1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) 2017 Richard Palethorpe <rpalethorpe@suse.com>
4 * Original POC by Daniel Jiang
5 */
6 /*
7 * Test for CVE-2017-2671 faulty locking on ping socket
8 *
9 * When sys_connect() is called with sockaddr.sin_family set to AF_UNSPEC on a
10 * ping socket; __udp_disconnect() gets called, which in turn calls the buggy
11 * function ping_unhashed(). This function does not obtain a rwlock before
12 * checking if the socket is hashed allowing the socket data to be pulled from
13 * underneath it in the time between calling sk_hashed() and gaining the write
14 * lock.
15 *
16 * Fixed in commit 43a6684519ab0a6c52024b5e25322476cabad893
17 *
18 * This test repeatedly 'connects' a ping socket correctly then calls
19 * connect() with AF_UNSPEC in two seperate threads to trigger the race
20 * condition. If the bug is present, then the test will most likely crash the
21 * system.
22 *
23 * The test requests root privileges so that it can ensure ping sockets are
24 * enabled. On distributions (including Android) where ping sockets are
25 * enabled by default, root privileges are not required.
26 */
27
28 #include <unistd.h>
29 #include <stdio.h>
30 #include <sys/socket.h>
31 #include <arpa/inet.h>
32 #include <stdlib.h>
33
34 #include "tst_test.h"
35 #include "tst_safe_net.h"
36 #include "tst_safe_pthread.h"
37
38 #include "tst_fuzzy_sync.h"
39
40 #define ATTEMPTS 0x80000
41 #define PING_SYSCTL_PATH "/proc/sys/net/ipv4/ping_group_range"
42
43 static int sockfd;
44 static unsigned int ping_min_grp, ping_max_grp;
45 static struct tst_fzsync_pair fzsync_pair;
46 static struct sockaddr_in iaddr, uaddr;
47 static void *connect_b(void *);
48
setup(void)49 static void setup(void)
50 {
51 iaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
52 uaddr = iaddr;
53 iaddr.sin_family = AF_INET;
54 uaddr.sin_family = AF_UNSPEC;
55
56 if (access(PING_SYSCTL_PATH, F_OK))
57 tst_brk(TCONF, "socket() does not support IPPROTO_ICMP");
58
59 SAFE_FILE_SCANF(PING_SYSCTL_PATH, "%u %u",
60 &ping_min_grp, &ping_max_grp);
61 SAFE_FILE_PRINTF(PING_SYSCTL_PATH, "0 0");
62
63 sockfd = SAFE_SOCKET(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
64 tst_res(TINFO, "Created ping socket, attempting to race...");
65
66 tst_fzsync_pair_init(&fzsync_pair);
67 }
68
cleanup(void)69 static void cleanup(void)
70 {
71 tst_fzsync_pair_cleanup(&fzsync_pair);
72
73 if (sockfd > 0)
74 SAFE_CLOSE(sockfd);
75
76 if (ping_min_grp | ping_max_grp)
77 SAFE_FILE_PRINTF(PING_SYSCTL_PATH, "%u %u",
78 ping_min_grp, ping_max_grp);
79 }
80
connect_b(void * param LTP_ATTRIBUTE_UNUSED)81 static void *connect_b(void * param LTP_ATTRIBUTE_UNUSED)
82 {
83 while (tst_fzsync_run_b(&fzsync_pair)) {
84 tst_fzsync_start_race_b(&fzsync_pair);
85 connect(sockfd, (struct sockaddr *)&uaddr, sizeof(uaddr));
86 tst_fzsync_end_race_b(&fzsync_pair);
87 }
88
89 return 0;
90 }
91
run(void)92 static void run(void)
93 {
94 tst_fzsync_pair_reset(&fzsync_pair, connect_b);
95 while (tst_fzsync_run_a(&fzsync_pair)) {
96 SAFE_CONNECT(sockfd,
97 (struct sockaddr *)&iaddr, sizeof(iaddr));
98
99 tst_fzsync_start_race_a(&fzsync_pair);
100 connect(sockfd, (struct sockaddr *)&uaddr, sizeof(uaddr));
101 tst_fzsync_end_race_a(&fzsync_pair);
102 }
103
104 tst_res(TPASS, "We didn't crash");
105 }
106
107 static struct tst_test test = {
108 .setup = setup,
109 .test_all = run,
110 .cleanup = cleanup,
111 .needs_root = 1,
112 .tags = (const struct tst_tag[]) {
113 {"linux-git", "43a6684519ab"},
114 {"CVE", "2017-2671"},
115 {}
116 }
117 };
118