![Thomas Graf](/assets/img/avatar_default.png)
Although RCU protection would be possible during diag dump, doing
so allows for concurrent table mutations which can render the
in-table offset between individual Netlink messages invalid and
thus cause legitimate sockets to be skipped in the dump.
Since the diag dump is relatively low volume and consistency is
more important than performance, the table mutex is held during
dump.
Reported-by: Andrey Wagin <avagin@gmail.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Fixes: e341694e3e
("netlink: Convert netlink_lookup() to use RCU protected hash table")
Signed-off-by: David S. Miller <davem@davemloft.net>
236 lines
5.2 KiB
C
236 lines
5.2 KiB
C
#include <linux/module.h>
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#include <net/sock.h>
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#include <linux/netlink.h>
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#include <linux/sock_diag.h>
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#include <linux/netlink_diag.h>
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#include <linux/rhashtable.h>
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#include "af_netlink.h"
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#ifdef CONFIG_NETLINK_MMAP
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static int sk_diag_put_ring(struct netlink_ring *ring, int nl_type,
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struct sk_buff *nlskb)
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{
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struct netlink_diag_ring ndr;
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ndr.ndr_block_size = ring->pg_vec_pages << PAGE_SHIFT;
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ndr.ndr_block_nr = ring->pg_vec_len;
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ndr.ndr_frame_size = ring->frame_size;
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ndr.ndr_frame_nr = ring->frame_max + 1;
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return nla_put(nlskb, nl_type, sizeof(ndr), &ndr);
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}
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static int sk_diag_put_rings_cfg(struct sock *sk, struct sk_buff *nlskb)
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{
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struct netlink_sock *nlk = nlk_sk(sk);
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int ret;
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mutex_lock(&nlk->pg_vec_lock);
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ret = sk_diag_put_ring(&nlk->rx_ring, NETLINK_DIAG_RX_RING, nlskb);
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if (!ret)
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ret = sk_diag_put_ring(&nlk->tx_ring, NETLINK_DIAG_TX_RING,
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nlskb);
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mutex_unlock(&nlk->pg_vec_lock);
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return ret;
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}
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#else
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static int sk_diag_put_rings_cfg(struct sock *sk, struct sk_buff *nlskb)
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{
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return 0;
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}
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#endif
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static int sk_diag_dump_groups(struct sock *sk, struct sk_buff *nlskb)
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{
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struct netlink_sock *nlk = nlk_sk(sk);
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if (nlk->groups == NULL)
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return 0;
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return nla_put(nlskb, NETLINK_DIAG_GROUPS, NLGRPSZ(nlk->ngroups),
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nlk->groups);
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}
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static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
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struct netlink_diag_req *req,
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u32 portid, u32 seq, u32 flags, int sk_ino)
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{
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struct nlmsghdr *nlh;
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struct netlink_diag_msg *rep;
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struct netlink_sock *nlk = nlk_sk(sk);
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nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
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flags);
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if (!nlh)
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return -EMSGSIZE;
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rep = nlmsg_data(nlh);
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rep->ndiag_family = AF_NETLINK;
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rep->ndiag_type = sk->sk_type;
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rep->ndiag_protocol = sk->sk_protocol;
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rep->ndiag_state = sk->sk_state;
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rep->ndiag_ino = sk_ino;
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rep->ndiag_portid = nlk->portid;
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rep->ndiag_dst_portid = nlk->dst_portid;
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rep->ndiag_dst_group = nlk->dst_group;
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sock_diag_save_cookie(sk, rep->ndiag_cookie);
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if ((req->ndiag_show & NDIAG_SHOW_GROUPS) &&
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sk_diag_dump_groups(sk, skb))
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goto out_nlmsg_trim;
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if ((req->ndiag_show & NDIAG_SHOW_MEMINFO) &&
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sock_diag_put_meminfo(sk, skb, NETLINK_DIAG_MEMINFO))
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goto out_nlmsg_trim;
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if ((req->ndiag_show & NDIAG_SHOW_RING_CFG) &&
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sk_diag_put_rings_cfg(sk, skb))
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goto out_nlmsg_trim;
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return nlmsg_end(skb, nlh);
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out_nlmsg_trim:
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nlmsg_cancel(skb, nlh);
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return -EMSGSIZE;
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}
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static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
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int protocol, int s_num)
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{
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struct netlink_table *tbl = &nl_table[protocol];
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struct rhashtable *ht = &tbl->hash;
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const struct bucket_table *htbl = rht_dereference(ht->tbl, ht);
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struct net *net = sock_net(skb->sk);
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struct netlink_diag_req *req;
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struct netlink_sock *nlsk;
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struct sock *sk;
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int ret = 0, num = 0, i;
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req = nlmsg_data(cb->nlh);
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for (i = 0; i < htbl->size; i++) {
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rht_for_each_entry(nlsk, htbl->buckets[i], ht, node) {
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sk = (struct sock *)nlsk;
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if (!net_eq(sock_net(sk), net))
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continue;
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if (num < s_num) {
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num++;
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continue;
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}
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if (sk_diag_fill(sk, skb, req,
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NETLINK_CB(cb->skb).portid,
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cb->nlh->nlmsg_seq,
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NLM_F_MULTI,
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sock_i_ino(sk)) < 0) {
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ret = 1;
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goto done;
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}
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num++;
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}
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}
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sk_for_each_bound(sk, &tbl->mc_list) {
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if (sk_hashed(sk))
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continue;
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if (!net_eq(sock_net(sk), net))
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continue;
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if (num < s_num) {
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num++;
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continue;
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}
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if (sk_diag_fill(sk, skb, req,
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NETLINK_CB(cb->skb).portid,
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cb->nlh->nlmsg_seq,
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NLM_F_MULTI,
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sock_i_ino(sk)) < 0) {
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ret = 1;
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goto done;
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}
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num++;
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}
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done:
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cb->args[0] = num;
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cb->args[1] = protocol;
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return ret;
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}
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static int netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
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{
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struct netlink_diag_req *req;
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int s_num = cb->args[0];
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req = nlmsg_data(cb->nlh);
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mutex_lock(&nl_sk_hash_lock);
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read_lock(&nl_table_lock);
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if (req->sdiag_protocol == NDIAG_PROTO_ALL) {
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int i;
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for (i = cb->args[1]; i < MAX_LINKS; i++) {
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if (__netlink_diag_dump(skb, cb, i, s_num))
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break;
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s_num = 0;
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}
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} else {
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if (req->sdiag_protocol >= MAX_LINKS) {
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read_unlock(&nl_table_lock);
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mutex_unlock(&nl_sk_hash_lock);
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return -ENOENT;
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}
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__netlink_diag_dump(skb, cb, req->sdiag_protocol, s_num);
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}
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read_unlock(&nl_table_lock);
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mutex_unlock(&nl_sk_hash_lock);
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return skb->len;
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}
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static int netlink_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
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{
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int hdrlen = sizeof(struct netlink_diag_req);
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struct net *net = sock_net(skb->sk);
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if (nlmsg_len(h) < hdrlen)
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return -EINVAL;
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if (h->nlmsg_flags & NLM_F_DUMP) {
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struct netlink_dump_control c = {
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.dump = netlink_diag_dump,
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};
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return netlink_dump_start(net->diag_nlsk, skb, h, &c);
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} else
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return -EOPNOTSUPP;
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}
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static const struct sock_diag_handler netlink_diag_handler = {
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.family = AF_NETLINK,
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.dump = netlink_diag_handler_dump,
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};
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static int __init netlink_diag_init(void)
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{
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return sock_diag_register(&netlink_diag_handler);
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}
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static void __exit netlink_diag_exit(void)
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{
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sock_diag_unregister(&netlink_diag_handler);
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}
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module_init(netlink_diag_init);
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module_exit(netlink_diag_exit);
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 16 /* AF_NETLINK */);
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