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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 <zlpnobody@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Liping Zhang 2017-05-14 21:35:22 +08:00 committed by Pablo Neira Ayuso
parent 87e94dbc21
commit fa803605ee
2 changed files with 57 additions and 23 deletions
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78
net/netfilter/nf_tables_api.c
View File

@ -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;

2
net/netfilter/nft_set_hash.c
View File

@ -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;