From 4ce5dc9316de50e0da84beafe55d1344f829cece Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 22 Feb 2024 10:50:19 +0000 Subject: [PATCH] inet: switch inet_dump_fib() to RCU protection No longer hold RTNL while calling inet_dump_fib(). Also change return value for a completed dump: Returning 0 instead of skb->len allows NLMSG_DONE to be appended to the skb. User space does not have to call us again to get a standalone NLMSG_DONE marker. Signed-off-by: Eric Dumazet Reviewed-by: Donald Hunter Signed-off-by: David S. Miller --- net/ipv4/fib_frontend.c | 37 ++++++++++++++++++------------------- net/ipv4/fib_trie.c | 4 ++-- 2 files changed, 20 insertions(+), 21 deletions(-) diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 39f67990e01c..bf3a2214fe29 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -990,7 +990,7 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) struct fib_dump_filter filter = { .dump_routes = true, .dump_exceptions = true, - .rtnl_held = true, + .rtnl_held = false, }; const struct nlmsghdr *nlh = cb->nlh; struct net *net = sock_net(skb->sk); @@ -998,12 +998,13 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) unsigned int e = 0, s_e; struct fib_table *tb; struct hlist_head *head; - int dumped = 0, err; + int dumped = 0, err = 0; + rcu_read_lock(); if (cb->strict_check) { err = ip_valid_fib_dump_req(net, nlh, &filter, cb); if (err < 0) - return err; + goto unlock; } else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) { struct rtmsg *rtm = nlmsg_data(nlh); @@ -1012,29 +1013,28 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) /* ipv4 does not use prefix flag */ if (filter.flags & RTM_F_PREFIX) - return skb->len; + goto unlock; if (filter.table_id) { tb = fib_get_table(net, filter.table_id); if (!tb) { if (rtnl_msg_family(cb->nlh) != PF_INET) - return skb->len; + goto unlock; NL_SET_ERR_MSG(cb->extack, "ipv4: FIB table does not exist"); - return -ENOENT; + err = -ENOENT; + goto unlock; } - - rcu_read_lock(); err = fib_table_dump(tb, skb, cb, &filter); - rcu_read_unlock(); - return skb->len ? : err; + if (err < 0 && skb->len) + err = skb->len; + goto unlock; } s_h = cb->args[0]; s_e = cb->args[1]; - rcu_read_lock(); - + err = 0; for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) { e = 0; head = &net->ipv4.fib_table_hash[h]; @@ -1047,9 +1047,8 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) err = fib_table_dump(tb, skb, cb, &filter); if (err < 0) { if (likely(skb->len)) - goto out; - - goto out_err; + err = skb->len; + goto out; } dumped = 1; next: @@ -1057,13 +1056,12 @@ next: } } out: - err = skb->len; -out_err: - rcu_read_unlock(); cb->args[1] = e; cb->args[0] = h; +unlock: + rcu_read_unlock(); return err; } @@ -1666,5 +1664,6 @@ void __init ip_fib_init(void) rtnl_register(PF_INET, RTM_NEWROUTE, inet_rtm_newroute, NULL, 0); rtnl_register(PF_INET, RTM_DELROUTE, inet_rtm_delroute, NULL, 0); - rtnl_register(PF_INET, RTM_GETROUTE, NULL, inet_dump_fib, 0); + rtnl_register(PF_INET, RTM_GETROUTE, NULL, inet_dump_fib, + RTNL_FLAG_DUMP_UNLOCKED); } diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 0fc7ab5832d1..f474106464d2 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -2368,7 +2368,7 @@ int fib_table_dump(struct fib_table *tb, struct sk_buff *skb, * and key == 0 means the dump has wrapped around and we are done. */ if (count && !key) - return skb->len; + return 0; while ((l = leaf_walk_rcu(&tp, key)) != NULL) { int err; @@ -2394,7 +2394,7 @@ int fib_table_dump(struct fib_table *tb, struct sk_buff *skb, cb->args[3] = key; cb->args[2] = count; - return skb->len; + return 0; } void __init fib_trie_init(void)