linux/fs/nfsd/auth.c
David Howells f05ef8db1a CRED: Fix NFSD regression
Fix a regression in NFSD's permission checking introduced by the credentials
patches.  There are two parts to the problem, both in nfsd_setuser():

 (1) The return value of set_groups() is -ve if in error, not 0, and should be
     checked appropriately.  0 indicates success.

 (2) The UID to use for fs accesses is in new->fsuid, not new->uid (which is
     0).  This causes CAP_DAC_OVERRIDE to always be set, rather than being
     cleared if the UID is anything other than 0 after squashing.

Reported-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
2009-01-07 15:40:44 -05:00

96 lines
2 KiB
C

/*
* linux/fs/nfsd/auth.c
*
* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
*/
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/nfsd/nfsd.h>
#include <linux/nfsd/export.h>
#include "auth.h"
int nfsexp_flags(struct svc_rqst *rqstp, struct svc_export *exp)
{
struct exp_flavor_info *f;
struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;
for (f = exp->ex_flavors; f < end; f++) {
if (f->pseudoflavor == rqstp->rq_flavor)
return f->flags;
}
return exp->ex_flags;
}
int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
{
struct group_info *rqgi;
struct group_info *gi;
struct cred *new;
int i;
int flags = nfsexp_flags(rqstp, exp);
int ret;
/* discard any old override before preparing the new set */
revert_creds(get_cred(current->real_cred));
new = prepare_creds();
if (!new)
return -ENOMEM;
new->fsuid = rqstp->rq_cred.cr_uid;
new->fsgid = rqstp->rq_cred.cr_gid;
rqgi = rqstp->rq_cred.cr_group_info;
if (flags & NFSEXP_ALLSQUASH) {
new->fsuid = exp->ex_anon_uid;
new->fsgid = exp->ex_anon_gid;
gi = groups_alloc(0);
} else if (flags & NFSEXP_ROOTSQUASH) {
if (!new->fsuid)
new->fsuid = exp->ex_anon_uid;
if (!new->fsgid)
new->fsgid = exp->ex_anon_gid;
gi = groups_alloc(rqgi->ngroups);
if (!gi)
goto oom;
for (i = 0; i < rqgi->ngroups; i++) {
if (!GROUP_AT(rqgi, i))
GROUP_AT(gi, i) = exp->ex_anon_gid;
else
GROUP_AT(gi, i) = GROUP_AT(rqgi, i);
}
} else {
gi = get_group_info(rqgi);
}
if (new->fsuid == (uid_t) -1)
new->fsuid = exp->ex_anon_uid;
if (new->fsgid == (gid_t) -1)
new->fsgid = exp->ex_anon_gid;
ret = set_groups(new, gi);
put_group_info(gi);
if (ret < 0)
goto error;
if (new->fsuid)
new->cap_effective = cap_drop_nfsd_set(new->cap_effective);
else
new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
new->cap_permitted);
put_cred(override_creds(new));
return 0;
oom:
ret = -ENOMEM;
error:
abort_creds(new);
return ret;
}