From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=220.197.31.4 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793179983; b=LLmEc77kY756VKooQOR1SY9MuYWQRDHURTxeltLDcSvwx/lCIq+lDsmNfDbYoozdWwfn HQyE21EnZrPZm4YwqYVX/7Nm9E19Z9vcaW88P/jvPMxfl7QUXDLc52xYyM32AeJRWwNok I5ZxR795SEj0p4Vi7d7gK1Q6/IowH7RICttCvsDnmL+CnJtNOlbQ7OkJ3uC55DWhVbH1o cSEgxw9GIsHfOKVHid2Jjy4cU13NMtMynkYEe+Dag3tlfcZZG7R3WxtK3kzbrF+ajeiHk mCPrnfYAAAGvg+dLm2PqNzIbtgV2QqBmHyBNv5v+CL1gq9Dx72Al5897EhtG7Hfy8Mg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793179983; h=DMARC-Filter:DKIM-Signature:Received:From:To:Cc:Subject:Date: Message-Id:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding:X-CM-TRANSID:X-Coremail-Antispam: X-CM-SenderInfo; bh=n1LfOovnyA+uYBnXvqyeflhbol4DwWZKYc0TgqSc7X0=; b=b89uFgq4OYVVWcVQjUpOCekXzK7XtOQjDjWfryRGjaWpZo45yINRnLf8ywZAeMf/w8m1 yRP/CNGYaHqAlVg1xCFL+dzsE/4BTe9CAsikfOy6oPSHK3OZ9YaDmu+eZKwhfZug86D5f pXMqRedv2u+9vfDnIQ4x+kpBcSDdTYydEBubl3U3AK63WkBbzt9htDO5Tu1LR+yoM+YtP hFvnZh0/pPS4xKOUkx+k0+j+5DBSYiBV+5X9l4wPxiepUH5ENkjyN1EbPgXP4aSNQlyfr aShiDRCsY2pbxl6sbaPJBxwa1XaUSe3f43STRtRRSTwtDRT0EIw0aXwm9G3w2g6yDzA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass header.d=163.com header.i=@163.com header.a=rsa-sha256 header.s=s110527 header.b=T6U8imWX; arc=none smtp.remote-ip=220.197.31.4 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2A982606A323 for ; Wed, 28 Oct 2026 09:33:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 2A982606A323 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, unprotected) header.d=163.com header.i=@163.com header.a=rsa-sha256 header.s=s110527 header.b=T6U8imWX 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=n1 LfOovnyA+uYBnXvqyeflhbol4DwWZKYc0TgqSc7X0=; b=T6U8imWXHgCW/3HMBp 896WNC9y+ZETYIubGD89Yabk6qGqp9uMFZRHOvEZrVR0spUgoqLWlb5whhNIgaLG v8CWdA7YDhAlXsJ9IUTC7Td3IQBVsK1FfESMOjhSZ7JnB3sbcmqJICZjid30Z1Cc ZwhEk5Y7UIyjMACe+1hi134KM= Received: from localhost.localdomain (unknown []) by gzsmtp2 (Coremail) with SMTP id PSgvCgBn5es1weFqGkWrCQ--.12186S4; Wed, 28 Oct 2026 17:32:40 +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 net v8 2/2] selftests: net: add TAP socket filter attach tests Date: Wed, 28 Oct 2026 17:32:35 +0800 Message-Id: <20261028093235.148649-3-clementwei90@163.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261028093235.148649-1-clementwei90@163.com> References: <20261028093235.148649-1-clementwei90@163.com> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:PSgvCgBn5es1weFqGkWrCQ--.12186S4 X-Coremail-Antispam: 1Uf129KBjvJXoW3JF45GF43AryxXF13ZFW8WFg_yoWfZr4fpa s5WayDGF1UXrW7Xws7ArW8uFWfAw4DGr15ZFs5K3s8Zrs8Gry5ua9akFWSkan2yr48uws0 kFyaya43WwsIqFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jq6wAUUUUU= X-CM-SenderInfo: 5fohzv5qwzvxizq6il2tof0z/xtbC4hiR-GrhwTjSoQAA3W From: Rongguang Wei reattach_filter_without_user_buffer() attaches a filter, makes the buffer the program was copied from unreadable, detaches the queue and attaches it again. It then attaches a second queue from a fresh socket, which starts without a filter of its own, so a clear IFF_NOFILTER shows that the filter was installed again from the kernel copy. attach_filter_bad_len_keeps_program() checks that a TUNATTACHFILTER with a bad length leaves the installed program and the filter state that TUNGETIFF reports alone, and that a queue attached afterwards still gets the filter. attach_filter_bad_prog_keeps_program() refuses a program with a valid length and instructions that bpf_check_classic() rejects, and checks the same properties: the filter state on the queue, and a queue attached afterwards still gets the saved program. 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 | 249 ++++++++++++++++++++++++++++++ 1 file changed, 249 insertions(+) diff --git a/tools/testing/selftests/net/tun.c b/tools/testing/selftests/net/tun.c index afaa81c9bac53..f27df2734dad1 100644 --- a/tools/testing/selftests/net/tun.c +++ b/tools/testing/selftests/net/tun.c @@ -8,9 +8,11 @@ #include #include #include +#include #include #include #include +#include #include #include "kselftest_harness.h" @@ -543,6 +545,253 @@ TEST_F(tun, reattach_close_delete) EXPECT_EQ(tun_delete(self->ifname), 0); } +/* accept: return skb->len. Three instructions on purpose, so that the + * length read back through TUNGETFILTER tells it apart from a rejected + * program that is shorter. + */ +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), +}; + +/* 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 tun_get_iff_flags(int fd) +{ + struct ifreq ifr = { 0 }; + + if (ioctl(fd, TUNGETIFF, (void *)&ifr) < 0) + return -1; + + return ifr.ifr_flags; +} + +/* + * 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, and a + * second queue is then attached from a fresh socket, which starts without a + * filter of its own. + */ +TEST_F(tun, reattach_filter_without_user_buffer) +{ + struct sock_fprog gf = { 0 }; + struct ifreq ifr = { 0 }; + short flags = 0; + void *prog; + int fd, 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); + + /* This memory is no longer readable */ + 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); + /* The queue is attached again, not left disabled */ + EXPECT_EQ(flags & IFF_DETACH_QUEUE, 0); + EXPECT_EQ(flags & IFF_NOFILTER, 0); + + /* The two checks below document the expected state, they cannot + * tell a reinstalled filter from no filter: tun_detach() leaves + * sk_filter alone, and TUNGETFILTER only returns the header. + */ + EXPECT_EQ(filter_get(self->fd, &gf), 0); + EXPECT_EQ(gf.len, ARRAY_SIZE(filter_accept)); + + /* A new queue starts without a filter, so a clear IFF_NOFILTER shows + * that the filter was installed again from the kernel copy. + */ + 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; + EXPECT_GE(ioctl(fd, TUNSETIFF, (void *)&ifr), 0); + + flags = tun_get_iff_flags(fd); + EXPECT_GE(flags, 0); + EXPECT_EQ(flags & IFF_NOFILTER, 0); + + close(fd); + + 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_accept, ARRAY_SIZE(filter_accept)), 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); + + flags = tun_get_iff_flags(fd); + EXPECT_GE(flags, 0); + EXPECT_EQ(flags & IFF_NOFILTER, IFF_NOFILTER); + + 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_accept, ARRAY_SIZE(filter_accept)), 0); + EXPECT_EQ(ioctl(self->fd, TUNDETACHFILTER, 0), 0); + + flags = tun_get_iff_flags(self->fd); + EXPECT_GE(flags, 0); + EXPECT_EQ(flags & IFF_NOFILTER, IFF_NOFILTER); + + EXPECT_EQ(tun_detach(self->fd, self->ifname), 0); + EXPECT_EQ(tun_attach(self->fd, self->ifname), 0); + + flags = tun_get_iff_flags(self->fd); + EXPECT_GE(flags, 0); + EXPECT_EQ(flags & IFF_NOFILTER, IFF_NOFILTER); +} + +/* A TUNATTACHFILTER with a bad length must leave the installed program and the + * filter state that TUNGETIFF reports alone. + */ +TEST_F(tun, attach_filter_bad_len_keeps_program) +{ + struct sock_fprog gf = { 0 }; + struct ifreq ifr = { 0 }; + short flags = 0; + int fd; + + 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)); + + flags = tun_get_iff_flags(self->fd); + EXPECT_GE(flags, 0); + EXPECT_EQ(flags & IFF_NOFILTER, 0); + + /* A queue attached afterwards still gets the filter, so the rejected + * ioctl left the saved program and filter_attached alone. + */ + 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; + EXPECT_GE(ioctl(fd, TUNSETIFF, (void *)&ifr), 0); + + flags = tun_get_iff_flags(fd); + EXPECT_GE(flags, 0); + EXPECT_EQ(flags & IFF_NOFILTER, 0); + + close(fd); +} + +/* A TUNATTACHFILTER with instructions that bpf_check_classic() rejects must + * be refused, and must leave the program installed already in place. + */ +TEST_F(tun, attach_filter_bad_prog_keeps_program) +{ + struct sock_fprog gf = { 0 }; + struct sock_filter bad[] = { + BPF_STMT(BPF_LD | BPF_W | BPF_LEN, 0), + BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0, 1, 0), + }; + struct ifreq ifr = { 0 }; + short flags = 0; + int fd; + + ASSERT_EQ(filter_attach(self->fd, filter_accept, + ARRAY_SIZE(filter_accept)), 0); + + errno = 0; + EXPECT_EQ(filter_attach(self->fd, bad, ARRAY_SIZE(bad)), -1); + EXPECT_EQ(errno, EINVAL); + + /* the program attached before is untouched */ + EXPECT_EQ(filter_get(self->fd, &gf), 0); + EXPECT_EQ(gf.len, ARRAY_SIZE(filter_accept)); + + /* IFF_NOFILTER comes from the socket's sk_filter, not from the saved + * header, so a clear flag shows the filter is still installed. + */ + flags = tun_get_iff_flags(self->fd); + EXPECT_GE(flags, 0); + EXPECT_EQ(flags & IFF_NOFILTER, 0); + + /* A queue attached afterwards still gets the filter, so the rejected + * program never replaced the saved one. + */ + 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; + EXPECT_GE(ioctl(fd, TUNSETIFF, (void *)&ifr), 0); + + flags = tun_get_iff_flags(fd); + EXPECT_GE(flags, 0); + EXPECT_EQ(flags & IFF_NOFILTER, 0); + + close(fd); +} + FIXTURE(tun_vnet_gso) { char ifname[IFNAMSIZ]; -- 2.43.0 No virus found Checked by Hillstone Network AntiVirus