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ipv6: remove RTNL protection from inet6_dump_fib() 

No longer hold RTNL while calling inet6_dump_fib().

Also change return value for a completed dump,
so that NLMSG_DONE can be appended to current skb,
saving one recvmsg() system call.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240329183053.644630-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-03-29 18:30:53 +00:00 committed by Jakub Kicinski
parent edaa34e68c
commit 5fc68320c1
1 changed files with 26 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
net/ipv6/ip6_fib.c
View File

@ -623,23 +623,22 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
struct rt6_rtnl_dump_arg arg = { struct rt6_rtnl_dump_arg arg = {
.filter.dump_exceptions = true, .filter.dump_exceptions = true,
.filter.dump_routes = true, .filter.dump_routes = true,
.filter.rtnl_held = true, .filter.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);
unsigned int h, s_h;
unsigned int e = 0, s_e; unsigned int e = 0, s_e;
struct hlist_head *head;
struct fib6_walker *w; struct fib6_walker *w;
struct fib6_table *tb; struct fib6_table *tb;
struct hlist_head *head; unsigned int h, s_h;
int res = 0; int err = 0;
rcu_read_lock();
if (cb->strict_check) { if (cb->strict_check) {
int err;
err = ip_valid_fib_dump_req(net, nlh, &arg.filter, cb); err = ip_valid_fib_dump_req(net, nlh, &arg.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);
@ -660,8 +659,10 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
* 2. allocate and initialize walker. * 2. allocate and initialize walker.
*/ */
w = kzalloc(sizeof(*w), GFP_ATOMIC); w = kzalloc(sizeof(*w), GFP_ATOMIC);
if (!w) if (!w) {
return -ENOMEM; err = -ENOMEM;
goto unlock;
}
w->func = fib6_dump_node; w->func = fib6_dump_node;
cb->args[2] = (long)w; cb->args[2] = (long)w;
} }
@ -675,46 +676,46 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
tb = fib6_get_table(net, arg.filter.table_id); tb = fib6_get_table(net, arg.filter.table_id);
if (!tb) { if (!tb) {
if (rtnl_msg_family(cb->nlh) != PF_INET6) if (rtnl_msg_family(cb->nlh) != PF_INET6)
goto out; goto unlock;
NL_SET_ERR_MSG_MOD(cb->extack, "FIB table does not exist"); NL_SET_ERR_MSG_MOD(cb->extack, "FIB table does not exist");
return -ENOENT; err = -ENOENT;
goto unlock;
} }
if (!cb->args[0]) { if (!cb->args[0]) {
res = fib6_dump_table(tb, skb, cb); err = fib6_dump_table(tb, skb, cb);
if (!res) if (!err)
cb->args[0] = 1; cb->args[0] = 1;
} }
goto out; 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();
for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) { for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
e = 0; e = 0;
head = &net->ipv6.fib_table_hash[h]; head = &net->ipv6.fib_table_hash[h];
hlist_for_each_entry_rcu(tb, head, tb6_hlist) { hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
if (e < s_e) if (e < s_e)
goto next; goto next;
res = fib6_dump_table(tb, skb, cb); err = fib6_dump_table(tb, skb, cb);
if (res != 0) if (err != 0)
goto out_unlock; goto out;
next: next:
e++; e++;
} }
} }
out_unlock: out:
rcu_read_unlock();
cb->args[1] = e; cb->args[1] = e;
cb->args[0] = h; cb->args[0] = h;
out:
res = res < 0 ? res : skb->len; unlock:
if (res <= 0) rcu_read_unlock();
if (err <= 0)
fib6_dump_end(cb); fib6_dump_end(cb);
return res; return err;
} }
void fib6_metric_set(struct fib6_info *f6i, int metric, u32 val) void fib6_metric_set(struct fib6_info *f6i, int metric, u32 val)
@ -2506,7 +2507,7 @@ int __init fib6_init(void)
goto out_kmem_cache_create; goto out_kmem_cache_create;
ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETROUTE, NULL, ret = rtnl_register_module(THIS_MODULE, PF_INET6, RTM_GETROUTE, NULL,
inet6_dump_fib, 0); inet6_dump_fib, RTNL_FLAG_DUMP_UNLOCKED);
if (ret) if (ret)
goto out_unregister_subsys; goto out_unregister_subsys;