/*-
 * Copyright (c) 1999-2002, 2008-2009 Robert N. M. Watson
 * Copyright (c) 2001 Ilmar S. Habibulin
 * Copyright (c) 2001-2003 Networks Associates Technology, Inc.
 * Copyright (c) 2006 SPARTA, Inc.
 * Copyright (c) 2008 Apple Inc.
 * All rights reserved.
 *
 * This software was developed by Robert Watson and Ilmar Habibulin for the
 * TrustedBSD Project.
 *
 * This software was developed for the FreeBSD Project in part by Network
 * Associates Laboratories, the Security Research Division of Network
 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
 * as part of the DARPA CHATS research program.
 *
 * This software was enhanced by SPARTA ISSO under SPAWAR contract
 * N66001-04-C-6019 ("SEFOS").
 *
 * This software was developed at the University of Cambridge Computer
 * Laboratory with support from a grant from Google, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include "opt_mac.h"

#include <sys/param.h>
#include <sys/condvar.h>
#include <sys/imgact.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mac.h>
#include <sys/proc.h>
#include <sys/rwlock.h>
#include <sys/sbuf.h>
#include <sys/sdt.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/file.h>
#include <sys/namei.h>
#include <sys/sysctl.h>

#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>

#include <security/mac/mac_framework.h>
#include <security/mac/mac_internal.h>
#include <security/mac/mac_policy.h>

static int      mac_mmap_revocation = 1;
SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation, CTLFLAG_RW,
    &mac_mmap_revocation, 0, "Revoke mmap access to files on subject "
    "relabel");

static int      mac_mmap_revocation_via_cow = 0;
SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation_via_cow, CTLFLAG_RW,
    &mac_mmap_revocation_via_cow, 0, "Revoke mmap access to files via "
    "copy-on-write semantics, or by removing all write access");

static void     mac_proc_vm_revoke_recurse(struct thread *td,
                    struct ucred *cred, struct vm_map *map);

static struct label *
mac_proc_label_alloc(void)
{
        struct label *label;

        label = mac_labelzone_alloc(M_WAITOK);
        MAC_POLICY_PERFORM(proc_init_label, label);
        return (label);
}

void
mac_proc_init(struct proc *p)
{

        if (mac_labeled & MPC_OBJECT_PROC)
                p->p_label = mac_proc_label_alloc();
        else
                p->p_label = NULL;
}

static void
mac_proc_label_free(struct label *label)
{

        MAC_POLICY_PERFORM_NOSLEEP(proc_destroy_label, label);
        mac_labelzone_free(label);
}

void
mac_proc_destroy(struct proc *p)
{

        if (p->p_label != NULL) {
                mac_proc_label_free(p->p_label);
                p->p_label = NULL;
        }
}

void
mac_thread_userret(struct thread *td)
{

        MAC_POLICY_PERFORM(thread_userret, td);
}

int
mac_execve_enter(struct image_params *imgp, struct mac *mac_p)
{
        struct label *label;
        struct mac mac;
        char *buffer;
        int error;

        if (mac_p == NULL)
                return (0);

        if (!(mac_labeled & MPC_OBJECT_CRED))
                return (EINVAL);

        error = copyin(mac_p, &mac, sizeof(mac));
        if (error)
                return (error);

        error = mac_check_structmac_consistent(&mac);
        if (error)
                return (error);

        buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK);
        error = copyinstr(mac.m_string, buffer, mac.m_buflen, NULL);
        if (error) {
                free(buffer, M_MACTEMP);
                return (error);
        }

        label = mac_cred_label_alloc();
        error = mac_cred_internalize_label(label, buffer);
        free(buffer, M_MACTEMP);
        if (error) {
                mac_cred_label_free(label);
                return (error);
        }
        imgp->execlabel = label;
        return (0);
}

void
mac_execve_exit(struct image_params *imgp)
{
        if (imgp->execlabel != NULL) {
                mac_cred_label_free(imgp->execlabel);
                imgp->execlabel = NULL;
        }
}

void
mac_execve_interpreter_enter(struct vnode *interpvp,
    struct label **interpvplabel)
{

        if (mac_labeled & MPC_OBJECT_VNODE) {
                *interpvplabel = mac_vnode_label_alloc();
                mac_vnode_copy_label(interpvp->v_label, *interpvplabel);
        } else
                *interpvplabel = NULL;
}

void
mac_execve_interpreter_exit(struct label *interpvplabel)
{

        if (interpvplabel != NULL)
                mac_vnode_label_free(interpvplabel);
}

/*
 * When relabeling a process, call out to the policies for the maximum
 * permission allowed for each object type we know about in its memory space,
 * and revoke access (in the least surprising ways we know) when necessary.
 * The process lock is not held here.
 */
void
mac_proc_vm_revoke(struct thread *td)
{
        struct ucred *cred;

        PROC_LOCK(td->td_proc);
        cred = crhold(td->td_proc->p_ucred);
        PROC_UNLOCK(td->td_proc);

        /* XXX freeze all other threads */
        mac_proc_vm_revoke_recurse(td, cred,
            &td->td_proc->p_vmspace->vm_map);
        /* XXX allow other threads to continue */

        crfree(cred);
}

static __inline const char *
prot2str(vm_prot_t prot)
{

        switch (prot & VM_PROT_ALL) {
        case VM_PROT_READ:
                return ("r--");
        case VM_PROT_READ | VM_PROT_WRITE:
                return ("rw-");
        case VM_PROT_READ | VM_PROT_EXECUTE:
                return ("r-x");
        case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE:
                return ("rwx");
        case VM_PROT_WRITE:
                return ("-w-");
        case VM_PROT_EXECUTE:
                return ("--x");
        case VM_PROT_WRITE | VM_PROT_EXECUTE:
                return ("-wx");
        default:
                return ("---");
        }
}

static void
mac_proc_vm_revoke_recurse(struct thread *td, struct ucred *cred,
    struct vm_map *map)
{
        vm_map_entry_t prev, vme;
        int result;
        vm_prot_t revokeperms;
        vm_object_t backing_object, object;
        vm_ooffset_t offset;
        struct vnode *vp;
        struct mount *mp;

        if (!mac_mmap_revocation)
                return;

        prev = &map->header;
        vm_map_lock(map);
        for (vme = vm_map_entry_first(map); vme != &map->header;
            prev = vme, vme = vm_map_entry_succ(prev)) {
                if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) {
                        mac_proc_vm_revoke_recurse(td, cred,
                            vme->object.sub_map);
                        continue;
                }
                /*
                 * Skip over entries that obviously are not shared.
                 */
                if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) ||
                    !vme->max_protection)
                        continue;
                /*
                 * Drill down to the deepest backing object.
                 */
                offset = vme->offset;
                object = vme->object.vm_object;
                if (object == NULL)
                        continue;
                VM_OBJECT_RLOCK(object);
                while ((backing_object = object->backing_object) != NULL) {
                        VM_OBJECT_RLOCK(backing_object);
                        offset += object->backing_object_offset;
                        VM_OBJECT_RUNLOCK(object);
                        object = backing_object;
                }
                VM_OBJECT_RUNLOCK(object);
                /*
                 * At the moment, vm_maps and objects aren't considered by
                 * the MAC system, so only things with backing by a normal
                 * object (read: vnodes) are checked.
                 */
                if (object->type != OBJT_VNODE)
                        continue;
                vp = (struct vnode *)object->handle;
                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                result = vme->max_protection;
                mac_vnode_check_mmap_downgrade(cred, vp, &result);
                VOP_UNLOCK(vp);
                /*
                 * Find out what maximum protection we may be allowing now
                 * but a policy needs to get removed.
                 */
                revokeperms = vme->max_protection & ~result;
                if (!revokeperms)
                        continue;
                printf("pid %ld: revoking %s perms from %#lx:%ld "
                    "(max %s/cur %s)\n", (long)td->td_proc->p_pid,
                    prot2str(revokeperms), (u_long)vme->start,
                    (long)(vme->end - vme->start),
                    prot2str(vme->max_protection), prot2str(vme->protection));
                /*
                 * This is the really simple case: if a map has more
                 * max_protection than is allowed, but it's not being
                 * actually used (that is, the current protection is still
                 * allowed), we can just wipe it out and do nothing more.
                 */
                if ((vme->protection & revokeperms) == 0) {
                        vme->max_protection -= revokeperms;
                } else {
                        if (revokeperms & VM_PROT_WRITE) {
                                /*
                                 * In the more complicated case, flush out all
                                 * pending changes to the object then turn it
                                 * copy-on-write.
                                 */
                                vm_object_reference(object);
                                (void) vn_start_write(vp, &mp, V_WAIT);
                                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                                VM_OBJECT_WLOCK(object);
                                vm_object_page_clean(object, offset, offset +
                                    vme->end - vme->start, OBJPC_SYNC);
                                VM_OBJECT_WUNLOCK(object);
                                VOP_UNLOCK(vp);
                                vn_finished_write(mp);
                                vm_object_deallocate(object);
                                /*
                                 * Why bother if there's no read permissions
                                 * anymore?  For the rest, we need to leave
                                 * the write permissions on for COW, or
                                 * remove them entirely if configured to.
                                 */
                                if (!mac_mmap_revocation_via_cow) {
                                        vme->max_protection &= ~VM_PROT_WRITE;
                                        vme->protection &= ~VM_PROT_WRITE;
                                } if ((revokeperms & VM_PROT_READ) == 0)
                                        vme->eflags |= MAP_ENTRY_COW |
                                            MAP_ENTRY_NEEDS_COPY;
                        }
                        if (revokeperms & VM_PROT_EXECUTE) {
                                vme->max_protection &= ~VM_PROT_EXECUTE;
                                vme->protection &= ~VM_PROT_EXECUTE;
                        }
                        if (revokeperms & VM_PROT_READ) {
                                vme->max_protection = 0;
                                vme->protection = 0;
                        }
                        pmap_protect(map->pmap, vme->start, vme->end,
                            vme->protection & ~revokeperms);
                        vm_map_try_merge_entries(map, prev, vme);
                }
        }
        vm_map_unlock(map);
}

MAC_CHECK_PROBE_DEFINE2(proc_check_debug, "struct ucred *", "struct proc *");

int
mac_proc_check_debug(struct ucred *cred, struct proc *p)
{
        int error;

        PROC_LOCK_ASSERT(p, MA_OWNED);

        MAC_POLICY_CHECK_NOSLEEP(proc_check_debug, cred, p);
        MAC_CHECK_PROBE2(proc_check_debug, error, cred, p);

        return (error);
}

MAC_CHECK_PROBE_DEFINE2(proc_check_sched, "struct ucred *", "struct proc *");

int
mac_proc_check_sched(struct ucred *cred, struct proc *p)
{
        int error;

        PROC_LOCK_ASSERT(p, MA_OWNED);

        MAC_POLICY_CHECK_NOSLEEP(proc_check_sched, cred, p);
        MAC_CHECK_PROBE2(proc_check_sched, error, cred, p);

        return (error);
}

MAC_CHECK_PROBE_DEFINE3(proc_check_signal, "struct ucred *", "struct proc *",
    "int");

int
mac_proc_check_signal(struct ucred *cred, struct proc *p, int signum)
{
        int error;

        PROC_LOCK_ASSERT(p, MA_OWNED);

        MAC_POLICY_CHECK_NOSLEEP(proc_check_signal, cred, p, signum);
        MAC_CHECK_PROBE3(proc_check_signal, error, cred, p, signum);

        return (error);
}

MAC_CHECK_PROBE_DEFINE2(proc_check_wait, "struct ucred *", "struct proc *");

int
mac_proc_check_wait(struct ucred *cred, struct proc *p)
{
        int error;

        PROC_LOCK_ASSERT(p, MA_OWNED);

        MAC_POLICY_CHECK_NOSLEEP(proc_check_wait, cred, p);
        MAC_CHECK_PROBE2(proc_check_wait, error, cred, p);

        return (error);
}