fs/nfsd/auth.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de> */
   3
   4 #include <linux/sched.h>
   5 #include "nfsd.h"
   6 #include "auth.h"
   7
   8 int nfsexp_flags(struct svc_rqst *rqstp, struct svc_export *exp)
   9 {
  10         struct exp_flavor_info *f;
  11         struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;
  12
  13         for (f = exp->ex_flavors; f < end; f++) {
  14                 if (f->pseudoflavor == rqstp->rq_cred.cr_flavor)
  15                         return f->flags;
  16         }
  17         return exp->ex_flags;
  18
  19 }
  20
  21 int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
  22 {
  23         struct group_info *rqgi;
  24         struct group_info *gi;
  25         struct cred *new;
  26         int i;
  27         int flags = nfsexp_flags(rqstp, exp);
  28
  29         validate_process_creds();
  30
  31         /* discard any old override before preparing the new set */
  32         revert_creds(get_cred(current_real_cred()));
  33         new = prepare_creds();
  34         if (!new)
  35                 return -ENOMEM;
  36
  37         new->fsuid = rqstp->rq_cred.cr_uid;
  38         new->fsgid = rqstp->rq_cred.cr_gid;
  39
  40         rqgi = rqstp->rq_cred.cr_group_info;
  41
  42         if (flags & NFSEXP_ALLSQUASH) {
  43                 new->fsuid = exp->ex_anon_uid;
  44                 new->fsgid = exp->ex_anon_gid;
  45                 gi = groups_alloc(0);
  46                 if (!gi)
  47                         goto oom;
  48         } else if (flags & NFSEXP_ROOTSQUASH) {
  49                 if (uid_eq(new->fsuid, GLOBAL_ROOT_UID))
  50                         new->fsuid = exp->ex_anon_uid;
  51                 if (gid_eq(new->fsgid, GLOBAL_ROOT_GID))
  52                         new->fsgid = exp->ex_anon_gid;
  53
  54                 gi = groups_alloc(rqgi->ngroups);
  55                 if (!gi)
  56                         goto oom;
  57
  58                 for (i = 0; i < rqgi->ngroups; i++) {
  59                         if (gid_eq(GLOBAL_ROOT_GID, rqgi->gid[i]))
  60                                 gi->gid[i] = exp->ex_anon_gid;
  61                         else
  62                                 gi->gid[i] = rqgi->gid[i];
  63                 }
  64
  65                 /* Each thread allocates its own gi, no race */
  66                 groups_sort(gi);
  67         } else {
  68                 gi = get_group_info(rqgi);
  69         }
  70
  71         if (uid_eq(new->fsuid, INVALID_UID))
  72                 new->fsuid = exp->ex_anon_uid;
  73         if (gid_eq(new->fsgid, INVALID_GID))
  74                 new->fsgid = exp->ex_anon_gid;
  75
  76         set_groups(new, gi);
  77         put_group_info(gi);
  78
  79         if (!uid_eq(new->fsuid, GLOBAL_ROOT_UID))
  80                 new->cap_effective = cap_drop_nfsd_set(new->cap_effective);
  81         else
  82                 new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
  83                                                         new->cap_permitted);
  84         validate_process_creds();
  85         put_cred(override_creds(new));
  86         put_cred(new);
  87         validate_process_creds();
  88         return 0;
  89
  90 oom:
  91         abort_creds(new);
  92         return -ENOMEM;
  93 }
  94