freebsd-dev/sys/security/lomac/kernel_interface.c

507 lines
13 KiB
C

/*-
* Copyright (c) 2001 Networks Associates Technology, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by NAI Labs, 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.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* 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.
*
* $Id$
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <sys/pipe.h>
#include <sys/socketvar.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include "kernel_interface.h"
#include "lomacfs.h"
#include "kernel_log.h"
/*
* Reuse the eflags field of proc.p_vmspace->vm_map.header (since it is
* currently not used for anything but a placeholder, and won't change
* generally...) as storage for our process-based information.
*
* This is the only really effective way to make thread-based MAC
* easy.
*/
#define p_eflags p_vmspace->vm_map.header.eflags
#define EF_HIGHEST_LEVEL 0x00010000
#define EF_LOWEST_LEVEL 0x00020000
#define EF_LEVEL_MASK 0x00030000
#define EF_ATTR_NONETDEMOTE 0x00040000
#define EF_ATTR_NODEMOTE 0x00080000
#define EF_ATTR_MASK 0x000c0000
static u_int
level2subjectbits(level_t level) {
switch (level) {
case LOMAC_HIGHEST_LEVEL:
return (EF_HIGHEST_LEVEL);
case LOMAC_LOWEST_LEVEL:
return (EF_LOWEST_LEVEL);
default:
panic("level2subjectbits: invalid level %d\n", level);
}
}
static level_t
subjectbits2level(u_int flags) {
switch (flags & EF_LEVEL_MASK) {
case EF_HIGHEST_LEVEL:
/*
* During an execve(), the kernel's original execve() creates a
* new vmspace and puts it into use before it has been initialized
* by us to contain a subject level. Since this is the only case
* when a subject may have a level not set, pretend that it
* is just a high-level file, and allow the lomacfs_open() to then
* succeed.
*/
case 0:
return (LOMAC_HIGHEST_LEVEL);
case EF_LOWEST_LEVEL:
return (LOMAC_LOWEST_LEVEL);
default:
panic("subjectbits2level: invalid flags %#x\n", flags);
}
}
static u_int
attr2subjectbits(u_int attr) {
u_int bits = 0;
if (attr & LOMAC_ATTR_NONETDEMOTE)
bits |= EF_ATTR_NONETDEMOTE;
if (attr & LOMAC_ATTR_NODEMOTE)
bits |= EF_ATTR_NODEMOTE;
return (bits);
}
static u_int
subjectbits2attr(u_int bits) {
u_int attr = 0;
if (bits & EF_ATTR_NONETDEMOTE)
attr |= LOMAC_ATTR_NONETDEMOTE;
if (bits & EF_ATTR_NODEMOTE)
attr |= LOMAC_ATTR_NODEMOTE;
return (attr);
}
static int
subject_lock(lomac_subject_t *p, int read) {
#ifdef USES_LOCKMGR
int hadlock;
hadlock = PROC_LOCKED(p);
if (hadlock)
PROC_UNLOCK(p);
#endif
if (read)
vm_map_lock_read(&p->p_vmspace->vm_map);
else
vm_map_lock(&p->p_vmspace->vm_map);
#ifdef USES_LOCKMGR
return (hadlock);
#else
return (0);
#endif
}
static void
subject_unlock(lomac_subject_t *p, int read, int hadlock) {
if (read)
vm_map_unlock_read(&p->p_vmspace->vm_map);
else
vm_map_unlock(&p->p_vmspace->vm_map);
#ifdef USES_LOCKMGR
if (hadlock)
PROC_LOCK(p);
#endif
}
void
init_subject_lattr(lomac_subject_t *p, lattr_t *lattr) {
int s;
s = subject_lock(p, 0);
p->p_eflags = level2subjectbits(lattr->level) |
attr2subjectbits(lattr->flags);
subject_unlock(p, 0, s);
}
/*
* Set/get the subject level on a process. The process must not be able
* to change, so either the process must be locked on entry or it must
* be held in exclusivity otherwise (executing on behalf of via a syscall,
* including as EITHER child or parent in a fork).
*/
void
set_subject_lattr(lomac_subject_t *p, lattr_t lattr) {
int s;
#ifdef INVARIANTS
do {
lattr_t oslattr;
get_subject_lattr(p, &oslattr);
if (lomac_must_demote(&lattr, &oslattr))
panic("raising subject level");
} while (0);
#endif /* !INVARIANTS */
s = subject_lock(p, 0);
p->p_eflags = (p->p_eflags & ~(EF_LEVEL_MASK | EF_ATTR_MASK)) |
level2subjectbits(lattr.level) |
attr2subjectbits(lattr.flags);
subject_unlock(p, 0, s);
kernel_vm_drop_perms(curthread, &lattr);
}
void
get_subject_lattr(lomac_subject_t *p, lattr_t *lattr) {
int s;
s = subject_lock(p, 1);
lattr->level = subjectbits2level(p->p_eflags);
lattr->flags = subjectbits2attr(p->p_eflags);
subject_unlock(p, 1, s);
}
static __inline u_int
level2lvnodebits(level_t level) {
switch (level) {
case LOMAC_HIGHEST_LEVEL:
return (LN_HIGHEST_LEVEL);
case LOMAC_LOWEST_LEVEL:
return (LN_LOWEST_LEVEL);
default:
panic("level2lvnodebits: invalid level %d\n", level);
}
}
static __inline level_t
lvnodebits2level(u_int flags) {
switch (flags & LN_LEVEL_MASK) {
case LN_HIGHEST_LEVEL:
return (LOMAC_HIGHEST_LEVEL);
case LN_LOWEST_LEVEL:
return (LOMAC_LOWEST_LEVEL);
default:
panic("lvnodebits2level: invalid flags %#x\n", flags);
}
}
static __inline unsigned int
attr2lvnodebits(unsigned int attr) {
unsigned int bits = 0;
if (attr & LOMAC_ATTR_LOWWRITE)
bits |= LN_ATTR_LOWWRITE;
if (attr & LOMAC_ATTR_LOWNOOPEN)
bits |= LN_ATTR_LOWNOOPEN;
if (attr & LOMAC_ATTR_NONETDEMOTE)
bits |= LN_ATTR_NONETDEMOTE;
if (attr & LOMAC_ATTR_NODEMOTE)
bits |= LN_ATTR_NODEMOTE;
return (bits);
}
static __inline unsigned int
lvnodebits2attr(unsigned int bits) {
unsigned int attr = 0;
if (bits & LN_ATTR_LOWWRITE)
attr |= LOMAC_ATTR_LOWWRITE;
if (bits & LN_ATTR_LOWNOOPEN)
attr |= LOMAC_ATTR_LOWNOOPEN;
if (bits & LN_ATTR_NONETDEMOTE)
attr |= LOMAC_ATTR_NONETDEMOTE;
if (bits & LN_ATTR_NODEMOTE)
attr |= LOMAC_ATTR_NODEMOTE;
return (attr);
}
/*
* These flags correspond to the same ones set in lomac_node{}s.
*/
#define UV_LEVEL_MASK 0x08000000
#define UV_LOWEST_LEVEL 0x00000000
#define UV_HIGHEST_LEVEL 0x08000000
#define UV_ATTR_LOWWRITE 0x10000000
#define UV_ATTR_LOWNOOPEN 0x20000000
#define UV_ATTR_NONETDEMOTE 0x40000000
#define UV_ATTR_NODEMOTE 0x80000000
#define UV_ATTR_MASK 0xf0000000
static __inline u_int
level2uvnodebits(level_t level) {
switch (level) {
case LOMAC_HIGHEST_LEVEL:
return (UV_HIGHEST_LEVEL);
case LOMAC_LOWEST_LEVEL:
return (UV_LOWEST_LEVEL);
default:
panic("level2uvnodebits: invalid level %d\n", level);
}
}
static __inline level_t
uvnodebits2level(u_int flags) {
switch (flags & UV_LEVEL_MASK) {
case UV_HIGHEST_LEVEL:
return (LOMAC_HIGHEST_LEVEL);
case UV_LOWEST_LEVEL:
return (LOMAC_LOWEST_LEVEL);
default:
panic("uvnodebits2level: invalid flags %#x\n", flags);
}
}
static __inline u_int
attr2uvnodebits(u_int attr) {
unsigned int bits = 0;
if (attr & LOMAC_ATTR_LOWWRITE)
bits |= UV_ATTR_LOWWRITE;
if (attr & LOMAC_ATTR_LOWNOOPEN)
bits |= UV_ATTR_LOWNOOPEN;
if (attr & LOMAC_ATTR_NONETDEMOTE)
bits |= UV_ATTR_NONETDEMOTE;
if (attr & LOMAC_ATTR_NODEMOTE)
bits |= UV_ATTR_NODEMOTE;
return (bits);
}
static __inline u_int
uvnodebits2attr(u_int bits) {
unsigned int attr = 0;
if (bits & UV_ATTR_LOWWRITE)
attr |= LOMAC_ATTR_LOWWRITE;
if (bits & UV_ATTR_LOWNOOPEN)
attr |= LOMAC_ATTR_LOWNOOPEN;
if (bits & UV_ATTR_NONETDEMOTE)
attr |= LOMAC_ATTR_NONETDEMOTE;
if (bits & UV_ATTR_NODEMOTE)
attr |= LOMAC_ATTR_NODEMOTE;
return (attr);
}
#define OBJ_LOWEST_LEVEL 0x8000 /* the highest level is implicit */
/*
* This code marks pipes with levels. We use a previously unnused bit
* in the pipe_state field of struct pipe to store the level
* information. Bit clear means LOMAC_HIGHEST_LEVEL, bit set means
* LOMAC_LOWEST_LEVEL. Since new pipes have clear bits by default,
* using clear bit as highest causes new pipes to start at the highest
* level automatically.
*/
#define PIPE_LEVEL_LOWEST 0x10000000
/* This code marks sockets created by socketpair() with levels. It
* uses a previouslt unused bit in the so_state field of struct socket
* to store the level information. Bit clear means
* LOMAC_HIGHEST_LEVEL, bit set means LOMAC_LOWEST_LEVEL. Since new
* sockets have clear bits by default, using clear bit as highest
* causes new sockets to start at the highest level automatically.
*/
#define SOCKET_LEVEL_LOWEST 0x4000
void
set_object_lattr(lomac_object_t *obj, lattr_t lattr) {
struct vnode *vp;
struct lomac_node *ln;
vm_object_t object;
struct pipe *pipe;
struct socket *socket;
switch (obj->lo_type) {
case LO_TYPE_LVNODE:
KASSERT(VISLOMAC(obj->lo_object.vnode),
("not a LOMACFS vnode"));
ln = VTOLOMAC(obj->lo_object.vnode);
ln->ln_flags =
(ln->ln_flags & ~(LN_LEVEL_MASK | LN_ATTR_MASK)) |
level2lvnodebits(lattr.level) |
attr2lvnodebits(lattr.flags);
break;
case LO_TYPE_UVNODE:
vp = obj->lo_object.vnode;
KASSERT(!VISLOMAC(vp), ("is a LOMACFS vnode"));
VI_LOCK(vp);
vp->v_flag = (vp->v_flag & ~(UV_LEVEL_MASK | UV_ATTR_MASK)) |
level2uvnodebits(lattr.level) |
attr2uvnodebits(lattr.flags);
VI_UNLOCK(vp);
break;
case LO_TYPE_VM_OBJECT:
object = obj->lo_object.vm_object;
KASSERT(object->type != OBJT_VNODE, ("object has a vnode"));
KASSERT(object->backing_object == NULL,
("is a backing object"));
if (lattr.level == LOMAC_HIGHEST_LEVEL)
vm_object_clear_flag(object, OBJ_LOWEST_LEVEL);
else
vm_object_set_flag(object, OBJ_LOWEST_LEVEL);
KASSERT(lattr.flags == 0,
("cannot set attr on a vm_object"));
break;
case LO_TYPE_PIPE:
pipe = obj->lo_object.pipe;
KASSERT(pipe->pipe_peer == NULL ||
(pipe->pipe_state & PIPE_LEVEL_LOWEST) ==
(pipe->pipe_peer->pipe_state & PIPE_LEVEL_LOWEST),
("pipe attrs unsynchronized"));
if (lattr.level == LOMAC_HIGHEST_LEVEL)
pipe->pipe_state &= ~PIPE_LEVEL_LOWEST;
else
pipe->pipe_state |= PIPE_LEVEL_LOWEST;
pipe = pipe->pipe_peer;
if (pipe != NULL) {
if (lattr.level == LOMAC_HIGHEST_LEVEL)
pipe->pipe_state &= ~PIPE_LEVEL_LOWEST;
else
pipe->pipe_state |= PIPE_LEVEL_LOWEST;
}
KASSERT(lattr.flags == 0, ("cannot set attr on a pipe"));
break;
case LO_TYPE_SOCKETPAIR:
socket = obj->lo_object.socket;
/* KASSERT that socket peer levels are synchronized */
if (lattr.level == LOMAC_HIGHEST_LEVEL)
socket->so_state &= ~SOCKET_LEVEL_LOWEST;
else
socket->so_state |= SOCKET_LEVEL_LOWEST;
#ifdef NOT_YET
pipe = pipe->pipe_peer;
if (pipe != NULL) {
if (lattr.level == LOMAC_HIGHEST_LEVEL)
pipe->pipe_state &= ~PIPE_LEVEL_LOWEST;
else
pipe->pipe_state |= PIPE_LEVEL_LOWEST;
}
KASSERT(lattr.flags == 0, ("cannot set attr on a pipe"));
#endif
break;
default:
panic("set_object_lattr: invalid lo_type %d", obj->lo_type);
}
}
void
get_object_lattr(const lomac_object_t *obj, lattr_t *lattr) {
struct vnode *vp;
struct lomac_node *ln;
vm_object_t object;
struct pipe *pipe;
struct socket *socket;
switch (obj->lo_type) {
case LO_TYPE_LVNODE:
KASSERT(VISLOMAC(obj->lo_object.vnode),
("not a LOMACFS vnode"));
ln = VTOLOMAC(obj->lo_object.vnode);
lattr->level = lvnodebits2level(ln->ln_flags);
lattr->flags = lvnodebits2attr(ln->ln_flags);
break;
case LO_TYPE_UVNODE:
vp = obj->lo_object.vnode;
KASSERT(!VISLOMAC(vp), ("is a LOMACFS vnode"));
VI_LOCK(vp);
lattr->level = uvnodebits2level(vp->v_flag);
lattr->flags = uvnodebits2attr(vp->v_flag);
VI_UNLOCK(vp);
break;
case LO_TYPE_VM_OBJECT:
object = obj->lo_object.vm_object;
KASSERT(object->type != OBJT_VNODE, ("object has a vnode"));
KASSERT(object->backing_object == NULL,
("is a backing object"));
lattr->level = (object->flags & OBJ_LOWEST_LEVEL) ?
LOMAC_LOWEST_LEVEL : LOMAC_HIGHEST_LEVEL;
lattr->flags = 0;
break;
case LO_TYPE_PIPE:
pipe = obj->lo_object.pipe;
lattr->level = (pipe->pipe_state & PIPE_LEVEL_LOWEST) ?
LOMAC_LOWEST_LEVEL : LOMAC_HIGHEST_LEVEL;
lattr->flags = 0;
break;
case LO_TYPE_SOCKETPAIR:
socket = obj->lo_object.socket;
lattr->level = (socket->so_state & SOCKET_LEVEL_LOWEST) ?
LOMAC_LOWEST_LEVEL : LOMAC_HIGHEST_LEVEL;
lattr->flags = 0;
break;
default:
panic("get_object_level: invalid lo_type %d", obj->lo_type);
}
}
/*
* Flag certain procs, like init(8) and kthreads, as "invincible".
*/
int
subject_do_not_demote(lomac_subject_t *subj) {
int inv = 0;
if (subj->p_pid == 1) {
inv = 1;
} else {
int had_lock = PROC_LOCKED(subj);
if (!had_lock)
PROC_LOCK(subj);
if (subj->p_flag & P_SYSTEM)
inv = 1;
if (!had_lock)
PROC_UNLOCK(subj);
}
return (inv);
}