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