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linux-next/net/can/gw.c
Johannes Berg 053c095a82 netlink: make nlmsg_end() and genlmsg_end() void 
Contrary to common expectations for an "int" return, these functions
return only a positive value -- if used correctly they cannot even
return 0 because the message header will necessarily be in the skb.

This makes the very common pattern of

  if (genlmsg_end(...) < 0) { ... }

be a whole bunch of dead code. Many places also simply do

  return nlmsg_end(...);

and the caller is expected to deal with it.

This also commonly (at least for me) causes errors, because it is very
common to write

  if (my_function(...))
    /* error condition */

and if my_function() does "return nlmsg_end()" this is of course wrong.

Additionally, there's not a single place in the kernel that actually
needs the message length returned, and if anyone needs it later then
it'll be very easy to just use skb->len there.

Remove this, and make the functions void. This removes a bunch of dead
code as described above. The patch adds lines because I did

-	return nlmsg_end(...);
+	nlmsg_end(...);
+	return 0;

I could have preserved all the function's return values by returning
skb->len, but instead I've audited all the places calling the affected
functions and found that none cared. A few places actually compared
the return value with <= 0 in dump functionality, but that could just
be changed to < 0 with no change in behaviour, so I opted for the more
efficient version.

One instance of the error I've made numerous times now is also present
in net/phonet/pn_netlink.c in the route_dumpit() function - it didn't
check for <0 or <=0 and thus broke out of the loop every single time.
I've preserved this since it will (I think) have caused the messages to
userspace to be formatted differently with just a single message for
every SKB returned to userspace. It's possible that this isn't needed
for the tools that actually use this, but I don't even know what they
are so couldn't test that changing this behaviour would be acceptable.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-18 01:03:45 -05:00

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/*
* gw.c - CAN frame Gateway/Router/Bridge with netlink interface
*
* Copyright (c) 2011 Volkswagen Group Electronic Research
* 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. Neither the name of Volkswagen nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* Alternatively, provided that this notice is retained in full, this
* software may be distributed under the terms of the GNU General
* Public License ("GPL") version 2, in which case the provisions of the
* GPL apply INSTEAD OF those given above.
*
* The provided data structures and external interfaces from this code
* are not restricted to be used by modules with a GPL compatible license.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
* OWNER 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 <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/rculist.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <linux/can.h>
#include <linux/can/core.h>
#include <linux/can/skb.h>
#include <linux/can/gw.h>
#include <net/rtnetlink.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#define CAN_GW_VERSION "20130117"
#define CAN_GW_NAME "can-gw"
MODULE_DESCRIPTION("PF_CAN netlink gateway");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
MODULE_ALIAS(CAN_GW_NAME);
#define CGW_MIN_HOPS 1
#define CGW_MAX_HOPS 6
#define CGW_DEFAULT_HOPS 1
static unsigned int max_hops __read_mostly = CGW_DEFAULT_HOPS;
module_param(max_hops, uint, S_IRUGO);
MODULE_PARM_DESC(max_hops,
"maximum " CAN_GW_NAME " routing hops for CAN frames "
"(valid values: " __stringify(CGW_MIN_HOPS) "-"
__stringify(CGW_MAX_HOPS) " hops, "
"default: " __stringify(CGW_DEFAULT_HOPS) ")");
static HLIST_HEAD(cgw_list);
static struct notifier_block notifier;
static struct kmem_cache *cgw_cache __read_mostly;
/* structure that contains the (on-the-fly) CAN frame modifications */
struct cf_mod {
struct {
struct can_frame and;
struct can_frame or;
struct can_frame xor;
struct can_frame set;
} modframe;
struct {
u8 and;
u8 or;
u8 xor;
u8 set;
} modtype;
void (*modfunc[MAX_MODFUNCTIONS])(struct can_frame *cf,
struct cf_mod *mod);
/* CAN frame checksum calculation after CAN frame modifications */
struct {
struct cgw_csum_xor xor;
struct cgw_csum_crc8 crc8;
} csum;
struct {
void (*xor)(struct can_frame *cf, struct cgw_csum_xor *xor);
void (*crc8)(struct can_frame *cf, struct cgw_csum_crc8 *crc8);
} csumfunc;
};
/*
* So far we just support CAN -> CAN routing and frame modifications.
*
* The internal can_can_gw structure contains data and attributes for
* a CAN -> CAN gateway job.
*/
struct can_can_gw {
struct can_filter filter;
int src_idx;
int dst_idx;
};
/* list entry for CAN gateways jobs */
struct cgw_job {
struct hlist_node list;
struct rcu_head rcu;
u32 handled_frames;
u32 dropped_frames;
u32 deleted_frames;
struct cf_mod mod;
union {
/* CAN frame data source */
struct net_device *dev;
} src;
union {
/* CAN frame data destination */
struct net_device *dev;
} dst;
union {
struct can_can_gw ccgw;
/* tbc */
};
u8 gwtype;
u8 limit_hops;
u16 flags;
};
/* modification functions that are invoked in the hot path in can_can_gw_rcv */
#define MODFUNC(func, op) static void func(struct can_frame *cf, \
struct cf_mod *mod) { op ; }
MODFUNC(mod_and_id, cf->can_id &= mod->modframe.and.can_id)
MODFUNC(mod_and_dlc, cf->can_dlc &= mod->modframe.and.can_dlc)
MODFUNC(mod_and_data, *(u64 *)cf->data &= *(u64 *)mod->modframe.and.data)
MODFUNC(mod_or_id, cf->can_id |= mod->modframe.or.can_id)
MODFUNC(mod_or_dlc, cf->can_dlc |= mod->modframe.or.can_dlc)
MODFUNC(mod_or_data, *(u64 *)cf->data |= *(u64 *)mod->modframe.or.data)
MODFUNC(mod_xor_id, cf->can_id ^= mod->modframe.xor.can_id)
MODFUNC(mod_xor_dlc, cf->can_dlc ^= mod->modframe.xor.can_dlc)
MODFUNC(mod_xor_data, *(u64 *)cf->data ^= *(u64 *)mod->modframe.xor.data)
MODFUNC(mod_set_id, cf->can_id = mod->modframe.set.can_id)
MODFUNC(mod_set_dlc, cf->can_dlc = mod->modframe.set.can_dlc)
MODFUNC(mod_set_data, *(u64 *)cf->data = *(u64 *)mod->modframe.set.data)
static inline void canframecpy(struct can_frame *dst, struct can_frame *src)
{
/*
* Copy the struct members separately to ensure that no uninitialized
* data are copied in the 3 bytes hole of the struct. This is needed
* to make easy compares of the data in the struct cf_mod.
*/
dst->can_id = src->can_id;
dst->can_dlc = src->can_dlc;
*(u64 *)dst->data = *(u64 *)src->data;
}
static int cgw_chk_csum_parms(s8 fr, s8 to, s8 re)
{
/*
* absolute dlc values 0 .. 7 => 0 .. 7, e.g. data [0]
* relative to received dlc -1 .. -8 :
* e.g. for received dlc = 8
* -1 => index = 7 (data[7])
* -3 => index = 5 (data[5])
* -8 => index = 0 (data[0])
*/
if (fr > -9 && fr < 8 &&
to > -9 && to < 8 &&
re > -9 && re < 8)
return 0;
else
return -EINVAL;
}
static inline int calc_idx(int idx, int rx_dlc)
{
if (idx < 0)
return rx_dlc + idx;
else
return idx;
}
static void cgw_csum_xor_rel(struct can_frame *cf, struct cgw_csum_xor *xor)
{
int from = calc_idx(xor->from_idx, cf->can_dlc);
int to = calc_idx(xor->to_idx, cf->can_dlc);
int res = calc_idx(xor->result_idx, cf->can_dlc);
u8 val = xor->init_xor_val;
int i;
if (from < 0 || to < 0 || res < 0)
return;
if (from <= to) {
for (i = from; i <= to; i++)
val ^= cf->data[i];
} else {
for (i = from; i >= to; i--)
val ^= cf->data[i];
}
cf->data[res] = val;
}
static void cgw_csum_xor_pos(struct can_frame *cf, struct cgw_csum_xor *xor)
{
u8 val = xor->init_xor_val;
int i;
for (i = xor->from_idx; i <= xor->to_idx; i++)
val ^= cf->data[i];
cf->data[xor->result_idx] = val;
}
static void cgw_csum_xor_neg(struct can_frame *cf, struct cgw_csum_xor *xor)
{
u8 val = xor->init_xor_val;
int i;
for (i = xor->from_idx; i >= xor->to_idx; i--)
val ^= cf->data[i];
cf->data[xor->result_idx] = val;
}
static void cgw_csum_crc8_rel(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
{
int from = calc_idx(crc8->from_idx, cf->can_dlc);
int to = calc_idx(crc8->to_idx, cf->can_dlc);
int res = calc_idx(crc8->result_idx, cf->can_dlc);
u8 crc = crc8->init_crc_val;
int i;
if (from < 0 || to < 0 || res < 0)
return;
if (from <= to) {
for (i = crc8->from_idx; i <= crc8->to_idx; i++)
crc = crc8->crctab[crc^cf->data[i]];
} else {
for (i = crc8->from_idx; i >= crc8->to_idx; i--)
crc = crc8->crctab[crc^cf->data[i]];
}
switch (crc8->profile) {
case CGW_CRC8PRF_1U8:
crc = crc8->crctab[crc^crc8->profile_data[0]];
break;
case CGW_CRC8PRF_16U8:
crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
break;
case CGW_CRC8PRF_SFFID_XOR:
crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
(cf->can_id >> 8 & 0xFF)];
break;
}
cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
}
static void cgw_csum_crc8_pos(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
{
u8 crc = crc8->init_crc_val;
int i;
for (i = crc8->from_idx; i <= crc8->to_idx; i++)
crc = crc8->crctab[crc^cf->data[i]];
switch (crc8->profile) {
case CGW_CRC8PRF_1U8:
crc = crc8->crctab[crc^crc8->profile_data[0]];
break;
case CGW_CRC8PRF_16U8:
crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
break;
case CGW_CRC8PRF_SFFID_XOR:
crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
(cf->can_id >> 8 & 0xFF)];
break;
}
cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
}
static void cgw_csum_crc8_neg(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
{
u8 crc = crc8->init_crc_val;
int i;
for (i = crc8->from_idx; i >= crc8->to_idx; i--)
crc = crc8->crctab[crc^cf->data[i]];
switch (crc8->profile) {
case CGW_CRC8PRF_1U8:
crc = crc8->crctab[crc^crc8->profile_data[0]];
break;
case CGW_CRC8PRF_16U8:
crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
break;
case CGW_CRC8PRF_SFFID_XOR:
crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
(cf->can_id >> 8 & 0xFF)];
break;
}
cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
}
/* the receive & process & send function */
static void can_can_gw_rcv(struct sk_buff *skb, void *data)
{
struct cgw_job *gwj = (struct cgw_job *)data;
struct can_frame *cf;
struct sk_buff *nskb;
int modidx = 0;
/*
* Do not handle CAN frames routed more than 'max_hops' times.
* In general we should never catch this delimiter which is intended
* to cover a misconfiguration protection (e.g. circular CAN routes).
*
* The Controller Area Network controllers only accept CAN frames with
* correct CRCs - which are not visible in the controller registers.
* According to skbuff.h documentation the csum_start element for IP
* checksums is undefined/unused when ip_summed == CHECKSUM_UNNECESSARY.
* Only CAN skbs can be processed here which already have this property.
*/
#define cgw_hops(skb) ((skb)->csum_start)
BUG_ON(skb->ip_summed != CHECKSUM_UNNECESSARY);
if (cgw_hops(skb) >= max_hops) {
/* indicate deleted frames due to misconfiguration */
gwj->deleted_frames++;
return;
}
if (!(gwj->dst.dev->flags & IFF_UP)) {
gwj->dropped_frames++;
return;
}
/* is sending the skb back to the incoming interface not allowed? */
if (!(gwj->flags & CGW_FLAGS_CAN_IIF_TX_OK) &&
can_skb_prv(skb)->ifindex == gwj->dst.dev->ifindex)
return;
/*
* clone the given skb, which has not been done in can_rcv()
*
* When there is at least one modification function activated,
* we need to copy the skb as we want to modify skb->data.
*/
if (gwj->mod.modfunc[0])
nskb = skb_copy(skb, GFP_ATOMIC);
else
nskb = skb_clone(skb, GFP_ATOMIC);
if (!nskb) {
gwj->dropped_frames++;
return;
}
/* put the incremented hop counter in the cloned skb */
cgw_hops(nskb) = cgw_hops(skb) + 1;
/* first processing of this CAN frame -> adjust to private hop limit */
if (gwj->limit_hops && cgw_hops(nskb) == 1)
cgw_hops(nskb) = max_hops - gwj->limit_hops + 1;
nskb->dev = gwj->dst.dev;
/* pointer to modifiable CAN frame */
cf = (struct can_frame *)nskb->data;
/* perform preprocessed modification functions if there are any */
while (modidx < MAX_MODFUNCTIONS && gwj->mod.modfunc[modidx])
(*gwj->mod.modfunc[modidx++])(cf, &gwj->mod);
/* check for checksum updates when the CAN frame has been modified */
if (modidx) {
if (gwj->mod.csumfunc.crc8)
(*gwj->mod.csumfunc.crc8)(cf, &gwj->mod.csum.crc8);
if (gwj->mod.csumfunc.xor)
(*gwj->mod.csumfunc.xor)(cf, &gwj->mod.csum.xor);
}
/* clear the skb timestamp if not configured the other way */
if (!(gwj->flags & CGW_FLAGS_CAN_SRC_TSTAMP))
nskb->tstamp.tv64 = 0;
/* send to netdevice */
if (can_send(nskb, gwj->flags & CGW_FLAGS_CAN_ECHO))
gwj->dropped_frames++;
else
gwj->handled_frames++;
}
static inline int cgw_register_filter(struct cgw_job *gwj)
{
return can_rx_register(gwj->src.dev, gwj->ccgw.filter.can_id,
gwj->ccgw.filter.can_mask, can_can_gw_rcv,
gwj, "gw");
}
static inline void cgw_unregister_filter(struct cgw_job *gwj)
{
can_rx_unregister(gwj->src.dev, gwj->ccgw.filter.can_id,
gwj->ccgw.filter.can_mask, can_can_gw_rcv, gwj);
}
static int cgw_notifier(struct notifier_block *nb,
unsigned long msg, void *ptr)
{
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
if (!net_eq(dev_net(dev), &init_net))
return NOTIFY_DONE;
if (dev->type != ARPHRD_CAN)
return NOTIFY_DONE;
if (msg == NETDEV_UNREGISTER) {
struct cgw_job *gwj = NULL;
struct hlist_node *nx;
ASSERT_RTNL();
hlist_for_each_entry_safe(gwj, nx, &cgw_list, list) {
if (gwj->src.dev == dev || gwj->dst.dev == dev) {
hlist_del(&gwj->list);
cgw_unregister_filter(gwj);
kmem_cache_free(cgw_cache, gwj);
}
}
}
return NOTIFY_DONE;
}
static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj, int type,
u32 pid, u32 seq, int flags)
{
struct cgw_frame_mod mb;
struct rtcanmsg *rtcan;
struct nlmsghdr *nlh;
nlh = nlmsg_put(skb, pid, seq, type, sizeof(*rtcan), flags);
if (!nlh)
return -EMSGSIZE;
rtcan = nlmsg_data(nlh);
rtcan->can_family = AF_CAN;
rtcan->gwtype = gwj->gwtype;
rtcan->flags = gwj->flags;
/* add statistics if available */
if (gwj->handled_frames) {
if (nla_put_u32(skb, CGW_HANDLED, gwj->handled_frames) < 0)
goto cancel;
}
if (gwj->dropped_frames) {
if (nla_put_u32(skb, CGW_DROPPED, gwj->dropped_frames) < 0)
goto cancel;
}
if (gwj->deleted_frames) {
if (nla_put_u32(skb, CGW_DELETED, gwj->deleted_frames) < 0)
goto cancel;
}
/* check non default settings of attributes */
if (gwj->limit_hops) {
if (nla_put_u8(skb, CGW_LIM_HOPS, gwj->limit_hops) < 0)
goto cancel;
}
if (gwj->mod.modtype.and) {
memcpy(&mb.cf, &gwj->mod.modframe.and, sizeof(mb.cf));
mb.modtype = gwj->mod.modtype.and;
if (nla_put(skb, CGW_MOD_AND, sizeof(mb), &mb) < 0)
goto cancel;
}
if (gwj->mod.modtype.or) {
memcpy(&mb.cf, &gwj->mod.modframe.or, sizeof(mb.cf));
mb.modtype = gwj->mod.modtype.or;
if (nla_put(skb, CGW_MOD_OR, sizeof(mb), &mb) < 0)
goto cancel;
}
if (gwj->mod.modtype.xor) {
memcpy(&mb.cf, &gwj->mod.modframe.xor, sizeof(mb.cf));
mb.modtype = gwj->mod.modtype.xor;
if (nla_put(skb, CGW_MOD_XOR, sizeof(mb), &mb) < 0)
goto cancel;
}
if (gwj->mod.modtype.set) {
memcpy(&mb.cf, &gwj->mod.modframe.set, sizeof(mb.cf));
mb.modtype = gwj->mod.modtype.set;
if (nla_put(skb, CGW_MOD_SET, sizeof(mb), &mb) < 0)
goto cancel;
}
if (gwj->mod.csumfunc.crc8) {
if (nla_put(skb, CGW_CS_CRC8, CGW_CS_CRC8_LEN,
&gwj->mod.csum.crc8) < 0)
goto cancel;
}
if (gwj->mod.csumfunc.xor) {
if (nla_put(skb, CGW_CS_XOR, CGW_CS_XOR_LEN,
&gwj->mod.csum.xor) < 0)
goto cancel;
}
if (gwj->gwtype == CGW_TYPE_CAN_CAN) {
if (gwj->ccgw.filter.can_id || gwj->ccgw.filter.can_mask) {
if (nla_put(skb, CGW_FILTER, sizeof(struct can_filter),
&gwj->ccgw.filter) < 0)
goto cancel;
}
if (nla_put_u32(skb, CGW_SRC_IF, gwj->ccgw.src_idx) < 0)
goto cancel;
if (nla_put_u32(skb, CGW_DST_IF, gwj->ccgw.dst_idx) < 0)
goto cancel;
}
nlmsg_end(skb, nlh);
return 0;
cancel:
nlmsg_cancel(skb, nlh);
return -EMSGSIZE;
}
/* Dump information about all CAN gateway jobs, in response to RTM_GETROUTE */
static int cgw_dump_jobs(struct sk_buff *skb, struct netlink_callback *cb)
{
struct cgw_job *gwj = NULL;
int idx = 0;
int s_idx = cb->args[0];
rcu_read_lock();
hlist_for_each_entry_rcu(gwj, &cgw_list, list) {
if (idx < s_idx)
goto cont;
if (cgw_put_job(skb, gwj, RTM_NEWROUTE, NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, NLM_F_MULTI) < 0)
break;
cont:
idx++;
}
rcu_read_unlock();
cb->args[0] = idx;
return skb->len;
}
static const struct nla_policy cgw_policy[CGW_MAX+1] = {
[CGW_MOD_AND] = { .len = sizeof(struct cgw_frame_mod) },
[CGW_MOD_OR] = { .len = sizeof(struct cgw_frame_mod) },
[CGW_MOD_XOR] = { .len = sizeof(struct cgw_frame_mod) },
[CGW_MOD_SET] = { .len = sizeof(struct cgw_frame_mod) },
[CGW_CS_XOR] = { .len = sizeof(struct cgw_csum_xor) },
[CGW_CS_CRC8] = { .len = sizeof(struct cgw_csum_crc8) },
[CGW_SRC_IF] = { .type = NLA_U32 },
[CGW_DST_IF] = { .type = NLA_U32 },
[CGW_FILTER] = { .len = sizeof(struct can_filter) },
[CGW_LIM_HOPS] = { .type = NLA_U8 },
};
/* check for common and gwtype specific attributes */
static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
u8 gwtype, void *gwtypeattr, u8 *limhops)
{
struct nlattr *tb[CGW_MAX+1];
struct cgw_frame_mod mb;
int modidx = 0;
int err = 0;
/* initialize modification & checksum data space */
memset(mod, 0, sizeof(*mod));
err = nlmsg_parse(nlh, sizeof(struct rtcanmsg), tb, CGW_MAX,
cgw_policy);
if (err < 0)
return err;
if (tb[CGW_LIM_HOPS]) {
*limhops = nla_get_u8(tb[CGW_LIM_HOPS]);
if (*limhops < 1 || *limhops > max_hops)
return -EINVAL;
}
/* check for AND/OR/XOR/SET modifications */
if (tb[CGW_MOD_AND]) {
nla_memcpy(&mb, tb[CGW_MOD_AND], CGW_MODATTR_LEN);
canframecpy(&mod->modframe.and, &mb.cf);
mod->modtype.and = mb.modtype;
if (mb.modtype & CGW_MOD_ID)
mod->modfunc[modidx++] = mod_and_id;
if (mb.modtype & CGW_MOD_DLC)
mod->modfunc[modidx++] = mod_and_dlc;
if (mb.modtype & CGW_MOD_DATA)
mod->modfunc[modidx++] = mod_and_data;
}
if (tb[CGW_MOD_OR]) {
nla_memcpy(&mb, tb[CGW_MOD_OR], CGW_MODATTR_LEN);
canframecpy(&mod->modframe.or, &mb.cf);
mod->modtype.or = mb.modtype;
if (mb.modtype & CGW_MOD_ID)
mod->modfunc[modidx++] = mod_or_id;
if (mb.modtype & CGW_MOD_DLC)
mod->modfunc[modidx++] = mod_or_dlc;
if (mb.modtype & CGW_MOD_DATA)
mod->modfunc[modidx++] = mod_or_data;
}
if (tb[CGW_MOD_XOR]) {
nla_memcpy(&mb, tb[CGW_MOD_XOR], CGW_MODATTR_LEN);
canframecpy(&mod->modframe.xor, &mb.cf);
mod->modtype.xor = mb.modtype;
if (mb.modtype & CGW_MOD_ID)
mod->modfunc[modidx++] = mod_xor_id;
if (mb.modtype & CGW_MOD_DLC)
mod->modfunc[modidx++] = mod_xor_dlc;
if (mb.modtype & CGW_MOD_DATA)
mod->modfunc[modidx++] = mod_xor_data;
}
if (tb[CGW_MOD_SET]) {
nla_memcpy(&mb, tb[CGW_MOD_SET], CGW_MODATTR_LEN);
canframecpy(&mod->modframe.set, &mb.cf);
mod->modtype.set = mb.modtype;
if (mb.modtype & CGW_MOD_ID)
mod->modfunc[modidx++] = mod_set_id;
if (mb.modtype & CGW_MOD_DLC)
mod->modfunc[modidx++] = mod_set_dlc;
if (mb.modtype & CGW_MOD_DATA)
mod->modfunc[modidx++] = mod_set_data;
}
/* check for checksum operations after CAN frame modifications */
if (modidx) {
if (tb[CGW_CS_CRC8]) {
struct cgw_csum_crc8 *c = nla_data(tb[CGW_CS_CRC8]);
err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
c->result_idx);
if (err)
return err;
nla_memcpy(&mod->csum.crc8, tb[CGW_CS_CRC8],
CGW_CS_CRC8_LEN);
/*
* select dedicated processing function to reduce
* runtime operations in receive hot path.
*/
if (c->from_idx < 0 || c->to_idx < 0 ||
c->result_idx < 0)
mod->csumfunc.crc8 = cgw_csum_crc8_rel;
else if (c->from_idx <= c->to_idx)
mod->csumfunc.crc8 = cgw_csum_crc8_pos;
else
mod->csumfunc.crc8 = cgw_csum_crc8_neg;
}
if (tb[CGW_CS_XOR]) {
struct cgw_csum_xor *c = nla_data(tb[CGW_CS_XOR]);
err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
c->result_idx);
if (err)
return err;
nla_memcpy(&mod->csum.xor, tb[CGW_CS_XOR],
CGW_CS_XOR_LEN);
/*
* select dedicated processing function to reduce
* runtime operations in receive hot path.
*/
if (c->from_idx < 0 || c->to_idx < 0 ||
c->result_idx < 0)
mod->csumfunc.xor = cgw_csum_xor_rel;
else if (c->from_idx <= c->to_idx)
mod->csumfunc.xor = cgw_csum_xor_pos;
else
mod->csumfunc.xor = cgw_csum_xor_neg;
}
}
if (gwtype == CGW_TYPE_CAN_CAN) {
/* check CGW_TYPE_CAN_CAN specific attributes */
struct can_can_gw *ccgw = (struct can_can_gw *)gwtypeattr;
memset(ccgw, 0, sizeof(*ccgw));
/* check for can_filter in attributes */
if (tb[CGW_FILTER])
nla_memcpy(&ccgw->filter, tb[CGW_FILTER],
sizeof(struct can_filter));
err = -ENODEV;
/* specifying two interfaces is mandatory */
if (!tb[CGW_SRC_IF] || !tb[CGW_DST_IF])
return err;
ccgw->src_idx = nla_get_u32(tb[CGW_SRC_IF]);
ccgw->dst_idx = nla_get_u32(tb[CGW_DST_IF]);
/* both indices set to 0 for flushing all routing entries */
if (!ccgw->src_idx && !ccgw->dst_idx)
return 0;
/* only one index set to 0 is an error */
if (!ccgw->src_idx || !ccgw->dst_idx)
return err;
}
/* add the checks for other gwtypes here */
return 0;
}
static int cgw_create_job(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct rtcanmsg *r;
struct cgw_job *gwj;
u8 limhops = 0;
int err = 0;
if (!netlink_capable(skb, CAP_NET_ADMIN))
return -EPERM;
if (nlmsg_len(nlh) < sizeof(*r))
return -EINVAL;
r = nlmsg_data(nlh);
if (r->can_family != AF_CAN)
return -EPFNOSUPPORT;
/* so far we only support CAN -> CAN routings */
if (r->gwtype != CGW_TYPE_CAN_CAN)
return -EINVAL;
gwj = kmem_cache_alloc(cgw_cache, GFP_KERNEL);
if (!gwj)
return -ENOMEM;
gwj->handled_frames = 0;
gwj->dropped_frames = 0;
gwj->deleted_frames = 0;
gwj->flags = r->flags;
gwj->gwtype = r->gwtype;
err = cgw_parse_attr(nlh, &gwj->mod, CGW_TYPE_CAN_CAN, &gwj->ccgw,
&limhops);
if (err < 0)
goto out;
err = -ENODEV;
/* ifindex == 0 is not allowed for job creation */
if (!gwj->ccgw.src_idx || !gwj->ccgw.dst_idx)
goto out;
gwj->src.dev = __dev_get_by_index(&init_net, gwj->ccgw.src_idx);
if (!gwj->src.dev)
goto out;
if (gwj->src.dev->type != ARPHRD_CAN)
goto out;
gwj->dst.dev = __dev_get_by_index(&init_net, gwj->ccgw.dst_idx);
if (!gwj->dst.dev)
goto out;
if (gwj->dst.dev->type != ARPHRD_CAN)
goto out;
gwj->limit_hops = limhops;
ASSERT_RTNL();
err = cgw_register_filter(gwj);
if (!err)
hlist_add_head_rcu(&gwj->list, &cgw_list);
out:
if (err)
kmem_cache_free(cgw_cache, gwj);
return err;
}
static void cgw_remove_all_jobs(void)
{
struct cgw_job *gwj = NULL;
struct hlist_node *nx;
ASSERT_RTNL();
hlist_for_each_entry_safe(gwj, nx, &cgw_list, list) {
hlist_del(&gwj->list);
cgw_unregister_filter(gwj);
kmem_cache_free(cgw_cache, gwj);
}
}
static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct cgw_job *gwj = NULL;
struct hlist_node *nx;
struct rtcanmsg *r;
struct cf_mod mod;
struct can_can_gw ccgw;
u8 limhops = 0;
int err = 0;
if (!netlink_capable(skb, CAP_NET_ADMIN))
return -EPERM;
if (nlmsg_len(nlh) < sizeof(*r))
return -EINVAL;
r = nlmsg_data(nlh);
if (r->can_family != AF_CAN)
return -EPFNOSUPPORT;
/* so far we only support CAN -> CAN routings */
if (r->gwtype != CGW_TYPE_CAN_CAN)
return -EINVAL;
err = cgw_parse_attr(nlh, &mod, CGW_TYPE_CAN_CAN, &ccgw, &limhops);
if (err < 0)
return err;
/* two interface indices both set to 0 => remove all entries */
if (!ccgw.src_idx && !ccgw.dst_idx) {
cgw_remove_all_jobs();
return 0;
}
err = -EINVAL;
ASSERT_RTNL();
/* remove only the first matching entry */
hlist_for_each_entry_safe(gwj, nx, &cgw_list, list) {
if (gwj->flags != r->flags)
continue;
if (gwj->limit_hops != limhops)
continue;
if (memcmp(&gwj->mod, &mod, sizeof(mod)))
continue;
/* if (r->gwtype == CGW_TYPE_CAN_CAN) - is made sure here */
if (memcmp(&gwj->ccgw, &ccgw, sizeof(ccgw)))
continue;
hlist_del(&gwj->list);
cgw_unregister_filter(gwj);
kmem_cache_free(cgw_cache, gwj);
err = 0;
break;
}
return err;
}
static __init int cgw_module_init(void)
{
/* sanitize given module parameter */
max_hops = clamp_t(unsigned int, max_hops, CGW_MIN_HOPS, CGW_MAX_HOPS);
pr_info("can: netlink gateway (rev " CAN_GW_VERSION ") max_hops=%d\n",
max_hops);
cgw_cache = kmem_cache_create("can_gw", sizeof(struct cgw_job),
0, 0, NULL);
if (!cgw_cache)
return -ENOMEM;
/* set notifier */
notifier.notifier_call = cgw_notifier;
register_netdevice_notifier(&notifier);
if (__rtnl_register(PF_CAN, RTM_GETROUTE, NULL, cgw_dump_jobs, NULL)) {
unregister_netdevice_notifier(&notifier);
kmem_cache_destroy(cgw_cache);
return -ENOBUFS;
}
/* Only the first call to __rtnl_register can fail */
__rtnl_register(PF_CAN, RTM_NEWROUTE, cgw_create_job, NULL, NULL);
__rtnl_register(PF_CAN, RTM_DELROUTE, cgw_remove_job, NULL, NULL);
return 0;
}
static __exit void cgw_module_exit(void)
{
rtnl_unregister_all(PF_CAN);
unregister_netdevice_notifier(&notifier);
rtnl_lock();
cgw_remove_all_jobs();
rtnl_unlock();
rcu_barrier(); /* Wait for completion of call_rcu()'s */
kmem_cache_destroy(cgw_cache);
}
module_init(cgw_module_init);
module_exit(cgw_module_exit);
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