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	unsigned int len;
 19
 20	len = sizeof(struct group_info) + sizeof(kgid_t) * gidsetsize;
 21	gi = kmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_NOWARN|__GFP_NORETRY);
 22	if (!gi)
 23		gi = __vmalloc(len, GFP_KERNEL_ACCOUNT, PAGE_KERNEL);
 24	if (!gi)
 25		return NULL;
 26
 27	atomic_set(&gi->usage, 1);
 28	gi->ngroups = gidsetsize;
 29	return gi;
 30}
 31
 32EXPORT_SYMBOL(groups_alloc);
 33
 34void groups_free(struct group_info *group_info)
 35{
 36	kvfree(group_info);
 37}
 38
 39EXPORT_SYMBOL(groups_free);
 40
 41/* export the group_info to a user-space array */
 42static int groups_to_user(gid_t __user *grouplist,
 43			  const struct group_info *group_info)
 44{
 45	struct user_namespace *user_ns = current_user_ns();
 46	int i;
 47	unsigned int count = group_info->ngroups;
 48
 49	for (i = 0; i < count; i++) {
 50		gid_t gid;
 51		gid = from_kgid_munged(user_ns, group_info->gid[i]);
 52		if (put_user(gid, grouplist+i))
 53			return -EFAULT;
 54	}
 55	return 0;
 56}
 57
 58/* fill a group_info from a user-space array - it must be allocated already */
 59static int groups_from_user(struct group_info *group_info,
 60    gid_t __user *grouplist)
 61{
 62	struct user_namespace *user_ns = current_user_ns();
 63	int i;
 64	unsigned int count = group_info->ngroups;
 65
 66	for (i = 0; i < count; i++) {
 67		gid_t gid;
 68		kgid_t kgid;
 69		if (get_user(gid, grouplist+i))
 70			return -EFAULT;
 71
 72		kgid = make_kgid(user_ns, gid);
 73		if (!gid_valid(kgid))
 74			return -EINVAL;
 75
 76		group_info->gid[i] = kgid;
 77	}
 78	return 0;
 79}
 80
 81static int gid_cmp(const void *_a, const void *_b)
 82{
 83	kgid_t a = *(kgid_t *)_a;
 84	kgid_t b = *(kgid_t *)_b;
 85
 86	return gid_gt(a, b) - gid_lt(a, b);
 87}
 88
 89void groups_sort(struct group_info *group_info)
 90{
 91	sort(group_info->gid, group_info->ngroups, sizeof(*group_info->gid),
 92	     gid_cmp, NULL);
 93}
 94EXPORT_SYMBOL(groups_sort);
 95
 96/* a simple bsearch */
 97int groups_search(const struct group_info *group_info, kgid_t grp)
 98{
 99	unsigned int left, right;
100
101	if (!group_info)
102		return 0;
103
104	left = 0;
105	right = group_info->ngroups;
106	while (left < right) {
107		unsigned int mid = (left+right)/2;
108		if (gid_gt(grp, group_info->gid[mid]))
109			left = mid + 1;
110		else if (gid_lt(grp, group_info->gid[mid]))
111			right = mid;
112		else
113			return 1;
114	}
115	return 0;
116}
117
118/**
119 * set_groups - Change a group subscription in a set of credentials
120 * @new: The newly prepared set of credentials to alter
121 * @group_info: The group list to install
122 */
123void set_groups(struct cred *new, struct group_info *group_info)
124{
125	put_group_info(new->group_info);
126	get_group_info(group_info);
127	new->group_info = group_info;
128}
129
130EXPORT_SYMBOL(set_groups);
131
132/**
133 * set_current_groups - Change current's group subscription
134 * @group_info: The group list to impose
135 *
136 * Validate a group subscription and, if valid, impose it upon current's task
137 * security record.
138 */
139int set_current_groups(struct group_info *group_info)
140{
141	struct cred *new;
142
143	new = prepare_creds();
144	if (!new)
145		return -ENOMEM;
146
147	set_groups(new, group_info);
148	return commit_creds(new);
149}
150
151EXPORT_SYMBOL(set_current_groups);
152
153SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
154{
155	const struct cred *cred = current_cred();
156	int i;
157
158	if (gidsetsize < 0)
159		return -EINVAL;
160
161	/* no need to grab task_lock here; it cannot change */
162	i = cred->group_info->ngroups;
163	if (gidsetsize) {
164		if (i > gidsetsize) {
165			i = -EINVAL;
166			goto out;
167		}
168		if (groups_to_user(grouplist, cred->group_info)) {
169			i = -EFAULT;
170			goto out;
171		}
172	}
173out:
174	return i;
175}
176
177bool may_setgroups(void)
178{
179	struct user_namespace *user_ns = current_user_ns();
180
181	return ns_capable(user_ns, CAP_SETGID) &&
182		userns_may_setgroups(user_ns);
183}
184
185/*
186 *	SMP: Our groups are copy-on-write. We can set them safely
187 *	without another task interfering.
188 */
189
190SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
191{
192	struct group_info *group_info;
193	int retval;
194
195	if (!may_setgroups())
196		return -EPERM;
197	if ((unsigned)gidsetsize > NGROUPS_MAX)
198		return -EINVAL;
199
200	group_info = groups_alloc(gidsetsize);
201	if (!group_info)
202		return -ENOMEM;
203	retval = groups_from_user(group_info, grouplist);
204	if (retval) {
205		put_group_info(group_info);
206		return retval;
207	}
208
209	groups_sort(group_info);
210	retval = set_current_groups(group_info);
211	put_group_info(group_info);
212
213	return retval;
214}
215
216/*
217 * Check whether we're fsgid/egid or in the supplemental group..
218 */
219int in_group_p(kgid_t grp)
220{
221	const struct cred *cred = current_cred();
222	int retval = 1;
223
224	if (!gid_eq(grp, cred->fsgid))
225		retval = groups_search(cred->group_info, grp);
226	return retval;
227}
228
229EXPORT_SYMBOL(in_group_p);
230
231int in_egroup_p(kgid_t grp)
232{
233	const struct cred *cred = current_cred();
234	int retval = 1;
235
236	if (!gid_eq(grp, cred->egid))
237		retval = groups_search(cred->group_info, grp);
238	return retval;
239}
240
241EXPORT_SYMBOL(in_egroup_p);

  1/*
  2 * Supplementary group IDs
  3 */
  4#include <linux/cred.h>
  5#include <linux/module.h>
  6#include <linux/slab.h>
  7#include <linux/security.h>
  8#include <linux/syscalls.h>
  9#include <asm/uaccess.h>
 10
 11/* init to 2 - one for init_task, one to ensure it is never freed */
 12struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
 13
 14struct group_info *groups_alloc(int gidsetsize)
 15{
 16	struct group_info *group_info;
 17	int nblocks;
 18	int i;
 19
 20	nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;
 21	/* Make sure we always allocate at least one indirect block pointer */
 22	nblocks = nblocks ? : 1;
 23	group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);
 24	if (!group_info)
 25		return NULL;
 26	group_info->ngroups = gidsetsize;
 27	group_info->nblocks = nblocks;
 28	atomic_set(&group_info->usage, 1);
 29
 30	if (gidsetsize <= NGROUPS_SMALL)
 31		group_info->blocks[0] = group_info->small_block;
 32	else {
 33		for (i = 0; i < nblocks; i++) {
 34			gid_t *b;
 35			b = (void *)__get_free_page(GFP_USER);
 36			if (!b)
 37				goto out_undo_partial_alloc;
 38			group_info->blocks[i] = b;
 39		}
 40	}
 41	return group_info;
 42
 43out_undo_partial_alloc:
 44	while (--i >= 0) {
 45		free_page((unsigned long)group_info->blocks[i]);
 46	}
 47	kfree(group_info);
 48	return NULL;
 49}
 50
 51EXPORT_SYMBOL(groups_alloc);
 52
 53void groups_free(struct group_info *group_info)
 54{
 55	if (group_info->blocks[0] != group_info->small_block) {
 56		int i;
 57		for (i = 0; i < group_info->nblocks; i++)
 58			free_page((unsigned long)group_info->blocks[i]);
 59	}
 60	kfree(group_info);
 61}
 62
 63EXPORT_SYMBOL(groups_free);
 64
 65/* export the group_info to a user-space array */
 66static int groups_to_user(gid_t __user *grouplist,
 67			  const struct group_info *group_info)
 68{
 69	int i;
 70	unsigned int count = group_info->ngroups;
 71
 72	for (i = 0; i < group_info->nblocks; i++) {
 73		unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
 74		unsigned int len = cp_count * sizeof(*grouplist);
 75
 76		if (copy_to_user(grouplist, group_info->blocks[i], len))
 77			return -EFAULT;
 78
 79		grouplist += NGROUPS_PER_BLOCK;
 80		count -= cp_count;
 81	}
 82	return 0;
 83}
 84
 85/* fill a group_info from a user-space array - it must be allocated already */
 86static int groups_from_user(struct group_info *group_info,
 87    gid_t __user *grouplist)
 88{
 89	int i;
 90	unsigned int count = group_info->ngroups;
 91
 92	for (i = 0; i < group_info->nblocks; i++) {
 93		unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
 94		unsigned int len = cp_count * sizeof(*grouplist);
 95
 96		if (copy_from_user(group_info->blocks[i], grouplist, len))
 97			return -EFAULT;
 98
 99		grouplist += NGROUPS_PER_BLOCK;
100		count -= cp_count;
101	}
102	return 0;
103}
104
105/* a simple Shell sort */
106static void groups_sort(struct group_info *group_info)
107{
108	int base, max, stride;
109	int gidsetsize = group_info->ngroups;
110
111	for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
112		; /* nothing */
113	stride /= 3;
114
115	while (stride) {
116		max = gidsetsize - stride;
117		for (base = 0; base < max; base++) {
118			int left = base;
119			int right = left + stride;
120			gid_t tmp = GROUP_AT(group_info, right);
121
122			while (left >= 0 && GROUP_AT(group_info, left) > tmp) {
123				GROUP_AT(group_info, right) =
124				    GROUP_AT(group_info, left);
125				right = left;
126				left -= stride;
127			}
128			GROUP_AT(group_info, right) = tmp;
129		}
130		stride /= 3;
131	}
132}
133
134/* a simple bsearch */
135int groups_search(const struct group_info *group_info, gid_t grp)
136{
137	unsigned int left, right;
138
139	if (!group_info)
140		return 0;
141
142	left = 0;
143	right = group_info->ngroups;
144	while (left < right) {
145		unsigned int mid = (left+right)/2;
146		if (grp > GROUP_AT(group_info, mid))
147			left = mid + 1;
148		else if (grp < GROUP_AT(group_info, mid))
149			right = mid;
150		else
151			return 1;
152	}
153	return 0;
154}
155
156/**
157 * set_groups - Change a group subscription in a set of credentials
158 * @new: The newly prepared set of credentials to alter
159 * @group_info: The group list to install
160 *
161 * Validate a group subscription and, if valid, insert it into a set
162 * of credentials.
163 */
164int set_groups(struct cred *new, struct group_info *group_info)
165{
166	put_group_info(new->group_info);
167	groups_sort(group_info);
168	get_group_info(group_info);
169	new->group_info = group_info;
170	return 0;
171}
172
173EXPORT_SYMBOL(set_groups);
174
175/**
176 * set_current_groups - Change current's group subscription
177 * @group_info: The group list to impose
178 *
179 * Validate a group subscription and, if valid, impose it upon current's task
180 * security record.
181 */
182int set_current_groups(struct group_info *group_info)
183{
184	struct cred *new;
185	int ret;
186
187	new = prepare_creds();
188	if (!new)
189		return -ENOMEM;
190
191	ret = set_groups(new, group_info);
192	if (ret < 0) {
193		abort_creds(new);
194		return ret;
195	}
196
197	return commit_creds(new);
198}
199
200EXPORT_SYMBOL(set_current_groups);
201
202SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
203{
204	const struct cred *cred = current_cred();
205	int i;
206
207	if (gidsetsize < 0)
208		return -EINVAL;
209
210	/* no need to grab task_lock here; it cannot change */
211	i = cred->group_info->ngroups;
212	if (gidsetsize) {
213		if (i > gidsetsize) {
214			i = -EINVAL;
215			goto out;
216		}
217		if (groups_to_user(grouplist, cred->group_info)) {
218			i = -EFAULT;
219			goto out;
220		}
221	}
222out:
223	return i;
224}
225
226/*
227 *	SMP: Our groups are copy-on-write. We can set them safely
228 *	without another task interfering.
229 */
230
231SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
232{
233	struct group_info *group_info;
234	int retval;
235
236	if (!nsown_capable(CAP_SETGID))
237		return -EPERM;
238	if ((unsigned)gidsetsize > NGROUPS_MAX)
239		return -EINVAL;
240
241	group_info = groups_alloc(gidsetsize);
242	if (!group_info)
243		return -ENOMEM;
244	retval = groups_from_user(group_info, grouplist);
245	if (retval) {
246		put_group_info(group_info);
247		return retval;
248	}
249
250	retval = set_current_groups(group_info);
251	put_group_info(group_info);
252
253	return retval;
254}
255
256/*
257 * Check whether we're fsgid/egid or in the supplemental group..
258 */
259int in_group_p(gid_t grp)
260{
261	const struct cred *cred = current_cred();
262	int retval = 1;
263
264	if (grp != cred->fsgid)
265		retval = groups_search(cred->group_info, grp);
266	return retval;
267}
268
269EXPORT_SYMBOL(in_group_p);
270
271int in_egroup_p(gid_t grp)
272{
273	const struct cred *cred = current_cred();
274	int retval = 1;
275
276	if (grp != cred->egid)
277		retval = groups_search(cred->group_info, grp);
278	return retval;
279}
280
281EXPORT_SYMBOL(in_egroup_p);