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ipv4: icmp: convert to dev_net_rcu()
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__icmp_send() must ensure rcu_read_lock() is held, as spotted
by Jakub.

Other ICMP uses of dev_net() seem safe, change them to dev_net_rcu()
to get LOCKDEP support.

Fixes: dde1bc0 ("[NETNS]: Add namespace for ICMP replying code.")
Closes: https://lore.kernel.org/netdev/20250203153633.46ce0337@kernel.org/
Reported-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250205155120.1676781-9-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Eric Dumazet authored and Jakub Kicinski committed Feb 7, 2025
1 parent 1395121 commit 4b8474a
Showing 1 changed file with 17 additions and 14 deletions.
31 changes: 17 additions & 14 deletions net/ipv4/icmp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -399,10 +399,10 @@ static void icmp_push_reply(struct sock *sk,

static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
{
struct ipcm_cookie ipc;
struct rtable *rt = skb_rtable(skb);
struct net *net = dev_net(rt->dst.dev);
struct net *net = dev_net_rcu(rt->dst.dev);
bool apply_ratelimit = false;
struct ipcm_cookie ipc;
struct flowi4 fl4;
struct sock *sk;
struct inet_sock *inet;
Expand Down Expand Up @@ -608,12 +608,14 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
struct sock *sk;

if (!rt)
goto out;
return;

rcu_read_lock();

if (rt->dst.dev)
net = dev_net(rt->dst.dev);
net = dev_net_rcu(rt->dst.dev);
else if (skb_in->dev)
net = dev_net(skb_in->dev);
net = dev_net_rcu(skb_in->dev);
else
goto out;

Expand Down Expand Up @@ -785,7 +787,8 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
icmp_xmit_unlock(sk);
out_bh_enable:
local_bh_enable();
out:;
out:
rcu_read_unlock();
}
EXPORT_SYMBOL(__icmp_send);

Expand Down Expand Up @@ -834,7 +837,7 @@ static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
* avoid additional coding at protocol handlers.
*/
if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
__ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
__ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS);
return;
}

Expand Down Expand Up @@ -868,7 +871,7 @@ static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
struct net *net;
u32 info = 0;

net = dev_net(skb_dst(skb)->dev);
net = dev_net_rcu(skb_dst(skb)->dev);

/*
* Incomplete header ?
Expand Down Expand Up @@ -979,7 +982,7 @@ static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
{
if (skb->len < sizeof(struct iphdr)) {
__ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
__ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS);
return SKB_DROP_REASON_PKT_TOO_SMALL;
}

Expand Down Expand Up @@ -1011,7 +1014,7 @@ static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
struct icmp_bxm icmp_param;
struct net *net;

net = dev_net(skb_dst(skb)->dev);
net = dev_net_rcu(skb_dst(skb)->dev);
/* should there be an ICMP stat for ignored echos? */
if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
return SKB_NOT_DROPPED_YET;
Expand Down Expand Up @@ -1040,9 +1043,9 @@ static enum skb_drop_reason icmp_echo(struct sk_buff *skb)

bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
{
struct net *net = dev_net_rcu(skb->dev);
struct icmp_ext_hdr *ext_hdr, _ext_hdr;
struct icmp_ext_echo_iio *iio, _iio;
struct net *net = dev_net(skb->dev);
struct inet6_dev *in6_dev;
struct in_device *in_dev;
struct net_device *dev;
Expand Down Expand Up @@ -1181,7 +1184,7 @@ static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
return SKB_NOT_DROPPED_YET;

out_err:
__ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
__ICMP_INC_STATS(dev_net_rcu(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
return SKB_DROP_REASON_PKT_TOO_SMALL;
}

Expand All @@ -1198,7 +1201,7 @@ int icmp_rcv(struct sk_buff *skb)
{
enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
struct rtable *rt = skb_rtable(skb);
struct net *net = dev_net(rt->dst.dev);
struct net *net = dev_net_rcu(rt->dst.dev);
struct icmphdr *icmph;

if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
Expand Down Expand Up @@ -1371,9 +1374,9 @@ int icmp_err(struct sk_buff *skb, u32 info)
struct iphdr *iph = (struct iphdr *)skb->data;
int offset = iph->ihl<<2;
struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
struct net *net = dev_net_rcu(skb->dev);
int type = icmp_hdr(skb)->type;
int code = icmp_hdr(skb)->code;
struct net *net = dev_net(skb->dev);

/*
* Use ping_err to handle all icmp errors except those
Expand Down

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