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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Supplementary group IDs
4 */
5#include <linux/cred.h>
6#include <linux/export.h>
7#include <linux/slab.h>
8#include <linux/security.h>
9#include <linux/sort.h>
10#include <linux/syscalls.h>
11#include <linux/user_namespace.h>
12#include <linux/vmalloc.h>
13#include <linux/uaccess.h>
14
15struct group_info *groups_alloc(int gidsetsize)
16{
17 struct group_info *gi;
18 gi = kvmalloc(struct_size(gi, gid, gidsetsize), GFP_KERNEL_ACCOUNT);
19 if (!gi)
20 return NULL;
21
22 refcount_set(&gi->usage, 1);
23 gi->ngroups = gidsetsize;
24 return gi;
25}
26
27EXPORT_SYMBOL(groups_alloc);
28
29void groups_free(struct group_info *group_info)
30{
31 kvfree(group_info);
32}
33
34EXPORT_SYMBOL(groups_free);
35
36/* export the group_info to a user-space array */
37static int groups_to_user(gid_t __user *grouplist,
38 const struct group_info *group_info)
39{
40 struct user_namespace *user_ns = current_user_ns();
41 int i;
42 unsigned int count = group_info->ngroups;
43
44 for (i = 0; i < count; i++) {
45 gid_t gid;
46 gid = from_kgid_munged(user_ns, group_info->gid[i]);
47 if (put_user(gid, grouplist+i))
48 return -EFAULT;
49 }
50 return 0;
51}
52
53/* fill a group_info from a user-space array - it must be allocated already */
54static int groups_from_user(struct group_info *group_info,
55 gid_t __user *grouplist)
56{
57 struct user_namespace *user_ns = current_user_ns();
58 int i;
59 unsigned int count = group_info->ngroups;
60
61 for (i = 0; i < count; i++) {
62 gid_t gid;
63 kgid_t kgid;
64 if (get_user(gid, grouplist+i))
65 return -EFAULT;
66
67 kgid = make_kgid(user_ns, gid);
68 if (!gid_valid(kgid))
69 return -EINVAL;
70
71 group_info->gid[i] = kgid;
72 }
73 return 0;
74}
75
76static int gid_cmp(const void *_a, const void *_b)
77{
78 kgid_t a = *(kgid_t *)_a;
79 kgid_t b = *(kgid_t *)_b;
80
81 return gid_gt(a, b) - gid_lt(a, b);
82}
83
84void groups_sort(struct group_info *group_info)
85{
86 sort(group_info->gid, group_info->ngroups, sizeof(*group_info->gid),
87 gid_cmp, NULL);
88}
89EXPORT_SYMBOL(groups_sort);
90
91/* a simple bsearch */
92int groups_search(const struct group_info *group_info, kgid_t grp)
93{
94 unsigned int left, right;
95
96 if (!group_info)
97 return 0;
98
99 left = 0;
100 right = group_info->ngroups;
101 while (left < right) {
102 unsigned int mid = (left+right)/2;
103 if (gid_gt(grp, group_info->gid[mid]))
104 left = mid + 1;
105 else if (gid_lt(grp, group_info->gid[mid]))
106 right = mid;
107 else
108 return 1;
109 }
110 return 0;
111}
112
113/**
114 * set_groups - Change a group subscription in a set of credentials
115 * @new: The newly prepared set of credentials to alter
116 * @group_info: The group list to install
117 */
118void set_groups(struct cred *new, struct group_info *group_info)
119{
120 put_group_info(new->group_info);
121 get_group_info(group_info);
122 new->group_info = group_info;
123}
124
125EXPORT_SYMBOL(set_groups);
126
127/**
128 * set_current_groups - Change current's group subscription
129 * @group_info: The group list to impose
130 *
131 * Validate a group subscription and, if valid, impose it upon current's task
132 * security record.
133 */
134int set_current_groups(struct group_info *group_info)
135{
136 struct cred *new;
137 const struct cred *old;
138 int retval;
139
140 new = prepare_creds();
141 if (!new)
142 return -ENOMEM;
143
144 old = current_cred();
145
146 set_groups(new, group_info);
147
148 retval = security_task_fix_setgroups(new, old);
149 if (retval < 0)
150 goto error;
151
152 return commit_creds(new);
153
154error:
155 abort_creds(new);
156 return retval;
157}
158
159EXPORT_SYMBOL(set_current_groups);
160
161SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
162{
163 const struct cred *cred = current_cred();
164 int i;
165
166 if (gidsetsize < 0)
167 return -EINVAL;
168
169 /* no need to grab task_lock here; it cannot change */
170 i = cred->group_info->ngroups;
171 if (gidsetsize) {
172 if (i > gidsetsize) {
173 i = -EINVAL;
174 goto out;
175 }
176 if (groups_to_user(grouplist, cred->group_info)) {
177 i = -EFAULT;
178 goto out;
179 }
180 }
181out:
182 return i;
183}
184
185bool may_setgroups(void)
186{
187 struct user_namespace *user_ns = current_user_ns();
188
189 return ns_capable_setid(user_ns, CAP_SETGID) &&
190 userns_may_setgroups(user_ns);
191}
192
193/*
194 * SMP: Our groups are copy-on-write. We can set them safely
195 * without another task interfering.
196 */
197
198SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
199{
200 struct group_info *group_info;
201 int retval;
202
203 if (!may_setgroups())
204 return -EPERM;
205 if ((unsigned)gidsetsize > NGROUPS_MAX)
206 return -EINVAL;
207
208 group_info = groups_alloc(gidsetsize);
209 if (!group_info)
210 return -ENOMEM;
211 retval = groups_from_user(group_info, grouplist);
212 if (retval) {
213 put_group_info(group_info);
214 return retval;
215 }
216
217 groups_sort(group_info);
218 retval = set_current_groups(group_info);
219 put_group_info(group_info);
220
221 return retval;
222}
223
224/*
225 * Check whether we're fsgid/egid or in the supplemental group..
226 */
227int in_group_p(kgid_t grp)
228{
229 const struct cred *cred = current_cred();
230 int retval = 1;
231
232 if (!gid_eq(grp, cred->fsgid))
233 retval = groups_search(cred->group_info, grp);
234 return retval;
235}
236
237EXPORT_SYMBOL(in_group_p);
238
239int in_egroup_p(kgid_t grp)
240{
241 const struct cred *cred = current_cred();
242 int retval = 1;
243
244 if (!gid_eq(grp, cred->egid))
245 retval = groups_search(cred->group_info, grp);
246 return retval;
247}
248
249EXPORT_SYMBOL(in_egroup_p);
1/*
2 * Supplementary group IDs
3 */
4#include <linux/cred.h>
5#include <linux/export.h>
6#include <linux/slab.h>
7#include <linux/security.h>
8#include <linux/syscalls.h>
9#include <linux/user_namespace.h>
10#include <asm/uaccess.h>
11
12struct group_info *groups_alloc(int gidsetsize)
13{
14 struct group_info *group_info;
15 int nblocks;
16 int i;
17
18 nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;
19 /* Make sure we always allocate at least one indirect block pointer */
20 nblocks = nblocks ? : 1;
21 group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);
22 if (!group_info)
23 return NULL;
24 group_info->ngroups = gidsetsize;
25 group_info->nblocks = nblocks;
26 atomic_set(&group_info->usage, 1);
27
28 if (gidsetsize <= NGROUPS_SMALL)
29 group_info->blocks[0] = group_info->small_block;
30 else {
31 for (i = 0; i < nblocks; i++) {
32 kgid_t *b;
33 b = (void *)__get_free_page(GFP_USER);
34 if (!b)
35 goto out_undo_partial_alloc;
36 group_info->blocks[i] = b;
37 }
38 }
39 return group_info;
40
41out_undo_partial_alloc:
42 while (--i >= 0) {
43 free_page((unsigned long)group_info->blocks[i]);
44 }
45 kfree(group_info);
46 return NULL;
47}
48
49EXPORT_SYMBOL(groups_alloc);
50
51void groups_free(struct group_info *group_info)
52{
53 if (group_info->blocks[0] != group_info->small_block) {
54 int i;
55 for (i = 0; i < group_info->nblocks; i++)
56 free_page((unsigned long)group_info->blocks[i]);
57 }
58 kfree(group_info);
59}
60
61EXPORT_SYMBOL(groups_free);
62
63/* export the group_info to a user-space array */
64static int groups_to_user(gid_t __user *grouplist,
65 const struct group_info *group_info)
66{
67 struct user_namespace *user_ns = current_user_ns();
68 int i;
69 unsigned int count = group_info->ngroups;
70
71 for (i = 0; i < count; i++) {
72 gid_t gid;
73 gid = from_kgid_munged(user_ns, GROUP_AT(group_info, i));
74 if (put_user(gid, grouplist+i))
75 return -EFAULT;
76 }
77 return 0;
78}
79
80/* fill a group_info from a user-space array - it must be allocated already */
81static int groups_from_user(struct group_info *group_info,
82 gid_t __user *grouplist)
83{
84 struct user_namespace *user_ns = current_user_ns();
85 int i;
86 unsigned int count = group_info->ngroups;
87
88 for (i = 0; i < count; i++) {
89 gid_t gid;
90 kgid_t kgid;
91 if (get_user(gid, grouplist+i))
92 return -EFAULT;
93
94 kgid = make_kgid(user_ns, gid);
95 if (!gid_valid(kgid))
96 return -EINVAL;
97
98 GROUP_AT(group_info, i) = kgid;
99 }
100 return 0;
101}
102
103/* a simple Shell sort */
104static void groups_sort(struct group_info *group_info)
105{
106 int base, max, stride;
107 int gidsetsize = group_info->ngroups;
108
109 for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
110 ; /* nothing */
111 stride /= 3;
112
113 while (stride) {
114 max = gidsetsize - stride;
115 for (base = 0; base < max; base++) {
116 int left = base;
117 int right = left + stride;
118 kgid_t tmp = GROUP_AT(group_info, right);
119
120 while (left >= 0 && gid_gt(GROUP_AT(group_info, left), tmp)) {
121 GROUP_AT(group_info, right) =
122 GROUP_AT(group_info, left);
123 right = left;
124 left -= stride;
125 }
126 GROUP_AT(group_info, right) = tmp;
127 }
128 stride /= 3;
129 }
130}
131
132/* a simple bsearch */
133int groups_search(const struct group_info *group_info, kgid_t grp)
134{
135 unsigned int left, right;
136
137 if (!group_info)
138 return 0;
139
140 left = 0;
141 right = group_info->ngroups;
142 while (left < right) {
143 unsigned int mid = (left+right)/2;
144 if (gid_gt(grp, GROUP_AT(group_info, mid)))
145 left = mid + 1;
146 else if (gid_lt(grp, GROUP_AT(group_info, mid)))
147 right = mid;
148 else
149 return 1;
150 }
151 return 0;
152}
153
154/**
155 * set_groups - Change a group subscription in a set of credentials
156 * @new: The newly prepared set of credentials to alter
157 * @group_info: The group list to install
158 */
159void set_groups(struct cred *new, struct group_info *group_info)
160{
161 put_group_info(new->group_info);
162 groups_sort(group_info);
163 get_group_info(group_info);
164 new->group_info = group_info;
165}
166
167EXPORT_SYMBOL(set_groups);
168
169/**
170 * set_current_groups - Change current's group subscription
171 * @group_info: The group list to impose
172 *
173 * Validate a group subscription and, if valid, impose it upon current's task
174 * security record.
175 */
176int set_current_groups(struct group_info *group_info)
177{
178 struct cred *new;
179
180 new = prepare_creds();
181 if (!new)
182 return -ENOMEM;
183
184 set_groups(new, group_info);
185 return commit_creds(new);
186}
187
188EXPORT_SYMBOL(set_current_groups);
189
190SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
191{
192 const struct cred *cred = current_cred();
193 int i;
194
195 if (gidsetsize < 0)
196 return -EINVAL;
197
198 /* no need to grab task_lock here; it cannot change */
199 i = cred->group_info->ngroups;
200 if (gidsetsize) {
201 if (i > gidsetsize) {
202 i = -EINVAL;
203 goto out;
204 }
205 if (groups_to_user(grouplist, cred->group_info)) {
206 i = -EFAULT;
207 goto out;
208 }
209 }
210out:
211 return i;
212}
213
214bool may_setgroups(void)
215{
216 struct user_namespace *user_ns = current_user_ns();
217
218 return ns_capable(user_ns, CAP_SETGID) &&
219 userns_may_setgroups(user_ns);
220}
221
222/*
223 * SMP: Our groups are copy-on-write. We can set them safely
224 * without another task interfering.
225 */
226
227SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
228{
229 struct group_info *group_info;
230 int retval;
231
232 if (!may_setgroups())
233 return -EPERM;
234 if ((unsigned)gidsetsize > NGROUPS_MAX)
235 return -EINVAL;
236
237 group_info = groups_alloc(gidsetsize);
238 if (!group_info)
239 return -ENOMEM;
240 retval = groups_from_user(group_info, grouplist);
241 if (retval) {
242 put_group_info(group_info);
243 return retval;
244 }
245
246 retval = set_current_groups(group_info);
247 put_group_info(group_info);
248
249 return retval;
250}
251
252/*
253 * Check whether we're fsgid/egid or in the supplemental group..
254 */
255int in_group_p(kgid_t grp)
256{
257 const struct cred *cred = current_cred();
258 int retval = 1;
259
260 if (!gid_eq(grp, cred->fsgid))
261 retval = groups_search(cred->group_info, grp);
262 return retval;
263}
264
265EXPORT_SYMBOL(in_group_p);
266
267int in_egroup_p(kgid_t grp)
268{
269 const struct cred *cred = current_cred();
270 int retval = 1;
271
272 if (!gid_eq(grp, cred->egid))
273 retval = groups_search(cred->group_info, grp);
274 return retval;
275}
276
277EXPORT_SYMBOL(in_egroup_p);