Commit b93e1fa7 authored Sep 07, 2016 by Guillaume Nault Committed by David S. Miller Sep 09, 2016

ipv4: fix value of ->nlmsg_flags reported in RTM_NEWROUTE events



fib_table_insert() inconsistently fills the nlmsg_flags field in its
notification messages.

Since commit b8f55831 ("[RTNETLINK]: Fix sending netlink message
when replace route."), the netlink message has its nlmsg_flags set to
NLM_F_REPLACE if the route replaced a preexisting one.

Then commit a2bb6d7d ("ipv4: include NLM_F_APPEND flag in append
route notifications") started setting nlmsg_flags to NLM_F_APPEND if
the route matched a preexisting one but was appended.

In other cases (exclusive creation or prepend), nlmsg_flags is 0.

This patch sets ->nlmsg_flags in all situations, preserving the
semantic of the NLM_F_* bits:

  * NLM_F_CREATE: a new fib entry has been created for this route.
  * NLM_F_EXCL: no other fib entry existed for this route.
  * NLM_F_REPLACE: this route has overwritten a preexisting fib entry.
  * NLM_F_APPEND: the new fib entry was added after other entries for
    the same route.

As a result, the possible flag combination can now be reported
(iproute2's terminology into parentheses):

  * NLM_F_CREATE | NLM_F_EXCL: route didn't exist, exclusive creation
    ("add").
  * NLM_F_CREATE | NLM_F_APPEND: route did already exist, new route
    added after preexisting ones ("append").
  * NLM_F_CREATE: route did already exist, new route added before
    preexisting ones ("prepend").
  * NLM_F_REPLACE: route did already exist, new route replaced the
    first preexisting one ("change").

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent e895cdce

net/ipv4/fib_trie.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -1081,7 +1081,7 @@ int fib_table_insert(struct fib_table tb, struct fib_config cfg)
		struct trie t = (struct trie )tb->tb_data;
		struct fib_alias fa, new_fa;
		struct key_vector l, tp;
		unsigned int nlflags = 0;
		u16 nlflags = NLM_F_EXCL;
		struct fib_info *fi;
		u8 plen = cfg->fc_dst_len;
		u8 slen = KEYLENGTH - plen;
		@@ -1126,6 +1126,8 @@ int fib_table_insert(struct fib_table tb, struct fib_config cfg)
		if (cfg->fc_nlflags & NLM_F_EXCL)
		goto out;

		nlflags &= ~NLM_F_EXCL;

		/* We have 2 goals:
		* 1. Find exact match for type, scope, fib_info to avoid
		* duplicate routes
		@@ -1151,6 +1153,7 @@ int fib_table_insert(struct fib_table tb, struct fib_config cfg)
		struct fib_info *fi_drop;
		u8 state;

		nlflags \|= NLM_F_REPLACE;
		fa = fa_first;
		if (fa_match) {
		if (fa == fa_match)
		@@ -1191,7 +1194,7 @@ int fib_table_insert(struct fib_table tb, struct fib_config cfg)
		if (state & FA_S_ACCESSED)
		rt_cache_flush(cfg->fc_nlinfo.nl_net);
		rtmsg_fib(RTM_NEWROUTE, htonl(key), new_fa, plen,
		tb->tb_id, &cfg->fc_nlinfo, NLM_F_REPLACE);
		tb->tb_id, &cfg->fc_nlinfo, nlflags);

		goto succeeded;
		}
		@@ -1203,7 +1206,7 @@ int fib_table_insert(struct fib_table tb, struct fib_config cfg)
		goto out;

		if (cfg->fc_nlflags & NLM_F_APPEND)
		nlflags = NLM_F_APPEND;
		nlflags \|= NLM_F_APPEND;
		else
		fa = fa_first;
		}
		@@ -1211,6 +1214,7 @@ int fib_table_insert(struct fib_table tb, struct fib_config cfg)
		if (!(cfg->fc_nlflags & NLM_F_CREATE))
		goto out;

		nlflags \|= NLM_F_CREATE;
		err = -ENOBUFS;
		new_fa = kmem_cache_alloc(fn_alias_kmem, GFP_KERNEL);
		if (!new_fa)