[PATCH 5.18 052/158] tcp/udp: Make early_demux back namespacified.

Greg Kroah-Hartman
2022-07-27T17:33:56Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 11052589cf5c0bab3b4884d423d5f60c38fcf25d ]

Commit e21145a9871a ("ipv4: namespacify ip_early_demux sysctl knob") made
it possible to enable/disable early_demux on a per-netns basis. Then, we
introduced two knobs, tcp_early_demux and udp_early_demux, to switch it for
TCP/UDP in commit dddb64bcb346 ("net: Add sysctl to toggle early demux for
tcp and udp"). However, the .proc_handler() was wrong and actually
disabled us from changing the behaviour in each netns.

We can execute early_demux if net.ipv4.ip_early_demux is on and each proto
.early_demux() handler is not NULL. When we toggle (tcp|udp)_early_demux,
the change itself is saved in each netns variable, but the .early_demux()
handler is a global variable, so the handler is switched based on the
init_net's sysctl variable. Thus, netns (tcp|udp)_early_demux knobs have
nothing to do with the logic. Whether we CAN execute proto .early_demux()
is always decided by init_net's sysctl knob, and whether we DO it or not is
by each netns ip_early_demux knob.

This patch namespacifies (tcp|udp)_early_demux again. For now, the users
of the .early_demux() handler are TCP and UDP only, and they are called
directly to avoid retpoline. So, we can remove the .early_demux() handler
from inet6?_protos and need not dereference them in ip6?_rcv_finish_core().
If another proto needs .early_demux(), we can restore it at that time.

Fixes: dddb64bcb346 ("net: Add sysctl to toggle early demux for tcp and udp")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20220713175207.7727-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/protocol.h | 4 ---
include/net/tcp.h | 2 +-
include/net/udp.h | 2 +-
net/ipv4/af_inet.c | 14 ++-------
net/ipv4/ip_input.c | 37 ++++++++++++++----------
net/ipv4/sysctl_net_ipv4.c | 59 ++------------------------------------
net/ipv6/ip6_input.c | 23 ++++++++-------
net/ipv6/tcp_ipv6.c | 9 ++----
net/ipv6/udp.c | 9 ++----
9 files changed, 45 insertions(+), 114 deletions(-)

diff --git a/include/net/protocol.h b/include/net/protocol.h
index f51c06ae365f..6aef8cb11cc8 100644
--- a/include/net/protocol.h
+++ b/include/net/protocol.h
@@ -35,8 +35,6 @@

/* This is used to register protocols. */
struct net_protocol {
- int (*early_demux)(struct sk_buff *skb);
- int (*early_demux_handler)(struct sk_buff *skb);
int (*handler)(struct sk_buff *skb);

/* This returns an error if we weren't able to handle the error. */
@@ -52,8 +50,6 @@ struct net_protocol {

#if IS_ENABLED(CONFIG_IPV6)
struct inet6_protocol {
- void (*early_demux)(struct sk_buff *skb);
- void (*early_demux_handler)(struct sk_buff *skb);
int (*handler)(struct sk_buff *skb);

/* This returns an error if we weren't able to handle the error. */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 2d9a78b3beaa..113ce516ce42 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -932,7 +932,7 @@ extern const struct inet_connection_sock_af_ops ipv6_specific;

INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb));
INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb));
-INDIRECT_CALLABLE_DECLARE(void tcp_v6_early_demux(struct sk_buff *skb));
+void tcp_v6_early_demux(struct sk_buff *skb);

#endif

diff --git a/include/net/udp.h b/include/net/udp.h
index f1c2a88c9005..07d0ceadcf6e 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -167,7 +167,7 @@ static inline void udp_csum_pull_header(struct sk_buff *skb)
typedef struct sock *(*udp_lookup_t)(const struct sk_buff *skb, __be16 sport,
__be16 dport);

-INDIRECT_CALLABLE_DECLARE(void udp_v6_early_demux(struct sk_buff *));
+void udp_v6_early_demux(struct sk_buff *skb);
INDIRECT_CALLABLE_DECLARE(int udpv6_rcv(struct sk_buff *));

struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 8c0a22a5b36c..f5d5911a8abd 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1711,24 +1711,14 @@ static const struct net_protocol igmp_protocol = {
};
#endif

-/* thinking of making this const? Don't.
- * early_demux can change based on sysctl.
- */
-static struct net_protocol tcp_protocol = {
- .early_demux = tcp_v4_early_demux,
- .early_demux_handler = tcp_v4_early_demux,
+static const struct net_protocol tcp_protocol = {
.handler = tcp_v4_rcv,
.err_handler = tcp_v4_err,
.no_policy = 1,
.icmp_strict_tag_validation = 1,
};

-/* thinking of making this const? Don't.
- * early_demux can change based on sysctl.
- */
-static struct net_protocol udp_protocol = {
- .early_demux = udp_v4_early_demux,
- .early_demux_handler = udp_v4_early_demux,
+static const struct net_protocol udp_protocol = {
.handler = udp_rcv,
.err_handler = udp_err,
.no_policy = 1,
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 95f7bb052784..f3fd6c398309 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -312,14 +312,13 @@ static bool ip_can_use_hint(const struct sk_buff *skb, const struct iphdr *iph,
ip_hdr(hint)->tos == iph->tos;
}

-INDIRECT_CALLABLE_DECLARE(int udp_v4_early_demux(struct sk_buff *));
-INDIRECT_CALLABLE_DECLARE(int tcp_v4_early_demux(struct sk_buff *));
+int tcp_v4_early_demux(struct sk_buff *skb);
+int udp_v4_early_demux(struct sk_buff *skb);
static int ip_rcv_finish_core(struct net *net, struct sock *sk,
struct sk_buff *skb, struct net_device *dev,
const struct sk_buff *hint)
{
const struct iphdr *iph = ip_hdr(skb);
- int (*edemux)(struct sk_buff *skb);
int err, drop_reason;
struct rtable *rt;

@@ -332,21 +331,29 @@ static int ip_rcv_finish_core(struct net *net, struct sock *sk,
goto drop_error;
}

- if (net->ipv4.sysctl_ip_early_demux &&
+ if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) &&
!skb_dst(skb) &&
!skb->sk &&
!ip_is_fragment(iph)) {
- const struct net_protocol *ipprot;
- int protocol = iph->protocol;
-
- ipprot = rcu_dereference(inet_protos[protocol]);
- if (ipprot && (edemux = READ_ONCE(ipprot->early_demux))) {
- err = INDIRECT_CALL_2(edemux, tcp_v4_early_demux,
- udp_v4_early_demux, skb);
- if (unlikely(err))
- goto drop_error;
- /* must reload iph, skb->head might have changed */
- iph = ip_hdr(skb);
+ switch (iph->protocol) {
+ case IPPROTO_TCP:
+ if (READ_ONCE(net->ipv4.sysctl_tcp_early_demux)) {
+ tcp_v4_early_demux(skb);
+
+ /* must reload iph, skb->head might have changed */
+ iph = ip_hdr(skb);
+ }
+ break;
+ case IPPROTO_UDP:
+ if (READ_ONCE(net->ipv4.sysctl_udp_early_demux)) {
+ err = udp_v4_early_demux(skb);
+ if (unlikely(err))
+ goto drop_error;
+
+ /* must reload iph, skb->head might have changed */
+ iph = ip_hdr(skb);
+ }
+ break;
}
}

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index ffe0264a51b8..6b718688865e 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -354,61 +354,6 @@ static int proc_tcp_fastopen_key(struct ctl_table *table, int write,
return ret;
}

-static void proc_configure_early_demux(int enabled, int protocol)
-{
- struct net_protocol *ipprot;
-#if IS_ENABLED(CONFIG_IPV6)
- struct inet6_protocol *ip6prot;
-#endif
-
- rcu_read_lock();
-
- ipprot = rcu_dereference(inet_protos[protocol]);
- if (ipprot)
- ipprot->early_demux = enabled ? ipprot->early_demux_handler :
- NULL;
-
-#if IS_ENABLED(CONFIG_IPV6)
- ip6prot = rcu_dereference(inet6_protos[protocol]);
- if (ip6prot)
- ip6prot->early_demux = enabled ? ip6prot->early_demux_handler :
- NULL;
-#endif
- rcu_read_unlock();
-}
-
-static int proc_tcp_early_demux(struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos)
-{
- int ret = 0;
-
- ret = proc_dou8vec_minmax(table, write, buffer, lenp, ppos);
-
- if (write && !ret) {
- int enabled = init_net.ipv4.sysctl_tcp_early_demux;
-
- proc_configure_early_demux(enabled, IPPROTO_TCP);
- }
-
- return ret;
-}
-
-static int proc_udp_early_demux(struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos)
-{
- int ret = 0;
-
- ret = proc_dou8vec_minmax(table, write, buffer, lenp, ppos);
-
- if (write && !ret) {
- int enabled = init_net.ipv4.sysctl_udp_early_demux;
-
- proc_configure_early_demux(enabled, IPPROTO_UDP);
- }
-
- return ret;
-}
-
static int proc_tfo_blackhole_detect_timeout(struct ctl_table *table,
int write, void *buffer,
size_t *lenp, loff_t *ppos)
@@ -711,14 +656,14 @@ static struct ctl_table ipv4_net_table[] = {
.data = &init_net.ipv4.sysctl_udp_early_demux,
.maxlen = sizeof(u8),
.mode = 0644,
- .proc_handler = proc_udp_early_demux
+ .proc_handler = proc_dou8vec_minmax,
},
{
.procname = "tcp_early_demux",
.data = &init_net.ipv4.sysctl_tcp_early_demux,
.maxlen = sizeof(u8),
.mode = 0644,
- .proc_handler = proc_tcp_early_demux
+ .proc_handler = proc_dou8vec_minmax,
},
{
.procname = "nexthop_compat_mode",
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 5b5ea35635f9..caba03e551ef 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -45,20 +45,23 @@
#include <net/inet_ecn.h>
#include <net/dst_metadata.h>

-INDIRECT_CALLABLE_DECLARE(void tcp_v6_early_demux(struct sk_buff *));
static void ip6_rcv_finish_core(struct net *net, struct sock *sk,
struct sk_buff *skb)
{
- void (*edemux)(struct sk_buff *skb);
-
- if (net->ipv4.sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
- const struct inet6_protocol *ipprot;
-
- ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
- if (ipprot && (edemux = READ_ONCE(ipprot->early_demux)))
- INDIRECT_CALL_2(edemux, tcp_v6_early_demux,
- udp_v6_early_demux, skb);
+ if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) &&
+ !skb_dst(skb) && !skb->sk) {
+ switch (ipv6_hdr(skb)->nexthdr) {
+ case IPPROTO_TCP:
+ if (READ_ONCE(net->ipv4.sysctl_tcp_early_demux))
+ tcp_v6_early_demux(skb);
+ break;
+ case IPPROTO_UDP:
+ if (READ_ONCE(net->ipv4.sysctl_udp_early_demux))
+ udp_v6_early_demux(skb);
+ break;
+ }
}
+
if (!skb_valid_dst(skb))
ip6_route_input(skb);
}
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index cbc5fff3d846..5185c11dc444 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1822,7 +1822,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
goto discard_it;
}

-INDIRECT_CALLABLE_SCOPE void tcp_v6_early_demux(struct sk_buff *skb)
+void tcp_v6_early_demux(struct sk_buff *skb)
{
const struct ipv6hdr *hdr;
const struct tcphdr *th;
@@ -2176,12 +2176,7 @@ struct proto tcpv6_prot = {
};
EXPORT_SYMBOL_GPL(tcpv6_prot);

-/* thinking of making this const? Don't.
- * early_demux can change based on sysctl.
- */
-static struct inet6_protocol tcpv6_protocol = {
- .early_demux = tcp_v6_early_demux,
- .early_demux_handler = tcp_v6_early_demux,
+static const struct inet6_protocol tcpv6_protocol = {
.handler = tcp_v6_rcv,
.err_handler = tcp_v6_err,
.flags = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index a535c3f2e4af..aea28bf701be 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1052,7 +1052,7 @@ static struct sock *__udp6_lib_demux_lookup(struct net *net,
return NULL;
}

-INDIRECT_CALLABLE_SCOPE void udp_v6_early_demux(struct sk_buff *skb)
+void udp_v6_early_demux(struct sk_buff *skb)
{
struct net *net = dev_net(skb->dev);
const struct udphdr *uh;
@@ -1660,12 +1660,7 @@ int udpv6_getsockopt(struct sock *sk, int level, int optname,
return ipv6_getsockopt(sk, level, optname, optval, optlen);
}

-/* thinking of making this const? Don't.
- * early_demux can change based on sysctl.
- */
-static struct inet6_protocol udpv6_protocol = {
- .early_demux = udp_v6_early_demux,
- .early_demux_handler = udp_v6_early_demux,
+static const struct inet6_protocol udpv6_protocol = {
.handler = udpv6_rcv,
.err_handler = udpv6_err,
.flags = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
--
2.35.1