From f6ac8585897684374a19863fff21186a05805286 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Sat, 2 Feb 2019 10:49:13 +0100 Subject: netfilter: nf_tables: unbind set in rule from commit path Anonymous sets that are bound to rules from the same transaction trigger a kernel splat from the abort path due to double set list removal and double free. This patch updates the logic to search for the transaction that is responsible for creating the set and disable the set list removal and release, given the rule is now responsible for this. Lookup is reverse since the transaction that adds the set is likely to be at the tail of the list. Moreover, this patch adds the unbind step to deliver the event from the commit path. This should not be done from the worker thread, since we have no guarantees of in-order delivery to the listener. This patch removes the assumption that both activate and deactivate callbacks need to be provided. Fixes: cd5125d8f518 ("netfilter: nf_tables: split set destruction in deactivate and destroy phase") Reported-by: Mikhail Morfikov Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_compat.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'net/netfilter/nft_compat.c') diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c index 5eb269428832..0732a2fc697c 100644 --- a/net/netfilter/nft_compat.c +++ b/net/netfilter/nft_compat.c @@ -587,10 +587,14 @@ static void nft_compat_activate_tg(const struct nft_ctx *ctx, } static void nft_compat_deactivate(const struct nft_ctx *ctx, - const struct nft_expr *expr) + const struct nft_expr *expr, + enum nft_trans_phase phase) { struct nft_xt *xt = container_of(expr->ops, struct nft_xt, ops); + if (phase == NFT_TRANS_COMMIT) + return; + if (--xt->listcnt == 0) list_del_init(&xt->head); } -- cgit v1.2.3 From 947e492c0fc2132ae5fca081a9c2952ccaab0404 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 5 Feb 2019 12:16:18 +0100 Subject: netfilter: nft_compat: don't use refcount_inc on newly allocated entry When I moved the refcount to refcount_t type I missed the fact that refcount_inc() will result in use-after-free warning with CONFIG_REFCOUNT_FULL=y builds. The correct fix would be to init the reference count to 1 at allocation time, but, unfortunately we cannot do this, as we can't undo that in case something else fails later in the batch. So only solution I see is to special-case the 'new entry' condition and replace refcount_inc() with a "delayed" refcount_set(1) in this case, as done here. The .activate callback can be removed to simplify things, we only need to make sure that deactivate() decrements/unlinks the entry from the list at end of transaction phase (commit or abort). Fixes: 12c44aba6618 ("netfilter: nft_compat: use refcnt_t type for nft_xt reference count") Reported-by: Jordan Glover Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_compat.c | 62 +++++++++++++++++----------------------------- 1 file changed, 23 insertions(+), 39 deletions(-) (limited to 'net/netfilter/nft_compat.c') diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c index 0732a2fc697c..fe64df848365 100644 --- a/net/netfilter/nft_compat.c +++ b/net/netfilter/nft_compat.c @@ -61,6 +61,21 @@ static struct nft_compat_net *nft_compat_pernet(struct net *net) return net_generic(net, nft_compat_net_id); } +static void nft_xt_get(struct nft_xt *xt) +{ + /* refcount_inc() warns on 0 -> 1 transition, but we can't + * init the reference count to 1 in .select_ops -- we can't + * undo such an increase when another expression inside the same + * rule fails afterwards. + */ + if (xt->listcnt == 0) + refcount_set(&xt->refcnt, 1); + else + refcount_inc(&xt->refcnt); + + xt->listcnt++; +} + static bool nft_xt_put(struct nft_xt *xt) { if (refcount_dec_and_test(&xt->refcnt)) { @@ -291,7 +306,7 @@ 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); - refcount_inc(&nft_xt->refcnt); + nft_xt_get(nft_xt); return 0; } @@ -504,7 +519,7 @@ __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); - refcount_inc(&nft_xt->refcnt); + nft_xt_get(nft_xt); return 0; } @@ -558,45 +573,16 @@ 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, enum nft_trans_phase phase) { struct nft_xt *xt = container_of(expr->ops, struct nft_xt, ops); - if (phase == NFT_TRANS_COMMIT) - return; - - if (--xt->listcnt == 0) - list_del_init(&xt->head); + if (phase == NFT_TRANS_ABORT || phase == NFT_TRANS_COMMIT) { + if (--xt->listcnt == 0) + list_del_init(&xt->head); + } } static void @@ -852,7 +838,6 @@ 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; @@ -870,7 +855,7 @@ nft_match_select_ops(const struct nft_ctx *ctx, nft_match->ops.size = matchsize; - nft_match->listcnt = 1; + nft_match->listcnt = 0; list_add(&nft_match->head, &cn->nft_match_list); return &nft_match->ops; @@ -957,7 +942,6 @@ 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; @@ -968,7 +952,7 @@ nft_target_select_ops(const struct nft_ctx *ctx, else nft_target->ops.eval = nft_target_eval_xt; - nft_target->listcnt = 1; + nft_target->listcnt = 0; list_add(&nft_target->head, &cn->nft_target_list); return &nft_target->ops; -- cgit v1.2.3