From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4F1B74E36FE for ; Tue, 29 Sep 2026 09:37:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.3 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790674667; cv=none; b=kZ+bellyOAd5z+i9SSG78YwPW2Kz5KTtOay7HIPmP4lSfjTEjngnri4I0EjMzAf/Eg/X85Sts2JgV/2gcSu02CEcmNM0omcMcMoS3HEvuE8rZ2Qg3YieXd9iySJ0xo4xjPqq5D2GpIIqjFGiHf+eGvJIRLFGBhZ9AxM3LfdRkWo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790674667; c=relaxed/simple; bh=y3DelGi6YCys+qthA0tcQ2u9nH0QxpVueFqbzgzc0+Q=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=mButreNrv/u6TwifwArhOuEZSbuADMvvniolM0MPtBrF+S8thf0T8GiLzfXnUaw81HiCJDSR23VRUQ7uPIs2l+c/wQI7YB/zPCrowCkhtzA62ln9dGiLwqK3BbUtMvqVLrAAVSHCP3lMTYsJOP14CYNHJcI0kqowARTDCHcDp3g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=S6qk9Sod; arc=none smtp.client-ip=117.135.210.3 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="S6qk9Sod" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=R0 r274GkxXLH1d2OcAvIB/rjlTMukuKN+QALwtCORFc=; b=S6qk9SodixlEpsw4vG FcSzW1r1y2SYn0g37RiOhWu6I+r6+AXAF3dIyvvOHsu/FsNvenFrBaviO6LuD7cm Any6Ufs+Sx8UmXq4+CWHXmItfQF54FPDFlF64+aZ8ns+S21S/dtB5gbx1yIu/X/i 2EeOJlfcjT/s2B1DZQ1XK3Vps= Received: from localhost.localdomain (unknown []) by gzga-smtp-mtada-g1-0 (Coremail) with SMTP id _____wCnt5nKhrtqVp7nBQ--.16613S6; Tue, 29 Sep 2026 17:37:25 +0800 (CST) From: Rongguang Wei To: netdev@vger.kernel.org Cc: willemdebruijn.kernel@gmail.com, jasowangio@gmail.com, andrew+netdev@lunn.ch, davem@davemloft.net, kuba@kernel.org, Rongguang Wei Subject: [PATCH v2 4/4] selftests: net: add TAP socket filter attach tests Date: Tue, 29 Sep 2026 17:37:12 +0800 Message-Id: <20260929093712.131096-5-clementwei90@163.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260929093712.131096-1-clementwei90@163.com> References: <20260929093712.131096-1-clementwei90@163.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wCnt5nKhrtqVp7nBQ--.16613S6 X-Coremail-Antispam: 1Uf129KBjvJXoW3JF45XF47Gr1rKw1fur4kZwb_yoW7KFWDpF WkWayDGr15WF47W3Z7ArW8ZFWfXw4kGF15Ars5K3s8ZFs8Jr95uanakFyFy3W0qr48ZwnY kFya9a45Cws8XFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07j2KZJUUUUU= X-CM-SenderInfo: 5fohzv5qwzvxizq6il2tof0z/xtbC4hVgy2q7htXG7wAA33 From: Rongguang Wei 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_descriptor() checks that a rejected TUNATTACHFILTER leaves both the saved descriptor 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 --- tools/testing/selftests/net/tun.c | 159 ++++++++++++++++++++++++++++++ 1 file changed, 159 insertions(+) diff --git a/tools/testing/selftests/net/tun.c b/tools/testing/selftests/net/tun.c index abe488bac50b..bf8d4d6f21f7 100644 --- a/tools/testing/selftests/net/tun.c +++ b/tools/testing/selftests/net/tun.c @@ -8,13 +8,19 @@ #include #include #include +#include #include #include +#include #include #include "kselftest_harness.h" #include "tuntap_helpers.h" +#ifndef ARRAY_SIZE +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) +#endif + static const char param_dev_geneve_name[] = "geneve1"; static unsigned char param_hwaddr_outer_dst[] = { 0x00, 0xfe, 0x98, 0x14, 0x22, 0x42 }; @@ -542,6 +548,159 @@ TEST_F(tun, reattach_close_delete) EXPECT_EQ(tun_delete(self->ifname), 0); } +/* accept: return skb->len */ +static const struct sock_filter filter_accept[] = { + BPF_STMT(BPF_LD | BPF_W | BPF_LEN, 0), + BPF_STMT(BPF_ALU | BPF_ADD | BPF_K, 0), + BPF_STMT(BPF_RET | BPF_A, 0), +}; + +/* drop: return 0 */ +static const struct sock_filter filter_drop[] = { + BPF_STMT(BPF_RET | BPF_K, 0), +}; + +/* Put the instructions in an anonymous mapping, so that the test can make the + * address unreadable afterwards. + */ +static void *filter_alloc(const struct sock_filter *insns, unsigned int len) +{ + void *p; + + p = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (p == MAP_FAILED) + return NULL; + + memcpy(p, insns, len * sizeof(*insns)); + + return p; +} + +static int filter_attach(int fd, const struct sock_filter *insns, unsigned int len) +{ + struct sock_fprog fp = { + .len = len, + .filter = (struct sock_filter *)insns, + }; + + return ioctl(fd, TUNATTACHFILTER, (void *)&fp); +} + +static int filter_get(int fd, struct sock_fprog *fp) +{ + return ioctl(fd, TUNGETFILTER, (void *)fp); +} + +static int tap_get_iff(int fd, short *flags) +{ + struct ifreq ifr = { 0 }; + + if (ioctl(fd, TUNGETIFF, (void *)&ifr) < 0) + return -1; + + *flags = ifr.ifr_flags; + + return 0; +} + +/* + * A queue can be attached long after the filter was configured, from a process + * that does not necessarily map the buffer the program was copied from, so + * the kernel has to keep its own copy of the program. Here the mapping is + * made unreadable before the queue is attached again: re-reading the user + * address used to fail with -EFAULT. + */ +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); + + EXPECT_EQ(tap_get_iff(self->fd, &flags), 0); + EXPECT_EQ(flags & IFF_NOFILTER, 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); +} + +/* A new queue attached with IFF_NOFILTER must not get the filter that is + * configured on the device. + */ +TEST_F(tun, attach_filter_nofilter_flag) +{ + struct ifreq ifr = { 0 }; + short flags = 0; + int fd; + + ASSERT_EQ(filter_attach(self->fd, filter_drop, ARRAY_SIZE(filter_drop)), 0); + + fd = open("/dev/net/tun", O_RDWR); + ASSERT_GE(fd, 0); + + strcpy(ifr.ifr_name, self->ifname); + ifr.ifr_flags = IFF_TAP | IFF_MULTI_QUEUE | IFF_NOFILTER; + EXPECT_GE(ioctl(fd, TUNSETIFF, (void *)&ifr), 0); + + EXPECT_EQ(tap_get_iff(fd, &flags), 0); + EXPECT_NE(flags & IFF_NOFILTER, 0); + + close(fd); +} + +/* After TUNDETACHFILTER a later attach must not install the filter again */ +TEST_F(tun, detach_filter_clears_reattach) +{ + short flags = 0; + + ASSERT_EQ(filter_attach(self->fd, filter_drop, ARRAY_SIZE(filter_drop)), 0); + EXPECT_EQ(ioctl(self->fd, TUNDETACHFILTER, 0), 0); + + EXPECT_EQ(tap_get_iff(self->fd, &flags), 0); + EXPECT_NE(flags & IFF_NOFILTER, 0); + + EXPECT_EQ(tun_detach(self->fd, self->ifname), 0); + EXPECT_EQ(tun_attach(self->fd, self->ifname), 0); + + EXPECT_EQ(tap_get_iff(self->fd, &flags), 0); + EXPECT_NE(flags & IFF_NOFILTER, 0); +} + +/* A TUNATTACHFILTER with a bad length must not clobber the saved descriptor */ +TEST_F(tun, attach_filter_bad_len_keeps_descriptor) +{ + struct sock_fprog gf = { 0 }; + short flags = 0; + + ASSERT_EQ(filter_attach(self->fd, filter_accept, ARRAY_SIZE(filter_accept)), 0); + + errno = 0; + EXPECT_EQ(filter_attach(self->fd, filter_accept, 0), -1); + EXPECT_EQ(errno, EINVAL); + + EXPECT_EQ(filter_get(self->fd, &gf), 0); + EXPECT_EQ(gf.len, ARRAY_SIZE(filter_accept)); + + EXPECT_EQ(tap_get_iff(self->fd, &flags), 0); + EXPECT_EQ(flags & IFF_NOFILTER, 0); +} + FIXTURE(tun_vnet_udptnl) { char ifname[IFNAMSIZ]; -- 2.25.1 No virus found Checked by Hillstone Network AntiVirus