Thanks, applying for 3.14.--b. On Wed, Dec 11, 2013 at 02:16:36PM +0400, Stanislav Kholmanskikh wrote: > There is an inconsistency in the handling of SUID/SGID file > bits after chown() between NFS and other local file systems. > > Local file systems (for example, ext3, ext4, xfs, btrfs) revoke > SUID/SGID bits after chown() on a regular file even if > the owner/group of the file has not been changed: > > ~# touch file; chmod ug+s file; chmod u+x file > ~# ls -l file > -rwsr-Sr-- 1 root root 0 Dec 6 04:49 file > ~# chown root file; ls -l file > -rwxr-Sr-- 1 root root 0 Dec 6 04:49 file > > but NFS doesn't do that: > > ~# touch file; chmod ug+s file; chmod u+x file > ~# ls -l file > -rwsr-Sr-- 1 root root 0 Dec 6 04:49 file > ~# chown root file; ls -l file > -rwsr-Sr-- 1 root root 0 Dec 6 04:49 file > > NFS does that only if the owner/group has been changed: > > ~# touch file; chmod ug+s file; chmod u+x file > ~# ls -l file > -rwsr-Sr-- 1 root root 0 Dec 6 05:02 file > ~# chown bin file; ls -l file > -rwxr-Sr-- 1 bin root 0 Dec 6 05:02 file > > See: http://pubs.opengroup.org/onlinepubs/9699919799/functions/chown.html > > "If the specified file is a regular file, one or more of > the S_IXUSR, S_IXGRP, or S_IXOTH bits of the file mode are set, > and the process has appropriate privileges, it is > implementation-defined whether the set-user-ID and set-group-ID > bits are altered." > > So both variants are acceptable by POSIX. > > This patch makes NFS to behave like local file systems. > > Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@xxxxxxxxxx> > --- > fs/nfsd/vfs.c | 3 +-- > 1 files changed, 1 insertions(+), 2 deletions(-) > > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > index 72cb28e..8226991 100644 > --- a/fs/nfsd/vfs.c > +++ b/fs/nfsd/vfs.c > @@ -348,8 +348,7 @@ nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap) > > /* Revoke setuid/setgid on chown */ > if (!S_ISDIR(inode->i_mode) && > - (((iap->ia_valid & ATTR_UID) && !uid_eq(iap->ia_uid, inode->i_uid)) || > - ((iap->ia_valid & ATTR_GID) && !gid_eq(iap->ia_gid, inode->i_gid)))) { > + ((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) { > iap->ia_valid |= ATTR_KILL_PRIV; > if (iap->ia_valid & ATTR_MODE) { > /* we're setting mode too, just clear the s*id bits */ > -- > 1.7.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
