diff mbox series

[05/11] net: xfrm: Localize sequence counter per network namespace

Message ID 20210331081847.3547641-6-steffen.klassert@secunet.com (mailing list archive)
State Accepted
Commit e88add19f68191448427a6e4eb059664650a837f
Delegated to: Netdev Maintainers
Headers show
Series [01/11] xfrm: interface: fix ipv4 pmtu check to honor ip header df | expand

Checks

Context Check Description
netdev/tree_selection success Guessing tree name failed - patch did not apply

Commit Message

Steffen Klassert March 31, 2021, 8:18 a.m. UTC 
From: "Ahmed S. Darwish" <a.darwish@linutronix.de>

A sequence counter write section must be serialized or its internal
state can get corrupted. The "xfrm_state_hash_generation" seqcount is
global, but its write serialization lock (net->xfrm.xfrm_state_lock) is
instantiated per network namespace. The write protection is thus
insufficient.

To provide full protection, localize the sequence counter per network
namespace instead. This should be safe as both the seqcount read and
write sections access data exclusively within the network namespace. It
also lays the foundation for transforming "xfrm_state_hash_generation"
data type from seqcount_t to seqcount_LOCKNAME_t in further commits.

Fixes: b65e3d7be06f ("xfrm: state: add sequence count to detect hash resizes")
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 include/net/netns/xfrm.h |  4 +++-
 net/xfrm/xfrm_state.c    | 10 +++++-----
 2 files changed, 8 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
index 59f45b1e9dac..b59d73d529ba 100644
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -72,7 +72,9 @@  struct netns_xfrm {
 #if IS_ENABLED(CONFIG_IPV6)
 	struct dst_ops		xfrm6_dst_ops;
 #endif
-	spinlock_t xfrm_state_lock;
+	spinlock_t		xfrm_state_lock;
+	seqcount_t		xfrm_state_hash_generation;
+
 	spinlock_t xfrm_policy_lock;
 	struct mutex xfrm_cfg_mutex;
 };
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index d01ca1a18418..ffd315cff984 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -44,7 +44,6 @@  static void xfrm_state_gc_task(struct work_struct *work);
  */
 
 static unsigned int xfrm_state_hashmax __read_mostly = 1 * 1024 * 1024;
-static __read_mostly seqcount_t xfrm_state_hash_generation = SEQCNT_ZERO(xfrm_state_hash_generation);
 static struct kmem_cache *xfrm_state_cache __ro_after_init;
 
 static DECLARE_WORK(xfrm_state_gc_work, xfrm_state_gc_task);
@@ -140,7 +139,7 @@  static void xfrm_hash_resize(struct work_struct *work)
 	}
 
 	spin_lock_bh(&net->xfrm.xfrm_state_lock);
-	write_seqcount_begin(&xfrm_state_hash_generation);
+	write_seqcount_begin(&net->xfrm.xfrm_state_hash_generation);
 
 	nhashmask = (nsize / sizeof(struct hlist_head)) - 1U;
 	odst = xfrm_state_deref_prot(net->xfrm.state_bydst, net);
@@ -156,7 +155,7 @@  static void xfrm_hash_resize(struct work_struct *work)
 	rcu_assign_pointer(net->xfrm.state_byspi, nspi);
 	net->xfrm.state_hmask = nhashmask;
 
-	write_seqcount_end(&xfrm_state_hash_generation);
+	write_seqcount_end(&net->xfrm.xfrm_state_hash_generation);
 	spin_unlock_bh(&net->xfrm.xfrm_state_lock);
 
 	osize = (ohashmask + 1) * sizeof(struct hlist_head);
@@ -1063,7 +1062,7 @@  xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr,
 
 	to_put = NULL;
 
-	sequence = read_seqcount_begin(&xfrm_state_hash_generation);
+	sequence = read_seqcount_begin(&net->xfrm.xfrm_state_hash_generation);
 
 	rcu_read_lock();
 	h = xfrm_dst_hash(net, daddr, saddr, tmpl->reqid, encap_family);
@@ -1176,7 +1175,7 @@  xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr,
 	if (to_put)
 		xfrm_state_put(to_put);
 
-	if (read_seqcount_retry(&xfrm_state_hash_generation, sequence)) {
+	if (read_seqcount_retry(&net->xfrm.xfrm_state_hash_generation, sequence)) {
 		*err = -EAGAIN;
 		if (x) {
 			xfrm_state_put(x);
@@ -2666,6 +2665,7 @@  int __net_init xfrm_state_init(struct net *net)
 	net->xfrm.state_num = 0;
 	INIT_WORK(&net->xfrm.state_hash_work, xfrm_hash_resize);
 	spin_lock_init(&net->xfrm.xfrm_state_lock);
+	seqcount_init(&net->xfrm.xfrm_state_hash_generation);
 	return 0;
 
 out_byspi: