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authorJohn Fastabend <john.fastabend@gmail.com>2014-10-06 08:28:52 +0400
committerDavid S. Miller <davem@davemloft.net>2014-10-07 02:02:33 +0400
commit18cdb37ebf4c986d9502405cbd16b0ac29770c25 (patch)
tree2bf659bf5d527447c11845ca06d15d1b69b9ab31
parent13990f8156862fe945a1a226850a6550c8988a33 (diff)
downloadlinux-18cdb37ebf4c986d9502405cbd16b0ac29770c25.tar.xz
net: sched: do not use tcf_proto 'tp' argument from call_rcu
Using the tcf_proto pointer 'tp' from inside the classifiers callback is not valid because it may have been cleaned up by another call_rcu occuring on another CPU. 'tp' is currently being used by tcf_unbind_filter() in this patch we move instances of tcf_unbind_filter outside of the call_rcu() context. This is safe to do because any running schedulers will either read the valid class field or it will be zeroed. And all schedulers today when the class is 0 do a lookup using the same call used by the tcf_exts_bind(). So even if we have a running classifier hit the null class pointer it will do a lookup and get to the same result. This is particularly fragile at the moment because the only way to verify this is to audit the schedulers call sites. Reported-by: Cong Wang <xiyou.wangconf@gmail.com> Signed-off-by: John Fastabend <john.r.fastabend@intel.com> Acked-by: Cong Wang <cwang@twopensource.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/sched/cls_basic.c5
-rw-r--r--net/sched/cls_bpf.c4
-rw-r--r--net/sched/cls_fw.c5
-rw-r--r--net/sched/cls_route.c8
4 files changed, 14 insertions, 8 deletions
diff --git a/net/sched/cls_basic.c b/net/sched/cls_basic.c
index 90647a8af8ca..cd61280941e5 100644
--- a/net/sched/cls_basic.c
+++ b/net/sched/cls_basic.c
@@ -91,9 +91,7 @@ static int basic_init(struct tcf_proto *tp)
static void basic_delete_filter(struct rcu_head *head)
{
struct basic_filter *f = container_of(head, struct basic_filter, rcu);
- struct tcf_proto *tp = f->tp;
- tcf_unbind_filter(tp, &f->res);
tcf_exts_destroy(&f->exts);
tcf_em_tree_destroy(&f->ematches);
kfree(f);
@@ -106,6 +104,7 @@ static void basic_destroy(struct tcf_proto *tp)
list_for_each_entry_safe(f, n, &head->flist, link) {
list_del_rcu(&f->link);
+ tcf_unbind_filter(tp, &f->res);
call_rcu(&f->rcu, basic_delete_filter);
}
RCU_INIT_POINTER(tp->root, NULL);
@@ -120,6 +119,7 @@ static int basic_delete(struct tcf_proto *tp, unsigned long arg)
list_for_each_entry(t, &head->flist, link)
if (t == f) {
list_del_rcu(&t->link);
+ tcf_unbind_filter(tp, &t->res);
call_rcu(&t->rcu, basic_delete_filter);
return 0;
}
@@ -222,6 +222,7 @@ static int basic_change(struct net *net, struct sk_buff *in_skb,
if (fold) {
list_replace_rcu(&fold->link, &fnew->link);
+ tcf_unbind_filter(tp, &fold->res);
call_rcu(&fold->rcu, basic_delete_filter);
} else {
list_add_rcu(&fnew->link, &head->flist);
diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 4318d067b0a0..eed49d1d0878 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -92,7 +92,6 @@ static int cls_bpf_init(struct tcf_proto *tp)
static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog)
{
- tcf_unbind_filter(tp, &prog->res);
tcf_exts_destroy(&prog->exts);
bpf_prog_destroy(prog->filter);
@@ -116,6 +115,7 @@ static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
list_for_each_entry(prog, &head->plist, link) {
if (prog == todel) {
list_del_rcu(&prog->link);
+ tcf_unbind_filter(tp, &prog->res);
call_rcu(&prog->rcu, __cls_bpf_delete_prog);
return 0;
}
@@ -131,6 +131,7 @@ static void cls_bpf_destroy(struct tcf_proto *tp)
list_for_each_entry_safe(prog, tmp, &head->plist, link) {
list_del_rcu(&prog->link);
+ tcf_unbind_filter(tp, &prog->res);
call_rcu(&prog->rcu, __cls_bpf_delete_prog);
}
@@ -282,6 +283,7 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
if (oldprog) {
list_replace_rcu(&prog->link, &oldprog->link);
+ tcf_unbind_filter(tp, &oldprog->res);
call_rcu(&oldprog->rcu, __cls_bpf_delete_prog);
} else {
list_add_rcu(&prog->link, &head->plist);
diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c
index da805aeeb65c..dbfdfd1f1a9f 100644
--- a/net/sched/cls_fw.c
+++ b/net/sched/cls_fw.c
@@ -123,9 +123,7 @@ static int fw_init(struct tcf_proto *tp)
static void fw_delete_filter(struct rcu_head *head)
{
struct fw_filter *f = container_of(head, struct fw_filter, rcu);
- struct tcf_proto *tp = f->tp;
- tcf_unbind_filter(tp, &f->res);
tcf_exts_destroy(&f->exts);
kfree(f);
}
@@ -143,6 +141,7 @@ static void fw_destroy(struct tcf_proto *tp)
while ((f = rtnl_dereference(head->ht[h])) != NULL) {
RCU_INIT_POINTER(head->ht[h],
rtnl_dereference(f->next));
+ tcf_unbind_filter(tp, &f->res);
call_rcu(&f->rcu, fw_delete_filter);
}
}
@@ -166,6 +165,7 @@ static int fw_delete(struct tcf_proto *tp, unsigned long arg)
fp = &pfp->next, pfp = rtnl_dereference(*fp)) {
if (pfp == f) {
RCU_INIT_POINTER(*fp, rtnl_dereference(f->next));
+ tcf_unbind_filter(tp, &f->res);
call_rcu(&f->rcu, fw_delete_filter);
return 0;
}
@@ -280,6 +280,7 @@ static int fw_change(struct net *net, struct sk_buff *in_skb,
RCU_INIT_POINTER(fnew->next, rtnl_dereference(pfp->next));
rcu_assign_pointer(*fp, fnew);
+ tcf_unbind_filter(tp, &f->res);
call_rcu(&f->rcu, fw_delete_filter);
*arg = (unsigned long)fnew;
diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
index b665aee661f7..6f22baae0afa 100644
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -269,9 +269,7 @@ static void
route4_delete_filter(struct rcu_head *head)
{
struct route4_filter *f = container_of(head, struct route4_filter, rcu);
- struct tcf_proto *tp = f->tp;
- tcf_unbind_filter(tp, &f->res);
tcf_exts_destroy(&f->exts);
kfree(f);
}
@@ -297,6 +295,7 @@ static void route4_destroy(struct tcf_proto *tp)
next = rtnl_dereference(f->next);
RCU_INIT_POINTER(b->ht[h2], next);
+ tcf_unbind_filter(tp, &f->res);
call_rcu(&f->rcu, route4_delete_filter);
}
}
@@ -338,6 +337,7 @@ static int route4_delete(struct tcf_proto *tp, unsigned long arg)
route4_reset_fastmap(head);
/* Delete it */
+ tcf_unbind_filter(tp, &f->res);
call_rcu(&f->rcu, route4_delete_filter);
/* Strip RTNL protected tree */
@@ -545,8 +545,10 @@ static int route4_change(struct net *net, struct sk_buff *in_skb,
route4_reset_fastmap(head);
*arg = (unsigned long)f;
- if (fold)
+ if (fold) {
+ tcf_unbind_filter(tp, &fold->res);
call_rcu(&fold->rcu, route4_delete_filter);
+ }
return 0;
errout: