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https://github.com/team-infusion-developers/android_kernel_samsung_msm8976.git
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d8bfd2f23b
commit 1995266727fa8143897e89b55f5d3c79aa828420 upstream.
Commit bdcf0a423ea1 ("kernel: make groups_sort calling a responsibility
group_info allocators") appears to break nfsd rootsquash in a pretty
major way.
It adds a call to groups_sort() inside the loop that copies/squashes
gids, which means the valid gids are sorted along with the following
garbage. The net result is that the highest numbered valid gids are
replaced with any lower-valued garbage gids, possibly including 0.
We should sort only once, after filling in all the gids.
Fixes: bdcf0a423ea1 ("kernel: make groups_sort calling a responsibility ...")
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Acked-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
99 lines
2.2 KiB
C
99 lines
2.2 KiB
C
/* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de> */
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#include <linux/sched.h>
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#include <linux/user_namespace.h>
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#include "nfsd.h"
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#include "auth.h"
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int nfsexp_flags(struct svc_rqst *rqstp, struct svc_export *exp)
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{
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struct exp_flavor_info *f;
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struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;
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for (f = exp->ex_flavors; f < end; f++) {
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if (f->pseudoflavor == rqstp->rq_cred.cr_flavor)
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return f->flags;
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}
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return exp->ex_flags;
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}
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int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
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{
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struct group_info *rqgi;
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struct group_info *gi;
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struct cred *new;
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int i;
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int flags = nfsexp_flags(rqstp, exp);
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int ret;
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validate_process_creds();
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/* discard any old override before preparing the new set */
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revert_creds(get_cred(current->real_cred));
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new = prepare_creds();
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if (!new)
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return -ENOMEM;
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new->fsuid = rqstp->rq_cred.cr_uid;
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new->fsgid = rqstp->rq_cred.cr_gid;
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rqgi = rqstp->rq_cred.cr_group_info;
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if (flags & NFSEXP_ALLSQUASH) {
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new->fsuid = exp->ex_anon_uid;
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new->fsgid = exp->ex_anon_gid;
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gi = groups_alloc(0);
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if (!gi)
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goto oom;
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} else if (flags & NFSEXP_ROOTSQUASH) {
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if (uid_eq(new->fsuid, GLOBAL_ROOT_UID))
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new->fsuid = exp->ex_anon_uid;
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if (gid_eq(new->fsgid, GLOBAL_ROOT_GID))
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new->fsgid = exp->ex_anon_gid;
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gi = groups_alloc(rqgi->ngroups);
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if (!gi)
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goto oom;
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for (i = 0; i < rqgi->ngroups; i++) {
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if (gid_eq(GLOBAL_ROOT_GID, GROUP_AT(rqgi, i)))
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GROUP_AT(gi, i) = exp->ex_anon_gid;
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else
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GROUP_AT(gi, i) = GROUP_AT(rqgi, i);
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}
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/* Each thread allocates its own gi, no race */
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groups_sort(gi);
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} else {
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gi = get_group_info(rqgi);
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}
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if (uid_eq(new->fsuid, INVALID_UID))
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new->fsuid = exp->ex_anon_uid;
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if (gid_eq(new->fsgid, INVALID_GID))
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new->fsgid = exp->ex_anon_gid;
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ret = set_groups(new, gi);
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put_group_info(gi);
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if (ret < 0)
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goto error;
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if (!uid_eq(new->fsuid, GLOBAL_ROOT_UID))
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new->cap_effective = cap_drop_nfsd_set(new->cap_effective);
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else
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new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
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new->cap_permitted);
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validate_process_creds();
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put_cred(override_creds(new));
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put_cred(new);
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validate_process_creds();
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return 0;
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oom:
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ret = -ENOMEM;
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error:
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abort_creds(new);
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return ret;
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}
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