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 "export.h"
7 #include "auth.h"
8
nfsexp_flags(struct svc_cred * cred,struct svc_export * exp)9 int nfsexp_flags(struct svc_cred *cred, struct svc_export *exp)
10 {
11 struct exp_flavor_info *f;
12 struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;
13
14 for (f = exp->ex_flavors; f < end; f++) {
15 if (f->pseudoflavor == cred->cr_flavor)
16 return f->flags;
17 }
18 return exp->ex_flags;
19
20 }
21
nfsd_setuser(struct svc_cred * cred,struct svc_export * exp)22 int nfsd_setuser(struct svc_cred *cred, struct svc_export *exp)
23 {
24 struct group_info *rqgi;
25 struct group_info *gi;
26 struct cred *new;
27 int i;
28 int flags = nfsexp_flags(cred, exp);
29
30 /* discard any old override before preparing the new set */
31 put_cred(revert_creds(get_cred(current_real_cred())));
32 new = prepare_creds();
33 if (!new)
34 return -ENOMEM;
35
36 new->fsuid = cred->cr_uid;
37 new->fsgid = cred->cr_gid;
38
39 rqgi = cred->cr_group_info;
40
41 if (flags & NFSEXP_ALLSQUASH) {
42 new->fsuid = exp->ex_anon_uid;
43 new->fsgid = exp->ex_anon_gid;
44 gi = groups_alloc(0);
45 if (!gi)
46 goto oom;
47 } else if (flags & NFSEXP_ROOTSQUASH) {
48 if (uid_eq(new->fsuid, GLOBAL_ROOT_UID))
49 new->fsuid = exp->ex_anon_uid;
50 if (gid_eq(new->fsgid, GLOBAL_ROOT_GID))
51 new->fsgid = exp->ex_anon_gid;
52
53 gi = groups_alloc(rqgi->ngroups);
54 if (!gi)
55 goto oom;
56
57 for (i = 0; i < rqgi->ngroups; i++) {
58 if (gid_eq(GLOBAL_ROOT_GID, rqgi->gid[i]))
59 gi->gid[i] = exp->ex_anon_gid;
60 else
61 gi->gid[i] = rqgi->gid[i];
62 }
63
64 /* Each thread allocates its own gi, no race */
65 groups_sort(gi);
66 } else {
67 gi = get_group_info(rqgi);
68 }
69
70 if (uid_eq(new->fsuid, INVALID_UID))
71 new->fsuid = exp->ex_anon_uid;
72 if (gid_eq(new->fsgid, INVALID_GID))
73 new->fsgid = exp->ex_anon_gid;
74
75 set_groups(new, gi);
76 put_group_info(gi);
77
78 if (!uid_eq(new->fsuid, GLOBAL_ROOT_UID))
79 new->cap_effective = cap_drop_nfsd_set(new->cap_effective);
80 else
81 new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
82 new->cap_permitted);
83 put_cred(override_creds(new));
84 return 0;
85
86 oom:
87 abort_creds(new);
88 return -ENOMEM;
89 }
90
91 /**
92 * nfsd_user_namespace - Get user_namespace in effect for an RPC request
93 * @rqstp: RPC execution context
94 *
95 * xpt_cred is set once at transport creation and never modified. The
96 * transport itself is reference-counted during request processing, so
97 * no explicit reference on the namespace is necessary.
98 *
99 * Return: the user_namespace from the transport credential, or
100 * init_user_ns if no credential was set. The returned namespace pointer
101 * is valid for the duration of the RPC request.
102 */
nfsd_user_namespace(const struct svc_rqst * rqstp)103 struct user_namespace *nfsd_user_namespace(const struct svc_rqst *rqstp)
104 {
105 const struct cred *cred = rqstp->rq_xprt->xpt_cred;
106
107 return cred ? cred->user_ns : &init_user_ns;
108 }
109