Re: [PATCH net v3 3/3] selftests: net: add TAP socket filter attach tests

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Rongguang Wei wrote:
> From: Rongguang Wei <weirongguang@kylinos.cn>
> 
> reattach_filter_without_user_buffer() attaches a filter, makes the buffer
> the program was copied from unreadable and then attaches the queue again,
> which used to fail with -EFAULT.
> 
> attach_filter_bad_len_keeps_program() checks that a rejected
> TUNATTACHFILTER leaves both the saved program and the installed filter
> alone.
> 
> attach_filter_nofilter_flag() and detach_filter_clears_reattach() cover the
> ways to attach a queue without a filter.
> 
> Signed-off-by: Rongguang Wei <weirongguang@kylinos.cn>

Reviewed-by: Willem de Bruijn <willemb@google.com>


> +TEST_F(tun, reattach_filter_without_user_buffer)
> +{
> +	struct sock_fprog gf = { 0 };
> +	short flags = 0;
> +	void *prog;
> +	int ret;
> +
> +	prog = filter_alloc(filter_accept, ARRAY_SIZE(filter_accept));
> +	ASSERT_NE(prog, NULL);
> +	ASSERT_EQ(filter_attach(self->fd, prog, ARRAY_SIZE(filter_accept)), 0);
> +
> +	EXPECT_EQ(tun_detach(self->fd, self->ifname), 0);
> +
> +	/* The process that called TUNATTACHFILTER no longer maps this memory */
> +	ASSERT_EQ(mprotect(prog, getpagesize(), PROT_NONE), 0);
> +
> +	ret = tun_attach(self->fd, self->ifname);
> +	EXPECT_EQ(ret, 0);
> +
> +	flags = tun_get_iff_flags(self->fd);
> +	EXPECT_GE(flags, 0);
> +	EXPECT_EQ(flags & IFF_NOFILTER, 0);

iff a respin is needed, consider adding the extra test to make sure that
tun_attach did not just succeed without attaching the program, as it does
before patch 2.

EXPECT_EQ(flags & IFF_DETACH_QUEUE, 0);

> +
> +	EXPECT_EQ(filter_get(self->fd, &gf), 0);
> +	EXPECT_EQ(gf.len, ARRAY_SIZE(filter_accept));
> +
> +	ASSERT_EQ(mprotect(prog, getpagesize(), PROT_READ | PROT_WRITE), 0);
> +	ASSERT_EQ(munmap(prog, getpagesize()), 0);
> +}