[mirror_ubuntu-artful-kernel.git] / kernel / groups.c

/*
 * Supplementary group IDs
 */
#include <linux/cred.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <asm/uaccess.h>

/* init to 2 - one for init_task, one to ensure it is never freed */
struct group_info init_groups = { .usage = ATOMIC_INIT(2) };

struct group_info *groups_alloc(int gidsetsize)
{
	struct group_info *group_info;
	int nblocks;
	int i;

	nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;
	/* Make sure we always allocate at least one indirect block pointer */
	nblocks = nblocks ? : 1;
	group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);
	if (!group_info)
		return NULL;
	group_info->ngroups = gidsetsize;
	group_info->nblocks = nblocks;
	atomic_set(&group_info->usage, 1);

	if (gidsetsize <= NGROUPS_SMALL)
		group_info->blocks[0] = group_info->small_block;
	else {
		for (i = 0; i < nblocks; i++) {
			gid_t *b;
			b = (void *)__get_free_page(GFP_USER);
			if (!b)
				goto out_undo_partial_alloc;
			group_info->blocks[i] = b;
		}
	}
	return group_info;

out_undo_partial_alloc:
	while (--i >= 0) {
		free_page((unsigned long)group_info->blocks[i]);
	}
	kfree(group_info);
	return NULL;
}

EXPORT_SYMBOL(groups_alloc);

void groups_free(struct group_info *group_info)
{
	if (group_info->blocks[0] != group_info->small_block) {
		int i;
		for (i = 0; i < group_info->nblocks; i++)
			free_page((unsigned long)group_info->blocks[i]);
	}
	kfree(group_info);
}

EXPORT_SYMBOL(groups_free);

/* export the group_info to a user-space array */
static int groups_to_user(gid_t __user *grouplist,
			  const struct group_info *group_info)
{
	int i;
	unsigned int count = group_info->ngroups;

	for (i = 0; i < group_info->nblocks; i++) {
		unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
		unsigned int len = cp_count * sizeof(*grouplist);

		if (copy_to_user(grouplist, group_info->blocks[i], len))
			return -EFAULT;

		grouplist += NGROUPS_PER_BLOCK;
		count -= cp_count;
	}
	return 0;
}

/* fill a group_info from a user-space array - it must be allocated already */
static int groups_from_user(struct group_info *group_info,
    gid_t __user *grouplist)
{
	int i;
	unsigned int count = group_info->ngroups;

	for (i = 0; i < group_info->nblocks; i++) {
		unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
		unsigned int len = cp_count * sizeof(*grouplist);

		if (copy_from_user(group_info->blocks[i], grouplist, len))
			return -EFAULT;

		grouplist += NGROUPS_PER_BLOCK;
		count -= cp_count;
	}
	return 0;
}

/* a simple Shell sort */
static void groups_sort(struct group_info *group_info)
{
	int base, max, stride;
	int gidsetsize = group_info->ngroups;

	for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
		; /* nothing */
	stride /= 3;

	while (stride) {
		max = gidsetsize - stride;
		for (base = 0; base < max; base++) {
			int left = base;
			int right = left + stride;
			gid_t tmp = GROUP_AT(group_info, right);

			while (left >= 0 && GROUP_AT(group_info, left) > tmp) {
				GROUP_AT(group_info, right) =
				    GROUP_AT(group_info, left);
				right = left;
				left -= stride;
			}
			GROUP_AT(group_info, right) = tmp;
		}
		stride /= 3;
	}
}

/* a simple bsearch */
int groups_search(const struct group_info *group_info, gid_t grp)
{
	unsigned int left, right;

	if (!group_info)
		return 0;

	left = 0;
	right = group_info->ngroups;
	while (left < right) {
		unsigned int mid = (left+right)/2;
		if (grp > GROUP_AT(group_info, mid))
			left = mid + 1;
		else if (grp < GROUP_AT(group_info, mid))
			right = mid;
		else
			return 1;
	}
	return 0;
}

/**
 * set_groups - Change a group subscription in a set of credentials
 * @new: The newly prepared set of credentials to alter
 * @group_info: The group list to install
 *
 * Validate a group subscription and, if valid, insert it into a set
 * of credentials.
 */
int set_groups(struct cred *new, struct group_info *group_info)
{
	put_group_info(new->group_info);
	groups_sort(group_info);
	get_group_info(group_info);
	new->group_info = group_info;
	return 0;
}

EXPORT_SYMBOL(set_groups);

/**
 * set_current_groups - Change current's group subscription
 * @group_info: The group list to impose
 *
 * Validate a group subscription and, if valid, impose it upon current's task
 * security record.
 */
int set_current_groups(struct group_info *group_info)
{
	struct cred *new;
	int ret;

	new = prepare_creds();
	if (!new)
		return -ENOMEM;

	ret = set_groups(new, group_info);
	if (ret < 0) {
		abort_creds(new);
		return ret;
	}

	return commit_creds(new);
}

EXPORT_SYMBOL(set_current_groups);

SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
{
	const struct cred *cred = current_cred();
	int i;

	if (gidsetsize < 0)
		return -EINVAL;

	/* no need to grab task_lock here; it cannot change */
	i = cred->group_info->ngroups;
	if (gidsetsize) {
		if (i > gidsetsize) {
			i = -EINVAL;
			goto out;
		}
		if (groups_to_user(grouplist, cred->group_info)) {
			i = -EFAULT;
			goto out;
		}
	}
out:
	return i;
}

/*
 *	SMP: Our groups are copy-on-write. We can set them safely
 *	without another task interfering.
 */

SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
{
	struct group_info *group_info;
	int retval;

	if (!capable(CAP_SETGID))
		return -EPERM;
	if ((unsigned)gidsetsize > NGROUPS_MAX)
		return -EINVAL;

	group_info = groups_alloc(gidsetsize);
	if (!group_info)
		return -ENOMEM;
	retval = groups_from_user(group_info, grouplist);
	if (retval) {
		put_group_info(group_info);
		return retval;
	}

	retval = set_current_groups(group_info);
	put_group_info(group_info);

	return retval;
}

/*
 * Check whether we're fsgid/egid or in the supplemental group..
 */
int in_group_p(gid_t grp)
{
	const struct cred *cred = current_cred();
	int retval = 1;

	if (grp != cred->fsgid)
		retval = groups_search(cred->group_info, grp);
	return retval;
}

EXPORT_SYMBOL(in_group_p);

int in_egroup_p(gid_t grp)
{
	const struct cred *cred = current_cred();
	int retval = 1;

	if (grp != cred->egid)
		retval = groups_search(cred->group_info, grp);
	return retval;
}

EXPORT_SYMBOL(in_egroup_p);
Commit	Line	Data
30639b6a AD	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 */
	12	struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
	13
	14	struct 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) + nblockssizeof(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
	43	out_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
	51	EXPORT_SYMBOL(groups_alloc);
	52
	53	void 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
	63	EXPORT_SYMBOL(groups_free);
	64
65	/* export the group_info to a user-space array */
66	static 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 */
86	static 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 */
106	static 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 */
135	int 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;
1c24de60	146	if (grp > GROUP_AT(group_info, mid))
30639b6a	147	left = mid + 1;
1c24de60	148	else if (grp < GROUP_AT(group_info, mid))
30639b6a AD	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	*/
	164	int set_groups(struct cred new, struct group_info group_info)
	165	{
30639b6a AD	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
	173	EXPORT_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	*/
	182	int 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
	200	EXPORT_SYMBOL(set_current_groups);
	201
	202	SYSCALL_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	}
	222	out:
	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
231	SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
232	{
233	struct group_info *group_info;
234	int retval;
235
236	if (!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	*/
259	int 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
269	EXPORT_SYMBOL(in_group_p);
270
271	int 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
281	EXPORT_SYMBOL(in_egroup_p);