diff options
author | Florian Westphal <fw@strlen.de> | 2019-01-14 14:28:48 +0100 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2019-01-18 02:29:41 +0100 |
commit | 12c44aba6618b7f6c437076e5722237190f6cd5f (patch) | |
tree | a23503ee9662241f43904219c08db82c09784c75 /net/netfilter/nft_compat.c | |
parent | 88a8121dc1d3d0dbddd411b79ed236b6b6ea415c (diff) | |
download | linux-12c44aba6618b7f6c437076e5722237190f6cd5f.tar.bz2 |
netfilter: nft_compat: use refcnt_t type for nft_xt reference count
Using standard integer type was fine while all operations on it were
guarded by the nftnl subsys mutex.
This isn't true anymore:
1. transactions are guarded only by a pernet mutex, so concurrent
rule manipulation in different netns is racy
2. the ->destroy hook runs from a work queue after the transaction
mutex has been released already.
cpu0 cpu1 (net 1) cpu2 (net 2)
kworker
nft_compat->destroy nft_compat->init nft_compat->init
if (--nft_xt->ref == 0) nft_xt->ref++ nft_xt->ref++
Switch to refcount_t. Doing this however only fixes a minor aspect,
nft_compat also performs linked-list operations in an unsafe way.
This is addressed in the next two patches.
Fixes: f102d66b335a ("netfilter: nf_tables: use dedicated mutex to guard transactions")
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/netfilter/nft_compat.c')
-rw-r--r-- | net/netfilter/nft_compat.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c index 7334e0b80a5e..acc85acad31b 100644 --- a/net/netfilter/nft_compat.c +++ b/net/netfilter/nft_compat.c @@ -26,7 +26,7 @@ struct nft_xt { struct list_head head; struct nft_expr_ops ops; - unsigned int refcnt; + refcount_t refcnt; /* Unlike other expressions, ops doesn't have static storage duration. * nft core assumes they do. We use kfree_rcu so that nft core can @@ -45,7 +45,7 @@ struct nft_xt_match_priv { static bool nft_xt_put(struct nft_xt *xt) { - if (--xt->refcnt == 0) { + if (refcount_dec_and_test(&xt->refcnt)) { list_del(&xt->head); kfree_rcu(xt, rcu_head); return true; @@ -273,7 +273,7 @@ nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr, return -EINVAL; nft_xt = container_of(expr->ops, struct nft_xt, ops); - nft_xt->refcnt++; + refcount_inc(&nft_xt->refcnt); return 0; } @@ -486,7 +486,7 @@ __nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr, return ret; nft_xt = container_of(expr->ops, struct nft_xt, ops); - nft_xt->refcnt++; + refcount_inc(&nft_xt->refcnt); return 0; } @@ -789,7 +789,7 @@ nft_match_select_ops(const struct nft_ctx *ctx, goto err; } - nft_match->refcnt = 0; + refcount_set(&nft_match->refcnt, 0); nft_match->ops.type = &nft_match_type; nft_match->ops.eval = nft_match_eval; nft_match->ops.init = nft_match_init; @@ -893,7 +893,7 @@ nft_target_select_ops(const struct nft_ctx *ctx, goto err; } - nft_target->refcnt = 0; + refcount_set(&nft_target->refcnt, 0); nft_target->ops.type = &nft_target_type; nft_target->ops.size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize)); nft_target->ops.init = nft_target_init; @@ -964,7 +964,7 @@ static void __exit nft_compat_module_exit(void) list_for_each_entry_safe(xt, next, &nft_target_list, head) { struct xt_target *target = xt->ops.data; - if (WARN_ON_ONCE(xt->refcnt)) + if (WARN_ON_ONCE(refcount_read(&xt->refcnt))) continue; module_put(target->me); kfree(xt); @@ -973,7 +973,7 @@ static void __exit nft_compat_module_exit(void) list_for_each_entry_safe(xt, next, &nft_match_list, head) { struct xt_match *match = xt->ops.data; - if (WARN_ON_ONCE(xt->refcnt)) + if (WARN_ON_ONCE(refcount_read(&xt->refcnt))) continue; module_put(match->me); kfree(xt); |