linux-kernel - nfsd bug: create file with specific uid/gid

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Message-ID: <475042FB.8020106@filmlight.ltd.uk>
Date:	Fri, 30 Nov 2007 17:06:03 +0000
From:	Roger Willcocks <roger@...mlight.ltd.uk>
To:	linux-kernel@...r.kernel.org
Subject: nfsd bug: create file with specific uid/gid

nfsd/vfs.c:nfsd_create (the v2 version of create) says:

"Set file attributes. Mode has already been set and
setting uid/gid works only for root"

but it doesn't actually test for root-ness (which could happen if the 
access is no-root-squash). There's similar code without the comment in 
nfsd_create_v3. In both cases the test:

    if ((iap->ia_valid &= ~(ATTR_UID|ATTR_GID|ATTR_MODE)) != 0)

should read:

    if (current->fsuid != 0)
        iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
    if ((iap->ia_valid &= ~ATTR_MODE) != 0)

although arguably they should return an EPERM error if the uid/gid bits 
are set, instead of silently ignoring them.

--
Roger

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