For IPv4, default route is learned via DHCPv4 and user is allowed to change
metric using config etc/network/interfaces. But for IPv6, default route can
be learned via RA, for which, currently a fixed metric value 1024 is used.
Ideally, user should be able to configure metric on default route for IPv6
similar to IPv4. This fix adds sysctl for the same.
Signed-off-by: Praveen Chaudhary <[email protected]>
Signed-off-by: Zhenggen Xu <[email protected]>
Changes in v1.
---
1.) Correct the call to rt6_add_dflt_router.
---
Changes in v2.
[Refer: lkml.org/lkml/2021/1/14/1400]
---
1.) Replace accept_ra_defrtr_metric to ra_defrtr_metric.
2.) Change Type to __u32 instead of __s32.
3.) Change description in Documentation/networking/ip-sysctl.rst.
4.) Use proc_douintvec instead of proc_dointvec.
5.) Code style in ndisc_router_discovery().
6.) Change Type to u32 instead of unsigned int.
---
Logs:
----------------------------------------------------------------
For IPv4:
----------------------------------------------------------------
Config in etc/network/interfaces
----------------------------------------------------------------
```
auto eth0
iface eth0 inet dhcp
metric 4261413864
```
IPv4 Kernel Route Table:
----------------------------------------------------------------
```
$ ip route list
default via 172.21.47.1 dev eth0 metric 4261413864
```
FRR Table, if a static route is configured.
[In real scenario, it is useful to prefer BGP learned default route over DHCPv4 default route.]
----------------------------------------------------------------
```
Codes: K - kernel route, C - connected, S - static, R - RIP,
O - OSPF, I - IS-IS, B - BGP, P - PIM, E - EIGRP, N - NHRP,
T - Table, v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
> - selected route, * - FIB route
S>* 0.0.0.0/0 [20/0] is directly connected, eth0, 00:00:03
K 0.0.0.0/0 [254/1000] via 172.21.47.1, eth0, 6d08h51m
```
----------------------------------------------------------------
***i.e. User can prefer Default Router learned via Routing Protocol in IPv4.***
***Similar behavior is not possible for IPv6, without this fix.***
----------------------------------------------------------------
After fix [for IPv6]:
----------------------------------------------------------------
```
sudo sysctl -w net.ipv6.conf.eth0.net.ipv6.conf.eth0.ra_defrtr_metric=1996489705
```
IP monitor: [When IPv6 RA is received]
----------------------------------------------------------------
```
default via fe80::xx16:xxxx:feb3:ce8e dev eth0 proto ra metric 1996489705 pref high
```
Kernel IPv6 routing table
----------------------------------------------------------------
```
$ ip -6 route list
default via fe80::be16:65ff:feb3:ce8e dev eth0 proto ra metric 1996489705 expires 21sec hoplimit 64 pref high
```
FRR Table, if a static route is configured.
[In real scenario, it is useful to prefer BGP learned default route over IPv6 RA default route.]
----------------------------------------------------------------
```
Codes: K - kernel route, C - connected, S - static, R - RIPng,
O - OSPFv3, I - IS-IS, B - BGP, N - NHRP, T - Table,
v - VNC, V - VNC-Direct, A - Babel, D - SHARP,
> - selected route, * - FIB route
S>* ::/0 [20/0] is directly connected, eth0, 00:00:06
K ::/0 [119/1001] via fe80::xx16:xxxx:feb3:ce8e, eth0, 6d07h43m
```
If the metric is changed later, the effect will be seen only when next IPv6
RA is received, because the default route must be fully controlled by RA msg.
Below metric is changed from 1996489705 to 1996489704.
----------------------------------------------------------------
```
$ sudo sysctl -w net.ipv6.conf.eth0.ra_defrtr_metric=1996489704
net.ipv6.conf.eth0.ra_defrtr_metric = 1996489704
```
IP monitor:
[On next IPv6 RA msg, Kernel deletes prev route and installs new route with updated metric]
----------------------------------------------------------------
```
Deleted default via fe80::xx16:xxxx:feb3:ce8e dev eth0 proto ra metric 1996489705 expires 3sec hoplimit 64 pref high
default via fe80::xx16:xxxx:feb3:ce8e dev eth0 proto ra metric 1996489704 pref high
```
---
Documentation/networking/ip-sysctl.rst | 12 ++++++++++++
include/linux/ipv6.h | 1 +
include/net/ip6_route.h | 3 ++-
include/uapi/linux/ipv6.h | 1 +
include/uapi/linux/sysctl.h | 1 +
net/ipv6/addrconf.c | 10 ++++++++++
net/ipv6/ndisc.c | 14 ++++++++++----
net/ipv6/route.c | 5 +++--
8 files changed, 40 insertions(+), 7 deletions(-)
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index dd2b12a32b73..c4b8d4b8d213 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -1871,6 +1871,18 @@ accept_ra_defrtr - BOOLEAN
- enabled if accept_ra is enabled.
- disabled if accept_ra is disabled.
+ra_defrtr_metric - INTEGER
+ Route metric for default route learned in Router Advertisement. This value
+ will be assigned as metric for the default route learned via IPv6 Router
+ Advertisement. Takes affect only if accept_ra_defrtr' is enabled.
+
+ Possible values are:
+ 0:
+ default value will be used for route metric
+ i.e. IP6_RT_PRIO_USER 1024.
+ 1 to 0xFFFFFFFF:
+ current value will be used for route metric.
+
accept_ra_from_local - BOOLEAN
Accept RA with source-address that is found on local machine
if the RA is otherwise proper and able to be accepted.
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index dda61d150a13..9d1f29f0c512 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -31,6 +31,7 @@ struct ipv6_devconf {
__s32 max_desync_factor;
__s32 max_addresses;
__s32 accept_ra_defrtr;
+ __u32 ra_defrtr_metric;
__s32 accept_ra_min_hop_limit;
__s32 accept_ra_pinfo;
__s32 ignore_routes_with_linkdown;
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 2a5277758379..f51a118bfce8 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -174,7 +174,8 @@ struct fib6_info *rt6_get_dflt_router(struct net *net,
struct net_device *dev);
struct fib6_info *rt6_add_dflt_router(struct net *net,
const struct in6_addr *gwaddr,
- struct net_device *dev, unsigned int pref);
+ struct net_device *dev, unsigned int pref,
+ u32 defrtr_usr_metric);
void rt6_purge_dflt_routers(struct net *net);
diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h
index 13e8751bf24a..70603775fe91 100644
--- a/include/uapi/linux/ipv6.h
+++ b/include/uapi/linux/ipv6.h
@@ -189,6 +189,7 @@ enum {
DEVCONF_ACCEPT_RA_RT_INFO_MIN_PLEN,
DEVCONF_NDISC_TCLASS,
DEVCONF_RPL_SEG_ENABLED,
+ DEVCONF_RA_DEFRTR_METRIC,
DEVCONF_MAX
};
diff --git a/include/uapi/linux/sysctl.h b/include/uapi/linux/sysctl.h
index 458179df9b27..1e05d3caa712 100644
--- a/include/uapi/linux/sysctl.h
+++ b/include/uapi/linux/sysctl.h
@@ -571,6 +571,7 @@ enum {
NET_IPV6_ACCEPT_SOURCE_ROUTE=25,
NET_IPV6_ACCEPT_RA_FROM_LOCAL=26,
NET_IPV6_ACCEPT_RA_RT_INFO_MIN_PLEN=27,
+ NET_IPV6_RA_DEFRTR_METRIC=28,
__NET_IPV6_MAX
};
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index eff2cacd5209..b13d3213e58f 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -205,6 +205,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
.max_desync_factor = MAX_DESYNC_FACTOR,
.max_addresses = IPV6_MAX_ADDRESSES,
.accept_ra_defrtr = 1,
+ .ra_defrtr_metric = 0,
.accept_ra_from_local = 0,
.accept_ra_min_hop_limit= 1,
.accept_ra_pinfo = 1,
@@ -260,6 +261,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
.max_desync_factor = MAX_DESYNC_FACTOR,
.max_addresses = IPV6_MAX_ADDRESSES,
.accept_ra_defrtr = 1,
+ .ra_defrtr_metric = 0,
.accept_ra_from_local = 0,
.accept_ra_min_hop_limit= 1,
.accept_ra_pinfo = 1,
@@ -5475,6 +5477,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
array[DEVCONF_MAX_DESYNC_FACTOR] = cnf->max_desync_factor;
array[DEVCONF_MAX_ADDRESSES] = cnf->max_addresses;
array[DEVCONF_ACCEPT_RA_DEFRTR] = cnf->accept_ra_defrtr;
+ array[DEVCONF_RA_DEFRTR_METRIC] = cnf->ra_defrtr_metric;
array[DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT] = cnf->accept_ra_min_hop_limit;
array[DEVCONF_ACCEPT_RA_PINFO] = cnf->accept_ra_pinfo;
#ifdef CONFIG_IPV6_ROUTER_PREF
@@ -6667,6 +6670,13 @@ static const struct ctl_table addrconf_sysctl[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
+ {
+ .procname = "ra_defrtr_metric",
+ .data = &ipv6_devconf.ra_defrtr_metric,
+ .maxlen = sizeof(u32),
+ .mode = 0644,
+ .proc_handler = proc_douintvec,
+ },
{
.procname = "accept_ra_min_hop_limit",
.data = &ipv6_devconf.accept_ra_min_hop_limit,
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 76717478f173..2bffed49f5c0 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1173,6 +1173,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
struct neighbour *neigh = NULL;
struct inet6_dev *in6_dev;
struct fib6_info *rt = NULL;
+ u32 defrtr_usr_metric;
struct net *net;
int lifetime;
struct ndisc_options ndopts;
@@ -1303,18 +1304,23 @@ static void ndisc_router_discovery(struct sk_buff *skb)
return;
}
}
- if (rt && lifetime == 0) {
+ /* Set default route metric if specified by user */
+ defrtr_usr_metric = in6_dev->cnf.accept_ra_defrtr_metric;
+ if (defrtr_usr_metric == 0)
+ defrtr_usr_metric = IP6_RT_PRIO_USER;
+ /* delete the route if lifetime is 0 or if metric needs change */
+ if (rt && ((lifetime == 0) || (rt->fib6_metric != defrtr_usr_metric))) {
ip6_del_rt(net, rt, false);
rt = NULL;
}
- ND_PRINTK(3, info, "RA: rt: %p lifetime: %d, for dev: %s\n",
- rt, lifetime, skb->dev->name);
+ ND_PRINTK(3, info, "RA: rt: %p lifetime: %d, metric: %d, for dev: %s\n",
+ rt, lifetime, defrtr_usr_metric, skb->dev->name);
if (!rt && lifetime) {
ND_PRINTK(3, info, "RA: adding default router\n");
rt = rt6_add_dflt_router(net, &ipv6_hdr(skb)->saddr,
- skb->dev, pref);
+ skb->dev, pref, defrtr_usr_metric);
if (!rt) {
ND_PRINTK(0, err,
"RA: %s failed to add default route\n",
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 188e114b29b4..64fe5b51b0c2 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4252,11 +4252,12 @@ struct fib6_info *rt6_get_dflt_router(struct net *net,
struct fib6_info *rt6_add_dflt_router(struct net *net,
const struct in6_addr *gwaddr,
struct net_device *dev,
- unsigned int pref)
+ unsigned int pref,
+ u32 defrtr_usr_metric)
{
struct fib6_config cfg = {
.fc_table = l3mdev_fib_table(dev) ? : RT6_TABLE_DFLT,
- .fc_metric = IP6_RT_PRIO_USER,
+ .fc_metric = defrtr_usr_metric ? : IP6_RT_PRIO_USER,
.fc_ifindex = dev->ifindex,
.fc_flags = RTF_GATEWAY | RTF_ADDRCONF | RTF_DEFAULT |
RTF_UP | RTF_EXPIRES | RTF_PREF(pref),
base-commit: 139711f033f636cc78b6aaf7363252241b9698ef
--
2.29.0
Hi Praveen,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on 139711f033f636cc78b6aaf7363252241b9698ef]
url: https://github.com/0day-ci/linux/commits/Praveen-Chaudhary/Allow-user-to-set-metric-on-default-route-learned-via-Router-Advertisement/20210115-160758
base: 139711f033f636cc78b6aaf7363252241b9698ef
config: nds32-randconfig-r015-20210115 (attached as .config)
compiler: nds32le-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/35f232fe80f8b50430aee1c6e534cba119c88de8
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Praveen-Chaudhary/Allow-user-to-set-metric-on-default-route-learned-via-Router-Advertisement/20210115-160758
git checkout 35f232fe80f8b50430aee1c6e534cba119c88de8
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=nds32
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All errors (new ones prefixed by >>):
net/ipv6/ndisc.c: In function 'ndisc_router_discovery':
>> net/ipv6/ndisc.c:1308:35: error: 'struct ipv6_devconf' has no member named 'accept_ra_defrtr_metric'; did you mean 'accept_ra_defrtr'?
1308 | defrtr_usr_metric = in6_dev->cnf.accept_ra_defrtr_metric;
| ^~~~~~~~~~~~~~~~~~~~~~~
| accept_ra_defrtr
Kconfig warnings: (for reference only)
WARNING: unmet direct dependencies detected for FRAME_POINTER
Depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
Selected by
- LATENCYTOP && DEBUG_KERNEL && STACKTRACE_SUPPORT && PROC_FS && !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
vim +1308 net/ipv6/ndisc.c
1241
1242 if (in6_dev->if_flags & IF_RS_SENT) {
1243 /*
1244 * flag that an RA was received after an RS was sent
1245 * out on this interface.
1246 */
1247 in6_dev->if_flags |= IF_RA_RCVD;
1248 }
1249
1250 /*
1251 * Remember the managed/otherconf flags from most recently
1252 * received RA message (RFC 2462) -- yoshfuji
1253 */
1254 old_if_flags = in6_dev->if_flags;
1255 in6_dev->if_flags = (in6_dev->if_flags & ~(IF_RA_MANAGED |
1256 IF_RA_OTHERCONF)) |
1257 (ra_msg->icmph.icmp6_addrconf_managed ?
1258 IF_RA_MANAGED : 0) |
1259 (ra_msg->icmph.icmp6_addrconf_other ?
1260 IF_RA_OTHERCONF : 0);
1261
1262 if (old_if_flags != in6_dev->if_flags)
1263 send_ifinfo_notify = true;
1264
1265 if (!in6_dev->cnf.accept_ra_defrtr) {
1266 ND_PRINTK(2, info,
1267 "RA: %s, defrtr is false for dev: %s\n",
1268 __func__, skb->dev->name);
1269 goto skip_defrtr;
1270 }
1271
1272 /* Do not accept RA with source-addr found on local machine unless
1273 * accept_ra_from_local is set to true.
1274 */
1275 net = dev_net(in6_dev->dev);
1276 if (!in6_dev->cnf.accept_ra_from_local &&
1277 ipv6_chk_addr(net, &ipv6_hdr(skb)->saddr, in6_dev->dev, 0)) {
1278 ND_PRINTK(2, info,
1279 "RA from local address detected on dev: %s: default router ignored\n",
1280 skb->dev->name);
1281 goto skip_defrtr;
1282 }
1283
1284 lifetime = ntohs(ra_msg->icmph.icmp6_rt_lifetime);
1285
1286 #ifdef CONFIG_IPV6_ROUTER_PREF
1287 pref = ra_msg->icmph.icmp6_router_pref;
1288 /* 10b is handled as if it were 00b (medium) */
1289 if (pref == ICMPV6_ROUTER_PREF_INVALID ||
1290 !in6_dev->cnf.accept_ra_rtr_pref)
1291 pref = ICMPV6_ROUTER_PREF_MEDIUM;
1292 #endif
1293 /* routes added from RAs do not use nexthop objects */
1294 rt = rt6_get_dflt_router(net, &ipv6_hdr(skb)->saddr, skb->dev);
1295 if (rt) {
1296 neigh = ip6_neigh_lookup(&rt->fib6_nh->fib_nh_gw6,
1297 rt->fib6_nh->fib_nh_dev, NULL,
1298 &ipv6_hdr(skb)->saddr);
1299 if (!neigh) {
1300 ND_PRINTK(0, err,
1301 "RA: %s got default router without neighbour\n",
1302 __func__);
1303 fib6_info_release(rt);
1304 return;
1305 }
1306 }
1307 /* Set default route metric if specified by user */
> 1308 defrtr_usr_metric = in6_dev->cnf.accept_ra_defrtr_metric;
1309 if (defrtr_usr_metric == 0)
1310 defrtr_usr_metric = IP6_RT_PRIO_USER;
1311 /* delete the route if lifetime is 0 or if metric needs change */
1312 if (rt && ((lifetime == 0) || (rt->fib6_metric != defrtr_usr_metric))) {
1313 ip6_del_rt(net, rt, false);
1314 rt = NULL;
1315 }
1316
1317 ND_PRINTK(3, info, "RA: rt: %p lifetime: %d, metric: %d, for dev: %s\n",
1318 rt, lifetime, defrtr_usr_metric, skb->dev->name);
1319 if (!rt && lifetime) {
1320 ND_PRINTK(3, info, "RA: adding default router\n");
1321
1322 rt = rt6_add_dflt_router(net, &ipv6_hdr(skb)->saddr,
1323 skb->dev, pref, defrtr_usr_metric);
1324 if (!rt) {
1325 ND_PRINTK(0, err,
1326 "RA: %s failed to add default route\n",
1327 __func__);
1328 return;
1329 }
1330
1331 neigh = ip6_neigh_lookup(&rt->fib6_nh->fib_nh_gw6,
1332 rt->fib6_nh->fib_nh_dev, NULL,
1333 &ipv6_hdr(skb)->saddr);
1334 if (!neigh) {
1335 ND_PRINTK(0, err,
1336 "RA: %s got default router without neighbour\n",
1337 __func__);
1338 fib6_info_release(rt);
1339 return;
1340 }
1341 neigh->flags |= NTF_ROUTER;
1342 } else if (rt) {
1343 rt->fib6_flags = (rt->fib6_flags & ~RTF_PREF_MASK) | RTF_PREF(pref);
1344 }
1345
1346 if (rt)
1347 fib6_set_expires(rt, jiffies + (HZ * lifetime));
1348 if (in6_dev->cnf.accept_ra_min_hop_limit < 256 &&
1349 ra_msg->icmph.icmp6_hop_limit) {
1350 if (in6_dev->cnf.accept_ra_min_hop_limit <= ra_msg->icmph.icmp6_hop_limit) {
1351 in6_dev->cnf.hop_limit = ra_msg->icmph.icmp6_hop_limit;
1352 fib6_metric_set(rt, RTAX_HOPLIMIT,
1353 ra_msg->icmph.icmp6_hop_limit);
1354 } else {
1355 ND_PRINTK(2, warn, "RA: Got route advertisement with lower hop_limit than minimum\n");
1356 }
1357 }
1358
1359 skip_defrtr:
1360
1361 /*
1362 * Update Reachable Time and Retrans Timer
1363 */
1364
1365 if (in6_dev->nd_parms) {
1366 unsigned long rtime = ntohl(ra_msg->retrans_timer);
1367
1368 if (rtime && rtime/1000 < MAX_SCHEDULE_TIMEOUT/HZ) {
1369 rtime = (rtime*HZ)/1000;
1370 if (rtime < HZ/100)
1371 rtime = HZ/100;
1372 NEIGH_VAR_SET(in6_dev->nd_parms, RETRANS_TIME, rtime);
1373 in6_dev->tstamp = jiffies;
1374 send_ifinfo_notify = true;
1375 }
1376
1377 rtime = ntohl(ra_msg->reachable_time);
1378 if (rtime && rtime/1000 < MAX_SCHEDULE_TIMEOUT/(3*HZ)) {
1379 rtime = (rtime*HZ)/1000;
1380
1381 if (rtime < HZ/10)
1382 rtime = HZ/10;
1383
1384 if (rtime != NEIGH_VAR(in6_dev->nd_parms, BASE_REACHABLE_TIME)) {
1385 NEIGH_VAR_SET(in6_dev->nd_parms,
1386 BASE_REACHABLE_TIME, rtime);
1387 NEIGH_VAR_SET(in6_dev->nd_parms,
1388 GC_STALETIME, 3 * rtime);
1389 in6_dev->nd_parms->reachable_time = neigh_rand_reach_time(rtime);
1390 in6_dev->tstamp = jiffies;
1391 send_ifinfo_notify = true;
1392 }
1393 }
1394 }
1395
1396 /*
1397 * Send a notify if RA changed managed/otherconf flags or timer settings
1398 */
1399 if (send_ifinfo_notify)
1400 inet6_ifinfo_notify(RTM_NEWLINK, in6_dev);
1401
1402 skip_linkparms:
1403
1404 /*
1405 * Process options.
1406 */
1407
1408 if (!neigh)
1409 neigh = __neigh_lookup(&nd_tbl, &ipv6_hdr(skb)->saddr,
1410 skb->dev, 1);
1411 if (neigh) {
1412 u8 *lladdr = NULL;
1413 if (ndopts.nd_opts_src_lladdr) {
1414 lladdr = ndisc_opt_addr_data(ndopts.nd_opts_src_lladdr,
1415 skb->dev);
1416 if (!lladdr) {
1417 ND_PRINTK(2, warn,
1418 "RA: invalid link-layer address length\n");
1419 goto out;
1420 }
1421 }
1422 ndisc_update(skb->dev, neigh, lladdr, NUD_STALE,
1423 NEIGH_UPDATE_F_WEAK_OVERRIDE|
1424 NEIGH_UPDATE_F_OVERRIDE|
1425 NEIGH_UPDATE_F_OVERRIDE_ISROUTER|
1426 NEIGH_UPDATE_F_ISROUTER,
1427 NDISC_ROUTER_ADVERTISEMENT, &ndopts);
1428 }
1429
1430 if (!ipv6_accept_ra(in6_dev)) {
1431 ND_PRINTK(2, info,
1432 "RA: %s, accept_ra is false for dev: %s\n",
1433 __func__, skb->dev->name);
1434 goto out;
1435 }
1436
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]
On 1/15/21 1:02 AM, Praveen Chaudhary wrote:
> For IPv4, default route is learned via DHCPv4 and user is allowed to change
> metric using config etc/network/interfaces. But for IPv6, default route can
> be learned via RA, for which, currently a fixed metric value 1024 is used.
>
> Ideally, user should be able to configure metric on default route for IPv6
> similar to IPv4. This fix adds sysctl for the same.
>
> Signed-off-by: Praveen Chaudhary <[email protected]>
> Signed-off-by: Zhenggen Xu <[email protected]>
>
> Changes in v1.
> ---
your trying to be too fancy in the log messages; everything after this
first '---' is dropped. Just Remove all of the '---' lines and '```' tags.
> 1.) Correct the call to rt6_add_dflt_router.
> ---
>
> Changes in v2.
> [Refer: lkml.org/lkml/2021/1/14/1400]
> ---
> 1.) Replace accept_ra_defrtr_metric to ra_defrtr_metric.
> 2.) Change Type to __u32 instead of __s32.
> 3.) Change description in Documentation/networking/ip-sysctl.rst.
> 4.) Use proc_douintvec instead of proc_dointvec.
> 5.) Code style in ndisc_router_discovery().
> 6.) Change Type to u32 instead of unsigned int.
> ---
>
> Logs:
> ----------------------------------------------------------------
> For IPv4:
> ----------------------------------------------------------------
>
> Config in etc/network/interfaces
> ----------------------------------------------------------------
> ```
> auto eth0
> iface eth0 inet dhcp
> metric 4261413864
how does that work for IPv4? Is the metric passed to the dhclient and it
inserts the route with the given metric or is a dhclient script used to
replace the route after insert?
> diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
> index dd2b12a32b73..c4b8d4b8d213 100644
> --- a/Documentation/networking/ip-sysctl.rst
> +++ b/Documentation/networking/ip-sysctl.rst
> @@ -1871,6 +1871,18 @@ accept_ra_defrtr - BOOLEAN
> - enabled if accept_ra is enabled.
> - disabled if accept_ra is disabled.
>
> +ra_defrtr_metric - INTEGER
> + Route metric for default route learned in Router Advertisement. This value
> + will be assigned as metric for the default route learned via IPv6 Router
> + Advertisement. Takes affect only if accept_ra_defrtr' is enabled.
stray ' after accept_ra_defrtr
> +
> + Possible values are:
> + 0:
> + default value will be used for route metric
> + i.e. IP6_RT_PRIO_USER 1024.
> + 1 to 0xFFFFFFFF:
> + current value will be used for route metric.
> +
> accept_ra_from_local - BOOLEAN
> Accept RA with source-address that is found on local machine
> if the RA is otherwise proper and able to be accepted.
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index eff2cacd5209..b13d3213e58f 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -205,6 +205,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
> .max_desync_factor = MAX_DESYNC_FACTOR,
> .max_addresses = IPV6_MAX_ADDRESSES,
> .accept_ra_defrtr = 1,
> + .ra_defrtr_metric = 0,
make the the '=' align column wise with the existing entries; seems like
your new line is missing a tab
> .accept_ra_from_local = 0,
> .accept_ra_min_hop_limit= 1,
> .accept_ra_pinfo = 1,
> @@ -260,6 +261,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
> .max_desync_factor = MAX_DESYNC_FACTOR,
> .max_addresses = IPV6_MAX_ADDRESSES,
> .accept_ra_defrtr = 1,
> + .ra_defrtr_metric = 0,
same here
> .accept_ra_from_local = 0,
> .accept_ra_min_hop_limit= 1,
> .accept_ra_pinfo = 1,
> @@ -5475,6 +5477,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
> array[DEVCONF_MAX_DESYNC_FACTOR] = cnf->max_desync_factor;
> array[DEVCONF_MAX_ADDRESSES] = cnf->max_addresses;
> array[DEVCONF_ACCEPT_RA_DEFRTR] = cnf->accept_ra_defrtr;
> + array[DEVCONF_RA_DEFRTR_METRIC] = cnf->ra_defrtr_metric;
> array[DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT] = cnf->accept_ra_min_hop_limit;
> array[DEVCONF_ACCEPT_RA_PINFO] = cnf->accept_ra_pinfo;
> #ifdef CONFIG_IPV6_ROUTER_PREF
> @@ -6667,6 +6670,13 @@ static const struct ctl_table addrconf_sysctl[] = {
> .mode = 0644,
> .proc_handler = proc_dointvec,
> },
> + {
> + .procname = "ra_defrtr_metric",
> + .data = &ipv6_devconf.ra_defrtr_metric,
> + .maxlen = sizeof(u32),
> + .mode = 0644,
> + .proc_handler = proc_douintvec,
> + },
> {
> .procname = "accept_ra_min_hop_limit",
> .data = &ipv6_devconf.accept_ra_min_hop_limit,
> diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
> index 76717478f173..2bffed49f5c0 100644
> --- a/net/ipv6/ndisc.c
> +++ b/net/ipv6/ndisc.c
> @@ -1173,6 +1173,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
> struct neighbour *neigh = NULL;
> struct inet6_dev *in6_dev;
> struct fib6_info *rt = NULL;
> + u32 defrtr_usr_metric;
> struct net *net;
> int lifetime;
> struct ndisc_options ndopts;
> @@ -1303,18 +1304,23 @@ static void ndisc_router_discovery(struct sk_buff *skb)
> return;
> }
> }
> - if (rt && lifetime == 0) {
> + /* Set default route metric if specified by user */
> + defrtr_usr_metric = in6_dev->cnf.accept_ra_defrtr_metric;
this tells me you did not compile this version of the patch since the
'accept_' has been dropped. Always compile and test every patch before
sending.
> On Jan 16, 2021, at 9:13 AM, David Ahern <[email protected]> wrote:
>
> On 1/15/21 1:02 AM, Praveen Chaudhary wrote:
>> For IPv4, default route is learned via DHCPv4 and user is allowed to change
>> metric using config etc/network/interfaces. But for IPv6, default route can
>> be learned via RA, for which, currently a fixed metric value 1024 is used.
>>
>> Ideally, user should be able to configure metric on default route for IPv6
>> similar to IPv4. This fix adds sysctl for the same.
>>
>> Signed-off-by: Praveen Chaudhary <[email protected]>
>> Signed-off-by: Zhenggen Xu <[email protected]>
>>
>> Changes in v1.
>> ---
>
> your trying to be too fancy in the log messages; everything after this
> first '---' is dropped. Just Remove all of the '---' lines and '```' tags.
>
Removed all ‘—‘ and ‘```’ in v3.
>> 1.) Correct the call to rt6_add_dflt_router.
>> ---
>>
>> Changes in v2.
>> [Refer: lkml.org/lkml/2021/1/14/1400]
>> ---
>> 1.) Replace accept_ra_defrtr_metric to ra_defrtr_metric.
>> 2.) Change Type to __u32 instead of __s32.
>> 3.) Change description in Documentation/networking/ip-sysctl.rst.
>> 4.) Use proc_douintvec instead of proc_dointvec.
>> 5.) Code style in ndisc_router_discovery().
>> 6.) Change Type to u32 instead of unsigned int.
>> ---
>>
>> Logs:
>> ----------------------------------------------------------------
>> For IPv4:
>> ----------------------------------------------------------------
>>
>> Config in etc/network/interfaces
>> ----------------------------------------------------------------
>> ```
>> auto eth0
>> iface eth0 inet dhcp
>> metric 4261413864
>
> how does that work for IPv4? Is the metric passed to the dhclient and it
> inserts the route with the given metric or is a dhclient script used to
> replace the route after insert?
>
>
Yes, DHCP client picks config under “iface eth0 inet dhcp” line and if metric is configured, then it adds the metric for all added routes.
>> diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
>> index dd2b12a32b73..c4b8d4b8d213 100644
>> --- a/Documentation/networking/ip-sysctl.rst
>> +++ b/Documentation/networking/ip-sysctl.rst
>> @@ -1871,6 +1871,18 @@ accept_ra_defrtr - BOOLEAN
>> - enabled if accept_ra is enabled.
>> - disabled if accept_ra is disabled.
>>
>> +ra_defrtr_metric - INTEGER
>> + Route metric for default route learned in Router Advertisement. This value
>> + will be assigned as metric for the default route learned via IPv6 Router
>> + Advertisement. Takes affect only if accept_ra_defrtr' is enabled.
>
> stray ' after accept_ra_defrtr
>
Removed.
>> +
>> + Possible values are:
>> + 0:
>> + default value will be used for route metric
>> + i.e. IP6_RT_PRIO_USER 1024.
>> + 1 to 0xFFFFFFFF:
>> + current value will be used for route metric.
>> +
>> accept_ra_from_local - BOOLEAN
>> Accept RA with source-address that is found on local machine
>> if the RA is otherwise proper and able to be accepted.
>
>
>
>> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
>> index eff2cacd5209..b13d3213e58f 100644
>> --- a/net/ipv6/addrconf.c
>> +++ b/net/ipv6/addrconf.c
>> @@ -205,6 +205,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
>> .max_desync_factor = MAX_DESYNC_FACTOR,
>> .max_addresses = IPV6_MAX_ADDRESSES,
>> .accept_ra_defrtr = 1,
>> + .ra_defrtr_metric = 0,
>
> make the the '=' align column wise with the existing entries; seems like
> your new line is missing a tab
Fixed.
>
>> .accept_ra_from_local = 0,
>> .accept_ra_min_hop_limit= 1,
>> .accept_ra_pinfo = 1,
>> @@ -260,6 +261,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
>> .max_desync_factor = MAX_DESYNC_FACTOR,
>> .max_addresses = IPV6_MAX_ADDRESSES,
>> .accept_ra_defrtr = 1,
>> + .ra_defrtr_metric = 0,
>
> same here
Fixed.
>
>> .accept_ra_from_local = 0,
>> .accept_ra_min_hop_limit= 1,
>> .accept_ra_pinfo = 1,
>> @@ -5475,6 +5477,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
>> array[DEVCONF_MAX_DESYNC_FACTOR] = cnf->max_desync_factor;
>> array[DEVCONF_MAX_ADDRESSES] = cnf->max_addresses;
>> array[DEVCONF_ACCEPT_RA_DEFRTR] = cnf->accept_ra_defrtr;
>> + array[DEVCONF_RA_DEFRTR_METRIC] = cnf->ra_defrtr_metric;
>> array[DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT] = cnf->accept_ra_min_hop_limit;
>> array[DEVCONF_ACCEPT_RA_PINFO] = cnf->accept_ra_pinfo;
>> #ifdef CONFIG_IPV6_ROUTER_PREF
>> @@ -6667,6 +6670,13 @@ static const struct ctl_table addrconf_sysctl[] = {
>> .mode = 0644,
>> .proc_handler = proc_dointvec,
>> },
>> + {
>> + .procname = "ra_defrtr_metric",
>> + .data = &ipv6_devconf.ra_defrtr_metric,
>> + .maxlen = sizeof(u32),
>> + .mode = 0644,
>> + .proc_handler = proc_douintvec,
>> + },
>> {
>> .procname = "accept_ra_min_hop_limit",
>> .data = &ipv6_devconf.accept_ra_min_hop_limit,
>> diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
>> index 76717478f173..2bffed49f5c0 100644
>> --- a/net/ipv6/ndisc.c
>> +++ b/net/ipv6/ndisc.c
>> @@ -1173,6 +1173,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
>> struct neighbour *neigh = NULL;
>> struct inet6_dev *in6_dev;
>> struct fib6_info *rt = NULL;
>> + u32 defrtr_usr_metric;
>> struct net *net;
>> int lifetime;
>> struct ndisc_options ndopts;
>> @@ -1303,18 +1304,23 @@ static void ndisc_router_discovery(struct sk_buff *skb)
>> return;
>> }
>> }
>> - if (rt && lifetime == 0) {
>> + /* Set default route metric if specified by user */
>> + defrtr_usr_metric = in6_dev->cnf.accept_ra_defrtr_metric;
>
> this tells me you did not compile this version of the patch since the
> 'accept_' has been dropped. Always compile and test every patch before
> sending.
Yeah one patch was pushed bit early. Sorry about that. I will take care of this now onwards.
I have respined the Patch (v3) after addressing your review comments. Build is done in our pipeline.
Build logs: https://dev.azure.com/sonicswitch/build/_build/results?buildId=1669&view=logs&j=011e1ec8-6569-5e69-4f06-baf193d1351e
Thanks a lot again for spending time for this Review,
This feature will help SONiC OS [and others Linux flavors] for better IPv6 support, so thanks again.
Praveen
https://github.com/praveen-li
On 1/19/21 3:17 PM, praveen chaudhary wrote:
>>> ----------------------------------------------------------------
>>> For IPv4:
>>> ----------------------------------------------------------------
>>>
>>> Config in etc/network/interfaces
>>> ----------------------------------------------------------------
>>> ```
>>> auto eth0
>>> iface eth0 inet dhcp
>>> metric 4261413864
>>
>> how does that work for IPv4? Is the metric passed to the dhclient and it
>> inserts the route with the given metric or is a dhclient script used to
>> replace the route after insert?
>>
>>
>
> Yes, DHCP client picks config under “iface eth0 inet dhcp” line and if metric is configured, then it adds the metric for all added routes.
As I recall ifupdown{2} forks dhclient as a process to handle dhcp
config, and I believe there is a script that handles adding the default
route with metric. Meaning ... it is not comparable to an RA.
>
> Thanks a lot again for spending time for this Review,
> This feature will help SONiC OS [and others Linux flavors] for better IPv6 support, so thanks again.
I think SONiC is an abomination, so that is definitely not the
motivation for my reviews. :-)
> On Jan 19, 2021, at 8:22 PM, David Ahern <[email protected]> wrote:
>
> On 1/19/21 3:17 PM, praveen chaudhary wrote:
>>>> ----------------------------------------------------------------
>>>> For IPv4:
>>>> ----------------------------------------------------------------
>>>>
>>>> Config in etc/network/interfaces
>>>> ----------------------------------------------------------------
>>>> ```
>>>> auto eth0
>>>> iface eth0 inet dhcp
>>>> metric 4261413864
>>>
>>> how does that work for IPv4? Is the metric passed to the dhclient and it
>>> inserts the route with the given metric or is a dhclient script used to
>>> replace the route after insert?
>>>
>>>
>>
>> Yes, DHCP client picks config under “iface eth0 inet dhcp” line and if metric is configured, then it adds the metric for all added routes.
>
> As I recall ifupdown{2} forks dhclient as a process to handle dhcp
> config, and I believe there is a script that handles adding the default
> route with metric. Meaning ... it is not comparable to an RA.
>
I hope, we both will agree that a fixed metric value on default route learned via RA
restricts Network Administrators today. And such issues hinder the deployment
of IPv6 only networks. So if we agree that in future we may need to allow a
configurable value for metric then this fix makes good sense.
BTW, kindly let me know if there is a better way to configure this metric. I think,
sysctl is the only way.
>>
>> Thanks a lot again for spending time for this Review,
>> This feature will help SONiC OS [and others Linux flavors] for better IPv6 support, so thanks again.
>
> I think SONiC is an abomination, so that is definitely not the
> motivation for my reviews. :-)
>
Trying to make things better day by day. That is the only solace for Software Engineers :-).
I really appreciate for your time to review this patch. Cheers.