uid16.c

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/*
 *  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/syscalls.h>

#include <asm/uaccess.h>

SYSCALL_DEFINE3(chown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
{
    long ret = sys_chown(filename, low2highuid(user), low2highgid(group));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(3, ret, filename, user, group);
    return ret;
}

SYSCALL_DEFINE3(lchown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
{
    long ret = sys_lchown(filename, low2highuid(user), low2highgid(group));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(3, ret, filename, user, group);
    return ret;
}

SYSCALL_DEFINE3(fchown16, unsigned int, fd, old_uid_t, user, old_gid_t, group)
{
    long ret = sys_fchown(fd, low2highuid(user), low2highgid(group));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(3, ret, fd, user, group);
    return ret;
}

SYSCALL_DEFINE2(setregid16, old_gid_t, rgid, old_gid_t, egid)
{
    long ret = sys_setregid(low2highgid(rgid), low2highgid(egid));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(2, ret, rgid, egid);
    return ret;
}

SYSCALL_DEFINE1(setgid16, old_gid_t, gid)
{
    long ret = sys_setgid(low2highgid(gid));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(1, ret, gid);
    return ret;
}

SYSCALL_DEFINE2(setreuid16, old_uid_t, ruid, old_uid_t, euid)
{
    long ret = sys_setreuid(low2highuid(ruid), low2highuid(euid));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(2, ret, ruid, euid);
    return ret;
}

SYSCALL_DEFINE1(setuid16, old_uid_t, uid)
{
    long ret = sys_setuid(low2highuid(uid));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(1, ret, uid);
    return ret;
}

SYSCALL_DEFINE3(setresuid16, old_uid_t, ruid, old_uid_t, euid, old_uid_t, suid)
{
    long ret = sys_setresuid(low2highuid(ruid), low2highuid(euid),
                 low2highuid(suid));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(3, ret, ruid, euid, suid);
    return ret;
}

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)
{
    long ret = sys_setresgid(low2highgid(rgid), low2highgid(egid),
                 low2highgid(sgid));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(3, ret, rgid, egid, sgid);
    return ret;
}


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)
{
    long ret = sys_setfsuid(low2highuid(uid));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(1, ret, uid);
    return ret;
}

SYSCALL_DEFINE1(setfsgid16, old_gid_t, gid)
{
    long ret = sys_setfsgid(low2highgid(gid));
    /* avoid REGPARM breakage on x86: */
    asmlinkage_protect(1, ret, gid);
    return ret;
}

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_AT(group_info, 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_AT(group_info, 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 (!nsown_capable(CAP_SETGID))
        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;
    }

    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()));
}