f2fs: report correct st_size for encrypted symlinks

stable inclusion
from stable-5.10.63
commit 3ac01789f6d9ca93ecc1faecd23414c13b4582c9
bugzilla: 182231 https://gitee.com/openeuler/kernel/issues/I4EFS1

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3ac01789f6d9ca93ecc1faecd23414c13b4582c9

--------------------------------

commit 461b43a8 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: cbaf042a ("f2fs crypto: add symlink encryption")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210702065350.209646-4-ebiggers@kernel.orgSigned-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/f2fs/namei.c

@@ -1307,9 +1307,18 @@ 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,
 	.listxattr	= f2fs_listxattr,
 };