From: Pablo Neira Ayuso <pablo@netfilter.org> stable inclusion from stable-v6.6.134 commit d81c3205085b54b18d311425671f20d5be0ba3d0 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14147 CVE: CVE-2026-31414 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 9c42bc9db90a154bc61ae337a070465f3393485a ] The expectation helper field is mostly unused. As a result, the netfilter codebase relies on accessing the helper through exp->master. Always set on the expectation helper field so it can be used to reach the helper. nf_ct_expect_init() is called from packet path where the skb owns the ct object, therefore accessing exp->master for the newly created expectation is safe. This saves a lot of updates in all callsites to pass the ct object as parameter to nf_ct_expect_init(). This is a preparation patches for follow up fixes. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Stable-dep-of: 917b61fa2042 ("netfilter: ctnetlink: ignore explicit helper on new expectations") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Li Xiasong <lixiasong1@huawei.com> --- include/net/netfilter/nf_conntrack_expect.h | 2 +- net/netfilter/nf_conntrack_broadcast.c | 2 +- net/netfilter/nf_conntrack_expect.c | 14 +++++++++++++- net/netfilter/nf_conntrack_h323_main.c | 12 ++++++------ net/netfilter/nf_conntrack_helper.c | 7 ++++++- net/netfilter/nf_conntrack_netlink.c | 2 +- net/netfilter/nf_conntrack_sip.c | 2 +- 7 files changed, 29 insertions(+), 12 deletions(-) diff --git a/include/net/netfilter/nf_conntrack_expect.h b/include/net/netfilter/nf_conntrack_expect.h index 165e7a03b8e9..1b01400b10bd 100644 --- a/include/net/netfilter/nf_conntrack_expect.h +++ b/include/net/netfilter/nf_conntrack_expect.h @@ -40,7 +40,7 @@ struct nf_conntrack_expect { struct nf_conntrack_expect *this); /* Helper to assign to new connection */ - struct nf_conntrack_helper *helper; + struct nf_conntrack_helper __rcu *helper; /* The conntrack of the master connection */ struct nf_conn *master; diff --git a/net/netfilter/nf_conntrack_broadcast.c b/net/netfilter/nf_conntrack_broadcast.c index 9fb9b8031298..721b3e87416b 100644 --- a/net/netfilter/nf_conntrack_broadcast.c +++ b/net/netfilter/nf_conntrack_broadcast.c @@ -70,7 +70,7 @@ int nf_conntrack_broadcast_help(struct sk_buff *skb, exp->expectfn = NULL; exp->flags = NF_CT_EXPECT_PERMANENT; exp->class = NF_CT_EXPECT_CLASS_DEFAULT; - exp->helper = NULL; + rcu_assign_pointer(exp->helper, helper); nf_ct_expect_related(exp, 0); nf_ct_expect_put(exp); diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c index 81ca348915c9..2fbd1fb1b92f 100644 --- a/net/netfilter/nf_conntrack_expect.c +++ b/net/netfilter/nf_conntrack_expect.c @@ -309,12 +309,19 @@ struct nf_conntrack_expect *nf_ct_expect_alloc(struct nf_conn *me) } EXPORT_SYMBOL_GPL(nf_ct_expect_alloc); +/* This function can only be used from packet path, where accessing + * master's helper is safe, because the packet holds a reference on + * the conntrack object. Never use it from control plane. + */ void nf_ct_expect_init(struct nf_conntrack_expect *exp, unsigned int class, u_int8_t family, const union nf_inet_addr *saddr, const union nf_inet_addr *daddr, u_int8_t proto, const __be16 *src, const __be16 *dst) { + struct nf_conntrack_helper *helper = NULL; + struct nf_conn *ct = exp->master; + struct nf_conn_help *help; int len; if (family == AF_INET) @@ -325,7 +332,12 @@ void nf_ct_expect_init(struct nf_conntrack_expect *exp, unsigned int class, exp->flags = 0; exp->class = class; exp->expectfn = NULL; - exp->helper = NULL; + + help = nfct_help(ct); + if (help) + helper = rcu_dereference(help->helper); + + rcu_assign_pointer(exp->helper, helper); exp->tuple.src.l3num = family; exp->tuple.dst.protonum = proto; diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c index 5a9bce24f3c3..0ef66ff56643 100644 --- a/net/netfilter/nf_conntrack_h323_main.c +++ b/net/netfilter/nf_conntrack_h323_main.c @@ -642,7 +642,7 @@ static int expect_h245(struct sk_buff *skb, struct nf_conn *ct, &ct->tuplehash[!dir].tuple.src.u3, &ct->tuplehash[!dir].tuple.dst.u3, IPPROTO_TCP, NULL, &port); - exp->helper = &nf_conntrack_helper_h245; + rcu_assign_pointer(exp->helper, &nf_conntrack_helper_h245); nathook = rcu_dereference(nfct_h323_nat_hook); if (memcmp(&ct->tuplehash[dir].tuple.src.u3, @@ -766,7 +766,7 @@ static int expect_callforwarding(struct sk_buff *skb, nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct), &ct->tuplehash[!dir].tuple.src.u3, &addr, IPPROTO_TCP, NULL, &port); - exp->helper = nf_conntrack_helper_q931; + rcu_assign_pointer(exp->helper, nf_conntrack_helper_q931); nathook = rcu_dereference(nfct_h323_nat_hook); if (memcmp(&ct->tuplehash[dir].tuple.src.u3, @@ -1233,7 +1233,7 @@ static int expect_q931(struct sk_buff *skb, struct nf_conn *ct, &ct->tuplehash[!dir].tuple.src.u3 : NULL, &ct->tuplehash[!dir].tuple.dst.u3, IPPROTO_TCP, NULL, &port); - exp->helper = nf_conntrack_helper_q931; + rcu_assign_pointer(exp->helper, nf_conntrack_helper_q931); exp->flags = NF_CT_EXPECT_PERMANENT; /* Accept multiple calls */ nathook = rcu_dereference(nfct_h323_nat_hook); @@ -1305,7 +1305,7 @@ static int process_gcf(struct sk_buff *skb, struct nf_conn *ct, nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct), &ct->tuplehash[!dir].tuple.src.u3, &addr, IPPROTO_UDP, NULL, &port); - exp->helper = nf_conntrack_helper_ras; + rcu_assign_pointer(exp->helper, nf_conntrack_helper_ras); if (nf_ct_expect_related(exp, 0) == 0) { pr_debug("nf_ct_ras: expect RAS "); @@ -1522,7 +1522,7 @@ static int process_acf(struct sk_buff *skb, struct nf_conn *ct, &ct->tuplehash[!dir].tuple.src.u3, &addr, IPPROTO_TCP, NULL, &port); exp->flags = NF_CT_EXPECT_PERMANENT; - exp->helper = nf_conntrack_helper_q931; + rcu_assign_pointer(exp->helper, nf_conntrack_helper_q931); if (nf_ct_expect_related(exp, 0) == 0) { pr_debug("nf_ct_ras: expect Q.931 "); @@ -1576,7 +1576,7 @@ static int process_lcf(struct sk_buff *skb, struct nf_conn *ct, &ct->tuplehash[!dir].tuple.src.u3, &addr, IPPROTO_TCP, NULL, &port); exp->flags = NF_CT_EXPECT_PERMANENT; - exp->helper = nf_conntrack_helper_q931; + rcu_assign_pointer(exp->helper, nf_conntrack_helper_q931); if (nf_ct_expect_related(exp, 0) == 0) { pr_debug("nf_ct_ras: expect Q.931 "); diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c index 10f72b5b4e1a..e4ac1abc7cbf 100644 --- a/net/netfilter/nf_conntrack_helper.c +++ b/net/netfilter/nf_conntrack_helper.c @@ -404,7 +404,7 @@ static bool expect_iter_me(struct nf_conntrack_expect *exp, void *data) const struct nf_conntrack_helper *me = data; const struct nf_conntrack_helper *this; - if (exp->helper == me) + if (rcu_access_pointer(exp->helper) == me) return true; this = rcu_dereference_protected(help->helper, @@ -426,6 +426,11 @@ void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me) nf_ct_expect_iterate_destroy(expect_iter_me, NULL); nf_ct_iterate_destroy(unhelp, me); + + /* nf_ct_iterate_destroy() does an unconditional synchronize_rcu() as + * last step, this ensures rcu readers of exp->helper are done. + * No need for another synchronize_rcu() here. + */ } EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister); diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index b4761a060e7a..566f9834325e 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -3561,7 +3561,7 @@ ctnetlink_alloc_expect(const struct nlattr * const cda[], struct nf_conn *ct, exp->class = class; exp->master = ct; - exp->helper = helper; + rcu_assign_pointer(exp->helper, helper); exp->tuple = *tuple; exp->mask.src.u3 = mask->src.u3; exp->mask.src.u.all = mask->src.u.all; diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c index 657839a58782..faf2e82f9d74 100644 --- a/net/netfilter/nf_conntrack_sip.c +++ b/net/netfilter/nf_conntrack_sip.c @@ -1297,7 +1297,7 @@ static int process_register_request(struct sk_buff *skb, unsigned int protoff, nf_ct_expect_init(exp, SIP_EXPECT_SIGNALLING, nf_ct_l3num(ct), saddr, &daddr, proto, NULL, &port); exp->timeout.expires = sip_timeout * HZ; - exp->helper = helper; + rcu_assign_pointer(exp->helper, helper); exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE; hooks = rcu_dereference(nf_nat_sip_hooks); -- 2.34.1