linux-hardened/kernel/uid16.c
Dominik Brodowski 55731b3cda fs: add do_fchownat(), ksys_fchown() helpers and ksys_{,l}chown() wrappers
Using the fs-interal do_fchownat() wrapper allows us to get rid of
fs-internal calls to the sys_fchownat() syscall.

Introducing the ksys_fchown() helper and the ksys_{,}chown() wrappers
allows us to avoid the in-kernel calls to the sys_{,l,f}chown() syscalls.
The ksys_ prefix denotes that these functions are meant as a drop-in
replacement for the syscalls. In particular, they use the same calling
convention as sys_{,l,f}chown().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02 20:15:59 +02:00

221 lines
5.1 KiB
C

// 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>
#include "uid16.h"
SYSCALL_DEFINE3(chown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
{
return ksys_chown(filename, low2highuid(user), low2highgid(group));
}
SYSCALL_DEFINE3(lchown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
{
return ksys_lchown(filename, low2highuid(user), low2highgid(group));
}
SYSCALL_DEFINE3(fchown16, unsigned int, fd, old_uid_t, user, old_gid_t, group)
{
return ksys_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()));
}