ext4: 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 ext4_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: f348c252320b ("ext4 crypto: add symlink encryption")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210702065350.209646-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

diff --git a/fs/ext4/symlink.c b/fs/ext4/symlink.c
index dd05af983092d6585237e47c440f146a9ab2ee21..69109746e6e2185c968706f1d622da40ff06b358 100644 (file)
--- a/fs/ext4/symlink.c
+++ b/fs/ext4/symlink.c
@@ -52,10 +52,20 @@ static const char *ext4_encrypted_get_link(struct dentry *dentry,
        return paddr;
 }
 
+static int ext4_encrypted_symlink_getattr(struct user_namespace *mnt_userns,
+                                         const struct path *path,
+                                         struct kstat *stat, u32 request_mask,
+                                         unsigned int query_flags)
+{
+       ext4_getattr(mnt_userns, path, stat, request_mask, query_flags);
+
+       return fscrypt_symlink_getattr(path, stat);
+}
+
 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
        .get_link       = ext4_encrypted_get_link,
        .setattr        = ext4_setattr,
-       .getattr        = ext4_getattr,
+       .getattr        = ext4_encrypted_symlink_getattr,
        .listxattr      = ext4_listxattr,
 };