos;
 	size_t busy_count = 0;
 	unsigned long ino;
+	char ino_str[50] = "";
 
 	spin_lock(&mk->mk_decrypted_inodes_lock);

@@ -838,11 +839,15 @@ static int check_for_busy_inodes(struct super_block *sb,
 	}
 	spin_unlock(&mk->mk_decrypted_inodes_lock);
 
+	/* If the inode is currently being created, ino may still be 0. */
+	if (ino)
+		snprintf(ino_str, sizeof(ino_str), ", including ino %lu", ino);
+
 	fscrypt_warn(NULL,
-		     "%s: %zu inode(s) still busy after removing key with %s %*phN, including ino %lu",
+		     "%s: %zu inode(s) still busy after removing key with %s %*phN%s",
 		     sb->s_id, busy_count, master_key_spec_type(&mk->mk_spec),
 		     master_key_spec_len(&mk->mk_spec), (u8 *)&mk->mk_spec.u,
-		     ino);
+		     ino_str);
 	return -EBUSY;
 }

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Eric Biggers

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2020-09-17 04:13 UTC #7 lore raw

PATCH v3 7/13 fscrypt: remove fscrypt_inherit_context()

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

Now that all filesystems have been converted to use fscrypt_prepare_new_inode() and fscrypt_set_context(), fscrypt_inherit_context() is no longer used. Remove it.

Signed-off-by Eric Biggers <[email protected]>

---
 fs/crypto/policy.c      | 37 -------------------------------------
 include/linux/fscrypt.h |  9 ---------
 2 files changed, 46 deletions(-)

fs/crypto/policy.c +0 ~~-37~~

index 7e96953d385ec..4ff893f7b030a 100644
@@ -628,43 +628,6 @@ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
 }
 EXPORT_SYMBOL(fscrypt_has_permitted_context);
 
-/**
- * fscrypt_inherit_context() - Sets a child context from its parent
- * @parent: Parent inode from which the context is inherited.
- * @child:  Child inode that inherits the context from @parent.
- * @fs_data:  private data given by FS.
- * @preload:  preload child i_crypt_info if true
- *
- * Return: 0 on success, -errno on failure
- */
-int fscrypt_inherit_context(struct inode *parent, struct inode *child,
-						void *fs_data, bool preload)
-{
-	u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
-	union fscrypt_context ctx;
-	int ctxsize;
-	struct fscrypt_info *ci;
-	int res;
-
-	res = fscrypt_get_encryption_info(parent);
-	if (res < 0)
-		return res;
-
-	ci = fscrypt_get_info(parent);
-	if (ci == NULL)
-		return -ENOKEY;
-
-	get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE);
-	ctxsize = fscrypt_new_context(&ctx, &ci->ci_policy, nonce);
-
-	BUILD_BUG_ON(sizeof(ctx) != FSCRYPT_SET_CONTEXT_MAX_SIZE);
-	res = parent->i_sb->s_cop->set_context(child, &ctx, ctxsize, fs_data);
-	if (res)
-		return res;
-	return preload ? fscrypt_get_encryption_info(child): 0;
-}
-EXPORT_SYMBOL(fscrypt_inherit_context);
-
 /**
  * fscrypt_set_context() - Set the fscrypt context of a new inode
  * @inode: a new inode

include/linux/fscrypt.h +0 -9

index 9cf7ca90f3abb..81d6ded243288 100644
@@ -156,8 +156,6 @@ int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg);
 int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *arg);
 int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg);
 int fscrypt_has_permitted_context(struct inode *parent, struct inode *child);
-int fscrypt_inherit_context(struct inode *parent, struct inode *child,
-			    void *fs_data, bool preload);
 int fscrypt_set_context(struct inode *inode, void *fs_data);
 
 struct fscrypt_dummy_context {

@@ -343,13 +341,6 @@ static inline int fscrypt_has_permitted_context(struct inode *parent,
 	return 0;
 }
 
-static inline int fscrypt_inherit_context(struct inode *parent,
-					  struct inode *child,
-					  void *fs_data, bool preload)
-{
-	return -EOPNOTSUPP;
-}
-
 static inline int fscrypt_set_context(struct inode *inode, void *fs_data)
 {
 	return -EOPNOTSUPP;

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Eric Biggers

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2020-09-17 04:13 UTC #8 lore raw

PATCH v3 8/13 fscrypt: require that fscrypt_encrypt_symlink() already has key

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

Now that all filesystems have been converted to use fscrypt_prepare_new_inode(), the encryption key for new symlink inodes is now already set up whenever we try to encrypt the symlink target. Enforce this rather than try to set up the key again when it may be too late to do so safely.

Signed-off-by Eric Biggers <[email protected]>

---
 fs/crypto/hooks.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

fs/crypto/hooks.c +7 -3

index 491b252843eb9..7748db5092409 100644
@@ -217,9 +217,13 @@ int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 	struct fscrypt_symlink_data *sd;
 	unsigned int ciphertext_len;
 
-	err = fscrypt_require_key(inode);
-	if (err)
-		return err;
+	/*
+	 * fscrypt_prepare_new_inode() should have already set up the new
+	 * symlink inode's encryption key.  We don't wait until now to do it,
+	 * since we may be in a filesystem transaction now.
+	 */
+	if (WARN_ON_ONCE(!fscrypt_has_encryption_key(inode)))
+		return -ENOKEY;
 
 	if (disk_link->name) {
 		/* filesystem-provided buffer */

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Eric Biggers

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2020-09-17 04:13 UTC #9 lore raw

PATCH v3 9/13 fscrypt: stop pretending that key setup is nofs-safe

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

fscrypt_get_encryption_info() has never actually been safe to call in a context that needs GFP_NOFS, since it calls crypto_alloc_skcipher().

crypto_alloc_skcipher() isn't GFP_NOFS-safe, even if called under memalloc_nofs_save(). This is because it may load kernel modules, and also because it internally takes crypto_alg_sem. Other tasks can do GFP_KERNEL allocations while holding crypto_alg_sem for write.

The use of fscrypt_init_mutex isn't GFP_NOFS-safe either.

So, stop pretending that fscrypt_get_encryption_info() is nofs-safe. I.e., when it allocates memory, just use GFP_KERNEL instead of GFP_NOFS.

Note, another reason to do this is that GFP_NOFS is deprecated in favor of using memalloc_nofs_save() in the proper places.

Signed-off-by Eric Biggers <[email protected]>

---
 fs/crypto/inline_crypt.c | 7 ++-----
 fs/crypto/keysetup.c     | 2 +-
 fs/crypto/keysetup_v1.c  | 8 ++++----
 3 files changed, 7 insertions(+), 10 deletions(-)

fs/crypto/inline_crypt.c +2 -5

index faa25541ccb68..89bffa82ed74a 100644
@@ -106,7 +106,7 @@ int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
 	crypto_cfg.data_unit_size = sb->s_blocksize;
 	crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci);
 	num_devs = fscrypt_get_num_devices(sb);
-	devs = kmalloc_array(num_devs, sizeof(*devs), GFP_NOFS);
+	devs = kmalloc_array(num_devs, sizeof(*devs), GFP_KERNEL);
 	if (!devs)
 		return -ENOMEM;
 	fscrypt_get_devices(sb, num_devs, devs);

@@ -135,9 +135,8 @@ int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
 	struct fscrypt_blk_crypto_key *blk_key;
 	int err;
 	int i;
-	unsigned int flags;
 
-	blk_key = kzalloc(struct_size(blk_key, devs, num_devs), GFP_NOFS);
+	blk_key = kzalloc(struct_size(blk_key, devs, num_devs), GFP_KERNEL);
 	if (!blk_key)
 		return -ENOMEM;

@@ -166,10 +165,8 @@ int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
 		}
 		queue_refs++;
 
-		flags = memalloc_nofs_save();
 		err = blk_crypto_start_using_key(&blk_key->base,
 						 blk_key->devs[i]);
-		memalloc_nofs_restore(flags);
 		if (err) {
 			fscrypt_err(inode,
 				    "error %d starting to use blk-crypto", err);

fs/crypto/keysetup.c +1 -1

index 6159168972146..47f19061ba10e 100644
@@ -488,7 +488,7 @@ fscrypt_setup_encryption_info(struct inode *inode,
 	if (res)
 		return res;
 
-	crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_NOFS);
+	crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_KERNEL);
 	if (!crypt_info)
 		return -ENOMEM;

fs/crypto/keysetup_v1.c +4 -4

index a3cb52572b05c..2762c53504323 100644
@@ -60,7 +60,7 @@ static int derive_key_aes(const u8 *master_key,
 		goto out;
 	}
 	crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
-	req = skcipher_request_alloc(tfm, GFP_NOFS);
+	req = skcipher_request_alloc(tfm, GFP_KERNEL);
 	if (!req) {
 		res = -ENOMEM;
 		goto out;

@@ -99,7 +99,7 @@ find_and_lock_process_key(const char *prefix,
 	const struct user_key_payload *ukp;
 	const struct fscrypt_key *payload;
 
-	description = kasprintf(GFP_NOFS, "%s%*phN", prefix,
+	description = kasprintf(GFP_KERNEL, "%s%*phN", prefix,
 				FSCRYPT_KEY_DESCRIPTOR_SIZE, descriptor);
 	if (!description)
 		return ERR_PTR(-ENOMEM);

@@ -228,7 +228,7 @@ fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key)
 		return dk;
 
 	/* Nope, allocate one. */
-	dk = kzalloc(sizeof(*dk), GFP_NOFS);
+	dk = kzalloc(sizeof(*dk), GFP_KERNEL);
 	if (!dk)
 		return ERR_PTR(-ENOMEM);
 	refcount_set(&dk->dk_refcount, 1);

@@ -272,7 +272,7 @@ static int setup_v1_file_key_derived(struct fscrypt_info *ci,
 	 * This cannot be a stack buffer because it will be passed to the
 	 * scatterlist crypto API during derive_key_aes().
 	 */
-	derived_key = kmalloc(ci->ci_mode->keysize, GFP_NOFS);
+	derived_key = kmalloc(ci->ci_mode->keysize, GFP_KERNEL);
 	if (!derived_key)
 		return -ENOMEM;

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Eric Biggers

author maintainer

2020-09-17 04:13 UTC #10 lore raw

PATCH v3 10/13 fscrypt: make "#define fscrypt_policy" user-only

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

The fscrypt UAPI header defines fscrypt_policy to fscrypt_policy_v1, for source compatibility with old userspace programs.

Internally, the kernel doesn't want that compatibility definition. Instead, fscrypt_private.h #undefs it and re-defines it to a union.

That works for now. However, in order to add fscrypt_operations::get_dummy_policy(), we'll need to forward declare 'union fscrypt_policy' in include/linux/fscrypt.h. That would cause build errors because "fscrypt_policy" is used in ioctl numbers.

To avoid this, modify the UAPI header to make the fscrypt_policy compatibility definition conditional on !__KERNEL__, and make the ioctls use fscrypt_policy_v1 instead of fscrypt_policy.

Note that this doesn't change the actual ioctl numbers.

Signed-off-by Eric Biggers <[email protected]>

---
 fs/crypto/fscrypt_private.h  | 1 -
 include/uapi/linux/fscrypt.h | 6 +++---
 2 files changed, 3 insertions(+), 4 deletions(-)

fs/crypto/fscrypt_private.h +0 -1

index 355f6d9377517..ac3352086ee44 100644
@@ -97,7 +97,6 @@ static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx)
 	return NULL;
 }
 
-#undef fscrypt_policy
 union fscrypt_policy {
 	u8 version;
 	struct fscrypt_policy_v1 v1;

include/uapi/linux/fscrypt.h +3 -3

index 7875709ccfebf..e5de603369381 100644
@@ -45,7 +45,6 @@ struct fscrypt_policy_v1 {
 	__u8 flags;
 	__u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
 };
-#define fscrypt_policy	fscrypt_policy_v1
 
 /*
  * Process-subscribed "logon" key description prefix and payload format.

@@ -156,9 +155,9 @@ struct fscrypt_get_key_status_arg {
 	__u32 __out_reserved[13];
 };
 
-#define FS_IOC_SET_ENCRYPTION_POLICY		_IOR('f', 19, struct fscrypt_policy)
+#define FS_IOC_SET_ENCRYPTION_POLICY		_IOR('f', 19, struct fscrypt_policy_v1)
 #define FS_IOC_GET_ENCRYPTION_PWSALT		_IOW('f', 20, __u8[16])
-#define FS_IOC_GET_ENCRYPTION_POLICY		_IOW('f', 21, struct fscrypt_policy)
+#define FS_IOC_GET_ENCRYPTION_POLICY		_IOW('f', 21, struct fscrypt_policy_v1)
 #define FS_IOC_GET_ENCRYPTION_POLICY_EX		_IOWR('f', 22, __u8[9]) /* size + version */
 #define FS_IOC_ADD_ENCRYPTION_KEY		_IOWR('f', 23, struct fscrypt_add_key_arg)
 #define FS_IOC_REMOVE_ENCRYPTION_KEY		_IOWR('f', 24, struct fscrypt_remove_key_arg)

@@ -170,6 +169,7 @@ struct fscrypt_get_key_status_arg {
 
 /* old names; don't add anything new here! */
 #ifndef __KERNEL__
+#define fscrypt_policy			fscrypt_policy_v1
 #define FS_KEY_DESCRIPTOR_SIZE		FSCRYPT_KEY_DESCRIPTOR_SIZE
 #define FS_POLICY_FLAGS_PAD_4		FSCRYPT_POLICY_FLAGS_PAD_4
 #define FS_POLICY_FLAGS_PAD_8		FSCRYPT_POLICY_FLAGS_PAD_8

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Eric Biggers

author maintainer

2020-09-17 04:13 UTC #11 lore raw

PATCH v3 11/13 fscrypt: move fscrypt_prepare_symlink() out-of-line

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

In preparation for moving the logic for "get the encryption policy inherited by new files in this directory" to a single place, make fscrypt_prepare_symlink() a regular function rather than an inline function that wraps __fscrypt_prepare_symlink().

This way, the new function fscrypt_policy_to_inherit() won't need to be exported to filesystems.

Signed-off-by Eric Biggers <[email protected]>

---
 fs/crypto/hooks.c       | 39 ++++++++++++++++++++++---
 include/linux/fscrypt.h | 63 ++++++++++-------------------------------
 2 files changed, 50 insertions(+), 52 deletions(-)

fs/crypto/hooks.c +35 -4

index 7748db5092409..a399c54947f28 100644
@@ -166,12 +166,43 @@ int fscrypt_prepare_setflags(struct inode *inode,
 	return 0;
 }
 
-int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
-			      unsigned int max_len,
-			      struct fscrypt_str *disk_link)
+/**
+ * fscrypt_prepare_symlink() - prepare to create a possibly-encrypted symlink
+ * @dir: directory in which the symlink is being created
+ * @target: plaintext symlink target
+ * @len: length of @target excluding null terminator
+ * @max_len: space the filesystem has available to store the symlink target
+ * @disk_link: (out) the on-disk symlink target being prepared
+ *
+ * This function computes the size the symlink target will require on-disk,
+ * stores it in @disk_link->len, and validates it against @max_len.  An
+ * encrypted symlink may be longer than the original.
+ *
+ * Additionally, @disk_link->name is set to @target if the symlink will be
+ * unencrypted, but left NULL if the symlink will be encrypted.  For encrypted
+ * symlinks, the filesystem must call fscrypt_encrypt_symlink() to create the
+ * on-disk target later.  (The reason for the two-step process is that some
+ * filesystems need to know the size of the symlink target before creating the
+ * inode, e.g. to determine whether it will be a "fast" or "slow" symlink.)
+ *
+ * Return: 0 on success, -ENAMETOOLONG if the symlink target is too long,
+ * -ENOKEY if the encryption key is missing, or another -errno code if a problem
+ * occurred while setting up the encryption key.
+ */
+int fscrypt_prepare_symlink(struct inode *dir, const char *target,
+			    unsigned int len, unsigned int max_len,
+			    struct fscrypt_str *disk_link)
 {
 	int err;
 
+	if (!IS_ENCRYPTED(dir) && !fscrypt_get_dummy_context(dir->i_sb)) {
+		disk_link->name = (unsigned char *)target;
+		disk_link->len = len + 1;
+		if (disk_link->len > max_len)
+			return -ENAMETOOLONG;
+		return 0;
+	}
+
 	/*
 	 * To calculate the size of the encrypted symlink target we need to know
 	 * the amount of NUL padding, which is determined by the flags set in

@@ -207,7 +238,7 @@ int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
 	disk_link->name = NULL;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(__fscrypt_prepare_symlink);
+EXPORT_SYMBOL_GPL(fscrypt_prepare_symlink);
 
 int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
 			      unsigned int len, struct fscrypt_str *disk_link)

include/linux/fscrypt.h +15 ~~-48~~

84 lines not on this page · raw message

Signature · 8 lines

2.28.0



_______________________________________________
Linux-f2fs-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Eric Biggers

author maintainer

2020-09-17 04:13 UTC #12 lore raw

PATCH v3 12/13 fscrypt: handle test_dummy_encryption in more logical way

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

The behavior of the test_dummy_encryption mount option is that when a new file (or directory or symlink) is created in an unencrypted directory, it's automatically encrypted using a dummy encryption policy. That's it; in particular, the encryption (or lack thereof) of existing files (or directories or symlinks) doesn't change.

Unfortunately the implementation of test_dummy_encryption is a bit weird and confusing. When test_dummy_encryption is enabled and a file is being created in an unencrypted directory, we set up an encryption key (->i_crypt_info) for the directory. This isn't actually used to do any encryption, however, since the directory is still unencrypted! Instead, ->i_crypt_info is only used for inheriting the encryption policy.

One consequence of this is that the filesystem ends up providing a "dummy context" (policy + nonce) instead of a "dummy policy". In commit ed318a6cc0b6 ("fscrypt: support test_dummy_encryption=v2"), I mistakenly thought this was required. However, actually the nonce only ends up being used to derive a key that is never used.

Another consequence of this implementation is that it allows for 'inode->i_crypt_info != NULL && !IS_ENCRYPTED(inode)', which is an edge case that can be forgotten about. For example, currently FS_IOC_GET_ENCRYPTION_POLICY on an unencrypted directory may return the dummy encryption policy when the filesystem is mounted with test_dummy_encryption. That seems like the wrong thing to do, since again, the directory itself is not actually encrypted.

Therefore, switch to a more logical and maintainable implementation where the dummy encryption policy inheritance is done without setting up keys for unencrypted directories. This involves:

- Adding a function fscrypt_policy_to_inherit() which returns the encryption policy to inherit from a directory. This can be a real policy, a dummy policy, or no policy.

- Replacing struct fscrypt_dummy_context, ->get_dummy_context(), etc. with struct fscrypt_dummy_policy, ->get_dummy_policy(), etc.

- Making fscrypt_fname_encrypted_size() take an fscrypt_policy instead of an inode.

Acked-by Jaegeuk Kim <[email protected]>

Signed-off-by Eric Biggers <[email protected]>

---
 fs/crypto/fname.c           |  11 ++--
 fs/crypto/fscrypt_private.h |   6 +-
 fs/crypto/hooks.c           |  30 ++++------
 fs/crypto/keysetup.c        |  33 +++--------
 fs/crypto/policy.c          | 113 ++++++++++++++++++++++--------------
 fs/ext4/ext4.h              |   6 +-
 fs/ext4/super.c             |  17 +++---
 fs/f2fs/f2fs.h              |   2 +-
 fs/f2fs/super.c             |  16 ++---
 include/linux/fscrypt.h     |  40 +++++--------
 10 files changed, 134 insertions(+), 140 deletions(-)

fs/crypto/fname.c +6 -5

index 47bcfddb278ba..eb13408b50a70 100644
@@ -242,11 +242,11 @@ static int base64_decode(const char *src, int len, u8 *dst)
 	return cp - dst;
 }
 
-bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
-				  u32 max_len, u32 *encrypted_len_ret)
+bool fscrypt_fname_encrypted_size(const union fscrypt_policy *policy,
+				  u32 orig_len, u32 max_len,
+				  u32 *encrypted_len_ret)
 {
-	const struct fscrypt_info *ci = inode->i_crypt_info;
-	int padding = 4 << (fscrypt_policy_flags(&ci->ci_policy) &
+	int padding = 4 << (fscrypt_policy_flags(policy) &
 			    FSCRYPT_POLICY_FLAGS_PAD_MASK);
 	u32 encrypted_len;

@@ -418,7 +418,8 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
 		return ret;
 
 	if (fscrypt_has_encryption_key(dir)) {
-		if (!fscrypt_fname_encrypted_size(dir, iname->len,
+		if (!fscrypt_fname_encrypted_size(&dir->i_crypt_info->ci_policy,
+						  iname->len,
 						  dir->i_sb->s_cop->max_namelen,
 						  &fname->crypto_buf.len))
 			return -ENAMETOOLONG;

fs/crypto/fscrypt_private.h +4 -2

index ac3352086ee44..4f5806a3b73d7 100644
@@ -291,8 +291,9 @@ void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
 /* fname.c */
 int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
 			  u8 *out, unsigned int olen);
-bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
-				  u32 max_len, u32 *encrypted_len_ret);
+bool fscrypt_fname_encrypted_size(const union fscrypt_policy *policy,
+				  u32 orig_len, u32 max_len,
+				  u32 *encrypted_len_ret);
 extern const struct dentry_operations fscrypt_d_ops;
 
 /* hkdf.c */

@@ -592,5 +593,6 @@ bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
 int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
 				const union fscrypt_context *ctx_u,
 				int ctx_size);
+const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir);
 
 #endif /* _FSCRYPT_PRIVATE_H */

fs/crypto/hooks.c +12 ~~-18~~

index a399c54947f28..42f5ee9f592d1 100644
@@ -193,30 +193,24 @@ int fscrypt_prepare_symlink(struct inode *dir, const char *target,
 			    unsigned int len, unsigned int max_len,
 			    struct fscrypt_str *disk_link)
 {
-	int err;
+	const union fscrypt_policy *policy;
 
-	if (!IS_ENCRYPTED(dir) && !fscrypt_get_dummy_context(dir->i_sb)) {
+	/*
+	 * To calculate the size of the encrypted symlink target we need to know
+	 * the amount of NUL padding, which is determined by the flags set in
+	 * the encryption policy which will be inherited from the directory.
+	 */
+	policy = fscrypt_policy_to_inherit(dir);
+	if (policy == NULL) {
+		/* Not encrypted */
 		disk_link->name = (unsigned char *)target;
 		disk_link->len = len + 1;
 		if (disk_link->len > max_len)
 			return -ENAMETOOLONG;
 		return 0;
 	}
-
-	/*
-	 * To calculate the size of the encrypted symlink target we need to know
-	 * the amount of NUL padding, which is determined by the flags set in
-	 * the encryption policy which will be inherited from the directory.
-	 * The easiest way to get access to this is to just load the directory's
-	 * fscrypt_info, since we'll need it to create the dir_entry anyway.
-	 *
-	 * Note: in test_dummy_encryption mode, @dir may be unencrypted.
-	 */
-	err = fscrypt_get_encryption_info(dir);
-	if (err)
-		return err;
-	if (!fscrypt_has_encryption_key(dir))
-		return -ENOKEY;
+	if (IS_ERR(policy))
+		return PTR_ERR(policy);
 
 	/*
 	 * Calculate the size of the encrypted symlink and verify it won't

@@ -229,7 +223,7 @@ int fscrypt_prepare_symlink(struct inode *dir, const char *target,
 	 * counting it (even though it is meaningless for ciphertext) is simpler
 	 * for now since filesystems will assume it is there and subtract it.
 	 */
-	if (!fscrypt_fname_encrypted_size(dir, len,
+	if (!fscrypt_fname_encrypted_size(policy, len,
 					  max_len - sizeof(struct fscrypt_symlink_data),
 					  &disk_link->len))
 		return -ENAMETOOLONG;

fs/crypto/keysetup.c +9 ~~-24~~

index 47f19061ba10e..d3c3e5d9b41f7 100644
@@ -547,7 +547,7 @@ fscrypt_setup_encryption_info(struct inode *inode,
 
 /**
  * fscrypt_get_encryption_info() - set up an inode's encryption key
- * @inode: the inode to set up the key for
+ * @inode: the inode to set up the key for.  Must be encrypted.
  *
  * Set up ->i_crypt_info, if it hasn't already been done.
  *

@@ -569,18 +569,8 @@ int fscrypt_get_encryption_info(struct inode *inode)
 
 	res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
 	if (res < 0) {
-		const union fscrypt_context *dummy_ctx =
-			fscrypt_get_dummy_context(inode->i_sb);
-
-		if (IS_ENCRYPTED(inode) || !dummy_ctx) {
-			fscrypt_warn(inode,
-				     "Error %d getting encryption context",
-				     res);
-			return res;
-		}
-		/* Fake up a context for an unencrypted directory */
-		res = fscrypt_context_size(dummy_ctx);
-		memcpy(&ctx, dummy_ctx, res);
+		fscrypt_warn(inode, "Error %d getting encryption context", res);
+		return res;
 	}
 
 	res = fscrypt_policy_from_context(&policy, &ctx, res);

@@ -627,17 +617,14 @@ EXPORT_SYMBOL(fscrypt_get_encryption_info);
 int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
 			      bool *encrypt_ret)
 {
-	int err;
+	const union fscrypt_policy *policy;
 	u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
 
-	if (!IS_ENCRYPTED(dir) && fscrypt_get_dummy_context(dir->i_sb) == NULL)
+	policy = fscrypt_policy_to_inherit(dir);
+	if (policy == NULL)
 		return 0;
-
-	err = fscrypt_get_encryption_info(dir);
-	if (err)
-		return err;
-	if (!fscrypt_has_encryption_key(dir))
-		return -ENOKEY;
+	if (IS_ERR(policy))
+		return PTR_ERR(policy);
 
 	if (WARN_ON_ONCE(inode->i_mode == 0))
 		return -EINVAL;

@@ -654,9 +641,7 @@ int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
 	*encrypt_ret = true;
 
 	get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE);
-	return fscrypt_setup_encryption_info(inode,
-					     &dir->i_crypt_info->ci_policy,
-					     nonce,
+	return fscrypt_setup_encryption_info(inode, policy, nonce,
 					     IS_CASEFOLDED(dir) &&
 					     S_ISDIR(inode->i_mode));
 }

fs/crypto/policy.c +69 ~~-44~~

184 lines not on this page · raw message

fs/ext4/ext4.h +3 -3

index 523e00d7b3924..f9a692c0a66c3 100644
@@ -1401,7 +1401,7 @@ struct ext4_super_block {
 #define EXT4_MF_FS_ABORTED		0x0002	/* Fatal error detected */
 
 #ifdef CONFIG_FS_ENCRYPTION
-#define DUMMY_ENCRYPTION_ENABLED(sbi) ((sbi)->s_dummy_enc_ctx.ctx != NULL)
+#define DUMMY_ENCRYPTION_ENABLED(sbi) ((sbi)->s_dummy_enc_policy.policy != NULL)
 #else
 #define DUMMY_ENCRYPTION_ENABLED(sbi) (0)
 #endif

@@ -1596,8 +1596,8 @@ struct ext4_sb_info {
 	atomic_t s_warning_count;
 	atomic_t s_msg_count;
 
-	/* Encryption context for '-o test_dummy_encryption' */
-	struct fscrypt_dummy_context s_dummy_enc_ctx;
+	/* Encryption policy for '-o test_dummy_encryption' */
+	struct fscrypt_dummy_policy s_dummy_enc_policy;
 
 	/*
 	 * Barrier between writepages ops and changing any inode's JOURNAL_DATA

fs/ext4/super.c +9 -8

index ea425b49b3456..7e77722406e2f 100644
@@ -1104,7 +1104,7 @@ static void ext4_put_super(struct super_block *sb)
 		crypto_free_shash(sbi->s_chksum_driver);
 	kfree(sbi->s_blockgroup_lock);
 	fs_put_dax(sbi->s_daxdev);
-	fscrypt_free_dummy_context(&sbi->s_dummy_enc_ctx);
+	fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy);
 #ifdef CONFIG_UNICODE
 	utf8_unload(sbi->s_encoding);
 #endif

@@ -1392,10 +1392,10 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
 	return res;
 }
 
-static const union fscrypt_context *
-ext4_get_dummy_context(struct super_block *sb)
+static const union fscrypt_policy *
+ext4_get_dummy_policy(struct super_block *sb)
 {
-	return EXT4_SB(sb)->s_dummy_enc_ctx.ctx;
+	return EXT4_SB(sb)->s_dummy_enc_policy.policy;
 }
 
 static bool ext4_has_stable_inodes(struct super_block *sb)

@@ -1414,7 +1414,7 @@ static const struct fscrypt_operations ext4_cryptops = {
 	.key_prefix		= "ext4:",
 	.get_context		= ext4_get_context,
 	.set_context		= ext4_set_context,
-	.get_dummy_context	= ext4_get_dummy_context,
+	.get_dummy_policy	= ext4_get_dummy_policy,
 	.empty_dir		= ext4_empty_dir,
 	.max_namelen		= EXT4_NAME_LEN,
 	.has_stable_inodes	= ext4_has_stable_inodes,

@@ -1888,12 +1888,13 @@ static int ext4_set_test_dummy_encryption(struct super_block *sb,
 	 * needed to allow it to be set or changed during remount.  We do allow
 	 * it to be specified during remount, but only if there is no change.
 	 */
-	if (is_remount && !sbi->s_dummy_enc_ctx.ctx) {
+	if (is_remount && !sbi->s_dummy_enc_policy.policy) {
 		ext4_msg(sb, KERN_WARNING,
 			 "Can't set test_dummy_encryption on remount");
 		return -1;
 	}
-	err = fscrypt_set_test_dummy_encryption(sb, arg, &sbi->s_dummy_enc_ctx);
+	err = fscrypt_set_test_dummy_encryption(sb, arg,
+						&sbi->s_dummy_enc_policy);
 	if (err) {
 		if (err == -EEXIST)
 			ext4_msg(sb, KERN_WARNING,

@@ -4935,7 +4936,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	for (i = 0; i < EXT4_MAXQUOTAS; i++)
 		kfree(get_qf_name(sb, sbi, i));
 #endif
-	fscrypt_free_dummy_context(&sbi->s_dummy_enc_ctx);
+	fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy);
 	ext4_blkdev_remove(sbi);
 	brelse(bh);
 out_fail:

fs/f2fs/f2fs.h +1 -1

index 0503371f88ed4..7c089ff7ff943 100644
@@ -138,7 +138,7 @@ struct f2fs_mount_info {
 	int fsync_mode;			/* fsync policy */
 	int fs_mode;			/* fs mode: LFS or ADAPTIVE */
 	int bggc_mode;			/* bggc mode: off, on or sync */
-	struct fscrypt_dummy_context dummy_enc_ctx; /* test dummy encryption */
+	struct fscrypt_dummy_policy dummy_enc_policy; /* test dummy encryption */
 	block_t unusable_cap_perc;	/* percentage for cap */
 	block_t unusable_cap;		/* Amount of space allowed to be
 					 * unusable when disabling checkpoint

fs/f2fs/super.c +8 -8

index dfa072fa80815..f2b3d1a279fb7 100644
@@ -433,12 +433,12 @@ static int f2fs_set_test_dummy_encryption(struct super_block *sb,
 	 * needed to allow it to be set or changed during remount.  We do allow
 	 * it to be specified during remount, but only if there is no change.
 	 */
-	if (is_remount && !F2FS_OPTION(sbi).dummy_enc_ctx.ctx) {
+	if (is_remount && !F2FS_OPTION(sbi).dummy_enc_policy.policy) {
 		f2fs_warn(sbi, "Can't set test_dummy_encryption on remount");
 		return -EINVAL;
 	}
 	err = fscrypt_set_test_dummy_encryption(
-		sb, arg, &F2FS_OPTION(sbi).dummy_enc_ctx);
+		sb, arg, &F2FS_OPTION(sbi).dummy_enc_policy);
 	if (err) {
 		if (err == -EEXIST)
 			f2fs_warn(sbi,

@@ -1275,7 +1275,7 @@ static void f2fs_put_super(struct super_block *sb)
 	for (i = 0; i < MAXQUOTAS; i++)
 		kfree(F2FS_OPTION(sbi).s_qf_names[i]);
 #endif
-	fscrypt_free_dummy_context(&F2FS_OPTION(sbi).dummy_enc_ctx);
+	fscrypt_free_dummy_policy(&F2FS_OPTION(sbi).dummy_enc_policy);
 	destroy_percpu_info(sbi);
 	for (i = 0; i < NR_PAGE_TYPE; i++)
 		kvfree(sbi->write_io[i]);

@@ -2482,10 +2482,10 @@ static int f2fs_set_context(struct inode *inode, const void *ctx, size_t len,
 				ctx, len, fs_data, XATTR_CREATE);
 }
 
-static const union fscrypt_context *
-f2fs_get_dummy_context(struct super_block *sb)
+static const union fscrypt_policy *
+f2fs_get_dummy_policy(struct super_block *sb)
 {
-	return F2FS_OPTION(F2FS_SB(sb)).dummy_enc_ctx.ctx;
+	return F2FS_OPTION(F2FS_SB(sb)).dummy_enc_policy.policy;
 }
 
 static bool f2fs_has_stable_inodes(struct super_block *sb)

@@ -2523,7 +2523,7 @@ static const struct fscrypt_operations f2fs_cryptops = {
 	.key_prefix		= "f2fs:",
 	.get_context		= f2fs_get_context,
 	.set_context		= f2fs_set_context,
-	.get_dummy_context	= f2fs_get_dummy_context,
+	.get_dummy_policy	= f2fs_get_dummy_policy,
 	.empty_dir		= f2fs_empty_dir,
 	.max_namelen		= F2FS_NAME_LEN,
 	.has_stable_inodes	= f2fs_has_stable_inodes,

@@ -3864,7 +3864,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 	for (i = 0; i < MAXQUOTAS; i++)
 		kfree(F2FS_OPTION(sbi).s_qf_names[i]);
 #endif
-	fscrypt_free_dummy_context(&F2FS_OPTION(sbi).dummy_enc_ctx);
+	fscrypt_free_dummy_policy(&F2FS_OPTION(sbi).dummy_enc_policy);
 	kvfree(options);
 free_sb_buf:
 	kfree(raw_super);

include/linux/fscrypt.h +13 ~~-27~~

index 39e7397a3f103..b3b0c5675c6b1 100644
@@ -21,7 +21,7 @@
 
 #define FS_CRYPTO_BLOCK_SIZE		16
 
-union fscrypt_context;
+union fscrypt_policy;
 struct fscrypt_info;
 struct seq_file;

@@ -62,8 +62,7 @@ struct fscrypt_operations {
 	int (*get_context)(struct inode *inode, void *ctx, size_t len);
 	int (*set_context)(struct inode *inode, const void *ctx, size_t len,
 			   void *fs_data);
-	const union fscrypt_context *(*get_dummy_context)(
-		struct super_block *sb);
+	const union fscrypt_policy *(*get_dummy_policy)(struct super_block *sb);
 	bool (*empty_dir)(struct inode *inode);
 	unsigned int max_namelen;
 	bool (*has_stable_inodes)(struct super_block *sb);

@@ -101,14 +100,6 @@ static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
 	return IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
 }
 
-static inline const union fscrypt_context *
-fscrypt_get_dummy_context(struct super_block *sb)
-{
-	if (!sb->s_cop->get_dummy_context)
-		return NULL;
-	return sb->s_cop->get_dummy_context(sb);
-}
-
 /*
  * When d_splice_alias() moves a directory's encrypted alias to its decrypted
  * alias as a result of the encryption key being added, DCACHE_ENCRYPTED_NAME

@@ -158,20 +149,21 @@ int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg);
 int fscrypt_has_permitted_context(struct inode *parent, struct inode *child);
 int fscrypt_set_context(struct inode *inode, void *fs_data);
 
-struct fscrypt_dummy_context {
-	const union fscrypt_context *ctx;
+struct fscrypt_dummy_policy {
+	const union fscrypt_policy *policy;
 };
 
-int fscrypt_set_test_dummy_encryption(struct super_block *sb,
-				      const substring_t *arg,
-				      struct fscrypt_dummy_context *dummy_ctx);
+int fscrypt_set_test_dummy_encryption(
+				struct super_block *sb,
+				const substring_t *arg,
+				struct fscrypt_dummy_policy *dummy_policy);
 void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
 					struct super_block *sb);
 static inline void
-fscrypt_free_dummy_context(struct fscrypt_dummy_context *dummy_ctx)
+fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
 {
-	kfree(dummy_ctx->ctx);
-	dummy_ctx->ctx = NULL;
+	kfree(dummy_policy->policy);
+	dummy_policy->policy = NULL;
 }
 
 /* keyring.c */

@@ -250,12 +242,6 @@ static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
 	return false;
 }
 
-static inline const union fscrypt_context *
-fscrypt_get_dummy_context(struct super_block *sb)
-{
-	return NULL;
-}
-
 static inline void fscrypt_handle_d_move(struct dentry *dentry)
 {
 }

@@ -346,7 +332,7 @@ static inline int fscrypt_set_context(struct inode *inode, void *fs_data)
 	return -EOPNOTSUPP;
 }
 
-struct fscrypt_dummy_context {
+struct fscrypt_dummy_policy {
 };
 
 static inline void fscrypt_show_test_dummy_encryption(struct seq_file *seq,

@@ -356,7 +342,7 @@ static inline void fscrypt_show_test_dummy_encryption(struct seq_file *seq,
 }
 
 static inline void
-fscrypt_free_dummy_context(struct fscrypt_dummy_context *dummy_ctx)
+fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
 {
 }

Signature · 8 lines

2.28.0



_______________________________________________
Linux-f2fs-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Eric Biggers

author maintainer

2020-09-17 04:13 UTC #13 lore raw

PATCH v3 13/13 fscrypt: make fscrypt_set_test_dummy_encryption() take a 'const char *'

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

fscrypt_set_test_dummy_encryption() requires that the optional argument to the test_dummy_encryption mount option be specified as a substring_t. That doesn't work well with filesystems that use the new mount API, since the new way of parsing mount options doesn't use substring_t.

Make it take the argument as a 'const char *' instead.

Instead of moving the match_strdup() into the callers in ext4 and f2fs, make them just use arg->from directly. Since the pattern is "test_dummy_encryption=%s", the argument will be null-terminated.

Signed-off-by Eric Biggers <[email protected]>

---
 fs/crypto/policy.c      | 20 ++++++--------------
 fs/ext4/super.c         |  2 +-
 fs/f2fs/super.c         |  2 +-
 include/linux/fscrypt.h |  5 +----
 4 files changed, 9 insertions(+), 20 deletions(-)

fs/crypto/policy.c +6 ~~-14~~

index 97cf07543651f..4441d9944b9ef 100644
@@ -697,8 +697,7 @@ EXPORT_SYMBOL_GPL(fscrypt_set_context);
 /**
  * fscrypt_set_test_dummy_encryption() - handle '-o test_dummy_encryption'
  * @sb: the filesystem on which test_dummy_encryption is being specified
- * @arg: the argument to the test_dummy_encryption option.
- *	 If no argument was specified, then @arg->from == NULL.
+ * @arg: the argument to the test_dummy_encryption option.  May be NULL.
  * @dummy_policy: the filesystem's current dummy policy (input/output, see
  *		  below)
  *

@@ -712,29 +711,23 @@ EXPORT_SYMBOL_GPL(fscrypt_set_context);
  *         -EEXIST if a different dummy policy is already set;
  *         or another -errno value.
  */
-int fscrypt_set_test_dummy_encryption(struct super_block *sb,
-				      const substring_t *arg,
+int fscrypt_set_test_dummy_encryption(struct super_block *sb, const char *arg,
 				      struct fscrypt_dummy_policy *dummy_policy)
 {
-	const char *argstr = "v2";
-	const char *argstr_to_free = NULL;
 	struct fscrypt_key_specifier key_spec = { 0 };
 	int version;
 	union fscrypt_policy *policy = NULL;
 	int err;
 
-	if (arg->from) {
-		argstr = argstr_to_free = match_strdup(arg);
-		if (!argstr)
-			return -ENOMEM;
-	}
+	if (!arg)
+		arg = "v2";
 
-	if (!strcmp(argstr, "v1")) {
+	if (!strcmp(arg, "v1")) {
 		version = FSCRYPT_POLICY_V1;
 		key_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
 		memset(key_spec.u.descriptor, 0x42,
 		       FSCRYPT_KEY_DESCRIPTOR_SIZE);
-	} else if (!strcmp(argstr, "v2")) {
+	} else if (!strcmp(arg, "v2")) {
 		version = FSCRYPT_POLICY_V2;
 		key_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER;
 		/* key_spec.u.identifier gets filled in when adding the key */

@@ -785,7 +778,6 @@ int fscrypt_set_test_dummy_encryption(struct super_block *sb,
 	err = 0;
 out:
 	kfree(policy);
-	kfree(argstr_to_free);
 	return err;
 }
 EXPORT_SYMBOL_GPL(fscrypt_set_test_dummy_encryption);

fs/ext4/super.c +1 -1

index 7e77722406e2f..ed5624285a475 100644
@@ -1893,7 +1893,7 @@ static int ext4_set_test_dummy_encryption(struct super_block *sb,
 			 "Can't set test_dummy_encryption on remount");
 		return -1;
 	}
-	err = fscrypt_set_test_dummy_encryption(sb, arg,
+	err = fscrypt_set_test_dummy_encryption(sb, arg->from,
 						&sbi->s_dummy_enc_policy);
 	if (err) {
 		if (err == -EEXIST)

fs/f2fs/super.c +1 -1

index f2b3d1a279fb7..c72d22c0c52e7 100644
@@ -438,7 +438,7 @@ static int f2fs_set_test_dummy_encryption(struct super_block *sb,
 		return -EINVAL;
 	}
 	err = fscrypt_set_test_dummy_encryption(
-		sb, arg, &F2FS_OPTION(sbi).dummy_enc_policy);
+		sb, arg->from, &F2FS_OPTION(sbi).dummy_enc_policy);
 	if (err) {
 		if (err == -EEXIST)
 			f2fs_warn(sbi,

include/linux/fscrypt.h +1 -4

index b3b0c5675c6b1..fc67c4cbaa968 100644
@@ -15,7 +15,6 @@
 
 #include <linux/fs.h>
 #include <linux/mm.h>
-#include <linux/parser.h>
 #include <linux/slab.h>
 #include <uapi/linux/fscrypt.h>

@@ -153,9 +152,7 @@ struct fscrypt_dummy_policy {
 	const union fscrypt_policy *policy;
 };
 
-int fscrypt_set_test_dummy_encryption(
-				struct super_block *sb,
-				const substring_t *arg,
+int fscrypt_set_test_dummy_encryption(struct super_block *sb, const char *arg,
 				struct fscrypt_dummy_policy *dummy_policy);
 void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
 					struct super_block *sb);

Signature · 8 lines

2.28.0



_______________________________________________
Linux-f2fs-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Jeff Layton

2020-09-17 12:33 UTC #14 lore raw

Re: [PATCH v3 13/13] fscrypt: make fscrypt_set_test_dummy_encryption() take a 'const char *'

Quoted 7 lines · Eric Biggers

From: Eric Biggers <[email protected]>
fscrypt_set_test_dummy_encryption() requires that the optional argument to the test_dummy_encryption mount option be specified as a substring_t. That doesn't work well with filesystems that use the new mount API, since the new way of parsing mount options doesn't use substring_t.

Quoted 6 lines

Make it take the argument as a 'const char *' instead.
Instead of moving the match_strdup() into the callers in ext4 and f2fs, make them just use arg->from directly. Since the pattern is "test_dummy_encryption=%s", the argument will be null-terminated.

Are you sure about that? I thought the point of substring_t was to give you a token from the string without null terminating it.

ISTM that when you just pass in ->from, you might end up with trailing arguments in your string like this. e.g.:

    "v2,foo,bar,baz"

...and then that might fail to match properly
in fscrypt_set_test_dummy_encryption.

Quoted 114 lines

Signed-off-by Eric Biggers <[email protected]>

---
 fs/crypto/policy.c      | 20 ++++++--------------
 fs/ext4/super.c         |  2 +-
 fs/f2fs/super.c         |  2 +-
 include/linux/fscrypt.h |  5 +----
 4 files changed, 9 insertions(+), 20 deletions(-)

fs/crypto/policy.c +6 ~~-14~~

index 97cf07543651f..4441d9944b9ef 100644
@@ -697,8 +697,7 @@ EXPORT_SYMBOL_GPL(fscrypt_set_context);
 /**
  * fscrypt_set_test_dummy_encryption() - handle '-o test_dummy_encryption'
  * @sb: the filesystem on which test_dummy_encryption is being specified
- * @arg: the argument to the test_dummy_encryption option.
- *	 If no argument was specified, then @arg->from == NULL.
+ * @arg: the argument to the test_dummy_encryption option.  May be NULL.
  * @dummy_policy: the filesystem's current dummy policy (input/output, see
  *		  below)
  *

@@ -712,29 +711,23 @@ EXPORT_SYMBOL_GPL(fscrypt_set_context);
  *         -EEXIST if a different dummy policy is already set;
  *         or another -errno value.
  */
-int fscrypt_set_test_dummy_encryption(struct super_block *sb,
-				      const substring_t *arg,
+int fscrypt_set_test_dummy_encryption(struct super_block *sb, const char *arg,
 				      struct fscrypt_dummy_policy *dummy_policy)
 {
-	const char *argstr = "v2";
-	const char *argstr_to_free = NULL;
 	struct fscrypt_key_specifier key_spec = { 0 };
 	int version;
 	union fscrypt_policy *policy = NULL;
 	int err;
 
-	if (arg->from) {
-		argstr = argstr_to_free = match_strdup(arg);
-		if (!argstr)
-			return -ENOMEM;
-	}
+	if (!arg)
+		arg = "v2";
 
-	if (!strcmp(argstr, "v1")) {
+	if (!strcmp(arg, "v1")) {
 		version = FSCRYPT_POLICY_V1;
 		key_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
 		memset(key_spec.u.descriptor, 0x42,
 		       FSCRYPT_KEY_DESCRIPTOR_SIZE);
-	} else if (!strcmp(argstr, "v2")) {
+	} else if (!strcmp(arg, "v2")) {
 		version = FSCRYPT_POLICY_V2;
 		key_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER;
 		/* key_spec.u.identifier gets filled in when adding the key */

@@ -785,7 +778,6 @@ int fscrypt_set_test_dummy_encryption(struct super_block *sb,
 	err = 0;
 out:
 	kfree(policy);
-	kfree(argstr_to_free);
 	return err;
 }
 EXPORT_SYMBOL_GPL(fscrypt_set_test_dummy_encryption);

fs/ext4/super.c +1 -1

index 7e77722406e2f..ed5624285a475 100644
@@ -1893,7 +1893,7 @@ static int ext4_set_test_dummy_encryption(struct super_block *sb,
 			 "Can't set test_dummy_encryption on remount");
 		return -1;
 	}
-	err = fscrypt_set_test_dummy_encryption(sb, arg,
+	err = fscrypt_set_test_dummy_encryption(sb, arg->from,
 						&sbi->s_dummy_enc_policy);
 	if (err) {
 		if (err == -EEXIST)

fs/f2fs/super.c +1 -1

index f2b3d1a279fb7..c72d22c0c52e7 100644
@@ -438,7 +438,7 @@ static int f2fs_set_test_dummy_encryption(struct super_block *sb,
 		return -EINVAL;
 	}
 	err = fscrypt_set_test_dummy_encryption(
-		sb, arg, &F2FS_OPTION(sbi).dummy_enc_policy);
+		sb, arg->from, &F2FS_OPTION(sbi).dummy_enc_policy);
 	if (err) {
 		if (err == -EEXIST)
 			f2fs_warn(sbi,

include/linux/fscrypt.h +1 -4

index b3b0c5675c6b1..fc67c4cbaa968 100644
@@ -15,7 +15,6 @@
 
 #include <linux/fs.h>
 #include <linux/mm.h>
-#include <linux/parser.h>
 #include <linux/slab.h>
 #include <uapi/linux/fscrypt.h>

@@ -153,9 +152,7 @@ struct fscrypt_dummy_policy {
 	const union fscrypt_policy *policy;
 };
 
-int fscrypt_set_test_dummy_encryption(
-				struct super_block *sb,
-				const substring_t *arg,
+int fscrypt_set_test_dummy_encryption(struct super_block *sb, const char *arg,
 				struct fscrypt_dummy_policy *dummy_policy);
 void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
 					struct super_block *sb);

Signature · 8 lines

Jeff Layton <[email protected]>



_______________________________________________
Linux-f2fs-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Eric Biggers

author maintainer

2020-09-17 15:29 UTC #15 lore raw

Re: [PATCH v3 13/13] fscrypt: make fscrypt_set_test_dummy_encryption() take a 'const char *'

Quoted 18 lines · Jeff Layton

Quoted 7 lines · Eric Biggers
From: Eric Biggers <[email protected]>
fscrypt_set_test_dummy_encryption() requires that the optional argument to the test_dummy_encryption mount option be specified as a substring_t. That doesn't work well with filesystems that use the new mount API, since the new way of parsing mount options doesn't use substring_t.
Quoted 6 lines
Make it take the argument as a 'const char *' instead.
Instead of moving the match_strdup() into the callers in ext4 and f2fs, make them just use arg->from directly. Since the pattern is "test_dummy_encryption=%s", the argument will be null-terminated.
Are you sure about that? I thought the point of substring_t was to give you a token from the string without null terminating it.

Quoted 8 lines

ISTM that when you just pass in ->from, you might end up with trailing arguments in your string like this. e.g.:
    "v2,foo,bar,baz"
...and then that might fail to match properly
in fscrypt_set_test_dummy_encryption.

Yes I'm sure, and I had also tested it. The use of match_token() here is to parse one null-terminated mount option at a time.

The reason that match_token() can return multiple substrings is that the pattern might be something like "foo=%d:%d".

But here it's just "test_dummy_encryption=%s". "%s" matches until end-of-string.

- Eric

_______________________________________________
Linux-f2fs-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Jeff Layton

2020-09-17 16:33 UTC #16 lore raw

Re: [PATCH v3 13/13] fscrypt: make fscrypt_set_test_dummy_encryption() take a 'const char *'

Quoted 28 lines · Eric Biggers

Quoted 18 lines · Jeff Layton
Quoted 7 lines · Eric Biggers
From: Eric Biggers <[email protected]>
fscrypt_set_test_dummy_encryption() requires that the optional argument to the test_dummy_encryption mount option be specified as a substring_t. That doesn't work well with filesystems that use the new mount API, since the new way of parsing mount options doesn't use substring_t.
Quoted 6 lines
Make it take the argument as a 'const char *' instead.
Instead of moving the match_strdup() into the callers in ext4 and f2fs, make them just use arg->from directly. Since the pattern is "test_dummy_encryption=%s", the argument will be null-terminated.
Are you sure about that? I thought the point of substring_t was to give you a token from the string without null terminating it.
Quoted 8 lines
ISTM that when you just pass in ->from, you might end up with trailing arguments in your string like this. e.g.:
    "v2,foo,bar,baz"
...and then that might fail to match properly
in fscrypt_set_test_dummy_encryption.

Quoted 7 lines

Yes I'm sure, and I had also tested it. The use of match_token() here is to parse one null-terminated mount option at a time.
The reason that match_token() can return multiple substrings is that the pattern might be something like "foo=%d:%d".
But here it's just "test_dummy_encryption=%s". "%s" matches until end-of-string.

Got it. Thanks for explaining!

Signature · 8 lines

Jeff Layton <[email protected]>



_______________________________________________
Linux-f2fs-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Eric Biggers

author maintainer

2020-09-21 22:35 UTC #17 lore raw

In reply to Eric Biggers

Quoted 64 lines · Eric Biggers

Hello,
This series reworks the implementation of creating new encrypted files by introducing new helper functions that allow filesystems to set up the inodes' keys earlier, prior to taking too many filesystem locks.
This fixes deadlocks that are possible during memory reclaim because fscrypt_get_encryption_info() isn't GFP_NOFS-safe, yet it's called during an ext4 transaction or under f2fs_lock_op(). It also fixes a similar deadlock where f2fs can try to recursively lock a page when the test_dummy_encryption mount option is in use.
It also solves an ordering problem that the ceph support for fscrypt
will have. For more details about this ordering problem, see the
discussion on Jeff Layton's RFC patchsets for ceph fscrypt support
(v1: https://lkml.kernel.org/linux-fscrypt/[email protected]/T/#u
v2: https://lkml.kernel.org/linux-fscrypt/[email protected]/T/#u
v3: https://lkml.kernel.org/linux-fscrypt/[email protected]/T/#u)
Note that v3 of the ceph patchset is based on v2 of this patchset.
Patch 1 adds the above-mentioned new helper functions. Patches 2-5 convert ext4, f2fs, and ubifs to use them, and patches 6-9 clean up a few things afterwards.
Finally, patches 10-13 change the implementation of test_dummy_encryption to no longer set up an encryption key for unencrypted directories, which was confusing and was causing problems.
This patchset applies to the master branch of
https://git.kernel.org/pub/scm/fs/fscrypt/fscrypt.git.
It can also be retrieved from tag "fscrypt-file-creation-v3" of
https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git.
I'm looking to apply this for 5.10; reviews are greatly appreciated!
Changed v2 => v3:
- Added patch that changes fscrypt_set_test_dummy_encryption() to take a 'const char *'. (Needed by ceph.)
- Fixed bug where fscrypt_prepare_new_inode() succeeded even if the new inode's key couldn't be set up.
- Fixed bug where fscrypt_prepare_new_inode() wouldn't derive the dirhash key for new casefolded directories.
- Made warning messages account for i_ino possibly being 0 now.
Changed v1 => v2:
- Added mention of another deadlock this fixes.
- Added patches to improve the test_dummy_encryption implementation.
- Dropped an ext4 cleanup patch that can be done separately later.
- Lots of small cleanups, and a couple small fixes.
Eric Biggers (13):
fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context()
ext4: factor out ext4_xattr_credits_for_new_inode()
ext4: use fscrypt_prepare_new_inode() and fscrypt_set_context()
f2fs: use fscrypt_prepare_new_inode() and fscrypt_set_context()
ubifs: use fscrypt_prepare_new_inode() and fscrypt_set_context()
fscrypt: adjust logging for in-creation inodes
fscrypt: remove fscrypt_inherit_context()
fscrypt: require that fscrypt_encrypt_symlink() already has key
fscrypt: stop pretending that key setup is nofs-safe
fscrypt: make "#define fscrypt_policy" user-only
fscrypt: move fscrypt_prepare_symlink() out-of-line
fscrypt: handle test_dummy_encryption in more logical way
fscrypt: make fscrypt_set_test_dummy_encryption() take a 'const char

Quoted 1 line

*'

All applied to fscrypt.git#master for 5.10.

I'd still really appreciate more reviews and acks, though.

- Eric

Jeff Layton

Acked-by

2020-09-22 11:29 UTC #18 lore raw

Quoted 67 lines · Eric Biggers

Quoted 64 lines · Eric Biggers
Hello,
This series reworks the implementation of creating new encrypted files by introducing new helper functions that allow filesystems to set up the inodes' keys earlier, prior to taking too many filesystem locks.
This fixes deadlocks that are possible during memory reclaim because fscrypt_get_encryption_info() isn't GFP_NOFS-safe, yet it's called during an ext4 transaction or under f2fs_lock_op(). It also fixes a similar deadlock where f2fs can try to recursively lock a page when the test_dummy_encryption mount option is in use.
It also solves an ordering problem that the ceph support for fscrypt
will have. For more details about this ordering problem, see the
discussion on Jeff Layton's RFC patchsets for ceph fscrypt support
(v1: https://lkml.kernel.org/linux-fscrypt/[email protected]/T/#u
v2: https://lkml.kernel.org/linux-fscrypt/[email protected]/T/#u
v3: https://lkml.kernel.org/linux-fscrypt/[email protected]/T/#u)
Note that v3 of the ceph patchset is based on v2 of this patchset.
Patch 1 adds the above-mentioned new helper functions. Patches 2-5 convert ext4, f2fs, and ubifs to use them, and patches 6-9 clean up a few things afterwards.
Finally, patches 10-13 change the implementation of test_dummy_encryption to no longer set up an encryption key for unencrypted directories, which was confusing and was causing problems.
This patchset applies to the master branch of
https://git.kernel.org/pub/scm/fs/fscrypt/fscrypt.git.
It can also be retrieved from tag "fscrypt-file-creation-v3" of
https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git.
I'm looking to apply this for 5.10; reviews are greatly appreciated!
Changed v2 => v3:
- Added patch that changes fscrypt_set_test_dummy_encryption() to take a 'const char *'. (Needed by ceph.)
- Fixed bug where fscrypt_prepare_new_inode() succeeded even if the new inode's key couldn't be set up.
- Fixed bug where fscrypt_prepare_new_inode() wouldn't derive the dirhash key for new casefolded directories.
- Made warning messages account for i_ino possibly being 0 now.
Changed v1 => v2:
- Added mention of another deadlock this fixes.
- Added patches to improve the test_dummy_encryption implementation.
- Dropped an ext4 cleanup patch that can be done separately later.
- Lots of small cleanups, and a couple small fixes.
Eric Biggers (13):
fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context()
ext4: factor out ext4_xattr_credits_for_new_inode()
ext4: use fscrypt_prepare_new_inode() and fscrypt_set_context()
f2fs: use fscrypt_prepare_new_inode() and fscrypt_set_context()
ubifs: use fscrypt_prepare_new_inode() and fscrypt_set_context()
fscrypt: adjust logging for in-creation inodes
fscrypt: remove fscrypt_inherit_context()
fscrypt: require that fscrypt_encrypt_symlink() already has key
fscrypt: stop pretending that key setup is nofs-safe
fscrypt: make "#define fscrypt_policy" user-only
fscrypt: move fscrypt_prepare_symlink() out-of-line
fscrypt: handle test_dummy_encryption in more logical way
fscrypt: make fscrypt_set_test_dummy_encryption() take a 'const char
Quoted 1 line
    *'

Quoted 4 lines

All applied to fscrypt.git#master for 5.10.
I'd still really appreciate more reviews and acks, though.

You can add this to all of the fscrypt: patches. I've tested this under the ceph patchset and it seems to do the right thing:

Acked-by Jeff Layton <[email protected]>

Eric Biggers

author maintainer

2020-09-22 13:50 UTC #19 lore raw

Quoted 11 lines · Jeff Layton

Quoted 5 lines
All applied to fscrypt.git#master for 5.10.
I'd still really appreciate more reviews and acks, though.
You can add this to all of the fscrypt: patches. I've tested this under the ceph patchset and it seems to do the right thing:
Acked-by Jeff Layton <[email protected]>

Thanks, added.

- Eric