freebsd-dev/sys/security/mac/mac_process.c
Tor Egge 3b582b4e72 Eliminate a deadlock when creating snapshots. Blocking vn_start_write() must
be called without any vnode locks held.  Remove calls to vn_start_write() and
vn_finished_write() in vnode_pager_putpages() and add these calls before the
vnode lock is obtained to most of the callers that don't already have them.
2006-03-02 22:13:28 +00:00

679 lines
16 KiB
C

/*-
* Copyright (c) 1999-2002 Robert N. M. Watson
* Copyright (c) 2001 Ilmar S. Habibulin
* Copyright (c) 2001-2003 Networks Associates Technology, Inc.
* Copyright (c) 2005 Samy Al Bahra
* 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.
*
* 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>
__FBSDID("$FreeBSD$");
#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/mutex.h>
#include <sys/mac.h>
#include <sys/proc.h>
#include <sys/sbuf.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 <sys/mac_policy.h>
#include <security/mac/mac_internal.h>
int mac_enforce_process = 1;
SYSCTL_INT(_security_mac, OID_AUTO, enforce_process, CTLFLAG_RW,
&mac_enforce_process, 0, "Enforce MAC policy on inter-process operations");
TUNABLE_INT("security.mac.enforce_process", &mac_enforce_process);
int mac_enforce_vm = 1;
SYSCTL_INT(_security_mac, OID_AUTO, enforce_vm, CTLFLAG_RW,
&mac_enforce_vm, 0, "Enforce MAC policy on vm operations");
TUNABLE_INT("security.mac.enforce_vm", &mac_enforce_vm);
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 int mac_enforce_suid = 1;
SYSCTL_INT(_security_mac, OID_AUTO, enforce_suid, CTLFLAG_RW,
&mac_enforce_suid, 0, "Enforce MAC policy on suid/sgid operations");
TUNABLE_INT("security.mac.enforce_suid", &mac_enforce_suid);
#ifdef MAC_DEBUG
static unsigned int nmaccreds, nmacprocs;
SYSCTL_UINT(_security_mac_debug_counters, OID_AUTO, creds, CTLFLAG_RD,
&nmaccreds, 0, "number of ucreds in use");
SYSCTL_UINT(_security_mac_debug_counters, OID_AUTO, procs, CTLFLAG_RD,
&nmacprocs, 0, "number of procs in use");
#endif
static void mac_cred_mmapped_drop_perms_recurse(struct thread *td,
struct ucred *cred, struct vm_map *map);
struct label *
mac_cred_label_alloc(void)
{
struct label *label;
label = mac_labelzone_alloc(M_WAITOK);
MAC_PERFORM(init_cred_label, label);
MAC_DEBUG_COUNTER_INC(&nmaccreds);
return (label);
}
void
mac_init_cred(struct ucred *cred)
{
cred->cr_label = mac_cred_label_alloc();
}
static struct label *
mac_proc_label_alloc(void)
{
struct label *label;
label = mac_labelzone_alloc(M_WAITOK);
MAC_PERFORM(init_proc_label, label);
MAC_DEBUG_COUNTER_INC(&nmacprocs);
return (label);
}
void
mac_init_proc(struct proc *p)
{
p->p_label = mac_proc_label_alloc();
}
void
mac_cred_label_free(struct label *label)
{
MAC_PERFORM(destroy_cred_label, label);
mac_labelzone_free(label);
MAC_DEBUG_COUNTER_DEC(&nmaccreds);
}
void
mac_destroy_cred(struct ucred *cred)
{
mac_cred_label_free(cred->cr_label);
cred->cr_label = NULL;
}
static void
mac_proc_label_free(struct label *label)
{
MAC_PERFORM(destroy_proc_label, label);
mac_labelzone_free(label);
MAC_DEBUG_COUNTER_DEC(&nmacprocs);
}
void
mac_destroy_proc(struct proc *p)
{
mac_proc_label_free(p->p_label);
p->p_label = NULL;
}
int
mac_externalize_cred_label(struct label *label, char *elements,
char *outbuf, size_t outbuflen)
{
int error;
MAC_EXTERNALIZE(cred, label, elements, outbuf, outbuflen);
return (error);
}
int
mac_internalize_cred_label(struct label *label, char *string)
{
int error;
MAC_INTERNALIZE(cred, label, string);
return (error);
}
/*
* Initialize MAC label for the first kernel process, from which other
* kernel processes and threads are spawned.
*/
void
mac_create_proc0(struct ucred *cred)
{
MAC_PERFORM(create_proc0, cred);
}
/*
* Initialize MAC label for the first userland process, from which other
* userland processes and threads are spawned.
*/
void
mac_create_proc1(struct ucred *cred)
{
MAC_PERFORM(create_proc1, cred);
}
void
mac_thread_userret(struct thread *td)
{
MAC_PERFORM(thread_userret, td);
}
/*
* When a new process is created, its label must be initialized. Generally,
* this involves inheritence from the parent process, modulo possible
* deltas. This function allows that processing to take place.
*/
void
mac_copy_cred(struct ucred *src, struct ucred *dest)
{
MAC_PERFORM(copy_cred_label, src->cr_label, dest->cr_label);
}
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);
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_internalize_cred_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;
}
}
/*
* 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_cred_mmapped_drop_perms(struct thread *td, struct ucred *cred)
{
/* XXX freeze all other threads */
mac_cred_mmapped_drop_perms_recurse(td, cred,
&td->td_proc->p_vmspace->vm_map);
/* XXX allow other threads to continue */
}
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_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred,
struct vm_map *map)
{
struct vm_map_entry *vme;
int vfslocked, 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;
vm_map_lock_read(map);
for (vme = map->header.next; vme != &map->header; vme = vme->next) {
if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) {
mac_cred_mmapped_drop_perms_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_LOCK(object);
while ((backing_object = object->backing_object) != NULL) {
VM_OBJECT_LOCK(backing_object);
offset += object->backing_object_offset;
VM_OBJECT_UNLOCK(object);
object = backing_object;
}
VM_OBJECT_UNLOCK(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;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
result = vme->max_protection;
mac_check_vnode_mmap_downgrade(cred, vp, &result);
VOP_UNLOCK(vp, 0, td);
/*
* Find out what maximum protection we may be allowing
* now but a policy needs to get removed.
*/
revokeperms = vme->max_protection & ~result;
if (!revokeperms) {
VFS_UNLOCK_GIANT(vfslocked);
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));
vm_map_lock_upgrade(map);
/*
* 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, td);
VM_OBJECT_LOCK(object);
vm_object_page_clean(object,
OFF_TO_IDX(offset),
OFF_TO_IDX(offset + vme->end - vme->start +
PAGE_MASK),
OBJPC_SYNC);
VM_OBJECT_UNLOCK(object);
VOP_UNLOCK(vp, 0, td);
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_simplify_entry(map, vme);
}
vm_map_lock_downgrade(map);
VFS_UNLOCK_GIANT(vfslocked);
}
vm_map_unlock_read(map);
}
/*
* When the subject's label changes, it may require revocation of privilege
* to mapped objects. This can't be done on-the-fly later with a unified
* buffer cache.
*/
void
mac_relabel_cred(struct ucred *cred, struct label *newlabel)
{
MAC_PERFORM(relabel_cred, cred, newlabel);
}
int
mac_check_cred_relabel(struct ucred *cred, struct label *newlabel)
{
int error;
MAC_CHECK(check_cred_relabel, cred, newlabel);
return (error);
}
int
mac_check_cred_visible(struct ucred *u1, struct ucred *u2)
{
int error;
if (!mac_enforce_process)
return (0);
MAC_CHECK(check_cred_visible, u1, u2);
return (error);
}
int
mac_check_proc_debug(struct ucred *cred, struct proc *proc)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_process)
return (0);
MAC_CHECK(check_proc_debug, cred, proc);
return (error);
}
int
mac_check_proc_sched(struct ucred *cred, struct proc *proc)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_process)
return (0);
MAC_CHECK(check_proc_sched, cred, proc);
return (error);
}
int
mac_check_proc_signal(struct ucred *cred, struct proc *proc, int signum)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_process)
return (0);
MAC_CHECK(check_proc_signal, cred, proc, signum);
return (error);
}
int
mac_check_proc_setuid(struct proc *proc, struct ucred *cred, uid_t uid)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_suid)
return (0);
MAC_CHECK(check_proc_setuid, cred, uid);
return (error);
}
int
mac_check_proc_seteuid(struct proc *proc, struct ucred *cred, uid_t euid)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_suid)
return (0);
MAC_CHECK(check_proc_seteuid, cred, euid);
return (error);
}
int
mac_check_proc_setgid(struct proc *proc, struct ucred *cred, gid_t gid)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_suid)
return (0);
MAC_CHECK(check_proc_setgid, cred, gid);
return (error);
}
int
mac_check_proc_setegid(struct proc *proc, struct ucred *cred, gid_t egid)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_suid)
return (0);
MAC_CHECK(check_proc_setegid, cred, egid);
return (error);
}
int
mac_check_proc_setgroups(struct proc *proc, struct ucred *cred,
int ngroups, gid_t *gidset)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_suid)
return (0);
MAC_CHECK(check_proc_setgroups, cred, ngroups, gidset);
return (error);
}
int
mac_check_proc_setreuid(struct proc *proc, struct ucred *cred, uid_t ruid,
uid_t euid)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_suid)
return (0);
MAC_CHECK(check_proc_setreuid, cred, ruid, euid);
return (error);
}
int
mac_check_proc_setregid(struct proc *proc, struct ucred *cred, gid_t rgid,
gid_t egid)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_suid)
return (0);
MAC_CHECK(check_proc_setregid, cred, rgid, egid);
return (error);
}
int
mac_check_proc_setresuid(struct proc *proc, struct ucred *cred, uid_t ruid,
uid_t euid, uid_t suid)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_suid)
return (0);
MAC_CHECK(check_proc_setresuid, cred, ruid, euid, suid);
return (error);
}
int
mac_check_proc_setresgid(struct proc *proc, struct ucred *cred, gid_t rgid,
gid_t egid, gid_t sgid)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_suid)
return (0);
MAC_CHECK(check_proc_setresgid, cred, rgid, egid, sgid);
return (error);
}
int
mac_check_proc_wait(struct ucred *cred, struct proc *proc)
{
int error;
PROC_LOCK_ASSERT(proc, MA_OWNED);
if (!mac_enforce_process)
return (0);
MAC_CHECK(check_proc_wait, cred, proc);
return (error);
}