[PATCH 3/4] f2fs: report correct st_size for encrypted symlinks

[Eric Biggers]

From: Eric Biggers <ebiggers at google.com>

commit 461b43a8f92e68e96c4424b31e15f2b35f1bbfa9 upstream.

The stat() family of syscalls report the wrong size for encrypted
symlinks, which has caused breakage in several userspace programs.

Fix this by calling fscrypt_symlink_getattr() after f2fs_getattr() for
encrypted symlinks.  This function computes the correct size by reading
and decrypting the symlink target (if it's not already cached).

For more details, see the commit which added fscrypt_symlink_getattr().

Fixes: cbaf042a3cc6 ("f2fs crypto: add symlink encryption")
Cc: stable at vger.kernel.org
Link: https://lore.kernel.org/r/20210702065350.209646-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers at google.com>
---
 fs/f2fs/namei.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index e20a0f9e6845..edc80855974a 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -1219,9 +1219,18 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
 	return target;
 }
 
+static int f2fs_encrypted_symlink_getattr(const struct path *path,
+					  struct kstat *stat, u32 request_mask,
+					  unsigned int query_flags)
+{
+	f2fs_getattr(path, stat, request_mask, query_flags);
+
+	return fscrypt_symlink_getattr(path, stat);
+}
+
 const struct inode_operations f2fs_encrypted_symlink_inode_operations = {
 	.get_link       = f2fs_encrypted_get_link,
-	.getattr	= f2fs_getattr,
+	.getattr	= f2fs_encrypted_symlink_getattr,
 	.setattr	= f2fs_setattr,
 #ifdef CONFIG_F2FS_FS_XATTR
 	.listxattr	= f2fs_listxattr,
-- 
2.33.0.153.gba50c8fa24-goog