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![Dominik Brodowski](/assets/img/avatar_default.png)
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>
221 lines
5.1 KiB
C
221 lines
5.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Wrapper functions for 16bit uid back compatibility. All nicely tied
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* together in the faint hope we can take the out in five years time.
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*/
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/notifier.h>
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#include <linux/reboot.h>
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#include <linux/prctl.h>
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#include <linux/capability.h>
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#include <linux/init.h>
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#include <linux/highuid.h>
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#include <linux/security.h>
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#include <linux/cred.h>
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#include <linux/syscalls.h>
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#include <linux/uaccess.h>
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#include "uid16.h"
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SYSCALL_DEFINE3(chown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
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{
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return ksys_chown(filename, low2highuid(user), low2highgid(group));
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}
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SYSCALL_DEFINE3(lchown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
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{
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return ksys_lchown(filename, low2highuid(user), low2highgid(group));
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}
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SYSCALL_DEFINE3(fchown16, unsigned int, fd, old_uid_t, user, old_gid_t, group)
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{
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return ksys_fchown(fd, low2highuid(user), low2highgid(group));
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}
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SYSCALL_DEFINE2(setregid16, old_gid_t, rgid, old_gid_t, egid)
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{
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return __sys_setregid(low2highgid(rgid), low2highgid(egid));
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}
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SYSCALL_DEFINE1(setgid16, old_gid_t, gid)
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{
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return __sys_setgid(low2highgid(gid));
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}
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SYSCALL_DEFINE2(setreuid16, old_uid_t, ruid, old_uid_t, euid)
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{
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return __sys_setreuid(low2highuid(ruid), low2highuid(euid));
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}
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SYSCALL_DEFINE1(setuid16, old_uid_t, uid)
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{
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return __sys_setuid(low2highuid(uid));
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}
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SYSCALL_DEFINE3(setresuid16, old_uid_t, ruid, old_uid_t, euid, old_uid_t, suid)
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{
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return __sys_setresuid(low2highuid(ruid), low2highuid(euid),
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low2highuid(suid));
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}
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SYSCALL_DEFINE3(getresuid16, old_uid_t __user *, ruidp, old_uid_t __user *, euidp, old_uid_t __user *, suidp)
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{
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const struct cred *cred = current_cred();
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int retval;
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old_uid_t ruid, euid, suid;
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ruid = high2lowuid(from_kuid_munged(cred->user_ns, cred->uid));
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euid = high2lowuid(from_kuid_munged(cred->user_ns, cred->euid));
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suid = high2lowuid(from_kuid_munged(cred->user_ns, cred->suid));
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if (!(retval = put_user(ruid, ruidp)) &&
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!(retval = put_user(euid, euidp)))
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retval = put_user(suid, suidp);
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return retval;
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}
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SYSCALL_DEFINE3(setresgid16, old_gid_t, rgid, old_gid_t, egid, old_gid_t, sgid)
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{
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return __sys_setresgid(low2highgid(rgid), low2highgid(egid),
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low2highgid(sgid));
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}
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SYSCALL_DEFINE3(getresgid16, old_gid_t __user *, rgidp, old_gid_t __user *, egidp, old_gid_t __user *, sgidp)
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{
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const struct cred *cred = current_cred();
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int retval;
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old_gid_t rgid, egid, sgid;
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rgid = high2lowgid(from_kgid_munged(cred->user_ns, cred->gid));
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egid = high2lowgid(from_kgid_munged(cred->user_ns, cred->egid));
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sgid = high2lowgid(from_kgid_munged(cred->user_ns, cred->sgid));
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if (!(retval = put_user(rgid, rgidp)) &&
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!(retval = put_user(egid, egidp)))
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retval = put_user(sgid, sgidp);
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return retval;
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}
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SYSCALL_DEFINE1(setfsuid16, old_uid_t, uid)
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{
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return __sys_setfsuid(low2highuid(uid));
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}
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SYSCALL_DEFINE1(setfsgid16, old_gid_t, gid)
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{
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return __sys_setfsgid(low2highgid(gid));
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}
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static int groups16_to_user(old_gid_t __user *grouplist,
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struct group_info *group_info)
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{
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struct user_namespace *user_ns = current_user_ns();
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int i;
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old_gid_t group;
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kgid_t kgid;
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for (i = 0; i < group_info->ngroups; i++) {
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kgid = group_info->gid[i];
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group = high2lowgid(from_kgid_munged(user_ns, kgid));
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if (put_user(group, grouplist+i))
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return -EFAULT;
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}
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return 0;
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}
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static int groups16_from_user(struct group_info *group_info,
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old_gid_t __user *grouplist)
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{
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struct user_namespace *user_ns = current_user_ns();
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int i;
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old_gid_t group;
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kgid_t kgid;
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for (i = 0; i < group_info->ngroups; i++) {
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if (get_user(group, grouplist+i))
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return -EFAULT;
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kgid = make_kgid(user_ns, low2highgid(group));
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if (!gid_valid(kgid))
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return -EINVAL;
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group_info->gid[i] = kgid;
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}
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return 0;
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}
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SYSCALL_DEFINE2(getgroups16, int, gidsetsize, old_gid_t __user *, grouplist)
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{
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const struct cred *cred = current_cred();
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int i;
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if (gidsetsize < 0)
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return -EINVAL;
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i = cred->group_info->ngroups;
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if (gidsetsize) {
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if (i > gidsetsize) {
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i = -EINVAL;
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goto out;
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}
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if (groups16_to_user(grouplist, cred->group_info)) {
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i = -EFAULT;
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goto out;
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}
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}
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out:
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return i;
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}
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SYSCALL_DEFINE2(setgroups16, int, gidsetsize, old_gid_t __user *, grouplist)
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{
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struct group_info *group_info;
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int retval;
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if (!may_setgroups())
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return -EPERM;
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if ((unsigned)gidsetsize > NGROUPS_MAX)
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return -EINVAL;
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group_info = groups_alloc(gidsetsize);
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if (!group_info)
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return -ENOMEM;
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retval = groups16_from_user(group_info, grouplist);
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if (retval) {
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put_group_info(group_info);
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return retval;
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}
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groups_sort(group_info);
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retval = set_current_groups(group_info);
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put_group_info(group_info);
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return retval;
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}
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SYSCALL_DEFINE0(getuid16)
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{
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return high2lowuid(from_kuid_munged(current_user_ns(), current_uid()));
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}
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SYSCALL_DEFINE0(geteuid16)
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{
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return high2lowuid(from_kuid_munged(current_user_ns(), current_euid()));
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}
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SYSCALL_DEFINE0(getgid16)
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{
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return high2lowgid(from_kgid_munged(current_user_ns(), current_gid()));
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}
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SYSCALL_DEFINE0(getegid16)
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{
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return high2lowgid(from_kgid_munged(current_user_ns(), current_egid()));
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}
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