kernel/git/stable/linux.git/net/ipv4/route.c, branch linux-5.5.y

rt_cpu_seq_next should increase position index

2020-01-24T10:42:18+00:00

if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. https://bugzilla.kernel.org/show_bug.cgi?id=206283 Signed-off-by: Vasily Averin Signed-off-by: David S. Miller

net: add bool confirm_neigh parameter for dst_ops.update_pmtu

2019-12-25T06:28:54+00:00

The MTU update code is supposed to be invoked in response to real networking events that update the PMTU. In IPv6 PMTU update function __ip6_rt_update_pmtu() we called dst_confirm_neigh() to update neighbor confirmed time. But for tunnel code, it will call pmtu before xmit, like: - tnl_update_pmtu() - skb_dst_update_pmtu() - ip6_rt_update_pmtu() - __ip6_rt_update_pmtu() - dst_confirm_neigh() If the tunnel remote dst mac address changed and we still do the neigh confirm, we will not be able to update neigh cache and ping6 remote will failed. So for this ip_tunnel_xmit() case, _EVEN_ if the MTU is changed, we should not be invoking dst_confirm_neigh() as we have no evidence of successful two-way communication at this point. On the other hand it is also important to keep the neigh reachability fresh for TCP flows, so we cannot remove this dst_confirm_neigh() call. To fix the issue, we have to add a new bool parameter for dst_ops.update_pmtu to choose whether we should do neigh update or not. I will add the parameter in this patch and set all the callers to true to comply with the previous way, and fix the tunnel code one by one on later patches. v5: No change. v4: No change. v3: Do not remove dst_confirm_neigh, but add a new bool parameter in dst_ops.update_pmtu to control whether we should do neighbor confirm. Also split the big patch to small ones for each area. v2: Remove dst_confirm_neigh in __ip6_rt_update_pmtu. Suggested-by: David Miller Reviewed-by: Guillaume Nault Acked-by: David Ahern Signed-off-by: Hangbin Liu Signed-off-by: David S. Miller

ipv4: use dst hint for ipv4 list receive

2019-11-21T22:45:55+00:00

This is alike the previous change, with some additional ipv4 specific quirk. Even when using the route hint we still have to do perform additional per packet checks about source address validity: a new helper is added to wrap them. Hints are explicitly disabled if the destination is a local broadcast, that keeps the code simple and local broadcast are a slower path anyway. UDP flood performances vs recvmmsg() receiver: vanilla patched delta Kpps Kpps % 1683 1871 +11 In the worst case scenario - each packet has a different destination address - the performance delta is within noise range. v3 -> v4: - re-enable hints for forward v2 -> v3: - really fix build (sic) and hint usage check - use fib4_has_custom_rules() helpers (David A.) - add ip_extract_route_hint() helper (Edward C.) - use prev skb as hint instead of copying data (Willem) v1 -> v2: - fix build issue with !CONFIG_IP_MULTIPLE_TABLES Signed-off-by: Paolo Abeni Reviewed-by: David Ahern Signed-off-by: David S. Miller

icmp: remove duplicate code

2019-11-05T22:03:11+00:00

The same code which recognizes ICMP error packets is duplicated several times. Use the icmp_is_err() and icmpv6_is_err() helpers instead, which do the same thing. ip_multipath_l3_keys() and tcf_nat_act() didn't check for all the error types, assume that they should instead. Signed-off-by: Matteo Croce Signed-off-by: David S. Miller

ipv4: fix race condition between route lookup and invalidation

2019-10-17T23:44:03+00:00

Jesse and Ido reported the following race condition: - Received packet A is forwarded and cached dst entry is taken from the nexthop ('nhc->nhc_rth_input'). Calls skb_dst_set() - Given Jesse has busy routers ("ingesting full BGP routing tables from multiple ISPs"), route is added / deleted and rt_cache_flush() is called - Received packet B tries to use the same cached dst entry from t0, but rt_cache_valid() is no longer true and it is replaced in rt_cache_route() by the newer one. This calls dst_dev_put() on the original dst entry which assigns the blackhole netdev to 'dst->dev' - dst_input(skb) is called on packet A and it is dropped due to 'dst->dev' being the blackhole netdev There are 2 issues in the v4 routing code: 1. A per-netns counter is used to do the validation of the route. That means whenever a route is changed in the netns, users of all routes in the netns needs to redo lookup. v6 has an implementation of only updating fn_sernum for routes that are affected. 2. When rt_cache_valid() returns false, rt_cache_route() is called to throw away the current cache, and create a new one. This seems unnecessary because as long as this route does not change, the route cache does not need to be recreated. To fully solve the above 2 issues, it probably needs quite some code changes and requires careful testing, and does not suite for net branch. So this patch only tries to add the deleted cached rt into the uncached list, so user could still be able to use it to receive packets until it's done. Fixes: 95c47f9cf5e0 ("ipv4: call dst_dev_put() properly") Signed-off-by: Wei Wang Reported-by: Ido Schimmel Reported-by: Jesse Hathaway Tested-by: Jesse Hathaway Acked-by: Martin KaFai Lau Cc: David Ahern Reviewed-by: Ido Schimmel Signed-off-by: David S. Miller

ipv4: Return -ENETUNREACH if we can't create route but saddr is valid

2019-10-17T23:36:17+00:00

...instead of -EINVAL. An issue was found with older kernel versions while unplugging a NFS client with pending RPCs, and the wrong error code here prevented it from recovering once link is back up with a configured address. Incidentally, this is not an issue anymore since commit 4f8943f80883 ("SUNRPC: Replace direct task wakeups from softirq context"), included in 5.2-rc7, had the effect of decoupling the forwarding of this error by using SO_ERROR in xs_wake_error(), as pointed out by Benjamin Coddington. To the best of my knowledge, this isn't currently causing any further issue, but the error code doesn't look appropriate anyway, and we might hit this in other paths as well. In detail, as analysed by Gonzalo Siero, once the route is deleted because the interface is down, and can't be resolved and we return -EINVAL here, this ends up, courtesy of inet_sk_rebuild_header(), as the socket error seen by tcp_write_err(), called by tcp_retransmit_timer(). In turn, tcp_write_err() indirectly calls xs_error_report(), which wakes up the RPC pending tasks with a status of -EINVAL. This is then seen by call_status() in the SUN RPC implementation, which aborts the RPC call calling rpc_exit(), instead of handling this as a potentially temporary condition, i.e. as a timeout. Return -EINVAL only if the input parameters passed to ip_route_output_key_hash_rcu() are actually invalid (this is the case if the specified source address is multicast, limited broadcast or all zeroes), but return -ENETUNREACH in all cases where, at the given moment, the given source address doesn't allow resolving the route. While at it, drop the initialisation of err to -ENETUNREACH, which was added to __ip_route_output_key() back then by commit 0315e3827048 ("net: Fix behaviour of unreachable, blackhole and prohibit routes"), but actually had no effect, as it was, and is, overwritten by the fib_lookup() return code assignment, and anyway ignored in all other branches, including the if (fl4->saddr) one: I find this rather confusing, as it would look like -ENETUNREACH is the "default" error, while that statement has no effect. Also note that after commit fc75fc8339e7 ("ipv4: dont create routes on down devices"), we would get -ENETUNREACH if the device is down, but -EINVAL if the source address is specified and we can't resolve the route, and this appears to be rather inconsistent. Reported-by: Stefan Walter Analysed-by: Benjamin Coddington Analysed-by: Gonzalo Siero Signed-off-by: Stefano Brivio Signed-off-by: David S. Miller

net: ipv4: avoid mixed n_redirects and rate_tokens usage

2019-10-05T00:27:04+00:00

Since commit c09551c6ff7f ("net: ipv4: use a dedicated counter for icmp_v4 redirect packets") we use 'n_redirects' to account for redirect packets, but we still use 'rate_tokens' to compute the redirect packets exponential backoff. If the device sent to the relevant peer any ICMP error packet after sending a redirect, it will also update 'rate_token' according to the leaking bucket schema; typically 'rate_token' will raise above BITS_PER_LONG and the redirect packets backoff algorithm will produce undefined behavior. Fix the issue using 'n_redirects' to compute the exponential backoff in ip_rt_send_redirect(). Note that we still clear rate_tokens after a redirect silence period, to avoid changing an established behaviour. The root cause predates git history; before the mentioned commit in the critical scenario, the kernel stopped sending redirects, after the mentioned commit the behavior more randomic. Reported-by: Xiumei Mu Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Fixes: c09551c6ff7f ("net: ipv4: use a dedicated counter for icmp_v4 redirect packets") Signed-off-by: Paolo Abeni Acked-by: Lorenzo Bianconi Signed-off-by: David S. Miller

ipv4: Revert removal of rt_uses_gateway

2019-09-21T01:23:33+00:00

Julian noted that rt_uses_gateway has a more subtle use than 'is gateway set': https://lore.kernel.org/netdev/alpine.LFD.2.21.1909151104060.2546@ja.home.ssi.bg/ Revert that part of the commit referenced in the Fixes tag. Currently, there are no u8 holes in 'struct rtable'. There is a 4-byte hole in the second cacheline which contains the gateway declaration. So move rt_gw_family down to the gateway declarations since they are always used together, and then re-use that u8 for rt_uses_gateway. End result is that rtable size is unchanged. Fixes: 1550c171935d ("ipv4: Prepare rtable for IPv6 gateway") Reported-by: Julian Anastasov Signed-off-by: David Ahern Reviewed-by: Julian Anastasov Signed-off-by: Jakub Kicinski

net: route dump netlink NLM_F_MULTI flag missing

2019-08-24T23:49:48+00:00

An excerpt from netlink(7) man page, In multipart messages (multiple nlmsghdr headers with associated payload in one byte stream) the first and all following headers have the NLM_F_MULTI flag set, except for the last header which has the type NLMSG_DONE. but, after (ee28906) there is a missing NLM_F_MULTI flag in the middle of a FIB dump. The result is user space applications following above man page excerpt may get confused and may stop parsing msg believing something went wrong. In the golang netlink lib [0] the library logic stops parsing believing the message is not a multipart message. Found this running Cilium[1] against net-next while adding a feature to auto-detect routes. I noticed with multiple route tables we no longer could detect the default routes on net tree kernels because the library logic was not returning them. Fix this by handling the fib_dump_info_fnhe() case the same way the fib_dump_info() handles it by passing the flags argument through the call chain and adding a flags argument to rt_fill_info(). Tested with Cilium stack and auto-detection of routes works again. Also annotated libs to dump netlink msgs and inspected NLM_F_MULTI and NLMSG_DONE flags look correct after this. Note: In inet_rtm_getroute() pass rt_fill_info() '0' for flags the same as is done for fib_dump_info() so this looks correct to me. [0] https://github.com/vishvananda/netlink/ [1] https://github.com/cilium/ Fixes: ee28906fd7a14 ("ipv4: Dump route exceptions if requested") Signed-off-by: John Fastabend Reviewed-by: Stefano Brivio Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2019-07-09T02:48:57+00:00

Two cases of overlapping changes, nothing fancy. Signed-off-by: David S. Miller