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inet: switch inet_dump_fib() to RCU protection

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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 <edumazet@google.com>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2024-02-22 10:50:19 +00:00 • committed by David S. Miller
parent 0ac3fa0c3b
commit 4ce5dc9316
2 changed files with 20 additions and 21 deletions
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35
net/ipv4/fib_frontend.c
View file

@ -990,7 +990,7 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
struct fib_dump_filter filter = { struct fib_dump_filter filter = {
.dump_routes = true, .dump_routes = true,
.dump_exceptions = true, .dump_exceptions = true,
.rtnl_held = true, .rtnl_held = false,
}; };
const struct nlmsghdr *nlh = cb->nlh; const struct nlmsghdr *nlh = cb->nlh;
struct net *net = sock_net(skb->sk); 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; unsigned int e = 0, s_e;
struct fib_table *tb; struct fib_table *tb;
struct hlist_head *head; struct hlist_head *head;
int dumped = 0, err; int dumped = 0, err = 0;
rcu_read_lock();
if (cb->strict_check) { if (cb->strict_check) {
err = ip_valid_fib_dump_req(net, nlh, &filter, cb); err = ip_valid_fib_dump_req(net, nlh, &filter, cb);
if (err < 0) if (err < 0)
return err; goto unlock;
} else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) { } else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) {
struct rtmsg *rtm = nlmsg_data(nlh); 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 */ /* ipv4 does not use prefix flag */
if (filter.flags & RTM_F_PREFIX) if (filter.flags & RTM_F_PREFIX)
return skb->len; goto unlock;
if (filter.table_id) { if (filter.table_id) {
tb = fib_get_table(net, filter.table_id); tb = fib_get_table(net, filter.table_id);
if (!tb) { if (!tb) {
if (rtnl_msg_family(cb->nlh) != PF_INET) 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"); 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); err = fib_table_dump(tb, skb, cb, &filter);
rcu_read_unlock(); if (err < 0 && skb->len)
return skb->len ? : err; err = skb->len;
goto unlock;
} }
s_h = cb->args[0]; s_h = cb->args[0];
s_e = cb->args[1]; s_e = cb->args[1];
rcu_read_lock(); err = 0;
for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) { for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
e = 0; e = 0;
head = &net->ipv4.fib_table_hash[h]; 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); err = fib_table_dump(tb, skb, cb, &filter);
if (err < 0) { if (err < 0) {
if (likely(skb->len)) if (likely(skb->len))
err = skb->len;
goto out; goto out;
goto out_err;
} }
dumped = 1; dumped = 1;
next: next:
@ -1057,13 +1056,12 @@ next:
} }
} }
out: out:
err = skb->len;
out_err:
rcu_read_unlock();
cb->args[1] = e; cb->args[1] = e;
cb->args[0] = h; cb->args[0] = h;
unlock:
rcu_read_unlock();
return err; 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_NEWROUTE, inet_rtm_newroute, NULL, 0);
rtnl_register(PF_INET, RTM_DELROUTE, inet_rtm_delroute, 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);
} }

4
net/ipv4/fib_trie.c
View file

@ -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. * and key == 0 means the dump has wrapped around and we are done.
*/ */
if (count && !key) if (count && !key)
return skb->len; return 0;
while ((l = leaf_walk_rcu(&tp, key)) != NULL) { while ((l = leaf_walk_rcu(&tp, key)) != NULL) {
int err; int err;
@ -2394,7 +2394,7 @@ int fib_table_dump(struct fib_table *tb, struct sk_buff *skb,
cb->args[3] = key; cb->args[3] = key;
cb->args[2] = count; cb->args[2] = count;
return skb->len; return 0;
} }
void __init fib_trie_init(void) void __init fib_trie_init(void)