Commit 710d10e1 authored Oct 10, 2015 by Subash Abhinov Kasiviswanathan

net: tun: Implement TUN_NOCHECKSUM



Revert the changes to TUN_NOCHECKSUM from commit 88255375
("net: tun: convert to hw_features"). This is needed to handle
scenarios where GRO coalesced packets are passed on to userspace
with an invalid checksum to programs capturing packets using
packet sockets.

If the checksum was validated before GRO coalesced the packets,
it is unnecessary to validate the checksum again. Userspace
should be allowed to set TUN_NOCHECKSUM on the underlying tun
interface.

Change-Id: I96071e8a07a01efc71612d5a6979d493339e2735
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>

parent 279ce12c

drivers/net/tun.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -1112,7 +1112,8 @@ static ssize_t tun_get_user(struct tun_struct tun, struct tun_file tfile,
		kfree_skb(skb);
		return -EINVAL;
		}
		}
		} else if (tun->flags & TUN_NOCHECKSUM)
		skb->ip_summed = CHECKSUM_UNNECESSARY;

		switch (tun->flags & TUN_TYPE_MASK) {
		case TUN_TUN_DEV:
		@@ -1956,9 +1957,10 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
		case TUNSETNOCSUM:
		/* Disable/Enable checksum */

		/* [unimplemented] */
		tun_debug(KERN_INFO, tun, "ignored: set checksum %s\n",
		arg ? "disabled" : "enabled");
		if (arg)
		tun->flags \|= TUN_NOCHECKSUM;
		else
		tun->flags &= ~TUN_NOCHECKSUM;
		break;

		case TUNSETPERSIST: