Messages in this thread Patch in this message | | | Date | Wed, 7 Dec 2005 15:13:28 +0200 (EET) | From | Pekka J Enberg <> | Subject | Re: [PATCH] ext3: return FSID for statvfs |
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Hi Andreas,
On Wed, 7 Dec 2005, Andreas Dilger wrote: > The bug mentions some reasons why this patch is sub-optimal - namely that > the beginning of the UUID has common fields in it. It may make more sense > to e.g. XOR the first 2 * u32 with the last 2 * u32 to reduce the chance > of an FSID collision. > > Also, there is a tiny memory of a security issue with exposing the FSID > to applications (something to do with NFS and guessing filehandles or > similar). I have no idea if that is even relevant any longer, but > thought I'd mention it.
Something like this?
This patch changes ext3_statfs() to return a FSID based on 64 bit XOR of the 128 bit filesystem UUID as suggested by Andreas Dilger. This patch is partial fix for Bugzilla Bug <http://bugzilla.kernel.org/show_bug.cgi?id=136>.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> ---
super.c | 5 +++++ 1 file changed, 5 insertions(+)
Index: 2.6/fs/ext3/super.c =================================================================== --- 2.6.orig/fs/ext3/super.c +++ 2.6/fs/ext3/super.c @@ -2294,6 +2294,7 @@ static int ext3_statfs (struct super_blo struct ext3_super_block *es = EXT3_SB(sb)->s_es; unsigned long overhead; int i; + u64 fsid; if (test_opt (sb, MINIX_DF)) overhead = 0; @@ -2340,6 +2341,10 @@ static int ext3_statfs (struct super_blo buf->f_files = le32_to_cpu(es->s_inodes_count); buf->f_ffree = ext3_count_free_inodes (sb); buf->f_namelen = EXT3_NAME_LEN; + fsid = le64_to_cpup((void *)es->s_uuid) ^ + le64_to_cpup((void *)es->s_uuid + sizeof(u64)); + buf->f_fsid.val[0] = fsid & 0xFFFFFFFFUL; + buf->f_fsid.val[1] = (fsid >> 32) & 0xFFFFFFFFUL; return 0; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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