diag.c

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#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/sock_diag.h>
#include <linux/unix_diag.h>
#include <linux/skbuff.h>
#include <linux/module.h>
#include <net/netlink.h>
#include <net/af_unix.h>
#include <net/tcp_states.h>

static int sk_diag_dump_name(struct sock *sk, struct sk_buff *nlskb)
{
    struct unix_address *addr = unix_sk(sk)->addr;

    if (!addr)
        return 0;

    return nla_put(nlskb, UNIX_DIAG_NAME, addr->len - sizeof(short),
               addr->name->sun_path);
}

static int sk_diag_dump_vfs(struct sock *sk, struct sk_buff *nlskb)
{
    struct dentry *dentry = unix_sk(sk)->path.dentry;

    if (dentry) {
        struct unix_diag_vfs uv = {
            .udiag_vfs_ino = dentry->d_inode->i_ino,
            .udiag_vfs_dev = dentry->d_sb->s_dev,
        };

        return nla_put(nlskb, UNIX_DIAG_VFS, sizeof(uv), &uv);
    }

    return 0;
}

static int sk_diag_dump_peer(struct sock *sk, struct sk_buff *nlskb)
{
    struct sock *peer;
    int ino;

    peer = unix_peer_get(sk);
    if (peer) {
        unix_state_lock(peer);
        ino = sock_i_ino(peer);
        unix_state_unlock(peer);
        sock_put(peer);

        return nla_put_u32(nlskb, UNIX_DIAG_PEER, ino);
    }

    return 0;
}

static int sk_diag_dump_icons(struct sock *sk, struct sk_buff *nlskb)
{
    struct sk_buff *skb;
    struct nlattr *attr;
    u32 *buf;
    int i;

    if (sk->sk_state == TCP_LISTEN) {
        spin_lock(&sk->sk_receive_queue.lock);

        attr = nla_reserve(nlskb, UNIX_DIAG_ICONS,
                   sk->sk_receive_queue.qlen * sizeof(u32));
        if (!attr)
            goto errout;

        buf = nla_data(attr);
        i = 0;
        skb_queue_walk(&sk->sk_receive_queue, skb) {
            struct sock *req, *peer;

            req = skb->sk;
            /*
             * The state lock is outer for the same sk's
             * queue lock. With the other's queue locked it's
             * OK to lock the state.
             */
            unix_state_lock_nested(req);
            peer = unix_sk(req)->peer;
            buf[i++] = (peer ? sock_i_ino(peer) : 0);
            unix_state_unlock(req);
        }
        spin_unlock(&sk->sk_receive_queue.lock);
    }

    return 0;

errout:
    spin_unlock(&sk->sk_receive_queue.lock);
    return -EMSGSIZE;
}

static int sk_diag_show_rqlen(struct sock *sk, struct sk_buff *nlskb)
{
    struct unix_diag_rqlen rql;

    if (sk->sk_state == TCP_LISTEN) {
        rql.udiag_rqueue = sk->sk_receive_queue.qlen;
        rql.udiag_wqueue = sk->sk_max_ack_backlog;
    } else {
        rql.udiag_rqueue = (u32) unix_inq_len(sk);
        rql.udiag_wqueue = (u32) unix_outq_len(sk);
    }

    return nla_put(nlskb, UNIX_DIAG_RQLEN, sizeof(rql), &rql);
}

static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_req *req,
        u32 portid, u32 seq, u32 flags, int sk_ino)
{
    struct nlmsghdr *nlh;
    struct unix_diag_msg *rep;

    nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
            flags);
    if (!nlh)
        return -EMSGSIZE;

    rep = nlmsg_data(nlh);
    rep->udiag_family = AF_UNIX;
    rep->udiag_type = sk->sk_type;
    rep->udiag_state = sk->sk_state;
    rep->udiag_ino = sk_ino;
    sock_diag_save_cookie(sk, rep->udiag_cookie);

    if ((req->udiag_show & UDIAG_SHOW_NAME) &&
        sk_diag_dump_name(sk, skb))
        goto out_nlmsg_trim;

    if ((req->udiag_show & UDIAG_SHOW_VFS) &&
        sk_diag_dump_vfs(sk, skb))
        goto out_nlmsg_trim;

    if ((req->udiag_show & UDIAG_SHOW_PEER) &&
        sk_diag_dump_peer(sk, skb))
        goto out_nlmsg_trim;

    if ((req->udiag_show & UDIAG_SHOW_ICONS) &&
        sk_diag_dump_icons(sk, skb))
        goto out_nlmsg_trim;

    if ((req->udiag_show & UDIAG_SHOW_RQLEN) &&
        sk_diag_show_rqlen(sk, skb))
        goto out_nlmsg_trim;

    if ((req->udiag_show & UDIAG_SHOW_MEMINFO) &&
        sock_diag_put_meminfo(sk, skb, UNIX_DIAG_MEMINFO))
        goto out_nlmsg_trim;

    return nlmsg_end(skb, nlh);

out_nlmsg_trim:
    nlmsg_cancel(skb, nlh);
    return -EMSGSIZE;
}

static int sk_diag_dump(struct sock *sk, struct sk_buff *skb, struct unix_diag_req *req,
        u32 portid, u32 seq, u32 flags)
{
    int sk_ino;

    unix_state_lock(sk);
    sk_ino = sock_i_ino(sk);
    unix_state_unlock(sk);

    if (!sk_ino)
        return 0;

    return sk_diag_fill(sk, skb, req, portid, seq, flags, sk_ino);
}

static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
    struct unix_diag_req *req;
    int num, s_num, slot, s_slot;
    struct net *net = sock_net(skb->sk);

    req = nlmsg_data(cb->nlh);

    s_slot = cb->args[0];
    num = s_num = cb->args[1];

    spin_lock(&unix_table_lock);
    for (slot = s_slot;
         slot < ARRAY_SIZE(unix_socket_table);
         s_num = 0, slot++) {
        struct sock *sk;
        struct hlist_node *node;

        num = 0;
        sk_for_each(sk, node, &unix_socket_table[slot]) {
            if (!net_eq(sock_net(sk), net))
                continue;
            if (num < s_num)
                goto next;
            if (!(req->udiag_states & (1 << sk->sk_state)))
                goto next;
            if (sk_diag_dump(sk, skb, req,
                     NETLINK_CB(cb->skb).portid,
                     cb->nlh->nlmsg_seq,
                     NLM_F_MULTI) < 0)
                goto done;
next:
            num++;
        }
    }
done:
    spin_unlock(&unix_table_lock);
    cb->args[0] = slot;
    cb->args[1] = num;

    return skb->len;
}

static struct sock *unix_lookup_by_ino(int ino)
{
    int i;
    struct sock *sk;

    spin_lock(&unix_table_lock);
    for (i = 0; i < ARRAY_SIZE(unix_socket_table); i++) {
        struct hlist_node *node;

        sk_for_each(sk, node, &unix_socket_table[i])
            if (ino == sock_i_ino(sk)) {
                sock_hold(sk);
                spin_unlock(&unix_table_lock);

                return sk;
            }
    }

    spin_unlock(&unix_table_lock);
    return NULL;
}

static int unix_diag_get_exact(struct sk_buff *in_skb,
                   const struct nlmsghdr *nlh,
                   struct unix_diag_req *req)
{
    int err = -EINVAL;
    struct sock *sk;
    struct sk_buff *rep;
    unsigned int extra_len;
    struct net *net = sock_net(in_skb->sk);

    if (req->udiag_ino == 0)
        goto out_nosk;

    sk = unix_lookup_by_ino(req->udiag_ino);
    err = -ENOENT;
    if (sk == NULL)
        goto out_nosk;

    err = sock_diag_check_cookie(sk, req->udiag_cookie);
    if (err)
        goto out;

    extra_len = 256;
again:
    err = -ENOMEM;
    rep = nlmsg_new(sizeof(struct unix_diag_msg) + extra_len, GFP_KERNEL);
    if (!rep)
        goto out;

    err = sk_diag_fill(sk, rep, req, NETLINK_CB(in_skb).portid,
               nlh->nlmsg_seq, 0, req->udiag_ino);
    if (err < 0) {
        nlmsg_free(rep);
        extra_len += 256;
        if (extra_len >= PAGE_SIZE)
            goto out;

        goto again;
    }
    err = netlink_unicast(net->diag_nlsk, rep, NETLINK_CB(in_skb).portid,
                  MSG_DONTWAIT);
    if (err > 0)
        err = 0;
out:
    if (sk)
        sock_put(sk);
out_nosk:
    return err;
}

static int unix_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
{
    int hdrlen = sizeof(struct unix_diag_req);
    struct net *net = sock_net(skb->sk);

    if (nlmsg_len(h) < hdrlen)
        return -EINVAL;

    if (h->nlmsg_flags & NLM_F_DUMP) {
        struct netlink_dump_control c = {
            .dump = unix_diag_dump,
        };
        return netlink_dump_start(net->diag_nlsk, skb, h, &c);
    } else
        return unix_diag_get_exact(skb, h, nlmsg_data(h));
}

static const struct sock_diag_handler unix_diag_handler = {
    .family = AF_UNIX,
    .dump = unix_diag_handler_dump,
};

static int __init unix_diag_init(void)
{
    return sock_diag_register(&unix_diag_handler);
}

static void __exit unix_diag_exit(void)
{
    sock_diag_unregister(&unix_diag_handler);
}

module_init(unix_diag_init);
module_exit(unix_diag_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 1 /* AF_LOCAL */);