4.20-stable review patch. If anyone has any objections, please let me know.
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From: Ido Schimmel idosch@mellanox.com
[ Upstream commit f97f4dd8b3bb9d0993d2491e0f22024c68109184 ]
IPv4 routing tables are flushed in two cases:
1. In response to events in the netdev and inetaddr notification chains 2. When a network namespace is being dismantled
In both cases only routes associated with a dead nexthop group are flushed. However, a nexthop group will only be marked as dead in case it is populated with actual nexthops using a nexthop device. This is not the case when the route in question is an error route (e.g., 'blackhole', 'unreachable').
Therefore, when a network namespace is being dismantled such routes are not flushed and leaked [1].
To reproduce: # ip netns add blue # ip -n blue route add unreachable 192.0.2.0/24 # ip netns del blue
Fix this by not skipping error routes that are not marked with RTNH_F_DEAD when flushing the routing tables.
To prevent the flushing of such routes in case #1, add a parameter to fib_table_flush() that indicates if the table is flushed as part of namespace dismantle or not.
Note that this problem does not exist in IPv6 since error routes are associated with the loopback device.
[1] unreferenced object 0xffff888066650338 (size 56): comm "ip", pid 1206, jiffies 4294786063 (age 26.235s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 b0 1c 62 61 80 88 ff ff ..........ba.... e8 8b a1 64 80 88 ff ff 00 07 00 08 fe 00 00 00 ...d............ backtrace: [<00000000856ed27d>] inet_rtm_newroute+0x129/0x220 [<00000000fcdfc00a>] rtnetlink_rcv_msg+0x397/0xa20 [<00000000cb85801a>] netlink_rcv_skb+0x132/0x380 [<00000000ebc991d2>] netlink_unicast+0x4c0/0x690 [<0000000014f62875>] netlink_sendmsg+0x929/0xe10 [<00000000bac9d967>] sock_sendmsg+0xc8/0x110 [<00000000223e6485>] ___sys_sendmsg+0x77a/0x8f0 [<000000002e94f880>] __sys_sendmsg+0xf7/0x250 [<00000000ccb1fa72>] do_syscall_64+0x14d/0x610 [<00000000ffbe3dae>] entry_SYSCALL_64_after_hwframe+0x49/0xbe [<000000003a8b605b>] 0xffffffffffffffff unreferenced object 0xffff888061621c88 (size 48): comm "ip", pid 1206, jiffies 4294786063 (age 26.235s) hex dump (first 32 bytes): 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk 6b 6b 6b 6b 6b 6b 6b 6b d8 8e 26 5f 80 88 ff ff kkkkkkkk..&_.... backtrace: [<00000000733609e3>] fib_table_insert+0x978/0x1500 [<00000000856ed27d>] inet_rtm_newroute+0x129/0x220 [<00000000fcdfc00a>] rtnetlink_rcv_msg+0x397/0xa20 [<00000000cb85801a>] netlink_rcv_skb+0x132/0x380 [<00000000ebc991d2>] netlink_unicast+0x4c0/0x690 [<0000000014f62875>] netlink_sendmsg+0x929/0xe10 [<00000000bac9d967>] sock_sendmsg+0xc8/0x110 [<00000000223e6485>] ___sys_sendmsg+0x77a/0x8f0 [<000000002e94f880>] __sys_sendmsg+0xf7/0x250 [<00000000ccb1fa72>] do_syscall_64+0x14d/0x610 [<00000000ffbe3dae>] entry_SYSCALL_64_after_hwframe+0x49/0xbe [<000000003a8b605b>] 0xffffffffffffffff
Fixes: 8cced9eff1d4 ("[NETNS]: Enable routing configuration in non-initial namespace.") Signed-off-by: Ido Schimmel idosch@mellanox.com Reviewed-by: David Ahern dsahern@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/net/ip_fib.h | 2 +- net/ipv4/fib_frontend.c | 4 ++-- net/ipv4/fib_trie.c | 15 ++++++++++++--- 3 files changed, 15 insertions(+), 6 deletions(-)
--- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -241,7 +241,7 @@ int fib_table_delete(struct net *, struc struct netlink_ext_ack *extack); int fib_table_dump(struct fib_table *table, struct sk_buff *skb, struct netlink_callback *cb, struct fib_dump_filter *filter); -int fib_table_flush(struct net *net, struct fib_table *table); +int fib_table_flush(struct net *net, struct fib_table *table, bool flush_all); struct fib_table *fib_trie_unmerge(struct fib_table *main_tb); void fib_table_flush_external(struct fib_table *table); void fib_free_table(struct fib_table *tb); --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -203,7 +203,7 @@ static void fib_flush(struct net *net) struct fib_table *tb;
hlist_for_each_entry_safe(tb, tmp, head, tb_hlist) - flushed += fib_table_flush(net, tb); + flushed += fib_table_flush(net, tb, false); }
if (flushed) @@ -1463,7 +1463,7 @@ static void ip_fib_net_exit(struct net *
hlist_for_each_entry_safe(tb, tmp, head, tb_hlist) { hlist_del(&tb->tb_hlist); - fib_table_flush(net, tb); + fib_table_flush(net, tb, true); fib_free_table(tb); } } --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -1856,7 +1856,7 @@ void fib_table_flush_external(struct fib }
/* Caller must hold RTNL. */ -int fib_table_flush(struct net *net, struct fib_table *tb) +int fib_table_flush(struct net *net, struct fib_table *tb, bool flush_all) { struct trie *t = (struct trie *)tb->tb_data; struct key_vector *pn = t->kv; @@ -1904,8 +1904,17 @@ int fib_table_flush(struct net *net, str hlist_for_each_entry_safe(fa, tmp, &n->leaf, fa_list) { struct fib_info *fi = fa->fa_info;
- if (!fi || !(fi->fib_flags & RTNH_F_DEAD) || - tb->tb_id != fa->tb_id) { + if (!fi || tb->tb_id != fa->tb_id || + (!(fi->fib_flags & RTNH_F_DEAD) && + !fib_props[fa->fa_type].error)) { + slen = fa->fa_slen; + continue; + } + + /* Do not flush error routes if network namespace is + * not being dismantled + */ + if (!flush_all && fib_props[fa->fa_type].error) { slen = fa->fa_slen; continue; }