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// 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);
 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);