Since commit 2b760fcf5cfb ("ipv6: hook up exception table to store dst
cache"), route exceptions reside in a separate hash table, and won't be
found by walking the FIB, so they won't be dumped to userspace on a
RTM_GETROUTE message.
This causes 'ip -6 route list cache' and 'ip -6 route flush cache' to
have no function anymore:
# ip -6 route get fc00:3::1
fc00:3::1 via fc00:1::2 dev veth_A-R1 src fc00:1::1 metric 1024 expires 539sec
mtu 1400 pref medium
# ip -6 route get fc00:4::1
fc00:4::1 via fc00:2::2 dev veth_A-R2 src fc00:2::1 metric 1024 expires 536sec
mtu 1500 pref medium
# ip -6 route list cache
# ip -6 route flush cache
# ip -6 route get fc00:3::1
fc00:3::1 via fc00:1::2 dev veth_A-R1 src fc00:1::1 metric 1024 expires 520sec
mtu 1400 pref medium
# ip -6 route get fc00:4::1
fc00:4::1 via fc00:2::2 dev veth_A-R2 src fc00:2::1 metric 1024 expires 519sec
mtu 1500 pref medium
because iproute2 lists cached routes using RTM_GETROUTE, and flushes them
by listing all the routes, and deleting them with RTM_DELROUTE one by one.
Look up exceptions in the hash table associated with the current fib6_info
in rt6_dump_route(), and, if present and not expired, add them to the
dump.
We might be unable to dump all the entries for a given node in a single
message, so keep track of how many entries were handled for the current
node in fib6_walker, and skip that amount in case we start from the same
partially dumped node.
Re-allow userspace to get FIB results by passing the RTM_F_CLONED flag as
filter, by reverting commit 08e814c9e8eb ("net/ipv6: Bail early if user
only wants cloned entries").
As we do this, we also have to honour this flag while filtering routes in
rt6_dump_route() and, if this filter effectively causes some results to be
discarded, by passing the NLM_F_DUMP_FILTERED flag back.
To flush cached routes, a procfs entry could be introduced instead: that's
how it works for IPv4. We already have a rt6_flush_exception() function
ready to be wired to it. However, this would not solve the issue for
listing, and wouldn't fix the issue with current and previous versions of
iproute2.
v2: Add tracking of number of entries to be skipped in current node after
a partial dump. As we restart from the same node, if not all the
exceptions for a given node fit in a single message, the dump will
not terminate, as suggested by Martin Lau. This is a concrete
possibility, setting up a big number of exceptions for the same route
actually causes the issue, suggested by David Ahern.
Reported-by: Jianlin Shi <ji...@redhat.com>
Fixes: 2b760fcf5cfb ("ipv6: hook up exception table to store dst cache")
Signed-off-by: Stefano Brivio <sbri...@redhat.com>
---
This will cause a non-trivial conflict with commit cc5c073a693f
("ipv6: Move exception bucket to fib6_nh") on net-next. I can submit
an equivalent patch against net-next, if it helps.
include/net/ip6_fib.h | 1 +
include/net/ip6_route.h | 2 +-
net/ipv6/ip6_fib.c | 24 ++++++++++-----
net/ipv6/route.c | 65 +++++++++++++++++++++++++++++++++++++----
4 files changed, 78 insertions(+), 14 deletions(-)
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index d6d936cbf6b3..fcac02a8ba74 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -316,6 +316,7 @@ struct fib6_walker {
enum fib6_walk_state state;
unsigned int skip;
unsigned int count;
+ unsigned int skip_in_node;
int (*func)(struct fib6_walker *);
void *args;
};
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 4790beaa86e0..b66c4aac56ab 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -178,7 +178,7 @@ struct rt6_rtnl_dump_arg {
struct fib_dump_filter filter;
};
-int rt6_dump_route(struct fib6_info *f6i, void *p_arg);
+int rt6_dump_route(struct fib6_info *f6i, void *p_arg, unsigned int skip);
void rt6_mtu_change(struct net_device *dev, unsigned int mtu);
void rt6_remove_prefsrc(struct inet6_ifaddr *ifp);
void rt6_clean_tohost(struct net *net, struct in6_addr *gateway);
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 008421b550c6..f468fa9b5da6 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -473,12 +473,22 @@ static int fib6_dump_node(struct fib6_walker *w)
struct fib6_info *rt;
for_each_fib6_walker_rt(w) {
- res = rt6_dump_route(rt, w->args);
- if (res < 0) {
+ res = rt6_dump_route(rt, w->args, w->skip_in_node);
+ if (res) {
/* Frame is full, suspend walking */
w->leaf = rt;
+
+ /* We'll restart from this node, so if some routes were
+ * already dumped, skip them next time.
+ */
+ if (res > 0)
+ w->skip_in_node += res;
+ else
+ w->skip_in_node = 0;
+
return 1;
}
+ w->skip_in_node = 0;
/* Multipath routes are dumped in one route with the
* RTA_MULTIPATH attribute. Jump 'rt' to point to the
@@ -530,6 +540,7 @@ static int fib6_dump_table(struct fib6_table *table, struct
sk_buff *skb,
if (cb->args[4] == 0) {
w->count = 0;
w->skip = 0;
+ w->skip_in_node = 0;
spin_lock_bh(&table->tb6_lock);
res = fib6_walk(net, w);
@@ -545,6 +556,7 @@ static int fib6_dump_table(struct fib6_table *table, struct
sk_buff *skb,
w->state = FWS_INIT;
w->node = w->root;
w->skip = w->count;
+ w->skip_in_node = 0;
} else
w->skip = 0;
@@ -581,13 +593,10 @@ static int inet6_dump_fib(struct sk_buff *skb, struct
netlink_callback *cb)
} else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) {
struct rtmsg *rtm = nlmsg_data(nlh);
- arg.filter.flags = rtm->rtm_flags & (RTM_F_PREFIX|RTM_F_CLONED);
+ if (rtm->rtm_flags & RTM_F_PREFIX)
+ arg.filter.flags = RTM_F_PREFIX;
}
- /* fib entries are never clones */
- if (arg.filter.flags & RTM_F_CLONED)
- goto out;
-
w = (void *)cb->args[2];
if (!w) {
/* New dump:
@@ -2045,6 +2054,7 @@ static void fib6_clean_tree(struct net *net, struct
fib6_node *root,
c.w.func = fib6_clean_node;
c.w.count = 0;
c.w.skip = 0;
+ c.w.skip_in_node = 0;
c.func = func;
c.sernum = sernum;
c.arg = arg;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 848e944f07df..554f88bd64f3 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4858,12 +4858,16 @@ static bool fib6_info_uses_dev(const struct fib6_info
*f6i,
return false;
}
-int rt6_dump_route(struct fib6_info *rt, void *p_arg)
+/* Return count of handled routes on failure, -1 if all failed, 0 on success */
+int rt6_dump_route(struct fib6_info *rt, void *p_arg, unsigned int skip)
{
struct rt6_rtnl_dump_arg *arg = (struct rt6_rtnl_dump_arg *) p_arg;
struct fib_dump_filter *filter = &arg->filter;
+ struct rt6_exception_bucket *bucket;
unsigned int flags = NLM_F_MULTI;
+ struct rt6_exception *rt6_ex;
struct net *net = arg->net;
+ int i, count = 0;
if (rt == net->ipv6.fib6_null_entry)
return 0;
@@ -4871,20 +4875,69 @@ int rt6_dump_route(struct fib6_info *rt, void *p_arg)
if ((filter->flags & RTM_F_PREFIX) &&
!(rt->fib6_flags & RTF_PREFIX_RT)) {
/* success since this is not a prefix route */
- return 1;
+ return 0;
}
if (filter->filter_set) {
if ((filter->rt_type && rt->fib6_type != filter->rt_type) ||
(filter->dev && !fib6_info_uses_dev(rt, filter->dev)) ||
(filter->protocol && rt->fib6_protocol !=
filter->protocol)) {
- return 1;
+ return 0;
}
flags |= NLM_F_DUMP_FILTERED;
}
- return rt6_fill_node(net, arg->skb, rt, NULL, NULL, NULL, 0,
- RTM_NEWROUTE, NETLINK_CB(arg->cb->skb).portid,
- arg->cb->nlh->nlmsg_seq, flags);
+ if (!(filter->flags & RTM_F_CLONED)) {
+ if (skip) {
+ skip--;
+ } else if (rt6_fill_node(net, arg->skb, rt, NULL, NULL, NULL,
+ 0, RTM_NEWROUTE,
+ NETLINK_CB(arg->cb->skb).portid,
+ arg->cb->nlh->nlmsg_seq, flags)) {
+ return -1;
+ } else {
+ count++;
+ }
+ } else {
+ flags |= NLM_F_DUMP_FILTERED;
+ }
+
+ bucket = rcu_dereference(rt->rt6i_exception_bucket);
+ if (!bucket)
+ return 0;
+
+ for (i = 0; i < FIB6_EXCEPTION_BUCKET_SIZE; i++) {
+ hlist_for_each_entry(rt6_ex, &bucket->chain, hlist) {
+ if (skip) {
+ skip--;
+ continue;
+ }
+
+ /* Expiration of entries doesn't bump sernum, insertion
+ * does. Removal is triggered by insertion.
+ *
+ * Count expired entries we go through as handled
+ * entries that we'll skip next time, in case of partial
+ * node dump. Otherwise, if entries expire between two
+ * partial dumps, we'll skip the wrong amount.
+ */
+ if (rt6_check_expired(rt6_ex->rt6i)) {
+ count++;
+ continue;
+ }
+
+ if (rt6_fill_node(net, arg->skb, rt, &rt6_ex->rt6i->dst,
+ NULL, NULL, 0, RTM_NEWROUTE,
+ NETLINK_CB(arg->cb->skb).portid,
+ arg->cb->nlh->nlmsg_seq, flags)) {
+ return count ? : -1;
+ }
+
+ count++;
+ }
+ bucket++;
+ }
+
+ return 0;
}
static int inet6_rtm_valid_getroute_req(struct sk_buff *skb,
--
2.20.1
