On Tue, 20 Aug 2013 22:46:30 +0200
Arnd Bergmann [off-list ref] wrote:

On Tuesday 20 August 2013, Dwight Engen wrote:

quoted

diff --git a/arch/powerpc/platforms/cell/spufs/inode.c

b/arch/powerpc/platforms/cell/spufs/inode.c index f390042..90fb308
100644 --- a/arch/powerpc/platforms/cell/spufs/inode.c

+++ b/arch/powerpc/platforms/cell/spufs/inode.c

@@ -620,12 +620,12 @@ spufs_parse_options(struct super_block *sb,

char *options, struct inode *root) case Opt_uid:
                        if (match_int(&args[0], &option))
                                return 0;
-                       root->i_uid = option;
+                       root->i_uid = make_kuid(&init_user_ns,
option); break;
                case Opt_gid:
                        if (match_int(&args[0], &option))
                                return 0;
-                       root->i_gid = option;
+                       root->i_gid = make_kgid(&init_user_ns,
option); break;
                case Opt_mode:
                        if (match_octal(&args[0], &option))

Doesn't this mean the uid/gid is taken from the initial namespace
rather than from the namespace of the 'mount' process calling this? I
think the logical choice would be to have the UID be the one that
gets passed here in the caller's namespace.

Yes, I agree. The other filesystems that take an Opt_uid as well do use
current_user_ns() and not init_user_ns. They also do a uid_valid()
check and fail the mount (or fallback to GLOBAL_ROOT_UID). So I think
that would look like this:

diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c
index f390042..87ba7cf 100644
--- a/arch/powerpc/platforms/cell/spufs/inode.c
+++ b/arch/powerpc/platforms/cell/spufs/inode.c

@@ -620,12 +620,16 @@ spufs_parse_options(struct super_block *sb, char *options, struct inode *root)
                case Opt_uid:
                        if (match_int(&args[0], &option))
                                return 0;
-                       root->i_uid = option;
+                       root->i_uid = make_kuid(current_user_ns(), option);
+                       if (!uid_valid(root->i_uid))
+                               return 0;
                        break;
                case Opt_gid:
                        if (match_int(&args[0], &option))
                                return 0;
-                       root->i_gid = option;
+                       root->i_gid = make_kgid(current_user_ns(), option);
+                       if (!gid_valid(root->i_gid))
+                               return 0;
                        break;
                case Opt_mode:
                        if (match_octal(&args[0], &option))

Again, I have not run tested this so we may just want to disable SPU_FS
with USER_NS until they can be tested together.