kernel/groups.c

Source file repositories/reference/linux-study-clean/kernel/groups.c

File Facts

System
Linux kernel
Corpus path
kernel/groups.c
Extension
.c
Size
5079 bytes
Lines
250
Domain
Core OS
Bucket
Scheduler, Processes, Timers, Sync, And Syscalls
Inferred role
Core OS: syscall or user/kernel boundary
Status
core implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

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_setid(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);

Annotation

Implementation Notes