afs: Support interacting with multiple user namespaces

Modify struct afs_file_status to store owner as a kuid_t and group as
a kgid_t.

In xdr_decode_AFSFetchStatus as owner is now a kuid_t and group is now
a kgid_t don't use the EXTRACT macro.  Instead perform the work of
the extract macro explicitly.  Read the value with ntohl and
convert it to the appropriate type with make_kuid or make_kgid.
Test if the value is different from what is stored in status and
update changed.   Update the value in status.

In xdr_encode_AFS_StoreStatus call from_kuid or from_kgid as
we are computing the on the wire encoding.

Initialize uids with GLOBAL_ROOT_UID instead of 0.
Initialize gids with GLOBAL_ROOT_GID instead of 0.

Cc: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index b960ff0..c2e930e 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -42,6 +42,8 @@ static void xdr_decode_AFSFetchStatus(const __be32 **_bp,
 	umode_t mode;
 	u64 data_version, size;
 	u32 changed = 0; /* becomes non-zero if ctime-type changes seen */
+	kuid_t owner;
+	kgid_t group;
 
 #define EXTRACT(DST)				\
 	do {					\
@@ -56,7 +58,9 @@ static void xdr_decode_AFSFetchStatus(const __be32 **_bp,
 	size = ntohl(*bp++);
 	data_version = ntohl(*bp++);
 	EXTRACT(status->author);
-	EXTRACT(status->owner);
+	owner = make_kuid(&init_user_ns, ntohl(*bp++));
+	changed |= !uid_eq(owner, status->owner);
+	status->owner = owner;
 	EXTRACT(status->caller_access); /* call ticket dependent */
 	EXTRACT(status->anon_access);
 	EXTRACT(status->mode);
@@ -65,7 +69,9 @@ static void xdr_decode_AFSFetchStatus(const __be32 **_bp,
 	bp++; /* seg size */
 	status->mtime_client = ntohl(*bp++);
 	status->mtime_server = ntohl(*bp++);
-	EXTRACT(status->group);
+	group = make_kgid(&init_user_ns, ntohl(*bp++));
+	changed |= !gid_eq(group, status->group);
+	status->group = group;
 	bp++; /* sync counter */
 	data_version |= (u64) ntohl(*bp++) << 32;
 	EXTRACT(status->lock_count);
@@ -181,12 +187,12 @@ static void xdr_encode_AFS_StoreStatus(__be32 **_bp, struct iattr *attr)
 
 	if (attr->ia_valid & ATTR_UID) {
 		mask |= AFS_SET_OWNER;
-		owner = attr->ia_uid;
+		owner = from_kuid(&init_user_ns, attr->ia_uid);
 	}
 
 	if (attr->ia_valid & ATTR_GID) {
 		mask |= AFS_SET_GROUP;
-		group = attr->ia_gid;
+		group = from_kgid(&init_user_ns, attr->ia_gid);
 	}
 
 	if (attr->ia_valid & ATTR_MODE) {