[PATCH 2/6] convert kuid_t to/from uid_t in ACLs

[Dwight Engen <dwight.engen@xxxxxxxxxx>]

Change permission check for setting ACL to use inode_owner_or_capable()
which will additionally allow a CAP_FOWNER user in a user namespace to
be able to set an ACL on an inode covered by the user namespace mapping.

Signed-off-by: Dwight Engen <dwight.engen@xxxxxxxxxx>
---
 fs/xfs/xfs_acl.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
index 306d883..11a91d6 100644
--- a/fs/xfs/xfs_acl.c
+++ b/fs/xfs/xfs_acl.c
@@ -68,14 +68,15 @@ xfs_acl_from_disk(
 
                switch (acl_e->e_tag) {
                case ACL_USER:
+                       acl_e->e_uid = xfs_uid_to_kuid(be32_to_cpu(ace->ae_id));
+                       break;
                case ACL_GROUP:
-                       acl_e->e_id = be32_to_cpu(ace->ae_id);
+                       acl_e->e_gid = xfs_gid_to_kgid(be32_to_cpu(ace->ae_id));
                        break;
                case ACL_USER_OBJ:
                case ACL_GROUP_OBJ:
                case ACL_MASK:
                case ACL_OTHER:
-                       acl_e->e_id = ACL_UNDEFINED_ID;
                        break;
                default:
                        goto fail;
@@ -101,7 +102,18 @@ xfs_acl_to_disk(struct xfs_acl *aclp, const struct 
posix_acl *acl)
                acl_e = &acl->a_entries[i];
 
                ace->ae_tag = cpu_to_be32(acl_e->e_tag);
-               ace->ae_id = cpu_to_be32(acl_e->e_id);
+               switch (acl_e->e_tag) {
+               case ACL_USER:
+                       ace->ae_id = cpu_to_be32(xfs_kuid_to_uid(acl_e->e_uid));
+                       break;
+               case ACL_GROUP:
+                       ace->ae_id = cpu_to_be32(xfs_kgid_to_gid(acl_e->e_gid));
+                       break;
+               default:
+                       ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
+                       break;
+               }
+
                ace->ae_perm = cpu_to_be16(acl_e->e_perm);
        }
 }
@@ -360,7 +372,7 @@ xfs_xattr_acl_set(struct dentry *dentry, const char *name,
                return -EINVAL;
        if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
                return value ? -EACCES : 0;
-       if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
+       if (!inode_owner_or_capable(inode))
                return -EPERM;
 
        if (!value)
-- 
1.8.1.4