/* $NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem Exp $ */
/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 2019 Gleb Smirnoff <glebius@FreeBSD.org>
* Copyright (c) 1996 Matthew R. Green
* All rights reserved.
*
* 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 ``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 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/param.h>
#include <sys/conf.h>
#include <sys/kernel.h>
#include <sys/epoch.h>
#include <sys/errno.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/ucred.h>
#include <sys/jail.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/pfil.h>
static MALLOC_DEFINE(M_PFIL, "pfil", "pfil(9) packet filter hooks");
static int pfil_ioctl(struct cdev *, u_long, caddr_t, int, struct thread *);
static struct cdevsw pfil_cdevsw = {
.d_ioctl = pfil_ioctl,
.d_name = PFILDEV,
.d_version = D_VERSION,
};
static struct cdev *pfil_dev;
static struct mtx pfil_lock;
MTX_SYSINIT(pfil_mtxinit, &pfil_lock, "pfil(9) lock", MTX_DEF);
#define PFIL_LOCK() mtx_lock(&pfil_lock)
#define PFIL_UNLOCK() mtx_unlock(&pfil_lock)
#define PFIL_LOCK_ASSERT() mtx_assert(&pfil_lock, MA_OWNED)
struct pfil_hook {
pfil_mbuf_chk_t hook_mbuf_chk;
pfil_mem_chk_t hook_mem_chk;
void *hook_ruleset;
int hook_flags;
int hook_links;
enum pfil_types hook_type;
const char *hook_modname;
const char *hook_rulname;
LIST_ENTRY(pfil_hook) hook_list;
};
struct pfil_link {
CK_STAILQ_ENTRY(pfil_link) link_chain;
pfil_mbuf_chk_t link_mbuf_chk;
pfil_mem_chk_t link_mem_chk;
void *link_ruleset;
int link_flags;
struct pfil_hook *link_hook;
struct epoch_context link_epoch_ctx;
};
typedef CK_STAILQ_HEAD(pfil_chain, pfil_link) pfil_chain_t;
struct pfil_head {
int head_nhooksin;
int head_nhooksout;
pfil_chain_t head_in;
pfil_chain_t head_out;
int head_flags;
enum pfil_types head_type;
LIST_ENTRY(pfil_head) head_list;
const char *head_name;
};
LIST_HEAD(pfilheadhead, pfil_head);
VNET_DEFINE_STATIC(struct pfilheadhead, pfil_head_list) =
LIST_HEAD_INITIALIZER(pfil_head_list);
#define V_pfil_head_list VNET(pfil_head_list)
LIST_HEAD(pfilhookhead, pfil_hook);
VNET_DEFINE_STATIC(struct pfilhookhead, pfil_hook_list) =
LIST_HEAD_INITIALIZER(pfil_hook_list);
#define V_pfil_hook_list VNET(pfil_hook_list)
static struct pfil_link *pfil_link_remove(pfil_chain_t *, pfil_hook_t );
static void pfil_link_free(epoch_context_t);
/*
* To couple a filtering point that provides memory pointer with a filter that
* works on mbufs only.
*/
static __noinline int
pfil_fake_mbuf(pfil_mbuf_chk_t func, void *mem, u_int len, struct ifnet *ifp,
int flags, void *ruleset, struct mbuf **mp)
{
struct mbuf m;
pfil_return_t rv;
(void)m_init(&m, M_NOWAIT, MT_DATA, M_NOFREE | M_PKTHDR);
m_extadd(&m, mem, len, NULL, NULL, NULL, 0, EXT_RXRING);
m.m_len = m.m_pkthdr.len = len;
*mp = &m;
rv = func(mp, ifp, flags, ruleset, NULL);
if (rv == PFIL_PASS && *mp != &m) {
/*
* Firewalls that need pfil_fake_mbuf() most likely don't
* know they need return PFIL_REALLOCED.
*/
rv = PFIL_REALLOCED;
}
return (rv);
}
static __always_inline int
pfil_mem_common(pfil_chain_t *pch, void *mem, u_int len, int flags,
struct ifnet *ifp, struct mbuf **m)
{
struct pfil_link *link;
pfil_return_t rv;
bool realloc = false;
NET_EPOCH_ASSERT();
KASSERT(flags == PFIL_IN || flags == PFIL_OUT,
("%s: unsupported flags %d", __func__, flags));
rv = PFIL_PASS;
CK_STAILQ_FOREACH(link, pch, link_chain) {
if (__predict_true(link->link_mem_chk != NULL && !realloc))
rv = link->link_mem_chk(mem, len, flags, ifp,
link->link_ruleset, m);
else if (!realloc)
rv = pfil_fake_mbuf(link->link_mbuf_chk, mem, len, ifp,
flags, link->link_ruleset, m);
else
rv = link->link_mbuf_chk(m, ifp, flags,
link->link_ruleset, NULL);
if (rv == PFIL_DROPPED || rv == PFIL_CONSUMED)
break;
else if (rv == PFIL_REALLOCED)
realloc = true;
}
if (realloc && rv == PFIL_PASS)
rv = PFIL_REALLOCED;
return (rv);
}
int
pfil_mem_in(struct pfil_head *head, void *mem, u_int len, struct ifnet *ifp,
struct mbuf **m)
{
return (pfil_mem_common(&head->head_in, mem, len, PFIL_IN, ifp, m));
}
int
pfil_mem_out(struct pfil_head *head, void *mem, u_int len, struct ifnet *ifp,
struct mbuf **m)
{
return (pfil_mem_common(&head->head_out, mem, len, PFIL_OUT, ifp, m));
}
static __always_inline int
pfil_mbuf_common(pfil_chain_t *pch, struct mbuf **m, struct ifnet *ifp,
int flags, struct inpcb *inp)
{
struct pfil_link *link;
pfil_return_t rv;
NET_EPOCH_ASSERT();
KASSERT((flags & ~(PFIL_IN|PFIL_OUT|PFIL_FWD)) == 0,
("%s: unsupported flags %#x", __func__, flags));
KASSERT((flags & ~PFIL_FWD) == PFIL_IN ||
(flags & ~PFIL_FWD) == PFIL_OUT,
("%s: conflicting directions %#x", __func__, flags));
rv = PFIL_PASS;
CK_STAILQ_FOREACH(link, pch, link_chain) {
rv = link->link_mbuf_chk(m, ifp, flags, link->link_ruleset,
inp);
if (rv == PFIL_DROPPED || rv == PFIL_CONSUMED)
break;
}
return (rv);
}
int
pfil_mbuf_in(struct pfil_head *head, struct mbuf **m, struct ifnet *ifp,
struct inpcb *inp)
{
return (pfil_mbuf_common(&head->head_in, m, ifp, PFIL_IN, inp));
}
int
pfil_mbuf_out(struct pfil_head *head, struct mbuf **m, struct ifnet *ifp,
struct inpcb *inp)
{
return (pfil_mbuf_common(&head->head_out, m, ifp, PFIL_OUT, inp));
}
int
pfil_mbuf_fwd(struct pfil_head *head, struct mbuf **m, struct ifnet *ifp,
struct inpcb *inp)
{
return (pfil_mbuf_common(&head->head_out, m, ifp, PFIL_OUT | PFIL_FWD, inp));
}
/*
* pfil_head_register() registers a pfil_head with the packet filter hook
* mechanism.
*/
pfil_head_t
pfil_head_register(struct pfil_head_args *pa)
{
struct pfil_head *head, *list;
MPASS(pa->pa_version == PFIL_VERSION);
head = malloc(sizeof(struct pfil_head), M_PFIL, M_WAITOK);
head->head_nhooksin = head->head_nhooksout = 0;
head->head_flags = pa->pa_flags;
head->head_type = pa->pa_type;
head->head_name = pa->pa_headname;
CK_STAILQ_INIT(&head->head_in);
CK_STAILQ_INIT(&head->head_out);
PFIL_LOCK();
LIST_FOREACH(list, &V_pfil_head_list, head_list)
if (strcmp(pa->pa_headname, list->head_name) == 0) {
printf("pfil: duplicate head \"%s\"\n",
pa->pa_headname);
}
LIST_INSERT_HEAD(&V_pfil_head_list, head, head_list);
PFIL_UNLOCK();
return (head);
}
/*
* pfil_head_unregister() removes a pfil_head from the packet filter hook
* mechanism. The producer of the hook promises that all outstanding
* invocations of the hook have completed before it unregisters the hook.
*/
void
pfil_head_unregister(pfil_head_t ph)
{
struct pfil_link *link, *next;
PFIL_LOCK();
LIST_REMOVE(ph, head_list);
CK_STAILQ_FOREACH_SAFE(link, &ph->head_in, link_chain, next) {
link->link_hook->hook_links--;
free(link, M_PFIL);
}
CK_STAILQ_FOREACH_SAFE(link, &ph->head_out, link_chain, next) {
link->link_hook->hook_links--;
free(link, M_PFIL);
}
PFIL_UNLOCK();
}
pfil_hook_t
pfil_add_hook(struct pfil_hook_args *pa)
{
struct pfil_hook *hook, *list;
MPASS(pa->pa_version == PFIL_VERSION);
hook = malloc(sizeof(struct pfil_hook), M_PFIL, M_WAITOK | M_ZERO);
hook->hook_mbuf_chk = pa->pa_mbuf_chk;
hook->hook_mem_chk = pa->pa_mem_chk;
hook->hook_ruleset = pa->pa_ruleset;
hook->hook_flags = pa->pa_flags;
hook->hook_type = pa->pa_type;
hook->hook_modname = pa->pa_modname;
hook->hook_rulname = pa->pa_rulname;
PFIL_LOCK();
LIST_FOREACH(list, &V_pfil_hook_list, hook_list)
if (strcmp(pa->pa_modname, list->hook_modname) == 0 &&
strcmp(pa->pa_rulname, list->hook_rulname) == 0) {
printf("pfil: duplicate hook \"%s:%s\"\n",
pa->pa_modname, pa->pa_rulname);
}
LIST_INSERT_HEAD(&V_pfil_hook_list, hook, hook_list);
PFIL_UNLOCK();
return (hook);
}
static int
pfil_unlink(struct pfil_link_args *pa, pfil_head_t head, pfil_hook_t hook)
{
struct pfil_link *in, *out;
PFIL_LOCK_ASSERT();
if (pa->pa_flags & PFIL_IN) {
in = pfil_link_remove(&head->head_in, hook);
if (in != NULL) {
head->head_nhooksin--;
hook->hook_links--;
}
} else
in = NULL;
if (pa->pa_flags & PFIL_OUT) {
out = pfil_link_remove(&head->head_out, hook);
if (out != NULL) {
head->head_nhooksout--;
hook->hook_links--;
}
} else
out = NULL;
PFIL_UNLOCK();
if (in != NULL)
NET_EPOCH_CALL(pfil_link_free, &in->link_epoch_ctx);
if (out != NULL)
NET_EPOCH_CALL(pfil_link_free, &out->link_epoch_ctx);
if (in == NULL && out == NULL)
return (ENOENT);
else
return (0);
}
int
pfil_link(struct pfil_link_args *pa)
{
struct pfil_link *in, *out, *link;
struct pfil_head *head;
struct pfil_hook *hook;
int error;
MPASS(pa->pa_version == PFIL_VERSION);
if ((pa->pa_flags & (PFIL_IN | PFIL_UNLINK)) == PFIL_IN)
in = malloc(sizeof(*in), M_PFIL, M_WAITOK | M_ZERO);
else
in = NULL;
if ((pa->pa_flags & (PFIL_OUT | PFIL_UNLINK)) == PFIL_OUT)
out = malloc(sizeof(*out), M_PFIL, M_WAITOK | M_ZERO);
else
out = NULL;
PFIL_LOCK();
if (pa->pa_flags & PFIL_HEADPTR)
head = pa->pa_head;
else
LIST_FOREACH(head, &V_pfil_head_list, head_list)
if (strcmp(pa->pa_headname, head->head_name) == 0)
break;
if (pa->pa_flags & PFIL_HOOKPTR)
hook = pa->pa_hook;
else
LIST_FOREACH(hook, &V_pfil_hook_list, hook_list)
if (strcmp(pa->pa_modname, hook->hook_modname) == 0 &&
strcmp(pa->pa_rulname, hook->hook_rulname) == 0)
break;
if (head == NULL || hook == NULL) {
error = ENOENT;
goto fail;
}
if (pa->pa_flags & PFIL_UNLINK)
return (pfil_unlink(pa, head, hook));
if (head->head_type != hook->hook_type ||
((hook->hook_flags & pa->pa_flags) & ~head->head_flags)) {
error = EINVAL;
goto fail;
}
if (pa->pa_flags & PFIL_IN)
CK_STAILQ_FOREACH(link, &head->head_in, link_chain)
if (link->link_hook == hook) {
error = EEXIST;
goto fail;
}
if (pa->pa_flags & PFIL_OUT)
CK_STAILQ_FOREACH(link, &head->head_out, link_chain)
if (link->link_hook == hook) {
error = EEXIST;
goto fail;
}
if (pa->pa_flags & PFIL_IN) {
in->link_hook = hook;
in->link_mbuf_chk = hook->hook_mbuf_chk;
in->link_mem_chk = hook->hook_mem_chk;
in->link_flags = hook->hook_flags;
in->link_ruleset = hook->hook_ruleset;
if (pa->pa_flags & PFIL_APPEND)
CK_STAILQ_INSERT_TAIL(&head->head_in, in, link_chain);
else
CK_STAILQ_INSERT_HEAD(&head->head_in, in, link_chain);
hook->hook_links++;
head->head_nhooksin++;
}
if (pa->pa_flags & PFIL_OUT) {
out->link_hook = hook;
out->link_mbuf_chk = hook->hook_mbuf_chk;
out->link_mem_chk = hook->hook_mem_chk;
out->link_flags = hook->hook_flags;
out->link_ruleset = hook->hook_ruleset;
if (pa->pa_flags & PFIL_APPEND)
CK_STAILQ_INSERT_HEAD(&head->head_out, out, link_chain);
else
CK_STAILQ_INSERT_TAIL(&head->head_out, out, link_chain);
hook->hook_links++;
head->head_nhooksout++;
}
PFIL_UNLOCK();
return (0);
fail:
PFIL_UNLOCK();
free(in, M_PFIL);
free(out, M_PFIL);
return (error);
}
static void
pfil_link_free(epoch_context_t ctx)
{
struct pfil_link *link;
link = __containerof(ctx, struct pfil_link, link_epoch_ctx);
free(link, M_PFIL);
}
/*
* pfil_remove_hook removes a filter from all filtering points.
*/
void
pfil_remove_hook(pfil_hook_t hook)
{
struct pfil_head *head;
struct pfil_link *in, *out;
PFIL_LOCK();
LIST_FOREACH(head, &V_pfil_head_list, head_list) {
retry:
in = pfil_link_remove(&head->head_in, hook);
if (in != NULL) {
head->head_nhooksin--;
hook->hook_links--;
NET_EPOCH_CALL(pfil_link_free, &in->link_epoch_ctx);
}
out = pfil_link_remove(&head->head_out, hook);
if (out != NULL) {
head->head_nhooksout--;
hook->hook_links--;
NET_EPOCH_CALL(pfil_link_free, &out->link_epoch_ctx);
}
if (in != NULL || out != NULL)
/* What if some stupid admin put same filter twice? */
goto retry;
}
LIST_REMOVE(hook, hook_list);
PFIL_UNLOCK();
MPASS(hook->hook_links == 0);
free(hook, M_PFIL);
}
/*
* Internal: Remove a pfil hook from a hook chain.
*/
static struct pfil_link *
pfil_link_remove(pfil_chain_t *chain, pfil_hook_t hook)
{
struct pfil_link *link;
PFIL_LOCK_ASSERT();
CK_STAILQ_FOREACH(link, chain, link_chain)
if (link->link_hook == hook) {
CK_STAILQ_REMOVE(chain, link, pfil_link, link_chain);
return (link);
}
return (NULL);
}
static void
pfil_init(const void *unused __unused)
{
struct make_dev_args args;
int error __diagused;
make_dev_args_init(&args);
args.mda_flags = MAKEDEV_WAITOK | MAKEDEV_CHECKNAME;
args.mda_devsw = &pfil_cdevsw;
args.mda_uid = UID_ROOT;
args.mda_gid = GID_WHEEL;
args.mda_mode = 0600;
error = make_dev_s(&args, &pfil_dev, PFILDEV);
KASSERT(error == 0, ("%s: failed to create dev: %d", __func__, error));
}
/*
* Make sure the pfil bits are first before any possible subsystem which
* might piggyback on the SI_SUB_PROTO_PFIL.
*/
SYSINIT(pfil_init, SI_SUB_PROTO_PFIL, SI_ORDER_FIRST, pfil_init, NULL);
/*
* User control interface.
*/
static int pfilioc_listheads(struct pfilioc_list *);
static int pfilioc_listhooks(struct pfilioc_list *);
static int pfilioc_link(struct pfilioc_link *);
static int
pfil_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
struct thread *td)
{
int error;
CURVNET_SET(TD_TO_VNET(td));
error = 0;
switch (cmd) {
case PFILIOC_LISTHEADS:
error = pfilioc_listheads((struct pfilioc_list *)addr);
break;
case PFILIOC_LISTHOOKS:
error = pfilioc_listhooks((struct pfilioc_list *)addr);
break;
case PFILIOC_LINK:
error = pfilioc_link((struct pfilioc_link *)addr);
break;
default:
error = EINVAL;
break;
}
CURVNET_RESTORE();
return (error);
}
static int
pfilioc_listheads(struct pfilioc_list *req)
{
struct pfil_head *head;
struct pfil_link *link;
struct pfilioc_head *iohead;
struct pfilioc_hook *iohook;
u_int nheads, nhooks, hd, hk;
int error;
PFIL_LOCK();
restart:
nheads = nhooks = 0;
LIST_FOREACH(head, &V_pfil_head_list, head_list) {
nheads++;
nhooks += head->head_nhooksin + head->head_nhooksout;
}
PFIL_UNLOCK();
if (req->pio_nheads < nheads || req->pio_nhooks < nhooks) {
req->pio_nheads = nheads;
req->pio_nhooks = nhooks;
return (0);
}
iohead = malloc(sizeof(*iohead) * nheads, M_TEMP, M_WAITOK);
iohook = malloc(sizeof(*iohook) * nhooks, M_TEMP, M_WAITOK);
hd = hk = 0;
PFIL_LOCK();
LIST_FOREACH(head, &V_pfil_head_list, head_list) {
if (hd + 1 > nheads ||
hk + head->head_nhooksin + head->head_nhooksout > nhooks) {
/* Configuration changed during malloc(). */
free(iohead, M_TEMP);
free(iohook, M_TEMP);
goto restart;
}
strlcpy(iohead[hd].pio_name, head->head_name,
sizeof(iohead[0].pio_name));
iohead[hd].pio_nhooksin = head->head_nhooksin;
iohead[hd].pio_nhooksout = head->head_nhooksout;
iohead[hd].pio_type = head->head_type;
CK_STAILQ_FOREACH(link, &head->head_in, link_chain) {
strlcpy(iohook[hk].pio_module,
link->link_hook->hook_modname,
sizeof(iohook[0].pio_module));
strlcpy(iohook[hk].pio_ruleset,
link->link_hook->hook_rulname,
sizeof(iohook[0].pio_ruleset));
hk++;
}
CK_STAILQ_FOREACH(link, &head->head_out, link_chain) {
strlcpy(iohook[hk].pio_module,
link->link_hook->hook_modname,
sizeof(iohook[0].pio_module));
strlcpy(iohook[hk].pio_ruleset,
link->link_hook->hook_rulname,
sizeof(iohook[0].pio_ruleset));
hk++;
}
hd++;
}
PFIL_UNLOCK();
error = copyout(iohead, req->pio_heads,
sizeof(*iohead) * min(hd, req->pio_nheads));
if (error == 0)
error = copyout(iohook, req->pio_hooks,
sizeof(*iohook) * min(req->pio_nhooks, hk));
req->pio_nheads = hd;
req->pio_nhooks = hk;
free(iohead, M_TEMP);
free(iohook, M_TEMP);
return (error);
}
static int
pfilioc_listhooks(struct pfilioc_list *req)
{
struct pfil_hook *hook;
struct pfilioc_hook *iohook;
u_int nhooks, hk;
int error;
PFIL_LOCK();
restart:
nhooks = 0;
LIST_FOREACH(hook, &V_pfil_hook_list, hook_list)
nhooks++;
PFIL_UNLOCK();
if (req->pio_nhooks < nhooks) {
req->pio_nhooks = nhooks;
return (0);
}
iohook = malloc(sizeof(*iohook) * nhooks, M_TEMP, M_WAITOK);
hk = 0;
PFIL_LOCK();
LIST_FOREACH(hook, &V_pfil_hook_list, hook_list) {
if (hk + 1 > nhooks) {
/* Configuration changed during malloc(). */
free(iohook, M_TEMP);
goto restart;
}
strlcpy(iohook[hk].pio_module, hook->hook_modname,
sizeof(iohook[0].pio_module));
strlcpy(iohook[hk].pio_ruleset, hook->hook_rulname,
sizeof(iohook[0].pio_ruleset));
iohook[hk].pio_type = hook->hook_type;
iohook[hk].pio_flags = hook->hook_flags;
hk++;
}
PFIL_UNLOCK();
error = copyout(iohook, req->pio_hooks,
sizeof(*iohook) * min(req->pio_nhooks, hk));
req->pio_nhooks = hk;
free(iohook, M_TEMP);
return (error);
}
static int
pfilioc_link(struct pfilioc_link *req)
{
struct pfil_link_args args;
if (req->pio_flags & ~(PFIL_IN | PFIL_OUT | PFIL_UNLINK | PFIL_APPEND))
return (EINVAL);
args.pa_version = PFIL_VERSION;
args.pa_flags = req->pio_flags;
args.pa_headname = req->pio_name;
args.pa_modname = req->pio_module;
args.pa_rulname = req->pio_ruleset;
return (pfil_link(&args));
}
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