f2fs: report correct st_size for encrypted symlinks

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@vger.kernel.org
Link: https://lore.kernel.org/r/20210702065350.209646-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index e149c8c66a71b16fb0026e2497f8184ce9b1335c..9c528e583c9d533c29a9259035b886345cfb6d7b 100644 (file)
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -1323,9 +1323,19 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
        return target;
 }
 
+static int f2fs_encrypted_symlink_getattr(struct user_namespace *mnt_userns,
+                                         const struct path *path,
+                                         struct kstat *stat, u32 request_mask,
+                                         unsigned int query_flags)
+{
+       f2fs_getattr(mnt_userns, 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,
        .listxattr      = f2fs_listxattr,
 };