ext4: report correct st_size for encrypted symlinks

commit 8c4bca10ceafc43b1ca0a9fab5fa27e13cbce99e 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 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/symlink.c b/fs/ext4/symlink.c
index dd05af983092d6585237e47c440f146a9ab2ee21..a9457fed351edd22d83aa92d99ee16feb3d0511e 100644 (file)
--- a/fs/ext4/symlink.c
+++ b/fs/ext4/symlink.c
@@ -52,10 +52,19 @@ static const char *ext4_encrypted_get_link(struct dentry *dentry,
        return paddr;
 }
 
+static int ext4_encrypted_symlink_getattr(const struct path *path,
+                                         struct kstat *stat, u32 request_mask,
+                                         unsigned int query_flags)
+{
+       ext4_getattr(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,
 };