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 /* discard any old override before preparing the new set */
30 revert_creds(get_cred(current_real_cred()));
31 new = prepare_creds();
32 if (!new)
33 return -ENOMEM;
34
35 new->fsuid = rqstp->rq_cred.cr_uid;
36 new->fsgid = rqstp->rq_cred.cr_gid;
37
38 rqgi = rqstp->rq_cred.cr_group_info;
39
40 if (flags & NFSEXP_ALLSQUASH) {
41 new->fsuid = exp->ex_anon_uid;
42 new->fsgid = exp->ex_anon_gid;
43 gi = groups_alloc(0);
44 if (!gi)
45 goto oom;
46 } else if (flags & NFSEXP_ROOTSQUASH) {
47 if (uid_eq(new->fsuid, GLOBAL_ROOT_UID))
48 new->fsuid = exp->ex_anon_uid;
49 if (gid_eq(new->fsgid, GLOBAL_ROOT_GID))
50 new->fsgid = exp->ex_anon_gid;
51
52 gi = groups_alloc(rqgi->ngroups);
53 if (!gi)
54 goto oom;
55
56 for (i = 0; i < rqgi->ngroups; i++) {
57 if (gid_eq(GLOBAL_ROOT_GID, rqgi->gid[i]))
58 gi->gid[i] = exp->ex_anon_gid;
59 else
60 gi->gid[i] = rqgi->gid[i];
61 }
62
63 /* Each thread allocates its own gi, no race */
64 groups_sort(gi);
65 } else {
66 gi = get_group_info(rqgi);
67 }
68
69 if (uid_eq(new->fsuid, INVALID_UID))
70 new->fsuid = exp->ex_anon_uid;
71 if (gid_eq(new->fsgid, INVALID_GID))
72 new->fsgid = exp->ex_anon_gid;
73
74 set_groups(new, gi);
75 put_group_info(gi);
76
77 if (!uid_eq(new->fsuid, GLOBAL_ROOT_UID))
78 new->cap_effective = cap_drop_nfsd_set(new->cap_effective);
79 else
80 new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
81 new->cap_permitted);
82 put_cred(override_creds(new));
83 put_cred(new);
84 return 0;
85
86 oom:
87 abort_creds(new);
88 return -ENOMEM;
89 }
90
91
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