On Fri, 19 Jul 2013 16:02:21 +1000 Dave Chinner <david@xxxxxxxxxxxxx> wrote: > On Wed, Jul 17, 2013 at 11:47:46AM -0400, Dwight Engen wrote: > > Signed-off-by: Dwight Engen <dwight.engen@xxxxxxxxxx> > > What's the reason for this patch? Its trying to ensure we only allow the XFS_IOC_FREE_EOFBLOCKS caller to affect the indoes they should be able to. http://oss.sgi.com/archives/xfs/2013-06/msg00955.html has a bit more background. This isn't really related to user namespaces per-se, so I guess it should be a separate patch, but since I modified the eofblocks structure I was trying to fix this as well. > > --- > > fs/xfs/xfs_fs.h | 1 + > > fs/xfs/xfs_icache.c | 4 ++++ > > fs/xfs/xfs_ioctl.c | 2 ++ > > 3 files changed, 7 insertions(+) > > > > diff --git a/fs/xfs/xfs_fs.h b/fs/xfs/xfs_fs.h > > index 7eb4a5e..aee4b12 100644 > > --- a/fs/xfs/xfs_fs.h > > +++ b/fs/xfs/xfs_fs.h > > @@ -361,6 +361,7 @@ struct xfs_fs_eofblocks { > > #define XFS_EOF_FLAGS_GID (1 << 2) /* filter by gid > > */ #define XFS_EOF_FLAGS_PRID (1 << 3) /* filter by > > project id */ #define XFS_EOF_FLAGS_MINFILESIZE (1 << 4) /* > > filter by min file size */ +#define XFS_EOF_FLAGS_PERM_CHECK > > (1 << 5) /* check can write inode */ #define > > XFS_EOF_FLAGS_VALID \ (XFS_EOF_FLAGS_SYNC | \ > > XFS_EOF_FLAGS_UID | \ > > diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c > > index d873ab9e..728283a 100644 > > --- a/fs/xfs/xfs_icache.c > > +++ b/fs/xfs/xfs_icache.c > > @@ -1247,6 +1247,10 @@ xfs_inode_free_eofblocks( > > if (!xfs_inode_match_id(ip, eofb)) > > return 0; > > > > + if (eofb->eof_flags & XFS_EOF_FLAGS_PERM_CHECK && > > + inode_permission(VFS_I(ip), MAY_WRITE)) > > + return 0; > > This assumes we are walking fully instantiated VFS inodes. That's > not necessarily true - we may be walking inodes that have already > been dropped from the VFS and are waiting for background reclaim to > clean them up. I suspect that this doesn't need to be done - we > normally stop background modification processes like this when we > convert the filesystem to read-only. I suspect the eof-blocks scan > code is missing that, and so it can potentially run on a RO > filesystem. That needs fixing similar to the way we stop and start > the periodic log work... So if there isn't a good way to check per-inode, maybe for now we should just restrict the ioctl caller to be capable(CAP_SYS_ADMIN)? > Also, gcc should throw warnings on that code (strange, it didn't > here on gcc-4.7) as it needs more parenthesis. i.e I don't think it needs them (& is higher precedence than &&), but I can add them for clarity if you like. > if ((eofb->eof_flags & XFS_EOF_FLAGS_PERM_CHECK) && > > > /* skip the inode if the file size is too small */ > > if (eofb->eof_flags & XFS_EOF_FLAGS_MINFILESIZE && > > XFS_ISIZE(ip) < eofb->eof_min_file_size) > > Oh, I see you are just copying other code. How did I miss that in a > past review? :( > > Hmmm - it looks like there's a bunch of them in xfs_inode_match_id() > as well, and you touched all those if() statements in a previous > patch. can you go back to the patch that touches > xfs_inode_match_id() and add the extra () there as well? Yep, I'll update those too. > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > > index abbbdcf..e63e359 100644 > > --- a/fs/xfs/xfs_ioctl.c > > +++ b/fs/xfs/xfs_ioctl.c > > @@ -1636,6 +1636,8 @@ xfs_file_ioctl( > > !gid_valid(keofb.eof_gid)) > > return XFS_ERROR(EINVAL); > > > > + keofb.eof_flags |= XFS_EOF_FLAGS_PERM_CHECK; > > We should be checking for the fs being RO here and aborting if it > is. inode_permission() would catch that but I agree there is no point waiting till then to find out. > Cheers, > > Dave. _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
