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);

  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);