forked from luck/tmp_suning_uos_patched
d936377414
Roi reported a crash in flower where tp->root was NULL in ->classify() callbacks. Reason is that in ->destroy() tp->root is set to NULL via RCU_INIT_POINTER(). It's problematic for some of the classifiers, because this doesn't respect RCU grace period for them, and as a result, still outstanding readers from tc_classify() will try to blindly dereference a NULL tp->root. The tp->root object is strictly private to the classifier implementation and holds internal data the core such as tc_ctl_tfilter() doesn't know about. Within some classifiers, such as cls_bpf, cls_basic, etc, tp->root is only checked for NULL in ->get() callback, but nowhere else. This is misleading and seemed to be copied from old classifier code that was not cleaned up properly. For example,d3fa76ee6b
("[NET_SCHED]: cls_basic: fix NULL pointer dereference") moved tp->root initialization into ->init() routine, where before it was part of ->change(), so ->get() had to deal with tp->root being NULL back then, so that was indeed a valid case, afterd3fa76ee6b
, not really anymore. We used to set tp->root to NULL long ago in ->destroy(), see47a1a1d4be
("pkt_sched: remove unnecessary xchg() in packet classifiers"); but the NULLifying was reintroduced with the RCUification, but it's not correct for every classifier implementation. In the cases that are fixed here with one exception of cls_cgroup, tp->root object is allocated and initialized inside ->init() callback, which is always performed at a point in time after we allocate a new tp, which means tp and thus tp->root was not globally visible in the tp chain yet (see tc_ctl_tfilter()). Also, on destruction tp->root is strictly kfree_rcu()'ed in ->destroy() handler, same for the tp which is kfree_rcu()'ed right when we return from ->destroy() in tcf_destroy(). This means, the head object's lifetime for such classifiers is always tied to the tp lifetime. The RCU callback invocation for the two kfree_rcu() could be out of order, but that's fine since both are independent. Dropping the RCU_INIT_POINTER(tp->root, NULL) for these classifiers here means that 1) we don't need a useless NULL check in fast-path and, 2) that outstanding readers of that tp in tc_classify() can still execute under respect with RCU grace period as it is actually expected. Things that haven't been touched here: cls_fw and cls_route. They each handle tp->root being NULL in ->classify() path for historic reasons, so their ->destroy() implementation can stay as is. If someone actually cares, they could get cleaned up at some point to avoid the test in fast path. cls_u32 doesn't set tp->root to NULL. For cls_rsvp, I just added a !head should anyone actually be using/testing it, so it at least aligns with cls_fw and cls_route. For cls_flower we additionally need to defer rhashtable destruction (to a sleepable context) after RCU grace period as concurrent readers might still access it. (Note that in this case we need to hold module reference to keep work callback address intact, since we only wait on module unload for all call_rcu()s to finish.) This fixes one race to bring RCU grace period guarantees back. Next step as worked on by Cong however is to fix1e052be69d
("net_sched: destroy proto tp when all filters are gone") to get the order of unlinking the tp in tc_ctl_tfilter() for the RTM_DELTFILTER case right by moving RCU_INIT_POINTER() before tcf_destroy() and let the notification for removal be done through the prior ->delete() callback. Both are independant issues. Once we have that right, we can then clean tp->root up for a number of classifiers by not making them RCU pointers, which requires a new callback (->uninit) that is triggered from tp's RCU callback, where we just kfree() tp->root from there. Fixes:1f947bf151
("net: sched: rcu'ify cls_bpf") Fixes:9888faefe1
("net: sched: cls_basic use RCU") Fixes:70da9f0bf9
("net: sched: cls_flow use RCU") Fixes:77b9900ef5
("tc: introduce Flower classifier") Fixes:bf3994d2ed
("net/sched: introduce Match-all classifier") Fixes:952313bd62
("net: sched: cls_cgroup use RCU") Reported-by: Roi Dayan <roid@mellanox.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: Roi Dayan <roid@mellanox.com> Cc: Jiri Pirko <jiri@mellanox.com> Acked-by: John Fastabend <john.r.fastabend@intel.com> Acked-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
315 lines
6.8 KiB
C
315 lines
6.8 KiB
C
/*
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* net/sched/cls_basic.c Basic Packet Classifier.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Thomas Graf <tgraf@suug.ch>
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/rtnetlink.h>
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#include <linux/skbuff.h>
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#include <net/netlink.h>
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#include <net/act_api.h>
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#include <net/pkt_cls.h>
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struct basic_head {
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u32 hgenerator;
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struct list_head flist;
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struct rcu_head rcu;
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};
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struct basic_filter {
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u32 handle;
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struct tcf_exts exts;
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struct tcf_ematch_tree ematches;
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struct tcf_result res;
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struct tcf_proto *tp;
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struct list_head link;
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struct rcu_head rcu;
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};
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static int basic_classify(struct sk_buff *skb, const struct tcf_proto *tp,
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struct tcf_result *res)
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{
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int r;
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struct basic_head *head = rcu_dereference_bh(tp->root);
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struct basic_filter *f;
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list_for_each_entry_rcu(f, &head->flist, link) {
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if (!tcf_em_tree_match(skb, &f->ematches, NULL))
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continue;
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*res = f->res;
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r = tcf_exts_exec(skb, &f->exts, res);
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if (r < 0)
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continue;
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return r;
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}
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return -1;
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}
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static unsigned long basic_get(struct tcf_proto *tp, u32 handle)
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{
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unsigned long l = 0UL;
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struct basic_head *head = rtnl_dereference(tp->root);
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struct basic_filter *f;
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list_for_each_entry(f, &head->flist, link) {
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if (f->handle == handle) {
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l = (unsigned long) f;
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break;
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}
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}
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return l;
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}
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static int basic_init(struct tcf_proto *tp)
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{
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struct basic_head *head;
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head = kzalloc(sizeof(*head), GFP_KERNEL);
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if (head == NULL)
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return -ENOBUFS;
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INIT_LIST_HEAD(&head->flist);
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rcu_assign_pointer(tp->root, head);
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return 0;
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}
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static void basic_delete_filter(struct rcu_head *head)
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{
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struct basic_filter *f = container_of(head, struct basic_filter, rcu);
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tcf_exts_destroy(&f->exts);
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tcf_em_tree_destroy(&f->ematches);
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kfree(f);
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}
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static bool basic_destroy(struct tcf_proto *tp, bool force)
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{
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struct basic_head *head = rtnl_dereference(tp->root);
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struct basic_filter *f, *n;
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if (!force && !list_empty(&head->flist))
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return false;
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list_for_each_entry_safe(f, n, &head->flist, link) {
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list_del_rcu(&f->link);
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tcf_unbind_filter(tp, &f->res);
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call_rcu(&f->rcu, basic_delete_filter);
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}
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kfree_rcu(head, rcu);
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return true;
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}
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static int basic_delete(struct tcf_proto *tp, unsigned long arg)
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{
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struct basic_filter *f = (struct basic_filter *) arg;
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list_del_rcu(&f->link);
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tcf_unbind_filter(tp, &f->res);
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call_rcu(&f->rcu, basic_delete_filter);
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return 0;
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}
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static const struct nla_policy basic_policy[TCA_BASIC_MAX + 1] = {
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[TCA_BASIC_CLASSID] = { .type = NLA_U32 },
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[TCA_BASIC_EMATCHES] = { .type = NLA_NESTED },
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};
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static int basic_set_parms(struct net *net, struct tcf_proto *tp,
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struct basic_filter *f, unsigned long base,
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struct nlattr **tb,
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struct nlattr *est, bool ovr)
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{
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int err;
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struct tcf_exts e;
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struct tcf_ematch_tree t;
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err = tcf_exts_init(&e, TCA_BASIC_ACT, TCA_BASIC_POLICE);
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if (err < 0)
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return err;
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err = tcf_exts_validate(net, tp, tb, est, &e, ovr);
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if (err < 0)
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goto errout;
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err = tcf_em_tree_validate(tp, tb[TCA_BASIC_EMATCHES], &t);
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if (err < 0)
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goto errout;
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if (tb[TCA_BASIC_CLASSID]) {
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f->res.classid = nla_get_u32(tb[TCA_BASIC_CLASSID]);
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tcf_bind_filter(tp, &f->res, base);
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}
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tcf_exts_change(tp, &f->exts, &e);
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tcf_em_tree_change(tp, &f->ematches, &t);
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f->tp = tp;
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return 0;
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errout:
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tcf_exts_destroy(&e);
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return err;
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}
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static int basic_change(struct net *net, struct sk_buff *in_skb,
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struct tcf_proto *tp, unsigned long base, u32 handle,
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struct nlattr **tca, unsigned long *arg, bool ovr)
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{
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int err;
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struct basic_head *head = rtnl_dereference(tp->root);
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struct nlattr *tb[TCA_BASIC_MAX + 1];
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struct basic_filter *fold = (struct basic_filter *) *arg;
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struct basic_filter *fnew;
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if (tca[TCA_OPTIONS] == NULL)
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return -EINVAL;
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err = nla_parse_nested(tb, TCA_BASIC_MAX, tca[TCA_OPTIONS],
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basic_policy);
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if (err < 0)
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return err;
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if (fold != NULL) {
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if (handle && fold->handle != handle)
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return -EINVAL;
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}
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fnew = kzalloc(sizeof(*fnew), GFP_KERNEL);
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if (!fnew)
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return -ENOBUFS;
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err = tcf_exts_init(&fnew->exts, TCA_BASIC_ACT, TCA_BASIC_POLICE);
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if (err < 0)
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goto errout;
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err = -EINVAL;
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if (handle) {
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fnew->handle = handle;
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} else if (fold) {
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fnew->handle = fold->handle;
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} else {
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unsigned int i = 0x80000000;
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do {
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if (++head->hgenerator == 0x7FFFFFFF)
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head->hgenerator = 1;
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} while (--i > 0 && basic_get(tp, head->hgenerator));
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if (i <= 0) {
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pr_err("Insufficient number of handles\n");
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goto errout;
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}
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fnew->handle = head->hgenerator;
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}
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err = basic_set_parms(net, tp, fnew, base, tb, tca[TCA_RATE], ovr);
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if (err < 0)
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goto errout;
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*arg = (unsigned long)fnew;
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if (fold) {
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list_replace_rcu(&fold->link, &fnew->link);
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tcf_unbind_filter(tp, &fold->res);
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call_rcu(&fold->rcu, basic_delete_filter);
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} else {
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list_add_rcu(&fnew->link, &head->flist);
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}
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return 0;
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errout:
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tcf_exts_destroy(&fnew->exts);
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kfree(fnew);
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return err;
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}
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static void basic_walk(struct tcf_proto *tp, struct tcf_walker *arg)
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{
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struct basic_head *head = rtnl_dereference(tp->root);
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struct basic_filter *f;
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list_for_each_entry(f, &head->flist, link) {
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if (arg->count < arg->skip)
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goto skip;
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if (arg->fn(tp, (unsigned long) f, arg) < 0) {
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arg->stop = 1;
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break;
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}
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skip:
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arg->count++;
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}
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}
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static int basic_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
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struct sk_buff *skb, struct tcmsg *t)
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{
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struct basic_filter *f = (struct basic_filter *) fh;
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struct nlattr *nest;
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if (f == NULL)
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return skb->len;
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t->tcm_handle = f->handle;
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nest = nla_nest_start(skb, TCA_OPTIONS);
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if (nest == NULL)
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goto nla_put_failure;
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if (f->res.classid &&
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nla_put_u32(skb, TCA_BASIC_CLASSID, f->res.classid))
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goto nla_put_failure;
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if (tcf_exts_dump(skb, &f->exts) < 0 ||
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tcf_em_tree_dump(skb, &f->ematches, TCA_BASIC_EMATCHES) < 0)
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goto nla_put_failure;
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nla_nest_end(skb, nest);
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if (tcf_exts_dump_stats(skb, &f->exts) < 0)
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goto nla_put_failure;
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return skb->len;
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nla_put_failure:
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nla_nest_cancel(skb, nest);
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return -1;
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}
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static struct tcf_proto_ops cls_basic_ops __read_mostly = {
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.kind = "basic",
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.classify = basic_classify,
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.init = basic_init,
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.destroy = basic_destroy,
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.get = basic_get,
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.change = basic_change,
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.delete = basic_delete,
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.walk = basic_walk,
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.dump = basic_dump,
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.owner = THIS_MODULE,
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};
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static int __init init_basic(void)
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{
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return register_tcf_proto_ops(&cls_basic_ops);
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}
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static void __exit exit_basic(void)
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{
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unregister_tcf_proto_ops(&cls_basic_ops);
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}
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module_init(init_basic)
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module_exit(exit_basic)
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MODULE_LICENSE("GPL");
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