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>

4 files changed, 15 insertions, 10 deletions

diff --git a/fs/afs/afs.h b/fs/afs/afs.h
index 3d8fd35c0dd0..3c462ff6db63 100644
--- a/fs/afs/afs.h
+++ b/fs/afs/afs.h
@@ -119,8 +119,8 @@ struct afs_file_status {
         u64                     size;           /* file size */
         afs_dataversion_t       data_version;   /* current data version */
         u32                     author;         /* author ID */
-        u32                     owner;          /* owner ID */
-        u32                     group;          /* group ID */
+        kuid_t                  owner;          /* owner ID */
+        kgid_t                  group;          /* group ID */
         afs_access_t            caller_access;  /* access rights for authenticated caller */
         afs_access_t            anon_access;    /* access rights for unauthenticated caller */
         umode_t                 mode;           /* UNIX mode */
diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index b960ff05ea0b..c2e930ec2888 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) {
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 95cffd38239f..789bc253b5f6 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -69,7 +69,7 @@ static int afs_inode_map_status(struct afs_vnode *vnode, struct key *key)
 
         set_nlink(inode, vnode->status.nlink);
         inode->i_uid            = vnode->status.owner;
-        inode->i_gid            = 0;
+        inode->i_gid            = GLOBAL_ROOT_GID;
         inode->i_size           = vnode->status.size;
         inode->i_ctime.tv_sec   = vnode->status.mtime_server;
         inode->i_ctime.tv_nsec  = 0;
@@ -175,8 +175,8 @@ struct inode *afs_iget_autocell(struct inode *dir, const char *dev_name,
         inode->i_mode           = S_IFDIR | S_IRUGO | S_IXUGO;
         inode->i_op             = &afs_autocell_inode_operations;
         set_nlink(inode, 2);
-        inode->i_uid            = 0;
-        inode->i_gid            = 0;
+        inode->i_uid            = GLOBAL_ROOT_UID;
+        inode->i_gid            = GLOBAL_ROOT_GID;
         inode->i_ctime.tv_sec   = get_seconds();
         inode->i_ctime.tv_nsec  = 0;
         inode->i_atime          = inode->i_mtime = inode->i_ctime;
diff --git a/init/Kconfig b/init/Kconfig
index 394d24f99efe..4570b02abcc5 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1071,7 +1071,6 @@ config UIDGID_CONVERTED
         default y
 
         # Filesystems
-        depends on AFS_FS = n
         depends on CIFS = n
         depends on CODA_FS = n
         depends on GFS2_FS = n