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 95