diff options
Diffstat (limited to 'target/linux/generic/backport-5.10/070-net-icmp-pass-zeroed-opts-from-icmp-v6-_ndo_send-bef.patch')
| -rw-r--r-- | target/linux/generic/backport-5.10/070-net-icmp-pass-zeroed-opts-from-icmp-v6-_ndo_send-bef.patch | 337 |
1 files changed, 337 insertions, 0 deletions
diff --git a/target/linux/generic/backport-5.10/070-net-icmp-pass-zeroed-opts-from-icmp-v6-_ndo_send-bef.patch b/target/linux/generic/backport-5.10/070-net-icmp-pass-zeroed-opts-from-icmp-v6-_ndo_send-bef.patch new file mode 100644 index 0000000000..d2c084424f --- /dev/null +++ b/target/linux/generic/backport-5.10/070-net-icmp-pass-zeroed-opts-from-icmp-v6-_ndo_send-bef.patch @@ -0,0 +1,337 @@ +From 4a25324891a32d080589a6e3a4dec2be2d9e3d60 Mon Sep 17 00:00:00 2001 +From: "Jason A. Donenfeld" <Jason@zx2c4.com> +Date: Tue, 23 Feb 2021 14:18:58 +0100 +Subject: [PATCH] net: icmp: pass zeroed opts from icmp{,v6}_ndo_send before + sending + +commit ee576c47db60432c37e54b1e2b43a8ca6d3a8dca upstream. + +The icmp{,v6}_send functions make all sorts of use of skb->cb, casting +it with IPCB or IP6CB, assuming the skb to have come directly from the +inet layer. But when the packet comes from the ndo layer, especially +when forwarded, there's no telling what might be in skb->cb at that +point. As a result, the icmp sending code risks reading bogus memory +contents, which can result in nasty stack overflows such as this one +reported by a user: + + panic+0x108/0x2ea + __stack_chk_fail+0x14/0x20 + __icmp_send+0x5bd/0x5c0 + icmp_ndo_send+0x148/0x160 + +In icmp_send, skb->cb is cast with IPCB and an ip_options struct is read +from it. The optlen parameter there is of particular note, as it can +induce writes beyond bounds. There are quite a few ways that can happen +in __ip_options_echo. For example: + + // sptr/skb are attacker-controlled skb bytes + sptr = skb_network_header(skb); + // dptr/dopt points to stack memory allocated by __icmp_send + dptr = dopt->__data; + // sopt is the corrupt skb->cb in question + if (sopt->rr) { + optlen = sptr[sopt->rr+1]; // corrupt skb->cb + skb->data + soffset = sptr[sopt->rr+2]; // corrupt skb->cb + skb->data + // this now writes potentially attacker-controlled data, over + // flowing the stack: + memcpy(dptr, sptr+sopt->rr, optlen); + } + +In the icmpv6_send case, the story is similar, but not as dire, as only +IP6CB(skb)->iif and IP6CB(skb)->dsthao are used. The dsthao case is +worse than the iif case, but it is passed to ipv6_find_tlv, which does +a bit of bounds checking on the value. + +This is easy to simulate by doing a `memset(skb->cb, 0x41, +sizeof(skb->cb));` before calling icmp{,v6}_ndo_send, and it's only by +good fortune and the rarity of icmp sending from that context that we've +avoided reports like this until now. For example, in KASAN: + + BUG: KASAN: stack-out-of-bounds in __ip_options_echo+0xa0e/0x12b0 + Write of size 38 at addr ffff888006f1f80e by task ping/89 + CPU: 2 PID: 89 Comm: ping Not tainted 5.10.0-rc7-debug+ #5 + Call Trace: + dump_stack+0x9a/0xcc + print_address_description.constprop.0+0x1a/0x160 + __kasan_report.cold+0x20/0x38 + kasan_report+0x32/0x40 + check_memory_region+0x145/0x1a0 + memcpy+0x39/0x60 + __ip_options_echo+0xa0e/0x12b0 + __icmp_send+0x744/0x1700 + +Actually, out of the 4 drivers that do this, only gtp zeroed the cb for +the v4 case, while the rest did not. So this commit actually removes the +gtp-specific zeroing, while putting the code where it belongs in the +shared infrastructure of icmp{,v6}_ndo_send. + +This commit fixes the issue by passing an empty IPCB or IP6CB along to +the functions that actually do the work. For the icmp_send, this was +already trivial, thanks to __icmp_send providing the plumbing function. +For icmpv6_send, this required a tiny bit of refactoring to make it +behave like the v4 case, after which it was straight forward. + +Fixes: a2b78e9b2cac ("sunvnet: generate ICMP PTMUD messages for smaller port MTUs") +Reported-by: SinYu <liuxyon@gmail.com> +Reviewed-by: Willem de Bruijn <willemb@google.com> +Link: https://lore.kernel.org/netdev/CAF=yD-LOF116aHub6RMe8vB8ZpnrrnoTdqhobEx+bvoA8AsP0w@mail.gmail.com/T/ +Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> +Link: https://lore.kernel.org/r/20210223131858.72082-1-Jason@zx2c4.com +Signed-off-by: Jakub Kicinski <kuba@kernel.org> +[Jason: backported to 5.10] +Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> +--- + include/linux/icmpv6.h | 17 ++++++++++++++--- + include/linux/ipv6.h | 1 - + include/net/icmp.h | 6 +++++- + net/ipv4/icmp.c | 5 +++-- + net/ipv6/icmp.c | 16 ++++++++-------- + net/ipv6/ip6_icmp.c | 12 +++++++----- + 6 files changed, 37 insertions(+), 20 deletions(-) + +--- a/drivers/net/gtp.c ++++ b/drivers/net/gtp.c +@@ -539,7 +539,6 @@ static int gtp_build_skb_ip4(struct sk_b + if (!skb_is_gso(skb) && (iph->frag_off & htons(IP_DF)) && + mtu < ntohs(iph->tot_len)) { + netdev_dbg(dev, "packet too big, fragmentation needed\n"); +- memset(IPCB(skb), 0, sizeof(*IPCB(skb))); + icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, + htonl(mtu)); + goto err_rt; +--- a/include/linux/icmpv6.h ++++ b/include/linux/icmpv6.h +@@ -3,6 +3,7 @@ + #define _LINUX_ICMPV6_H + + #include <linux/skbuff.h> ++#include <linux/ipv6.h> + #include <uapi/linux/icmpv6.h> + + static inline struct icmp6hdr *icmp6_hdr(const struct sk_buff *skb) +@@ -15,13 +16,16 @@ static inline struct icmp6hdr *icmp6_hdr + #if IS_ENABLED(CONFIG_IPV6) + + typedef void ip6_icmp_send_t(struct sk_buff *skb, u8 type, u8 code, __u32 info, +- const struct in6_addr *force_saddr); ++ const struct in6_addr *force_saddr, ++ const struct inet6_skb_parm *parm); + #if IS_BUILTIN(CONFIG_IPV6) + void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info, +- const struct in6_addr *force_saddr); +-static inline void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info) ++ const struct in6_addr *force_saddr, ++ const struct inet6_skb_parm *parm); ++static inline void __icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info, ++ const struct inet6_skb_parm *parm) + { +- icmp6_send(skb, type, code, info, NULL); ++ icmp6_send(skb, type, code, info, NULL, parm); + } + static inline int inet6_register_icmp_sender(ip6_icmp_send_t *fn) + { +@@ -34,18 +38,28 @@ static inline int inet6_unregister_icmp_ + return 0; + } + #else +-extern void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info); ++extern void __icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info, ++ const struct inet6_skb_parm *parm); + extern int inet6_register_icmp_sender(ip6_icmp_send_t *fn); + extern int inet6_unregister_icmp_sender(ip6_icmp_send_t *fn); + #endif + ++static inline void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info) ++{ ++ __icmpv6_send(skb, type, code, info, IP6CB(skb)); ++} ++ + int ip6_err_gen_icmpv6_unreach(struct sk_buff *skb, int nhs, int type, + unsigned int data_len); + + #if IS_ENABLED(CONFIG_NF_NAT) + void icmpv6_ndo_send(struct sk_buff *skb_in, u8 type, u8 code, __u32 info); + #else +-#define icmpv6_ndo_send icmpv6_send ++static inline void icmpv6_ndo_send(struct sk_buff *skb_in, u8 type, u8 code, __u32 info) ++{ ++ struct inet6_skb_parm parm = { 0 }; ++ __icmpv6_send(skb_in, type, code, info, &parm); ++} + #endif + + #else +--- a/include/linux/ipv6.h ++++ b/include/linux/ipv6.h +@@ -84,7 +84,6 @@ struct ipv6_params { + __s32 autoconf; + }; + extern struct ipv6_params ipv6_defaults; +-#include <linux/icmpv6.h> + #include <linux/tcp.h> + #include <linux/udp.h> + +--- a/include/net/icmp.h ++++ b/include/net/icmp.h +@@ -46,7 +46,11 @@ static inline void icmp_send(struct sk_b + #if IS_ENABLED(CONFIG_NF_NAT) + void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info); + #else +-#define icmp_ndo_send icmp_send ++static inline void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) ++{ ++ struct ip_options opts = { 0 }; ++ __icmp_send(skb_in, type, code, info, &opts); ++} + #endif + + int icmp_rcv(struct sk_buff *skb); +--- a/net/ipv4/icmp.c ++++ b/net/ipv4/icmp.c +@@ -775,13 +775,14 @@ EXPORT_SYMBOL(__icmp_send); + void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) + { + struct sk_buff *cloned_skb = NULL; ++ struct ip_options opts = { 0 }; + enum ip_conntrack_info ctinfo; + struct nf_conn *ct; + __be32 orig_ip; + + ct = nf_ct_get(skb_in, &ctinfo); + if (!ct || !(ct->status & IPS_SRC_NAT)) { +- icmp_send(skb_in, type, code, info); ++ __icmp_send(skb_in, type, code, info, &opts); + return; + } + +@@ -796,7 +797,7 @@ void icmp_ndo_send(struct sk_buff *skb_i + + orig_ip = ip_hdr(skb_in)->saddr; + ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; +- icmp_send(skb_in, type, code, info); ++ __icmp_send(skb_in, type, code, info, &opts); + ip_hdr(skb_in)->saddr = orig_ip; + out: + consume_skb(cloned_skb); +--- a/net/ipv6/icmp.c ++++ b/net/ipv6/icmp.c +@@ -331,10 +331,9 @@ static int icmpv6_getfrag(void *from, ch + } + + #if IS_ENABLED(CONFIG_IPV6_MIP6) +-static void mip6_addr_swap(struct sk_buff *skb) ++static void mip6_addr_swap(struct sk_buff *skb, const struct inet6_skb_parm *opt) + { + struct ipv6hdr *iph = ipv6_hdr(skb); +- struct inet6_skb_parm *opt = IP6CB(skb); + struct ipv6_destopt_hao *hao; + struct in6_addr tmp; + int off; +@@ -351,7 +350,7 @@ static void mip6_addr_swap(struct sk_buf + } + } + #else +-static inline void mip6_addr_swap(struct sk_buff *skb) {} ++static inline void mip6_addr_swap(struct sk_buff *skb, const struct inet6_skb_parm *opt) {} + #endif + + static struct dst_entry *icmpv6_route_lookup(struct net *net, +@@ -446,7 +445,8 @@ static int icmp6_iif(const struct sk_buf + * Send an ICMP message in response to a packet in error + */ + void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info, +- const struct in6_addr *force_saddr) ++ const struct in6_addr *force_saddr, ++ const struct inet6_skb_parm *parm) + { + struct inet6_dev *idev = NULL; + struct ipv6hdr *hdr = ipv6_hdr(skb); +@@ -542,7 +542,7 @@ void icmp6_send(struct sk_buff *skb, u8 + if (!(skb->dev->flags & IFF_LOOPBACK) && !icmpv6_global_allow(net, type)) + goto out_bh_enable; + +- mip6_addr_swap(skb); ++ mip6_addr_swap(skb, parm); + + sk = icmpv6_xmit_lock(net); + if (!sk) +@@ -559,7 +559,7 @@ void icmp6_send(struct sk_buff *skb, u8 + /* select a more meaningful saddr from input if */ + struct net_device *in_netdev; + +- in_netdev = dev_get_by_index(net, IP6CB(skb)->iif); ++ in_netdev = dev_get_by_index(net, parm->iif); + if (in_netdev) { + ipv6_dev_get_saddr(net, in_netdev, &fl6.daddr, + inet6_sk(sk)->srcprefs, +@@ -640,7 +640,7 @@ EXPORT_SYMBOL(icmp6_send); + */ + void icmpv6_param_prob(struct sk_buff *skb, u8 code, int pos) + { +- icmp6_send(skb, ICMPV6_PARAMPROB, code, pos, NULL); ++ icmp6_send(skb, ICMPV6_PARAMPROB, code, pos, NULL, IP6CB(skb)); + kfree_skb(skb); + } + +@@ -697,10 +697,10 @@ int ip6_err_gen_icmpv6_unreach(struct sk + } + if (type == ICMP_TIME_EXCEEDED) + icmp6_send(skb2, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, +- info, &temp_saddr); ++ info, &temp_saddr, IP6CB(skb2)); + else + icmp6_send(skb2, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, +- info, &temp_saddr); ++ info, &temp_saddr, IP6CB(skb2)); + if (rt) + ip6_rt_put(rt); + +--- a/net/ipv6/ip6_icmp.c ++++ b/net/ipv6/ip6_icmp.c +@@ -33,23 +33,25 @@ int inet6_unregister_icmp_sender(ip6_icm + } + EXPORT_SYMBOL(inet6_unregister_icmp_sender); + +-void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info) ++void __icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info, ++ const struct inet6_skb_parm *parm) + { + ip6_icmp_send_t *send; + + rcu_read_lock(); + send = rcu_dereference(ip6_icmp_send); + if (send) +- send(skb, type, code, info, NULL); ++ send(skb, type, code, info, NULL, parm); + rcu_read_unlock(); + } +-EXPORT_SYMBOL(icmpv6_send); ++EXPORT_SYMBOL(__icmpv6_send); + #endif + + #if IS_ENABLED(CONFIG_NF_NAT) + #include <net/netfilter/nf_conntrack.h> + void icmpv6_ndo_send(struct sk_buff *skb_in, u8 type, u8 code, __u32 info) + { ++ struct inet6_skb_parm parm = { 0 }; + struct sk_buff *cloned_skb = NULL; + enum ip_conntrack_info ctinfo; + struct in6_addr orig_ip; +@@ -57,7 +59,7 @@ void icmpv6_ndo_send(struct sk_buff *skb + + ct = nf_ct_get(skb_in, &ctinfo); + if (!ct || !(ct->status & IPS_SRC_NAT)) { +- icmpv6_send(skb_in, type, code, info); ++ __icmpv6_send(skb_in, type, code, info, &parm); + return; + } + +@@ -72,7 +74,7 @@ void icmpv6_ndo_send(struct sk_buff *skb + + orig_ip = ipv6_hdr(skb_in)->saddr; + ipv6_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.in6; +- icmpv6_send(skb_in, type, code, info); ++ __icmpv6_send(skb_in, type, code, info, &parm); + ipv6_hdr(skb_in)->saddr = orig_ip; + out: + consume_skb(cloned_skb); |