[Devel] [PATCH RH7 v2] pfcache: hide trusted.pfcache from listxattr

[Pavel Tikhomirov]

Need it to be able to rsync xattrs for encripted containers which
have pfcache_csum disabled on superblock.

When there is no PFCACHE_CSUM on superblock or we are not
capable(CAP_SYS_ADMIN), we do not allow get/set trusted.pfcache.
So hide trusted.pfcache from list also in thouse two cases.

Tested that: list/get xattr "trusted.pfcache" is OK on file
setxattred on vz7.17.11 kernel, xattr entry on which had wrong
e_name_index (reverted EXT4_XATTR_INDEX_TRUSTED_CSUM), works as
there is no such entry at all. As in ext4_xattr_list_entries
-> ext4_xattr_handler where is special check for it.

v2: do checks in ext4_xattr_trusted_list which is used for
listing trusted.xxx xattrs

https://jira.sw.ru/browse/PSBM-52180
Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 fs/ext4/xattr_trusted.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/ext4/xattr_trusted.c b/fs/ext4/xattr_trusted.c
index 49dd83f..131b6b8 100644
--- a/fs/ext4/xattr_trusted.c
+++ b/fs/ext4/xattr_trusted.c
@@ -19,6 +19,11 @@ ext4_xattr_trusted_list(struct dentry *dentry, char *list, size_t list_size,
 	const size_t prefix_len = XATTR_TRUSTED_PREFIX_LEN;
 	const size_t total_len = prefix_len + name_len + 1;
 
+	if (!strcmp(name, EXT4_DATA_CSUM_NAME) &&
+	    (!capable(CAP_SYS_ADMIN) ||
+	     !test_opt2(dentry->d_inode->i_sb, PFCACHE_CSUM)))
+		return 0;
+
 	if (!ve_capable(CAP_SYS_ADMIN))
 		return 0;
 
-- 
2.5.5