@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0-only
bind_bhash
cmsg_sender
+diag_uid
fin_ack_lat
gro
hwtstamp_config
@@ -1,3 +1,3 @@
-TEST_GEN_PROGS := test_unix_oob unix_connect
+TEST_GEN_PROGS := diag_uid test_unix_oob unix_connect
include ../../lib.mk
new file mode 100644
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright Amazon.com Inc. or its affiliates. */
+
+#define _GNU_SOURCE
+#include <sched.h>
+
+#include <unistd.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <linux/sock_diag.h>
+#include <linux/unix_diag.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/un.h>
+
+#include "../../kselftest_harness.h"
+
+FIXTURE(diag_uid)
+{
+ int netlink_fd;
+ int unix_fd;
+ __u32 inode;
+ __u64 cookie;
+};
+
+FIXTURE_VARIANT(diag_uid)
+{
+ int unshare;
+ int udiag_show;
+};
+
+FIXTURE_VARIANT_ADD(diag_uid, uid)
+{
+ .unshare = 0,
+ .udiag_show = UDIAG_SHOW_UID
+};
+
+FIXTURE_VARIANT_ADD(diag_uid, uid_unshare)
+{
+ .unshare = CLONE_NEWUSER,
+ .udiag_show = UDIAG_SHOW_UID
+};
+
+FIXTURE_SETUP(diag_uid)
+{
+ struct stat file_stat;
+ socklen_t optlen;
+ int ret;
+
+ if (variant->unshare)
+ ASSERT_EQ(unshare(variant->unshare), 0);
+
+ self->netlink_fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG);
+ ASSERT_NE(self->netlink_fd, -1);
+
+ self->unix_fd = socket(AF_UNIX, SOCK_STREAM, 0);
+ ASSERT_NE(self->unix_fd, -1);
+
+ ret = fstat(self->unix_fd, &file_stat);
+ ASSERT_EQ(ret, 0);
+
+ self->inode = file_stat.st_ino;
+
+ optlen = sizeof(self->cookie);
+ ret = getsockopt(self->unix_fd, SOL_SOCKET, SO_COOKIE, &self->cookie, &optlen);
+ ASSERT_EQ(ret, 0);
+}
+
+FIXTURE_TEARDOWN(diag_uid)
+{
+ close(self->netlink_fd);
+ close(self->unix_fd);
+}
+
+int send_request(struct __test_metadata *_metadata,
+ FIXTURE_DATA(diag_uid) *self,
+ const FIXTURE_VARIANT(diag_uid) *variant)
+{
+ struct {
+ struct nlmsghdr nlh;
+ struct unix_diag_req udr;
+ } req = {
+ .nlh = {
+ .nlmsg_len = sizeof(req),
+ .nlmsg_type = SOCK_DIAG_BY_FAMILY,
+ .nlmsg_flags = NLM_F_REQUEST
+ },
+ .udr = {
+ .sdiag_family = AF_UNIX,
+ .udiag_ino = self->inode,
+ .udiag_cookie = {
+ (__u32)self->cookie,
+ (__u32)(self->cookie >> 32)
+ },
+ .udiag_show = variant->udiag_show
+ }
+ };
+ struct sockaddr_nl nladdr = {
+ .nl_family = AF_NETLINK
+ };
+ struct iovec iov = {
+ .iov_base = &req,
+ .iov_len = sizeof(req)
+ };
+ struct msghdr msg = {
+ .msg_name = &nladdr,
+ .msg_namelen = sizeof(nladdr),
+ .msg_iov = &iov,
+ .msg_iovlen = 1
+ };
+
+ return sendmsg(self->netlink_fd, &msg, 0);
+}
+
+void render_response(struct __test_metadata *_metadata,
+ struct unix_diag_req *udr, __u32 len)
+{
+ unsigned int rta_len = len - NLMSG_LENGTH(sizeof(*udr));
+ struct rtattr *attr;
+ uid_t uid;
+
+ ASSERT_GT(len, sizeof(*udr));
+ ASSERT_EQ(udr->sdiag_family, AF_UNIX);
+
+ attr = (struct rtattr *)(udr + 1);
+ ASSERT_NE(RTA_OK(attr, rta_len), 0);
+ ASSERT_EQ(attr->rta_type, UNIX_DIAG_UID);
+
+ uid = *(uid_t *)RTA_DATA(attr);
+ ASSERT_EQ(uid, getuid());
+}
+
+void receive_response(struct __test_metadata *_metadata,
+ FIXTURE_DATA(diag_uid) *self)
+{
+ long buf[8192 / sizeof(long)];
+ struct sockaddr_nl nladdr = {
+ .nl_family = AF_NETLINK
+ };
+ struct iovec iov = {
+ .iov_base = buf,
+ .iov_len = sizeof(buf)
+ };
+ struct msghdr msg = {
+ .msg_name = &nladdr,
+ .msg_namelen = sizeof(nladdr),
+ .msg_iov = &iov,
+ .msg_iovlen = 1
+ };
+ struct unix_diag_req *udr;
+ struct nlmsghdr *nlh;
+ int ret;
+
+ ret = recvmsg(self->netlink_fd, &msg, 0);
+ ASSERT_GT(ret, 0);
+
+ nlh = (struct nlmsghdr *)buf;
+ ASSERT_NE(NLMSG_OK(nlh, ret), 0);
+ ASSERT_EQ(nlh->nlmsg_type, SOCK_DIAG_BY_FAMILY);
+
+ render_response(_metadata, NLMSG_DATA(nlh), nlh->nlmsg_len);
+
+ nlh = NLMSG_NEXT(nlh, ret);
+ ASSERT_EQ(NLMSG_OK(nlh, ret), 0);
+}
+
+TEST_F(diag_uid, 1)
+{
+ int ret;
+
+ ret = send_request(_metadata, self, variant);
+ ASSERT_GT(ret, 0);
+
+ receive_response(_metadata, self);
+}
+
+TEST_HARNESS_MAIN
The test prog dumps a single AF_UNIX socket's UID with and without unshare(CLONE_NEWUSER) and checks if it matches the result of getuid(). Without the preceding patch, the test prog is killed by a NULL deref in sk_diag_dump_uid(). # ./diag_uid TAP version 13 1..2 # Starting 2 tests from 3 test cases. # RUN diag_uid.uid.1 ... BUG: kernel NULL pointer dereference, address: 0000000000000270 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 105212067 P4D 105212067 PUD 1051fe067 PMD 0 Oops: 0000 [#1] PREEMPT SMP NOPTI Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.amzn2022.0.1 04/01/2014 RIP: 0010:sk_diag_fill (./include/net/sock.h:920 net/unix/diag.c:119 net/unix/diag.c:170) ... # 1: Test terminated unexpectedly by signal 9 # FAIL diag_uid.uid.1 not ok 1 diag_uid.uid.1 # RUN diag_uid.uid_unshare.1 ... # 1: Test terminated by timeout # FAIL diag_uid.uid_unshare.1 not ok 2 diag_uid.uid_unshare.1 # FAILED: 0 / 2 tests passed. # Totals: pass:0 fail:2 xfail:0 xpass:0 skip:0 error:0 With the patch, the test succeeds. # ./diag_uid TAP version 13 1..2 # Starting 2 tests from 3 test cases. # RUN diag_uid.uid.1 ... # OK diag_uid.uid.1 ok 1 diag_uid.uid.1 # RUN diag_uid.uid_unshare.1 ... # OK diag_uid.uid_unshare.1 ok 2 diag_uid.uid_unshare.1 # PASSED: 2 / 2 tests passed. # Totals: pass:2 fail:0 xfail:0 xpass:0 skip:0 error:0 Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> --- tools/testing/selftests/net/.gitignore | 1 + tools/testing/selftests/net/af_unix/Makefile | 2 +- .../testing/selftests/net/af_unix/diag_uid.c | 178 ++++++++++++++++++ 3 files changed, 180 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/net/af_unix/diag_uid.c