[PATCH v4 2/3] ipv4: Namespaceify tcp_fastopen_key knob

From: Haishuang Yan
Date: Fri Sep 22 2017 - 09:49:47 EST

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In reply to: Haishuang Yan: "[PATCH v4 3/3] ipv4: Namespaceify tcp_fastopen_blackhole_timeout knob"
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Different namespace application might require different tcp_fastopen_key
independently of the host.

David Miller pointed out there is a leak without releasing the context
of tcp_fastopen_key during netns teardown. So add the release action in
exit_batch path.

Tested:
1. Container namespace:
# cat /proc/sys/net/ipv4/tcp_fastopen_key:
2817fff2-f803cf97-eadfd1f3-78c0992b

cookie key in tcp syn packets:
Fast Open Cookie
Kind: TCP Fast Open Cookie (34)
Length: 10
Fast Open Cookie: 1e5dd82a8c492ca9

2. Host:
# cat /proc/sys/net/ipv4/tcp_fastopen_key:
107d7c5f-68eb2ac7-02fb06e6-ed341702

cookie key in tcp syn packets:
Fast Open Cookie
Kind: TCP Fast Open Cookie (34)
Length: 10
Fast Open Cookie: e213c02bf0afbc8a

Signed-off-by: Haishuang Yan <yanhaishuang@xxxxxxxxxxxxxxxxxxxx>
---
include/net/netns/ipv4.h | 4 +++
include/net/tcp.h | 6 ++---
net/ipv4/af_inet.c | 2 +-
net/ipv4/sysctl_net_ipv4.c | 26 +++++++++----------
net/ipv4/tcp.c | 2 +-
net/ipv4/tcp_fastopen.c | 64 +++++++++++++++++++++++++++++++---------------
net/ipv4/tcp_ipv4.c | 6 +++++
7 files changed, 70 insertions(+), 40 deletions(-)

diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index ce6dde0..66b8335 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -36,6 +36,8 @@ struct inet_timewait_death_row {
int sysctl_max_tw_buckets;
};

+struct tcp_fastopen_context;
+
struct netns_ipv4 {
#ifdef CONFIG_SYSCTL
struct ctl_table_header *forw_hdr;
@@ -128,6 +130,8 @@ struct netns_ipv4 {
struct inet_timewait_death_row tcp_death_row;
int sysctl_max_syn_backlog;
int sysctl_tcp_fastopen;
+ struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
+ spinlock_t tcp_fastopen_ctx_lock;

#ifdef CONFIG_NET_L3_MASTER_DEV
int sysctl_udp_l3mdev_accept;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index f628967..e27bd18 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1556,13 +1556,13 @@ struct tcp_fastopen_request {
};
void tcp_free_fastopen_req(struct tcp_sock *tp);

-extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
-int tcp_fastopen_reset_cipher(void *key, unsigned int len);
+void tcp_fastopen_ctx_destroy(struct net *net);
+int tcp_fastopen_reset_cipher(struct net *net, void *key, unsigned int len);
void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct tcp_fastopen_cookie *foc);
-void tcp_fastopen_init_key_once(bool publish);
+void tcp_fastopen_init_key_once(struct net *net);
bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
struct tcp_fastopen_cookie *cookie);
bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index ddd126d..43a1bbe 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -222,7 +222,7 @@ int inet_listen(struct socket *sock, int backlog)
(tcp_fastopen & TFO_SERVER_ENABLE) &&
!inet_csk(sk)->icsk_accept_queue.fastopenq.max_qlen) {
fastopen_queue_tune(sk, backlog);
- tcp_fastopen_init_key_once(true);
+ tcp_fastopen_init_key_once(sock_net(sk));
}

err = inet_csk_listen_start(sk, backlog);
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index e31e853c..20e19fe 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -251,10 +251,12 @@ static int proc_allowed_congestion_control(struct ctl_table *ctl,
return ret;
}

-static int proc_tcp_fastopen_key(struct ctl_table *ctl, int write,
+static int proc_tcp_fastopen_key(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
{
+ struct net *net = container_of(table->data, struct net,
+ ipv4.sysctl_tcp_fastopen);
struct ctl_table tbl = { .maxlen = (TCP_FASTOPEN_KEY_LENGTH * 2 + 10) };
struct tcp_fastopen_context *ctxt;
int ret;
@@ -265,7 +267,7 @@ static int proc_tcp_fastopen_key(struct ctl_table *ctl, int write,
return -ENOMEM;

rcu_read_lock();
- ctxt = rcu_dereference(tcp_fastopen_ctx);
+ ctxt = rcu_dereference(net->ipv4.tcp_fastopen_ctx);
if (ctxt)
memcpy(user_key, ctxt->key, TCP_FASTOPEN_KEY_LENGTH);
else
@@ -282,12 +284,7 @@ static int proc_tcp_fastopen_key(struct ctl_table *ctl, int write,
ret = -EINVAL;
goto bad_key;
}
- /* Generate a dummy secret but don't publish it. This
- * is needed so we don't regenerate a new key on the
- * first invocation of tcp_fastopen_cookie_gen
- */
- tcp_fastopen_init_key_once(false);
- tcp_fastopen_reset_cipher(user_key, TCP_FASTOPEN_KEY_LENGTH);
+ tcp_fastopen_reset_cipher(net, user_key, TCP_FASTOPEN_KEY_LENGTH);
}

bad_key:
@@ -401,12 +398,6 @@ static int proc_tcp_available_ulp(struct ctl_table *ctl,
.proc_handler = proc_dointvec
},
{
- .procname = "tcp_fastopen_key",
- .mode = 0600,
- .maxlen = ((TCP_FASTOPEN_KEY_LENGTH * 2) + 10),
- .proc_handler = proc_tcp_fastopen_key,
- },
- {
.procname = "tcp_fastopen_blackhole_timeout_sec",
.data = &sysctl_tcp_fastopen_blackhole_timeout,
.maxlen = sizeof(int),
@@ -1085,6 +1076,13 @@ static int proc_tcp_available_ulp(struct ctl_table *ctl,
.mode = 0644,
.proc_handler = proc_dointvec,
},
+ {
+ .procname = "tcp_fastopen_key",
+ .mode = 0600,
+ .data = &init_net.ipv4.sysctl_tcp_fastopen,
+ .maxlen = ((TCP_FASTOPEN_KEY_LENGTH * 2) + 10),
+ .proc_handler = proc_tcp_fastopen_key,
+ },
#ifdef CONFIG_IP_ROUTE_MULTIPATH
{
.procname = "fib_multipath_use_neigh",
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index dac56c4..23225c9 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2749,7 +2749,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
case TCP_FASTOPEN:
if (val >= 0 && ((1 << sk->sk_state) & (TCPF_CLOSE |
TCPF_LISTEN))) {
- tcp_fastopen_init_key_once(true);
+ tcp_fastopen_init_key_once(net);

fastopen_queue_tune(sk, val);
} else {
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index 31b08ec..4eae44a 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -9,13 +9,18 @@
#include <net/inetpeer.h>
#include <net/tcp.h>

-struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
-
-static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock);
-
-void tcp_fastopen_init_key_once(bool publish)
+void tcp_fastopen_init_key_once(struct net *net)
{
- static u8 key[TCP_FASTOPEN_KEY_LENGTH];
+ u8 key[TCP_FASTOPEN_KEY_LENGTH];
+ struct tcp_fastopen_context *ctxt;
+
+ rcu_read_lock();
+ ctxt = rcu_dereference(net->ipv4.tcp_fastopen_ctx);
+ if (ctxt) {
+ rcu_read_unlock();
+ return;
+ }
+ rcu_read_unlock();

/* tcp_fastopen_reset_cipher publishes the new context
* atomically, so we allow this race happening here.
@@ -23,8 +28,8 @@ void tcp_fastopen_init_key_once(bool publish)
* All call sites of tcp_fastopen_cookie_gen also check
* for a valid cookie, so this is an acceptable risk.
*/
- if (net_get_random_once(key, sizeof(key)) && publish)
- tcp_fastopen_reset_cipher(key, sizeof(key));
+ get_random_bytes(key, sizeof(key));
+ tcp_fastopen_reset_cipher(net, key, sizeof(key));
}

static void tcp_fastopen_ctx_free(struct rcu_head *head)
@@ -35,7 +40,22 @@ static void tcp_fastopen_ctx_free(struct rcu_head *head)
kfree(ctx);
}

-int tcp_fastopen_reset_cipher(void *key, unsigned int len)
+void tcp_fastopen_ctx_destroy(struct net *net)
+{
+ struct tcp_fastopen_context *ctxt;
+
+ spin_lock(&net->ipv4.tcp_fastopen_ctx_lock);
+
+ ctxt = rcu_dereference_protected(net->ipv4.tcp_fastopen_ctx,
+ lockdep_is_held(&net->ipv4.tcp_fastopen_ctx_lock));
+ rcu_assign_pointer(net->ipv4.tcp_fastopen_ctx, NULL);
+ spin_unlock(&net->ipv4.tcp_fastopen_ctx_lock);
+
+ if (ctxt)
+ call_rcu(&ctxt->rcu, tcp_fastopen_ctx_free);
+}
+
+int tcp_fastopen_reset_cipher(struct net *net, void *key, unsigned int len)
{
int err;
struct tcp_fastopen_context *ctx, *octx;
@@ -59,26 +79,27 @@ int tcp_fastopen_reset_cipher(void *key, unsigned int len)
}
memcpy(ctx->key, key, len);

- spin_lock(&tcp_fastopen_ctx_lock);
+ spin_lock(&net->ipv4.tcp_fastopen_ctx_lock);

- octx = rcu_dereference_protected(tcp_fastopen_ctx,
- lockdep_is_held(&tcp_fastopen_ctx_lock));
- rcu_assign_pointer(tcp_fastopen_ctx, ctx);
- spin_unlock(&tcp_fastopen_ctx_lock);
+ octx = rcu_dereference_protected(net->ipv4.tcp_fastopen_ctx,
+ lockdep_is_held(&net->ipv4.tcp_fastopen_ctx_lock));
+ rcu_assign_pointer(net->ipv4.tcp_fastopen_ctx, ctx);
+ spin_unlock(&net->ipv4.tcp_fastopen_ctx_lock);

if (octx)
call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
return err;
}

-static bool __tcp_fastopen_cookie_gen(const void *path,
+static bool __tcp_fastopen_cookie_gen(struct net *net,
+ const void *path,
struct tcp_fastopen_cookie *foc)
{
struct tcp_fastopen_context *ctx;
bool ok = false;

rcu_read_lock();
- ctx = rcu_dereference(tcp_fastopen_ctx);
+ ctx = rcu_dereference(net->ipv4.tcp_fastopen_ctx);
if (ctx) {
crypto_cipher_encrypt_one(ctx->tfm, foc->val, path);
foc->len = TCP_FASTOPEN_COOKIE_SIZE;
@@ -94,7 +115,8 @@ static bool __tcp_fastopen_cookie_gen(const void *path,
*
* XXX (TFO) - refactor when TCP_FASTOPEN_COOKIE_SIZE != AES_BLOCK_SIZE.
*/
-static bool tcp_fastopen_cookie_gen(struct request_sock *req,
+static bool tcp_fastopen_cookie_gen(struct net *net,
+ struct request_sock *req,
struct sk_buff *syn,
struct tcp_fastopen_cookie *foc)
{
@@ -102,7 +124,7 @@ static bool tcp_fastopen_cookie_gen(struct request_sock *req,
const struct iphdr *iph = ip_hdr(syn);

__be32 path[4] = { iph->saddr, iph->daddr, 0, 0 };
- return __tcp_fastopen_cookie_gen(path, foc);
+ return __tcp_fastopen_cookie_gen(net, path, foc);
}

#if IS_ENABLED(CONFIG_IPV6)
@@ -110,13 +132,13 @@ static bool tcp_fastopen_cookie_gen(struct request_sock *req,
const struct ipv6hdr *ip6h = ipv6_hdr(syn);
struct tcp_fastopen_cookie tmp;

- if (__tcp_fastopen_cookie_gen(&ip6h->saddr, &tmp)) {
+ if (__tcp_fastopen_cookie_gen(net, &ip6h->saddr, &tmp)) {
struct in6_addr *buf = &tmp.addr;
int i;

for (i = 0; i < 4; i++)
buf->s6_addr32[i] ^= ip6h->daddr.s6_addr32[i];
- return __tcp_fastopen_cookie_gen(buf, foc);
+ return __tcp_fastopen_cookie_gen(net, buf, foc);
}
}
#endif
@@ -296,7 +318,7 @@ struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
goto fastopen;

if (foc->len >= 0 && /* Client presents or requests a cookie */
- tcp_fastopen_cookie_gen(req, skb, &valid_foc) &&
+ tcp_fastopen_cookie_gen(sock_net(sk), req, skb, &valid_foc) &&
foc->len == TCP_FASTOPEN_COOKIE_SIZE &&
foc->len == valid_foc.len &&
!memcmp(foc->val, valid_foc.val, foc->len)) {
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 88409b1..49c74c0 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2473,6 +2473,7 @@ static int __net_init tcp_sk_init(struct net *net)
net->ipv4.sysctl_tcp_timestamps = 1;

net->ipv4.sysctl_tcp_fastopen = TFO_CLIENT_ENABLE;
+ spin_lock_init(&net->ipv4.tcp_fastopen_ctx_lock);

return 0;
fail:
@@ -2483,7 +2484,12 @@ static int __net_init tcp_sk_init(struct net *net)

static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
{
+ struct net *net;
+
inet_twsk_purge(&tcp_hashinfo, AF_INET);
+
+ list_for_each_entry(net, net_exit_list, exit_list)
+ tcp_fastopen_ctx_destroy(net);
}

static struct pernet_operations __net_initdata tcp_sk_ops = {
--
1.8.3.1

Next message: Andrey Konovalov: "Re: usb/sounds: slab-out-of-bounds read in snd_usb_create_streams"
Previous message: Christoph Hellwig: "Re: [PATCH V6 1/3] dma-mapping: Introduce device_is_coherent() as ahelper"
In reply to: Haishuang Yan: "[PATCH v4 3/3] ipv4: Namespaceify tcp_fastopen_blackhole_timeout knob"
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