1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) 2017 Richard Palethorpe <rpalethorpe@suse.com>
4 * Copyright (c) 2012, Kees Cook <keescook@chromium.org>
5 */
6 /*
7 * Check that memory after the string terminator in all the utsname fields has
8 * been zeroed. cve-2012-0957 leaked kernel memory through the release field
9 * when the UNAME26 personality was set.
10 *
11 * Thanks to Kees Cook for the original proof of concept:
12 * http://www.securityfocus.com/bid/55855/info
13 */
14
15 #include <string.h>
16 #include <sys/utsname.h>
17 #include "tst_test.h"
18 #include "lapi/personality.h"
19
20 static struct utsname saved_buf;
21
check_field(char * bytes,char * saved_bytes,size_t length,char * field)22 static int check_field(char *bytes, char *saved_bytes, size_t length,
23 char *field)
24 {
25 size_t i = strlen(bytes) + 1;
26
27 for (; i < length; i++) {
28 if (bytes[i] && (bytes[i] != saved_bytes[i])) {
29 tst_res(TFAIL, "Bytes leaked in %s!", field);
30 return 1;
31 }
32 }
33 return 0;
34 }
35
36
try_leak_bytes(unsigned int test_nr)37 static void try_leak_bytes(unsigned int test_nr)
38 {
39 struct utsname buf;
40
41 memset(&buf, 0, sizeof(buf));
42
43 if (uname(&buf))
44 tst_brk(TBROK | TERRNO, "Call to uname failed");
45
46 if (!test_nr)
47 memcpy(&saved_buf, &buf, sizeof(saved_buf));
48
49 #define CHECK_FIELD(field_name) \
50 (check_field(buf.field_name, saved_buf.field_name, \
51 ARRAY_SIZE(buf.field_name), #field_name))
52
53 if (!(CHECK_FIELD(release) |
54 CHECK_FIELD(sysname) |
55 CHECK_FIELD(nodename) |
56 CHECK_FIELD(version) |
57 CHECK_FIELD(machine) |
58 #ifdef HAVE_STRUCT_UTSNAME_DOMAINNAME
59 CHECK_FIELD(domainname) |
60 #endif
61 0)) {
62 tst_res(TPASS, "No bytes leaked");
63 }
64 #undef CHECK_FIELD
65 }
66
run(unsigned int test_nr)67 static void run(unsigned int test_nr)
68 {
69 if (!test_nr) {
70 tst_res(TINFO, "Calling uname with default personality");
71 } else {
72 SAFE_PERSONALITY(PER_LINUX | UNAME26);
73 tst_res(TINFO, "Calling uname with UNAME26 personality");
74 }
75
76 try_leak_bytes(test_nr);
77 }
78
79 static struct tst_test test = {
80 .test = run,
81 .tcnt = 2,
82 .tags = (const struct tst_tag[]) {
83 {"CVE", "2012-0957"},
84 {}
85 }
86 };
87