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 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 (!nsown_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;
 
 }

KUKURU3 Media and press kit

About

KUKURU3 is an indie developer situated in Belgrade. He is shrouded in mystery, as are most of his coding decisions.

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Currently working on Panzerwehr 1949, with multiple other prototypes in the work. All other games are temporarily on hold until Panzerwehr 1949 sees the light of day

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