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fscrypt: fix renaming and linking special files

PATCH In review Eric Biggers 2 participants 2 messages Mar 16, 2017 – Mar 20, 2017

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Stable branch ext4 file system F2FS file system
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Eric Biggers

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PATCH 1/1 fscrypt: fix renaming and linking special files

From: Eric Biggers <[email protected]>

commit 42d97eb0ade31e1bc537d086842f5d6e766d9d51 upstream. Please apply to 4.4-stable; it is already in 4.9-stable. This is a backport of the fix to fs/ext4/ and fs/f2fs/ for old kernels.

Attempting to link a device node, named pipe, or socket file into an encrypted directory through rename(2) or link(2) always failed with EPERM. This happened because fscrypt_has_permitted_context() saw that the file was unencrypted and forbid creating the link. This behavior was unexpected because such files are never encrypted; only regular files, directories, and symlinks can be encrypted.

To fix this, make fscrypt_has_permitted_context() always return true on special files.

This will be covered by a test in my encryption xfstests patchset.

Fixes 9bd8212f981e ("ext4 crypto: add encryption policy and password salt support")
Signed-off-by Eric Biggers <[email protected]>
Reviewed-by Richard Weinberger <[email protected]>
Cc [email protected]
Signed-off-by Theodore Ts'o <[email protected]>
---
 fs/ext4/crypto_policy.c | 6 ++++++
 fs/f2fs/crypto_policy.c | 5 +++++
 2 files changed, 11 insertions(+)
fs/ext4/crypto_policy.c +6 -0
index 8a9feb341f31..dd561f916f0b 100644
@@ -156,6 +156,12 @@ int ext4_is_child_context_consistent_with_parent(struct inode *parent,
 		WARN_ON(1);	/* Should never happen */
 		return 0;
 	}
+
+	/* No restrictions on file types which are never encrypted */
+	if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) &&
+	    !S_ISLNK(child->i_mode))
+		return 1;
+
 	/* no restrictions if the parent directory is not encrypted */
 	if (!ext4_encrypted_inode(parent))
 		return 1;
fs/f2fs/crypto_policy.c +5 -0
index e504f548b64e..5bbd1989d5e6 100644
@@ -149,6 +149,11 @@ int f2fs_is_child_context_consistent_with_parent(struct inode *parent,
 		BUG_ON(1);
 	}
 
+	/* No restrictions on file types which are never encrypted */
+	if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) &&
+	    !S_ISLNK(child->i_mode))
+		return 1;
+
 	/* no restrictions if the parent directory is not encrypted */
 	if (!f2fs_encrypted_inode(parent))
 		return 1;
Signature · 1 line
2.12.0.367.g23dc2f6d3c-goog
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#1 lore raw
Quoted 5 lines · Eric Biggers

From: Eric Biggers <[email protected]>

commit 42d97eb0ade31e1bc537d086842f5d6e766d9d51 upstream. Please apply to 4.4-stable; it is already in 4.9-stable. This is a backport of the fix to fs/ext4/ and fs/f2fs/ for old kernels.

Thanks, now applied.

greg k-h