fscrypt: fix renaming and linking special files

commit 42d97eb0ade31e1bc537d086842f5d6e766d9d51 upstream.

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 <ebiggers@google.com>
Reviewed-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index 6865663aac69..abc18847b98d 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -171,6 +171,11 @@ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
                 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 (!parent->i_sb->s_cop->is_encrypted(parent))
                 return 1;