netlink: Always copy on mmap TX. (4682a035) · Commits · 戴 / test

net/netlink/af_netlink.c

+16 −36

Original line number	Original line	Diff line number	Diff line
	@@ -525,14 +525,14 @@ out:
	return err;		return err;
	}		}

	static void netlink_frame_flush_dcache(const struct nl_mmap_hdr *hdr)		static void netlink_frame_flush_dcache(const struct nl_mmap_hdr *hdr, unsigned int nm_len)
	{		{
	#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 1		#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 1
	struct page p_start, p_end;		struct page p_start, p_end;

	/* First page is flushed through netlink_{get,set}_status */		/* First page is flushed through netlink_{get,set}_status */
	p_start = pgvec_to_page(hdr + PAGE_SIZE);		p_start = pgvec_to_page(hdr + PAGE_SIZE);
	p_end = pgvec_to_page((void *)hdr + NL_MMAP_HDRLEN + hdr->nm_len - 1);		p_end = pgvec_to_page((void *)hdr + NL_MMAP_HDRLEN + nm_len - 1);
	while (p_start <= p_end) {		while (p_start <= p_end) {
	flush_dcache_page(p_start);		flush_dcache_page(p_start);
	p_start++;		p_start++;
	@@ -714,24 +714,16 @@ static int netlink_mmap_sendmsg(struct sock sk, struct msghdr msg,
	struct nl_mmap_hdr *hdr;		struct nl_mmap_hdr *hdr;
	struct sk_buff *skb;		struct sk_buff *skb;
	unsigned int maxlen;		unsigned int maxlen;
	bool excl = true;
	int err = 0, len = 0;		int err = 0, len = 0;

	/* Netlink messages are validated by the receiver before processing.
	* In order to avoid userspace changing the contents of the message
	* after validation, the socket and the ring may only be used by a
	* single process, otherwise we fall back to copying.
	*/
	if (atomic_long_read(&sk->sk_socket->file->f_count) > 1 \|\|
	atomic_read(&nlk->mapped) > 1)
	excl = false;

	mutex_lock(&nlk->pg_vec_lock);		mutex_lock(&nlk->pg_vec_lock);

	ring = &nlk->tx_ring;		ring = &nlk->tx_ring;
	maxlen = ring->frame_size - NL_MMAP_HDRLEN;		maxlen = ring->frame_size - NL_MMAP_HDRLEN;

	do {		do {
			unsigned int nm_len;

	hdr = netlink_current_frame(ring, NL_MMAP_STATUS_VALID);		hdr = netlink_current_frame(ring, NL_MMAP_STATUS_VALID);
	if (hdr == NULL) {		if (hdr == NULL) {
	if (!(msg->msg_flags & MSG_DONTWAIT) &&		if (!(msg->msg_flags & MSG_DONTWAIT) &&
	@@ -739,35 +731,23 @@ static int netlink_mmap_sendmsg(struct sock sk, struct msghdr msg,
	schedule();		schedule();
	continue;		continue;
	}		}
	if (hdr->nm_len > maxlen) {
			nm_len = ACCESS_ONCE(hdr->nm_len);
			if (nm_len > maxlen) {
	err = -EINVAL;		err = -EINVAL;
	goto out;		goto out;
	}		}

	netlink_frame_flush_dcache(hdr);		netlink_frame_flush_dcache(hdr, nm_len);

	if (likely(dst_portid == 0 && dst_group == 0 && excl)) {		skb = alloc_skb(nm_len, GFP_KERNEL);
	skb = alloc_skb_head(GFP_KERNEL);
	if (skb == NULL) {
	err = -ENOBUFS;
	goto out;
	}
	sock_hold(sk);
	netlink_ring_setup_skb(skb, sk, ring, hdr);
	NETLINK_CB(skb).flags \|= NETLINK_SKB_TX;
	__skb_put(skb, hdr->nm_len);
	netlink_set_status(hdr, NL_MMAP_STATUS_RESERVED);
	atomic_inc(&ring->pending);
	} else {
	skb = alloc_skb(hdr->nm_len, GFP_KERNEL);
	if (skb == NULL) {		if (skb == NULL) {
	err = -ENOBUFS;		err = -ENOBUFS;
	goto out;		goto out;
	}		}
	__skb_put(skb, hdr->nm_len);		__skb_put(skb, nm_len);
	memcpy(skb->data, (void *)hdr + NL_MMAP_HDRLEN, hdr->nm_len);		memcpy(skb->data, (void *)hdr + NL_MMAP_HDRLEN, nm_len);
	netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);		netlink_set_status(hdr, NL_MMAP_STATUS_UNUSED);
	}

	netlink_increment_head(ring);		netlink_increment_head(ring);

	@@ -813,7 +793,7 @@ static void netlink_queue_mmaped_skb(struct sock sk, struct sk_buff skb)
	hdr->nm_pid = NETLINK_CB(skb).creds.pid;		hdr->nm_pid = NETLINK_CB(skb).creds.pid;
	hdr->nm_uid = from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);		hdr->nm_uid = from_kuid(sk_user_ns(sk), NETLINK_CB(skb).creds.uid);
	hdr->nm_gid = from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);		hdr->nm_gid = from_kgid(sk_user_ns(sk), NETLINK_CB(skb).creds.gid);
	netlink_frame_flush_dcache(hdr);		netlink_frame_flush_dcache(hdr, hdr->nm_len);
	netlink_set_status(hdr, NL_MMAP_STATUS_VALID);		netlink_set_status(hdr, NL_MMAP_STATUS_VALID);

	NETLINK_CB(skb).flags \|= NETLINK_SKB_DELIVERED;		NETLINK_CB(skb).flags \|= NETLINK_SKB_DELIVERED;

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