[PATCH net 5/8] netfilter: nf_tables: memleak in hw offload abort path
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: 2021-06-22 22:01:02
Also in:
netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Release flow from the abort path, this is easy to reproduce since
b72920f6e4a9 ("netfilter: nftables: counter hardware offload support").
If the preparation phase fails, then the abort path is exercised without
releasing the flow rule object.
unreferenced object 0xffff8881f0fa7700 (size 128):
comm "nft", pid 1335, jiffies 4294931120 (age 4163.740s)
hex dump (first 32 bytes):
08 e4 de 13 82 88 ff ff 98 e4 de 13 82 88 ff ff ................
48 e4 de 13 82 88 ff ff 01 00 00 00 00 00 00 00 H...............
backtrace:
[<00000000634547e7>] flow_rule_alloc+0x26/0x80
[<00000000c8426156>] nft_flow_rule_create+0xc9/0x3f0 [nf_tables]
[<0000000075ff8e46>] nf_tables_newrule+0xc79/0x10a0 [nf_tables]
[<00000000ba65e40e>] nfnetlink_rcv_batch+0xaac/0xf90 [nfnetlink]
[<00000000505c614a>] nfnetlink_rcv+0x1bb/0x1f0 [nfnetlink]
[<00000000eb78e1fe>] netlink_unicast+0x34b/0x480
[<00000000a8f72c94>] netlink_sendmsg+0x3af/0x690
[<000000009cb1ddf4>] sock_sendmsg+0x96/0xa0
[<0000000039d06e44>] ____sys_sendmsg+0x3fe/0x440
[<00000000137e82ca>] ___sys_sendmsg+0xd8/0x140
[<000000000c6bf6a6>] __sys_sendmsg+0xb3/0x130
[<0000000043bd6268>] do_syscall_64+0x40/0xb0
[<00000000afdebc2d>] entry_SYSCALL_64_after_hwframe+0x44/0xae
Remove flow rule release from the offload commit path, otherwise error
from the offload commit phase might trigger a double-free due to the
execution of the abort_offload -> abort. After this patch, the abort
path takes care of releasing the flow rule.
This fix also needs to move the nft_flow_rule_create() call before the
transaction object is added otherwise the abort path might find a NULL
pointer to the flow rule object for the NFT_CHAIN_HW_OFFLOAD case.
While at it, rename BASIC-like goto tags to slightly more meaningful
names rather than adding a new "err3" tag.
Fixes: 63b48c73ff56 ("netfilter: nf_tables_offload: undo updates if transaction fails")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/netfilter/nf_tables_api.c | 51 +++++++++++++++++++------------
net/netfilter/nf_tables_offload.c | 17 -----------
2 files changed, 31 insertions(+), 37 deletions(-)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index bf4d6ec9fc55..ca9ec8721e6c 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c@@ -3243,9 +3243,9 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info, u8 genmask = nft_genmask_next(info->net); struct nft_rule *rule, *old_rule = NULL; struct nft_expr_info *expr_info = NULL; + struct nft_flow_rule *flow = NULL; int family = nfmsg->nfgen_family; struct net *net = info->net; - struct nft_flow_rule *flow; struct nft_userdata *udata; struct nft_table *table; struct nft_chain *chain;
@@ -3340,13 +3340,13 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info, nla_for_each_nested(tmp, nla[NFTA_RULE_EXPRESSIONS], rem) { err = -EINVAL; if (nla_type(tmp) != NFTA_LIST_ELEM) - goto err1; + goto err_release_expr; if (n == NFT_RULE_MAXEXPRS) - goto err1; + goto err_release_expr; err = nf_tables_expr_parse(&ctx, tmp, &expr_info[n]); if (err < 0) { NL_SET_BAD_ATTR(extack, tmp); - goto err1; + goto err_release_expr; } size += expr_info[n].ops->size; n++;
@@ -3355,7 +3355,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info, /* Check for overflow of dlen field */ err = -EFBIG; if (size >= 1 << 12) - goto err1; + goto err_release_expr; if (nla[NFTA_RULE_USERDATA]) { ulen = nla_len(nla[NFTA_RULE_USERDATA]);
@@ -3366,7 +3366,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info, err = -ENOMEM; rule = kzalloc(sizeof(*rule) + size + usize, GFP_KERNEL); if (rule == NULL) - goto err1; + goto err_release_expr; nft_activate_next(net, rule);
@@ -3385,7 +3385,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info, err = nf_tables_newexpr(&ctx, &expr_info[i], expr); if (err < 0) { NL_SET_BAD_ATTR(extack, expr_info[i].attr); - goto err2; + goto err_release_rule; } if (expr_info[i].ops->validate)
@@ -3395,16 +3395,24 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info, expr = nft_expr_next(expr); } + if (chain->flags & NFT_CHAIN_HW_OFFLOAD) { + flow = nft_flow_rule_create(net, rule); + if (IS_ERR(flow)) { + err = PTR_ERR(flow); + goto err_release_rule; + } + } + if (info->nlh->nlmsg_flags & NLM_F_REPLACE) { trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule); if (trans == NULL) { err = -ENOMEM; - goto err2; + goto err_destroy_flow_rule; } err = nft_delrule(&ctx, old_rule); if (err < 0) { nft_trans_destroy(trans); - goto err2; + goto err_destroy_flow_rule; } list_add_tail_rcu(&rule->list, &old_rule->list);
@@ -3412,7 +3420,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info, trans = nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule); if (!trans) { err = -ENOMEM; - goto err2; + goto err_destroy_flow_rule; } if (info->nlh->nlmsg_flags & NLM_F_APPEND) {
@@ -3430,21 +3438,19 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info, kvfree(expr_info); chain->use++; + if (flow) + nft_trans_flow_rule(trans) = flow; + if (nft_net->validate_state == NFT_VALIDATE_DO) return nft_table_validate(net, table); - if (chain->flags & NFT_CHAIN_HW_OFFLOAD) { - flow = nft_flow_rule_create(net, rule); - if (IS_ERR(flow)) - return PTR_ERR(flow); - - nft_trans_flow_rule(trans) = flow; - } - return 0; -err2: + +err_destroy_flow_rule: + nft_flow_rule_destroy(flow); +err_release_rule: nf_tables_rule_release(&ctx, rule); -err1: +err_release_expr: for (i = 0; i < n; i++) { if (expr_info[i].ops) { module_put(expr_info[i].ops->type->owner);
@@ -8839,11 +8845,16 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action) nft_rule_expr_deactivate(&trans->ctx, nft_trans_rule(trans), NFT_TRANS_ABORT); + if (trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD) + nft_flow_rule_destroy(nft_trans_flow_rule(trans)); break; case NFT_MSG_DELRULE: trans->ctx.chain->use++; nft_clear(trans->ctx.net, nft_trans_rule(trans)); nft_rule_expr_activate(&trans->ctx, nft_trans_rule(trans)); + if (trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD) + nft_flow_rule_destroy(nft_trans_flow_rule(trans)); + nft_trans_destroy(trans); break; case NFT_MSG_NEWSET:
diff --git a/net/netfilter/nf_tables_offload.c b/net/netfilter/nf_tables_offload.c
index a48c5fd53a80..ec701b84844f 100644
--- a/net/netfilter/nf_tables_offload.c
+++ b/net/netfilter/nf_tables_offload.c@@ -594,23 +594,6 @@ int nft_flow_rule_offload_commit(struct net *net) } } - list_for_each_entry(trans, &nft_net->commit_list, list) { - if (trans->ctx.family != NFPROTO_NETDEV) - continue; - - switch (trans->msg_type) { - case NFT_MSG_NEWRULE: - case NFT_MSG_DELRULE: - if (!(trans->ctx.chain->flags & NFT_CHAIN_HW_OFFLOAD)) - continue; - - nft_flow_rule_destroy(nft_trans_flow_rule(trans)); - break; - default: - break; - } - } - return err; }
--
2.30.2