From fa803605eef39372e53d7813002d73a3fcf10c88 Mon Sep 17 00:00:00 2001 From: Liping Zhang Date: Sun, 14 May 2017 21:35:22 +0800 Subject: [PATCH] netfilter: nf_tables: can't assume lock is acquired when dumping set elems When dumping the elements related to a specified set, we may invoke the nf_tables_dump_set with the NFNL_SUBSYS_NFTABLES lock not acquired. So we should use the proper rcu operation to avoid race condition, just like other nft dump operations. Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 78 +++++++++++++++++++++++++---------- net/netfilter/nft_set_hash.c | 2 +- 2 files changed, 57 insertions(+), 23 deletions(-) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 559225029740..5f4a4d48b871 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -3367,35 +3367,50 @@ static int nf_tables_dump_setelem(const struct nft_ctx *ctx, return nf_tables_fill_setelem(args->skb, set, elem); } +struct nft_set_dump_ctx { + const struct nft_set *set; + struct nft_ctx ctx; +}; + static int nf_tables_dump_set(struct sk_buff *skb, struct netlink_callback *cb) { + struct nft_set_dump_ctx *dump_ctx = cb->data; struct net *net = sock_net(skb->sk); - u8 genmask = nft_genmask_cur(net); + struct nft_af_info *afi; + struct nft_table *table; struct nft_set *set; struct nft_set_dump_args args; - struct nft_ctx ctx; - struct nlattr *nla[NFTA_SET_ELEM_LIST_MAX + 1]; + bool set_found = false; struct nfgenmsg *nfmsg; struct nlmsghdr *nlh; struct nlattr *nest; u32 portid, seq; - int event, err; + int event; - err = nlmsg_parse(cb->nlh, sizeof(struct nfgenmsg), nla, - NFTA_SET_ELEM_LIST_MAX, nft_set_elem_list_policy, - NULL); - if (err < 0) - return err; + rcu_read_lock(); + list_for_each_entry_rcu(afi, &net->nft.af_info, list) { + if (afi != dump_ctx->ctx.afi) + continue; - err = nft_ctx_init_from_elemattr(&ctx, net, cb->skb, cb->nlh, - (void *)nla, genmask); - if (err < 0) - return err; + list_for_each_entry_rcu(table, &afi->tables, list) { + if (table != dump_ctx->ctx.table) + continue; - set = nf_tables_set_lookup(ctx.table, nla[NFTA_SET_ELEM_LIST_SET], - genmask); - if (IS_ERR(set)) - return PTR_ERR(set); + list_for_each_entry_rcu(set, &table->sets, list) { + if (set == dump_ctx->set) { + set_found = true; + break; + } + } + break; + } + break; + } + + if (!set_found) { + rcu_read_unlock(); + return -ENOENT; + } event = nfnl_msg_type(NFNL_SUBSYS_NFTABLES, NFT_MSG_NEWSETELEM); portid = NETLINK_CB(cb->skb).portid; @@ -3407,11 +3422,11 @@ static int nf_tables_dump_set(struct sk_buff *skb, struct netlink_callback *cb) goto nla_put_failure; nfmsg = nlmsg_data(nlh); - nfmsg->nfgen_family = ctx.afi->family; + nfmsg->nfgen_family = afi->family; nfmsg->version = NFNETLINK_V0; - nfmsg->res_id = htons(ctx.net->nft.base_seq & 0xffff); + nfmsg->res_id = htons(net->nft.base_seq & 0xffff); - if (nla_put_string(skb, NFTA_SET_ELEM_LIST_TABLE, ctx.table->name)) + if (nla_put_string(skb, NFTA_SET_ELEM_LIST_TABLE, table->name)) goto nla_put_failure; if (nla_put_string(skb, NFTA_SET_ELEM_LIST_SET, set->name)) goto nla_put_failure; @@ -3422,12 +3437,13 @@ static int nf_tables_dump_set(struct sk_buff *skb, struct netlink_callback *cb) args.cb = cb; args.skb = skb; - args.iter.genmask = nft_genmask_cur(ctx.net); + args.iter.genmask = nft_genmask_cur(net); args.iter.skip = cb->args[0]; args.iter.count = 0; args.iter.err = 0; args.iter.fn = nf_tables_dump_setelem; - set->ops->walk(&ctx, set, &args.iter); + set->ops->walk(&dump_ctx->ctx, set, &args.iter); + rcu_read_unlock(); nla_nest_end(skb, nest); nlmsg_end(skb, nlh); @@ -3441,9 +3457,16 @@ static int nf_tables_dump_set(struct sk_buff *skb, struct netlink_callback *cb) return skb->len; nla_put_failure: + rcu_read_unlock(); return -ENOSPC; } +static int nf_tables_dump_set_done(struct netlink_callback *cb) +{ + kfree(cb->data); + return 0; +} + static int nf_tables_getsetelem(struct net *net, struct sock *nlsk, struct sk_buff *skb, const struct nlmsghdr *nlh, const struct nlattr * const nla[]) @@ -3465,7 +3488,18 @@ static int nf_tables_getsetelem(struct net *net, struct sock *nlsk, if (nlh->nlmsg_flags & NLM_F_DUMP) { struct netlink_dump_control c = { .dump = nf_tables_dump_set, + .done = nf_tables_dump_set_done, }; + struct nft_set_dump_ctx *dump_ctx; + + dump_ctx = kmalloc(sizeof(*dump_ctx), GFP_KERNEL); + if (!dump_ctx) + return -ENOMEM; + + dump_ctx->set = set; + dump_ctx->ctx = ctx; + + c.data = dump_ctx; return netlink_dump_start(nlsk, skb, nlh, &c); } return -EOPNOTSUPP; diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c index 8ec086b6b56b..3d3a6df4ce70 100644 --- a/net/netfilter/nft_set_hash.c +++ b/net/netfilter/nft_set_hash.c @@ -222,7 +222,7 @@ static void nft_hash_walk(const struct nft_ctx *ctx, struct nft_set *set, struct nft_set_elem elem; int err; - err = rhashtable_walk_init(&priv->ht, &hti, GFP_KERNEL); + err = rhashtable_walk_init(&priv->ht, &hti, GFP_ATOMIC); iter->err = err; if (err) return; -- 2.34.1