// SPDX-License-Identifier: GPL-2.0/* * Supplementary group IDs */#include <linux/cred.h>#include <linux/export.h>#include <linux/slab.h>#include <linux/security.h>#include <linux/sort.h>#include <linux/syscalls.h>#include <linux/user_namespace.h>#include <linux/vmalloc.h>#include <linux/uaccess.h> struct group_info *groups_alloc(int gidsetsize){	struct group_info *gi;	unsigned int len; 	len = sizeof(struct group_info) + sizeof(kgid_t) * gidsetsize;	gi = kmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_NOWARN|__GFP_NORETRY);	if (!gi)		gi = __vmalloc(len, GFP_KERNEL_ACCOUNT, PAGE_KERNEL);	if (!gi)		return NULL; 	atomic_set(&gi->usage, 1);	gi->ngroups = gidsetsize;	return gi;} EXPORT_SYMBOL(groups_alloc); void groups_free(struct group_info *group_info){	kvfree(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){	struct user_namespace *user_ns = current_user_ns();	int i;	unsigned int count = group_info->ngroups; 	for (i = 0; i < count; i++) {		gid_t gid;		gid = from_kgid_munged(user_ns, group_info->gid[i]);		if (put_user(gid, grouplist+i))			return -EFAULT;	}	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){	struct user_namespace *user_ns = current_user_ns();	int i;	unsigned int count = group_info->ngroups; 	for (i = 0; i < count; i++) {		gid_t gid;		kgid_t kgid;		if (get_user(gid, grouplist+i))			return -EFAULT; 		kgid = make_kgid(user_ns, gid);		if (!gid_valid(kgid))			return -EINVAL; 		group_info->gid[i] = kgid;	}	return 0;} static int gid_cmp(const void *_a, const void *_b){	kgid_t a = *(kgid_t *)_a;	kgid_t b = *(kgid_t *)_b; 	return gid_gt(a, b) - gid_lt(a, b);} void groups_sort(struct group_info *group_info){	sort(group_info->gid, group_info->ngroups, sizeof(*group_info->gid),	     gid_cmp, NULL);}EXPORT_SYMBOL(groups_sort); /* a simple bsearch */int groups_search(const struct group_info *group_info, kgid_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 (gid_gt(grp, group_info->gid[mid]))			left = mid + 1;		else if (gid_lt(grp, group_info->gid[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 */void set_groups(struct cred *new, struct group_info *group_info){	put_group_info(new->group_info);	get_group_info(group_info);	new->group_info = group_info;} 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; 	new = prepare_creds();	if (!new)		return -ENOMEM; 	set_groups(new, group_info);	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;} bool may_setgroups(void){	struct user_namespace *user_ns = current_user_ns(); 	return ns_capable(user_ns, CAP_SETGID) &&		userns_may_setgroups(user_ns);} /* *	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 (!may_setgroups())		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;	} 	groups_sort(group_info);	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(kgid_t grp){	const struct cred *cred = current_cred();	int retval = 1; 	if (!gid_eq(grp, cred->fsgid))		retval = groups_search(cred->group_info, grp);	return retval;} EXPORT_SYMBOL(in_group_p); int in_egroup_p(kgid_t grp){	const struct cred *cred = current_cred();	int retval = 1; 	if (!gid_eq(grp, cred->egid))		retval = groups_search(cred->group_info, grp);	return retval;} EXPORT_SYMBOL(in_egroup_p);