// SPDX-License-Identifier: GPL-2.0
/*
 *      Wrapper functions for 16bit uid back compatibility. All nicely tied
 *      together in the faint hope we can take the out in five years time.
 */

#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/prctl.h>
#include <linux/capability.h>
#include <linux/init.h>
#include <linux/highuid.h>
#include <linux/security.h>
#include <linux/cred.h>
#include <linux/syscalls.h>

#include <linux/uaccess.h>

SYSCALL_DEFINE3(chown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
{
        return sys_chown(filename, low2highuid(user), low2highgid(group));
}

SYSCALL_DEFINE3(lchown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
{
        return sys_lchown(filename, low2highuid(user), low2highgid(group));
}

SYSCALL_DEFINE3(fchown16, unsigned int, fd, old_uid_t, user, old_gid_t, group)
{
        return sys_fchown(fd, low2highuid(user), low2highgid(group));
}

SYSCALL_DEFINE2(setregid16, old_gid_t, rgid, old_gid_t, egid)
{
        return sys_setregid(low2highgid(rgid), low2highgid(egid));
}

SYSCALL_DEFINE1(setgid16, old_gid_t, gid)
{
        return sys_setgid(low2highgid(gid));
}

SYSCALL_DEFINE2(setreuid16, old_uid_t, ruid, old_uid_t, euid)
{
        return sys_setreuid(low2highuid(ruid), low2highuid(euid));
}

SYSCALL_DEFINE1(setuid16, old_uid_t, uid)
{
        return sys_setuid(low2highuid(uid));
}

SYSCALL_DEFINE3(setresuid16, old_uid_t, ruid, old_uid_t, euid, old_uid_t, suid)
{
        return sys_setresuid(low2highuid(ruid), low2highuid(euid),
                                 low2highuid(suid));
}

SYSCALL_DEFINE3(getresuid16, old_uid_t __user *, ruidp, old_uid_t __user *, euidp, old_uid_t __user *, suidp)
{
        const struct cred *cred = current_cred();
        int retval;
        old_uid_t ruid, euid, suid;

        ruid = high2lowuid(from_kuid_munged(cred->user_ns, cred->uid));
        euid = high2lowuid(from_kuid_munged(cred->user_ns, cred->euid));
        suid = high2lowuid(from_kuid_munged(cred->user_ns, cred->suid));

        if (!(retval   = put_user(ruid, ruidp)) &&
            !(retval   = put_user(euid, euidp)))
                retval = put_user(suid, suidp);

        return retval;
}

SYSCALL_DEFINE3(setresgid16, old_gid_t, rgid, old_gid_t, egid, old_gid_t, sgid)
{
        return sys_setresgid(low2highgid(rgid), low2highgid(egid),
                                 low2highgid(sgid));
}


SYSCALL_DEFINE3(getresgid16, old_gid_t __user *, rgidp, old_gid_t __user *, egidp, old_gid_t __user *, sgidp)
{
        const struct cred *cred = current_cred();
        int retval;
        old_gid_t rgid, egid, sgid;

        rgid = high2lowgid(from_kgid_munged(cred->user_ns, cred->gid));
        egid = high2lowgid(from_kgid_munged(cred->user_ns, cred->egid));
        sgid = high2lowgid(from_kgid_munged(cred->user_ns, cred->sgid));

        if (!(retval   = put_user(rgid, rgidp)) &&
            !(retval   = put_user(egid, egidp)))
                retval = put_user(sgid, sgidp);

        return retval;
}

SYSCALL_DEFINE1(setfsuid16, old_uid_t, uid)
{
        return sys_setfsuid(low2highuid(uid));
}

SYSCALL_DEFINE1(setfsgid16, old_gid_t, gid)
{
        return sys_setfsgid(low2highgid(gid));
}

static int groups16_to_user(old_gid_t __user *grouplist,
    struct group_info *group_info)
{
        struct user_namespace *user_ns = current_user_ns();
        int i;
        old_gid_t group;
        kgid_t kgid;

        for (i = 0; i < group_info->ngroups; i++) {
                kgid = group_info->gid[i];
                group = high2lowgid(from_kgid_munged(user_ns, kgid));
                if (put_user(group, grouplist+i))
                        return -EFAULT;
        }

        return 0;
}

static int groups16_from_user(struct group_info *group_info,
    old_gid_t __user *grouplist)
{
        struct user_namespace *user_ns = current_user_ns();
        int i;
        old_gid_t group;
        kgid_t kgid;

        for (i = 0; i < group_info->ngroups; i++) {
                if (get_user(group, grouplist+i))
                        return  -EFAULT;

                kgid = make_kgid(user_ns, low2highgid(group));
                if (!gid_valid(kgid))
                        return -EINVAL;

                group_info->gid[i] = kgid;
        }

        return 0;
}

SYSCALL_DEFINE2(getgroups16, int, gidsetsize, old_gid_t __user *, grouplist)
{
        const struct cred *cred = current_cred();
        int i;

        if (gidsetsize < 0)
                return -EINVAL;

        i = cred->group_info->ngroups;
        if (gidsetsize) {
                if (i > gidsetsize) {
                        i = -EINVAL;
                        goto out;
                }
                if (groups16_to_user(grouplist, cred->group_info)) {
                        i = -EFAULT;
                        goto out;
                }
        }
out:
        return i;
}

SYSCALL_DEFINE2(setgroups16, int, gidsetsize, old_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 = groups16_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;
}

SYSCALL_DEFINE0(getuid16)
{
        return high2lowuid(from_kuid_munged(current_user_ns(), current_uid()));
}

SYSCALL_DEFINE0(geteuid16)
{
        return high2lowuid(from_kuid_munged(current_user_ns(), current_euid()));
}

SYSCALL_DEFINE0(getgid16)
{
        return high2lowgid(from_kgid_munged(current_user_ns(), current_gid()));
}

SYSCALL_DEFINE0(getegid16)
{
        return high2lowgid(from_kgid_munged(current_user_ns(), current_egid()));
}