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authorFlorian Westphal <fw@strlen.de>2019-01-14 14:28:50 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2019-01-18 02:29:42 +0100
commitb2e3d68d1251a051a620f9086e18f7ffa6833b5b (patch)
tree760de639d95d4ecfe13a661b50598dcb670b7a23 /net
parentcf52572ebbd7189a1966c2b5fc34b97078cd1dce (diff)
netfilter: nft_compat: destroy function must not have side effects
The nft_compat destroy function deletes the nft_xt object from a list. This isn't allowed anymore. Destroy functions are called asynchronously, i.e. next batch can find the object that has a pending ->destroy() invocation: cpu0 cpu1 worker ->destroy for_each_entry() if (x == ... return x->ops; list_del(x) kfree_rcu(x) expr->ops->... // ops was free'd To resolve this, the list_del needs to occur before the transaction mutex gets released. nf_tables has a 'deactivate' hook for this purpose, so use that to unlink the object from the list. Fixes: 0935d5588400 ("netfilter: nf_tables: asynchronous release") Reported-by: Taehee Yoo <ap420073@gmail.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nft_compat.c48
1 files changed, 47 insertions, 1 deletions
diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c
index abed3490a8f8..5eb269428832 100644
--- a/net/netfilter/nft_compat.c
+++ b/net/netfilter/nft_compat.c
@@ -29,6 +29,9 @@ struct nft_xt {
struct nft_expr_ops ops;
refcount_t refcnt;
+ /* used only when transaction mutex is locked */
+ unsigned int listcnt;
+
/* Unlike other expressions, ops doesn't have static storage duration.
* nft core assumes they do. We use kfree_rcu so that nft core can
* can check expr->ops->size even after nft_compat->destroy() frees
@@ -61,7 +64,7 @@ static struct nft_compat_net *nft_compat_pernet(struct net *net)
static bool nft_xt_put(struct nft_xt *xt)
{
if (refcount_dec_and_test(&xt->refcnt)) {
- list_del(&xt->head);
+ WARN_ON_ONCE(!list_empty(&xt->head));
kfree_rcu(xt, rcu_head);
return true;
}
@@ -555,6 +558,43 @@ nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
__nft_match_destroy(ctx, expr, nft_expr_priv(expr));
}
+static void nft_compat_activate(const struct nft_ctx *ctx,
+ const struct nft_expr *expr,
+ struct list_head *h)
+{
+ struct nft_xt *xt = container_of(expr->ops, struct nft_xt, ops);
+
+ if (xt->listcnt == 0)
+ list_add(&xt->head, h);
+
+ xt->listcnt++;
+}
+
+static void nft_compat_activate_mt(const struct nft_ctx *ctx,
+ const struct nft_expr *expr)
+{
+ struct nft_compat_net *cn = nft_compat_pernet(ctx->net);
+
+ nft_compat_activate(ctx, expr, &cn->nft_match_list);
+}
+
+static void nft_compat_activate_tg(const struct nft_ctx *ctx,
+ const struct nft_expr *expr)
+{
+ struct nft_compat_net *cn = nft_compat_pernet(ctx->net);
+
+ nft_compat_activate(ctx, expr, &cn->nft_target_list);
+}
+
+static void nft_compat_deactivate(const struct nft_ctx *ctx,
+ const struct nft_expr *expr)
+{
+ struct nft_xt *xt = container_of(expr->ops, struct nft_xt, ops);
+
+ if (--xt->listcnt == 0)
+ list_del_init(&xt->head);
+}
+
static void
nft_match_large_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
{
@@ -808,6 +848,8 @@ nft_match_select_ops(const struct nft_ctx *ctx,
nft_match->ops.eval = nft_match_eval;
nft_match->ops.init = nft_match_init;
nft_match->ops.destroy = nft_match_destroy;
+ nft_match->ops.activate = nft_compat_activate_mt;
+ nft_match->ops.deactivate = nft_compat_deactivate;
nft_match->ops.dump = nft_match_dump;
nft_match->ops.validate = nft_match_validate;
nft_match->ops.data = match;
@@ -824,6 +866,7 @@ nft_match_select_ops(const struct nft_ctx *ctx,
nft_match->ops.size = matchsize;
+ nft_match->listcnt = 1;
list_add(&nft_match->head, &cn->nft_match_list);
return &nft_match->ops;
@@ -910,6 +953,8 @@ nft_target_select_ops(const struct nft_ctx *ctx,
nft_target->ops.size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize));
nft_target->ops.init = nft_target_init;
nft_target->ops.destroy = nft_target_destroy;
+ nft_target->ops.activate = nft_compat_activate_tg;
+ nft_target->ops.deactivate = nft_compat_deactivate;
nft_target->ops.dump = nft_target_dump;
nft_target->ops.validate = nft_target_validate;
nft_target->ops.data = target;
@@ -919,6 +964,7 @@ nft_target_select_ops(const struct nft_ctx *ctx,
else
nft_target->ops.eval = nft_target_eval_xt;
+ nft_target->listcnt = 1;
list_add(&nft_target->head, &cn->nft_target_list);
return &nft_target->ops;