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ext4: do not unnecessarily null-terminate encrypted symlink data

PATCH Applied Eric Biggers 2 participants 5 messages Sep 22, 2016 – Sep 30, 2016

Subsystems (4)
VFS ext4 file system F2FS file system fscrypt: file system level encryption support
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Eric Biggers

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#0 lore raw

PATCH 1/1 ext4: do not unnecessarily null-terminate encrypted symlink data

Null-terminating the fscrypt_symlink_data on read is unnecessary because it is not string data --- it contains binary ciphertext.

Signed-off-by Eric Biggers <[email protected]>
---
 fs/ext4/symlink.c | 2 --
 1 file changed, 2 deletions(-)
fs/ext4/symlink.c +0 -2
index 0a26cbd..fdf1c61 100644
@@ -30,7 +30,6 @@ static const char *ext4_encrypted_get_link(struct dentry *dentry,
 	char *caddr, *paddr = NULL;
 	struct fscrypt_str cstr, pstr;
 	struct fscrypt_symlink_data *sd;
-	loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
 	int res;
 	u32 max_size = inode->i_sb->s_blocksize;
 

@@ -49,7 +48,6 @@ static const char *ext4_encrypted_get_link(struct dentry *dentry,
 		if (IS_ERR(cpage))
 			return ERR_CAST(cpage);
 		caddr = page_address(cpage);
-		caddr[size] = 0;
 	}
 
 	/* Symlink is encrypted */
Signature · 1 line
2.8.0.rc3.226.g39d4020
author
#1 lore raw

PATCH 1/1 f2fs: do not unnecessarily null-terminate encrypted symlink data

Null-terminating the fscrypt_symlink_data on read is unnecessary because it is not string data --- it contains binary ciphertext.

Signed-off-by Eric Biggers <[email protected]>
---
 fs/f2fs/namei.c | 2 --
 1 file changed, 2 deletions(-)
fs/f2fs/namei.c +0 -2
index afd5633..5b4733e 100644
@@ -1010,7 +1010,6 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
 	struct fscrypt_str cstr = FSTR_INIT(NULL, 0);
 	struct fscrypt_str pstr = FSTR_INIT(NULL, 0);
 	struct fscrypt_symlink_data *sd;
-	loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
 	u32 max_size = inode->i_sb->s_blocksize;
 	int res;
 

@@ -1025,7 +1024,6 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
 	if (IS_ERR(cpage))
 		return ERR_CAST(cpage);
 	caddr = page_address(cpage);
-	caddr[size] = 0;
 
 	/* Symlink is encrypted */
 	sd = (struct fscrypt_symlink_data *)caddr;
Signature · 1 line
2.8.0.rc3.226.g39d4020
author
#2 lore raw

PATCH 1/1 fscrypto: use standard macros to compute length of fname ciphertext

In reply to Eric Biggers
Signed-off-by Eric Biggers <[email protected]>
---
 fs/crypto/fname.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)
fs/crypto/fname.c +5 -12
index 90697c7..9a28133 100644
@@ -14,11 +14,6 @@
 #include <linux/ratelimit.h>
 #include <linux/fscrypto.h>
 
-static u32 size_round_up(size_t size, size_t blksize)
-{
-	return ((size + blksize - 1) / blksize) * blksize;
-}
-
 /**
  * fname_crypt_complete() - completion callback for filename crypto
  * @req: The asynchronous cipher request context

@@ -60,10 +55,9 @@ static int fname_encrypt(struct inode *inode,
 	if (iname->len <= 0 || iname->len > lim)
 		return -EIO;
 
-	ciphertext_len = (iname->len < FS_CRYPTO_BLOCK_SIZE) ?
-					FS_CRYPTO_BLOCK_SIZE : iname->len;
-	ciphertext_len = size_round_up(ciphertext_len, padding);
-	ciphertext_len = (ciphertext_len > lim) ? lim : ciphertext_len;
+	ciphertext_len = max(iname->len, (u32)FS_CRYPTO_BLOCK_SIZE);
+	ciphertext_len = round_up(ciphertext_len, padding);
+	ciphertext_len = min(ciphertext_len, lim);
 
 	if (ciphertext_len <= sizeof(buf)) {
 		workbuf = buf;

@@ -233,9 +227,8 @@ u32 fscrypt_fname_encrypted_size(struct inode *inode, u32 ilen)
 
 	if (ci)
 		padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK);
-	if (ilen < FS_CRYPTO_BLOCK_SIZE)
-		ilen = FS_CRYPTO_BLOCK_SIZE;
-	return size_round_up(ilen, padding);
+	ilen = max(ilen, (u32)FS_CRYPTO_BLOCK_SIZE);
+	return round_up(ilen, padding);
 }
 EXPORT_SYMBOL(fscrypt_fname_encrypted_size);
Signature · 1 line
2.8.0.rc3.226.g39d4020