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| author | Eric Dumazet <edumazet@google.com> | 2025-08-28 19:58:19 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-08-29 19:36:32 -0700 |
| commit | 11709573cc4e48dc34c80fc7ab9ce5b159e29695 (patch) | |
| tree | f68ded1c7935feea830798cbd5e2143319b40397 | |
| parent | 9085e56501d93af9f2d7bd16f7fcfacdde47b99c (diff) | |
| download | linux-11709573cc4e48dc34c80fc7ab9ce5b159e29695.tar.gz linux-11709573cc4e48dc34c80fc7ab9ce5b159e29695.tar.bz2 linux-11709573cc4e48dc34c80fc7ab9ce5b159e29695.zip | |
ipv6: use RCU in ip6_output()
Use RCU in ip6_output() in order to use dst_dev_rcu() to prevent
possible UAF.
We can remove rcu_read_lock()/rcu_read_unlock() pairs
from ip6_finish_output2().
Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20250828195823.3958522-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/ipv6/ip6_output.c | 29 |
1 files changed, 15 insertions, 14 deletions
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index e234640433d6..9d64c13bab5e 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -60,7 +60,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb) { struct dst_entry *dst = skb_dst(skb); - struct net_device *dev = dst_dev(dst); + struct net_device *dev = dst_dev_rcu(dst); struct inet6_dev *idev = ip6_dst_idev(dst); unsigned int hh_len = LL_RESERVED_SPACE(dev); const struct in6_addr *daddr, *nexthop; @@ -70,15 +70,12 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * /* Be paranoid, rather than too clever. */ if (unlikely(hh_len > skb_headroom(skb)) && dev->header_ops) { - /* Make sure idev stays alive */ - rcu_read_lock(); + /* idev stays alive because we hold rcu_read_lock(). */ skb = skb_expand_head(skb, hh_len); if (!skb) { IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); - rcu_read_unlock(); return -ENOMEM; } - rcu_read_unlock(); } hdr = ipv6_hdr(skb); @@ -123,7 +120,6 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len); - rcu_read_lock(); nexthop = rt6_nexthop(dst_rt6_info(dst), daddr); neigh = __ipv6_neigh_lookup_noref(dev, nexthop); @@ -131,7 +127,6 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * if (unlikely(!neigh)) neigh = __neigh_create(&nd_tbl, nexthop, dev, false); if (IS_ERR(neigh)) { - rcu_read_unlock(); IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTNOROUTES); kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL); return -EINVAL; @@ -139,7 +134,6 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * } sock_confirm_neigh(skb, neigh); ret = neigh_output(neigh, skb, false); - rcu_read_unlock(); return ret; } @@ -233,22 +227,29 @@ static int ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff *s int ip6_output(struct net *net, struct sock *sk, struct sk_buff *skb) { struct dst_entry *dst = skb_dst(skb); - struct net_device *dev = dst_dev(dst), *indev = skb->dev; - struct inet6_dev *idev = ip6_dst_idev(dst); + struct net_device *dev, *indev = skb->dev; + struct inet6_dev *idev; + int ret; skb->protocol = htons(ETH_P_IPV6); + rcu_read_lock(); + dev = dst_dev_rcu(dst); + idev = ip6_dst_idev(dst); skb->dev = dev; if (unlikely(!idev || READ_ONCE(idev->cnf.disable_ipv6))) { IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); + rcu_read_unlock(); kfree_skb_reason(skb, SKB_DROP_REASON_IPV6DISABLED); return 0; } - return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, - net, sk, skb, indev, dev, - ip6_finish_output, - !(IP6CB(skb)->flags & IP6SKB_REROUTED)); + ret = NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, + net, sk, skb, indev, dev, + ip6_finish_output, + !(IP6CB(skb)->flags & IP6SKB_REROUTED)); + rcu_read_unlock(); + return ret; } EXPORT_SYMBOL(ip6_output); |