diff options
author | Phil Sutter <phil@nwl.cc> | 2023-11-09 18:01:16 +0300 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2023-12-22 14:08:38 +0300 |
commit | 3d483faa66639ad96d8373046c47f2b2d76fdf76 (patch) | |
tree | a12daa3a6e7cebd9e9b5a587fec29e6f03b15a10 /net/netfilter/nf_tables_api.c | |
parent | f649be6d9c84960e358f350914a0673411467b11 (diff) | |
download | linux-3d483faa66639ad96d8373046c47f2b2d76fdf76.tar.xz |
netfilter: nf_tables: Add locking for NFT_MSG_GETSETELEM_RESET requests
Set expressions' dump callbacks are not concurrency-safe per-se with
reset bit set. If two CPUs reset the same element at the same time,
values may underrun at least with element-attached counters and quotas.
Prevent this by introducing dedicated callbacks for nfnetlink and the
asynchronous dump handling to serialize access.
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter/nf_tables_api.c')
-rw-r--r-- | net/netfilter/nf_tables_api.c | 98 |
1 files changed, 81 insertions, 17 deletions
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 9b58593e7729..ed6b6bcd6608 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -5817,10 +5817,6 @@ static int nf_tables_dump_set(struct sk_buff *skb, struct netlink_callback *cb) nla_nest_end(skb, nest); nlmsg_end(skb, nlh); - if (dump_ctx->reset && args.iter.count > args.iter.skip) - audit_log_nft_set_reset(table, cb->seq, - args.iter.count - args.iter.skip); - rcu_read_unlock(); if (args.iter.err && args.iter.err != -EMSGSIZE) @@ -5836,6 +5832,26 @@ nla_put_failure: return -ENOSPC; } +static int nf_tables_dumpreset_set(struct sk_buff *skb, + struct netlink_callback *cb) +{ + struct nftables_pernet *nft_net = nft_pernet(sock_net(skb->sk)); + struct nft_set_dump_ctx *dump_ctx = cb->data; + int ret, skip = cb->args[0]; + + mutex_lock(&nft_net->commit_mutex); + + ret = nf_tables_dump_set(skb, cb); + + if (cb->args[0] > skip) + audit_log_nft_set_reset(dump_ctx->ctx.table, cb->seq, + cb->args[0] - skip); + + mutex_unlock(&nft_net->commit_mutex); + + return ret; +} + static int nf_tables_dump_set_start(struct netlink_callback *cb) { struct nft_set_dump_ctx *dump_ctx = cb->data; @@ -6079,13 +6095,8 @@ static int nf_tables_getsetelem(struct sk_buff *skb, { struct netlink_ext_ack *extack = info->extack; struct nft_set_dump_ctx dump_ctx; - int rem, err = 0, nelems = 0; - struct net *net = info->net; struct nlattr *attr; - bool reset = false; - - if (NFNL_MSG_TYPE(info->nlh->nlmsg_type) == NFT_MSG_GETSETELEM_RESET) - reset = true; + int rem, err = 0; if (info->nlh->nlmsg_flags & NLM_F_DUMP) { struct netlink_dump_control c = { @@ -6095,7 +6106,7 @@ static int nf_tables_getsetelem(struct sk_buff *skb, .module = THIS_MODULE, }; - err = nft_set_dump_ctx_init(&dump_ctx, skb, info, nla, reset); + err = nft_set_dump_ctx_init(&dump_ctx, skb, info, nla, false); if (err) return err; @@ -6106,22 +6117,75 @@ static int nf_tables_getsetelem(struct sk_buff *skb, if (!nla[NFTA_SET_ELEM_LIST_ELEMENTS]) return -EINVAL; - err = nft_set_dump_ctx_init(&dump_ctx, skb, info, nla, reset); + err = nft_set_dump_ctx_init(&dump_ctx, skb, info, nla, false); if (err) return err; nla_for_each_nested(attr, nla[NFTA_SET_ELEM_LIST_ELEMENTS], rem) { - err = nft_get_set_elem(&dump_ctx.ctx, dump_ctx.set, attr, reset); + err = nft_get_set_elem(&dump_ctx.ctx, dump_ctx.set, attr, false); + if (err < 0) { + NL_SET_BAD_ATTR(extack, attr); + break; + } + } + + return err; +} + +static int nf_tables_getsetelem_reset(struct sk_buff *skb, + const struct nfnl_info *info, + const struct nlattr * const nla[]) +{ + struct nftables_pernet *nft_net = nft_pernet(info->net); + struct netlink_ext_ack *extack = info->extack; + struct nft_set_dump_ctx dump_ctx; + int rem, err = 0, nelems = 0; + struct nlattr *attr; + + if (info->nlh->nlmsg_flags & NLM_F_DUMP) { + struct netlink_dump_control c = { + .start = nf_tables_dump_set_start, + .dump = nf_tables_dumpreset_set, + .done = nf_tables_dump_set_done, + .module = THIS_MODULE, + }; + + err = nft_set_dump_ctx_init(&dump_ctx, skb, info, nla, true); + if (err) + return err; + + c.data = &dump_ctx; + return nft_netlink_dump_start_rcu(info->sk, skb, info->nlh, &c); + } + + if (!nla[NFTA_SET_ELEM_LIST_ELEMENTS]) + return -EINVAL; + + if (!try_module_get(THIS_MODULE)) + return -EINVAL; + rcu_read_unlock(); + mutex_lock(&nft_net->commit_mutex); + rcu_read_lock(); + + err = nft_set_dump_ctx_init(&dump_ctx, skb, info, nla, true); + if (err) + goto out_unlock; + + nla_for_each_nested(attr, nla[NFTA_SET_ELEM_LIST_ELEMENTS], rem) { + err = nft_get_set_elem(&dump_ctx.ctx, dump_ctx.set, attr, true); if (err < 0) { NL_SET_BAD_ATTR(extack, attr); break; } nelems++; } + audit_log_nft_set_reset(dump_ctx.ctx.table, nft_net->base_seq, nelems); - if (reset) - audit_log_nft_set_reset(dump_ctx.ctx.table, nft_pernet(net)->base_seq, - nelems); +out_unlock: + rcu_read_unlock(); + mutex_unlock(&nft_net->commit_mutex); + rcu_read_lock(); + module_put(THIS_MODULE); return err; } @@ -9095,7 +9159,7 @@ static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = { .policy = nft_set_elem_list_policy, }, [NFT_MSG_GETSETELEM_RESET] = { - .call = nf_tables_getsetelem, + .call = nf_tables_getsetelem_reset, .type = NFNL_CB_RCU, .attr_count = NFTA_SET_ELEM_LIST_MAX, .policy = nft_set_elem_list_policy, |