From fa6040c84fefcb902992def41bb9be6f06c09557 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 17 Jun 2024 21:14:12 +0800 Subject: [PATCH 1/2] net: fix __dst_negative_advice() race stable inclusion from stable-v5.10.219 commit 2295a7ef5c8c49241bff769e7826ef2582e532a6 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA436B CVE: CVE-2024-36971 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2295a7ef5c8c49241bff769e7826ef2582e532a6 --------------------------- commit 92f1655aa2b2294d0b49925f3b875a634bd3b59e upstream. __dst_negative_advice() does not enforce proper RCU rules when sk->dst_cache must be cleared, leading to possible UAF. RCU rules are that we must first clear sk->sk_dst_cache, then call dst_release(old_dst). Note that sk_dst_reset(sk) is implementing this protocol correctly, while __dst_negative_advice() uses the wrong order. Given that ip6_negative_advice() has special logic against RTF_CACHE, this means each of the three ->negative_advice() existing methods must perform the sk_dst_reset() themselves. Note the check against NULL dst is centralized in __dst_negative_advice(), there is no need to duplicate it in various callbacks. Many thanks to Clement Lecigne for tracking this issue. This old bug became visible after the blamed commit, using UDP sockets. Fixes: a87cb3e48ee8 ("net: Facility to report route quality of connected sockets") Reported-by: Clement Lecigne Diagnosed-by: Clement Lecigne Signed-off-by: Eric Dumazet Cc: Tom Herbert Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20240528114353.1794151-1-edumazet@google.com Signed-off-by: Jakub Kicinski [Lee: Stable backport] Signed-off-by: Lee Jones Signed-off-by: Greg Kroah-Hartman Signed-off-by: Liu Jian --- include/net/dst_ops.h | 2 +- include/net/sock.h | 13 +++---------- net/ipv4/route.c | 22 ++++++++-------------- net/ipv6/route.c | 29 +++++++++++++++-------------- net/xfrm/xfrm_policy.c | 11 +++-------- 5 files changed, 30 insertions(+), 47 deletions(-) diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h index f3f5d02f2e73..ddc6ca4a33bc 100644 --- a/include/net/dst_ops.h +++ b/include/net/dst_ops.h @@ -25,7 +25,7 @@ struct dst_ops { void (*destroy)(struct dst_entry *); void (*ifdown)(struct dst_entry *, struct net_device *dev, int how); - struct dst_entry * (*negative_advice)(struct dst_entry *); + void (*negative_advice)(struct sock *sk, struct dst_entry *); void (*link_failure)(struct sk_buff *); void (*update_pmtu)(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb, u32 mtu, diff --git a/include/net/sock.h b/include/net/sock.h index 68ea7250a1aa..1438f332edf6 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2059,17 +2059,10 @@ sk_dst_get(struct sock *sk) static inline void __dst_negative_advice(struct sock *sk) { - struct dst_entry *ndst, *dst = __sk_dst_get(sk); + struct dst_entry *dst = __sk_dst_get(sk); - if (dst && dst->ops->negative_advice) { - ndst = dst->ops->negative_advice(dst); - - if (ndst != dst) { - rcu_assign_pointer(sk->sk_dst_cache, ndst); - sk_tx_queue_clear(sk); - WRITE_ONCE(sk->sk_dst_pending_confirm, 0); - } - } + if (dst && dst->ops->negative_advice) + dst->ops->negative_advice(sk, dst); } static inline void dst_negative_advice(struct sock *sk) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 81ccad22a904..eef01be09780 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -137,7 +137,8 @@ static int ip_rt_gc_timeout __read_mostly = RT_GC_TIMEOUT; static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie); static unsigned int ipv4_default_advmss(const struct dst_entry *dst); static unsigned int ipv4_mtu(const struct dst_entry *dst); -static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst); +static void ipv4_negative_advice(struct sock *sk, + struct dst_entry *dst); static void ipv4_link_failure(struct sk_buff *skb); static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb, u32 mtu, @@ -866,22 +867,15 @@ static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buf __ip_do_redirect(rt, skb, &fl4, true); } -static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst) +static void ipv4_negative_advice(struct sock *sk, + struct dst_entry *dst) { struct rtable *rt = (struct rtable *)dst; - struct dst_entry *ret = dst; - if (rt) { - if (dst->obsolete > 0) { - ip_rt_put(rt); - ret = NULL; - } else if ((rt->rt_flags & RTCF_REDIRECTED) || - rt->dst.expires) { - ip_rt_put(rt); - ret = NULL; - } - } - return ret; + if ((dst->obsolete > 0) || + (rt->rt_flags & RTCF_REDIRECTED) || + rt->dst.expires) + sk_dst_reset(sk); } /* diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 38c820e5c00a..96b3ddafb8d1 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -85,7 +85,8 @@ enum rt6_nud_state { static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie); static unsigned int ip6_default_advmss(const struct dst_entry *dst); static unsigned int ip6_mtu(const struct dst_entry *dst); -static struct dst_entry *ip6_negative_advice(struct dst_entry *); +static void ip6_negative_advice(struct sock *sk, + struct dst_entry *dst); static void ip6_dst_destroy(struct dst_entry *); static void ip6_dst_ifdown(struct dst_entry *, struct net_device *dev, int how); @@ -2630,24 +2631,24 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie) return dst_ret; } -static struct dst_entry *ip6_negative_advice(struct dst_entry *dst) +static void ip6_negative_advice(struct sock *sk, + struct dst_entry *dst) { struct rt6_info *rt = (struct rt6_info *) dst; - if (rt) { - if (rt->rt6i_flags & RTF_CACHE) { - rcu_read_lock(); - if (rt6_check_expired(rt)) { - rt6_remove_exception_rt(rt); - dst = NULL; - } - rcu_read_unlock(); - } else { - dst_release(dst); - dst = NULL; + if (rt->rt6i_flags & RTF_CACHE) { + rcu_read_lock(); + if (rt6_check_expired(rt)) { + /* counteract the dst_release() in sk_dst_reset() */ + dst_hold(dst); + sk_dst_reset(sk); + + rt6_remove_exception_rt(rt); } + rcu_read_unlock(); + return; } - return dst; + sk_dst_reset(sk); } static void ip6_link_failure(struct sk_buff *skb) diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 92803d2a8828..c7a827d4265c 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -3791,15 +3791,10 @@ static void xfrm_link_failure(struct sk_buff *skb) /* Impossible. Such dst must be popped before reaches point of failure. */ } -static struct dst_entry *xfrm_negative_advice(struct dst_entry *dst) +static void xfrm_negative_advice(struct sock *sk, struct dst_entry *dst) { - if (dst) { - if (dst->obsolete) { - dst_release(dst); - dst = NULL; - } - } - return dst; + if (dst->obsolete) + sk_dst_reset(sk); } static void xfrm_init_pmtu(struct xfrm_dst **bundle, int nr) -- Gitee From b9d6876befd00f3ce6ce9e74f9f762f87e847c4e Mon Sep 17 00:00:00 2001 From: Liu Jian Date: Mon, 17 Jun 2024 21:14:13 +0800 Subject: [PATCH 2/2] net: fix kabi breakage in struct dst_ops Offering: HULK hulk inclusion category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA436B CVE: CVE-2024-36971 -------------------------------- Fix kabi breakage in struct dst_ops. Fixes: 92f1655aa2b2 ("net: fix __dst_negative_advice() race") Signed-off-by: Liu Jian --- include/net/dst_ops.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/net/dst_ops.h b/include/net/dst_ops.h index ddc6ca4a33bc..6b68d31b4847 100644 --- a/include/net/dst_ops.h +++ b/include/net/dst_ops.h @@ -25,7 +25,11 @@ struct dst_ops { void (*destroy)(struct dst_entry *); void (*ifdown)(struct dst_entry *, struct net_device *dev, int how); +#ifdef __GENKSYMS__ + struct dst_entry * (*negative_advice)(struct dst_entry *); +#else void (*negative_advice)(struct sock *sk, struct dst_entry *); +#endif void (*link_failure)(struct sk_buff *); void (*update_pmtu)(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb, u32 mtu, -- Gitee