From ee059170b1f7e94e55fa6cadee544e176a6e59c2 Mon Sep 17 00:00:00 2001 From: Pedro Tammela Date: Thu, 9 Feb 2023 11:37:39 -0300 Subject: net/sched: tcindex: update imperfect hash filters respecting rcu The imperfect hash area can be updated while packets are traversing, which will cause a use-after-free when 'tcf_exts_exec()' is called with the destroyed tcf_ext. CPU 0: CPU 1: tcindex_set_parms tcindex_classify tcindex_lookup tcindex_lookup tcf_exts_change tcf_exts_exec [UAF] Stop operating on the shared area directly, by using a local copy, and update the filter with 'rcu_replace_pointer()'. Delete the old filter version only after a rcu grace period elapsed. Fixes: 9b0d4446b569 ("net: sched: avoid atomic swap in tcf_exts_change") Reported-by: valis Suggested-by: valis Signed-off-by: Jamal Hadi Salim Signed-off-by: Pedro Tammela Link: https://lore.kernel.org/r/20230209143739.279867-1-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski --- net/sched/cls_tcindex.c | 34 ++++++++++++++++++++++++++++++---- 1 file changed, 30 insertions(+), 4 deletions(-) (limited to 'net/sched') diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c index ee2a050c887b..ba7f22a49397 100644 --- a/net/sched/cls_tcindex.c +++ b/net/sched/cls_tcindex.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -339,6 +340,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base, struct tcf_result cr = {}; int err, balloc = 0; struct tcf_exts e; + bool update_h = false; err = tcf_exts_init(&e, net, TCA_TCINDEX_ACT, TCA_TCINDEX_POLICE); if (err < 0) @@ -456,10 +458,13 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base, } } - if (cp->perfect) + if (cp->perfect) { r = cp->perfect + handle; - else - r = tcindex_lookup(cp, handle) ? : &new_filter_result; + } else { + /* imperfect area is updated in-place using rcu */ + update_h = !!tcindex_lookup(cp, handle); + r = &new_filter_result; + } if (r == &new_filter_result) { f = kzalloc(sizeof(*f), GFP_KERNEL); @@ -485,7 +490,28 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base, rcu_assign_pointer(tp->root, cp); - if (r == &new_filter_result) { + if (update_h) { + struct tcindex_filter __rcu **fp; + struct tcindex_filter *cf; + + f->result.res = r->res; + tcf_exts_change(&f->result.exts, &r->exts); + + /* imperfect area bucket */ + fp = cp->h + (handle % cp->hash); + + /* lookup the filter, guaranteed to exist */ + for (cf = rcu_dereference_bh_rtnl(*fp); cf; + fp = &cf->next, cf = rcu_dereference_bh_rtnl(*fp)) + if (cf->key == handle) + break; + + f->next = cf->next; + + cf = rcu_replace_pointer(*fp, f, 1); + tcf_exts_get_net(&cf->result.exts); + tcf_queue_work(&cf->rwork, tcindex_destroy_fexts_work); + } else if (r == &new_filter_result) { struct tcindex_filter *nfp; struct tcindex_filter __rcu **fp; -- cgit v1.2.3 From 21c167aa0ba943a7cac2f6969814f83bb701666b Mon Sep 17 00:00:00 2001 From: Pedro Tammela Date: Fri, 10 Feb 2023 17:08:25 -0300 Subject: net/sched: act_ctinfo: use percpu stats The tc action act_ctinfo was using shared stats, fix it to use percpu stats since bstats_update() must be called with locks or with a percpu pointer argument. tdc results: 1..12 ok 1 c826 - Add ctinfo action with default setting ok 2 0286 - Add ctinfo action with dscp ok 3 4938 - Add ctinfo action with valid cpmark and zone ok 4 7593 - Add ctinfo action with drop control ok 5 2961 - Replace ctinfo action zone and action control ok 6 e567 - Delete ctinfo action with valid index ok 7 6a91 - Delete ctinfo action with invalid index ok 8 5232 - List ctinfo actions ok 9 7702 - Flush ctinfo actions ok 10 3201 - Add ctinfo action with duplicate index ok 11 8295 - Add ctinfo action with invalid index ok 12 3964 - Replace ctinfo action with invalid goto_chain control Fixes: 24ec483cec98 ("net: sched: Introduce act_ctinfo action") Reviewed-by: Jamal Hadi Salim Signed-off-by: Pedro Tammela Reviewed-by: Larysa Zaremba Link: https://lore.kernel.org/r/20230210200824.444856-1-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski --- net/sched/act_ctinfo.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'net/sched') diff --git a/net/sched/act_ctinfo.c b/net/sched/act_ctinfo.c index 4b1b59da5c0b..4d15b6a6169c 100644 --- a/net/sched/act_ctinfo.c +++ b/net/sched/act_ctinfo.c @@ -93,7 +93,7 @@ TC_INDIRECT_SCOPE int tcf_ctinfo_act(struct sk_buff *skb, cp = rcu_dereference_bh(ca->params); tcf_lastuse_update(&ca->tcf_tm); - bstats_update(&ca->tcf_bstats, skb); + tcf_action_update_bstats(&ca->common, skb); action = READ_ONCE(ca->tcf_action); wlen = skb_network_offset(skb); @@ -212,8 +212,8 @@ static int tcf_ctinfo_init(struct net *net, struct nlattr *nla, index = actparm->index; err = tcf_idr_check_alloc(tn, &index, a, bind); if (!err) { - ret = tcf_idr_create(tn, index, est, a, - &act_ctinfo_ops, bind, false, flags); + ret = tcf_idr_create_from_flags(tn, index, est, a, + &act_ctinfo_ops, bind, flags); if (ret) { tcf_idr_cleanup(tn, index); return ret; -- cgit v1.2.3 From 42018a322bd453e38b3ffee294982243e50a484f Mon Sep 17 00:00:00 2001 From: Pedro Tammela Date: Mon, 13 Feb 2023 22:47:29 -0300 Subject: net/sched: tcindex: search key must be 16 bits Syzkaller found an issue where a handle greater than 16 bits would trigger a null-ptr-deref in the imperfect hash area update. general protection fault, probably for non-canonical address 0xdffffc0000000015: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x00000000000000a8-0x00000000000000af] CPU: 0 PID: 5070 Comm: syz-executor456 Not tainted 6.2.0-rc7-syzkaller-00112-gc68f345b7c42 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023 RIP: 0010:tcindex_set_parms+0x1a6a/0x2990 net/sched/cls_tcindex.c:509 Code: 01 e9 e9 fe ff ff 4c 8b bd 28 fe ff ff e8 0e 57 7d f9 48 8d bb a8 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 94 0c 00 00 48 8b 85 f8 fd ff ff 48 8b 9b a8 00 RSP: 0018:ffffc90003d3ef88 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000015 RSI: ffffffff8803a102 RDI: 00000000000000a8 RBP: ffffc90003d3f1d8 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff88801e2b10a8 R13: dffffc0000000000 R14: 0000000000030000 R15: ffff888017b3be00 FS: 00005555569af300(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000056041c6d2000 CR3: 000000002bfca000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tcindex_change+0x1ea/0x320 net/sched/cls_tcindex.c:572 tc_new_tfilter+0x96e/0x2220 net/sched/cls_api.c:2155 rtnetlink_rcv_msg+0x959/0xca0 net/core/rtnetlink.c:6132 netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2574 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1365 netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1942 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg+0xd3/0x120 net/socket.c:734 ____sys_sendmsg+0x334/0x8c0 net/socket.c:2476 ___sys_sendmsg+0x110/0x1b0 net/socket.c:2530 __sys_sendmmsg+0x18f/0x460 net/socket.c:2616 __do_sys_sendmmsg net/socket.c:2645 [inline] __se_sys_sendmmsg net/socket.c:2642 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2642 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 Fixes: ee059170b1f7 ("net/sched: tcindex: update imperfect hash filters respecting rcu") Signed-off-by: Jamal Hadi Salim Signed-off-by: Pedro Tammela Reported-by: syzbot Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- net/sched/cls_tcindex.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/sched') diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c index ba7f22a49397..6640e75eaa02 100644 --- a/net/sched/cls_tcindex.c +++ b/net/sched/cls_tcindex.c @@ -503,7 +503,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base, /* lookup the filter, guaranteed to exist */ for (cf = rcu_dereference_bh_rtnl(*fp); cf; fp = &cf->next, cf = rcu_dereference_bh_rtnl(*fp)) - if (cf->key == handle) + if (cf->key == (u16)handle) break; f->next = cf->next; -- cgit v1.2.3