1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* 32-bit test to check vDSO mremap.
*
* Copyright (c) 2016 Dmitry Safonov
* Suggested-by: Andrew Lutomirski
*/
/*
* Can be built statically:
* gcc -Os -Wall -static -m32 test_mremap_vdso.c
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdbool.h>
#include <sys/mman.h>
#include <sys/auxv.h>
#include <sys/syscall.h>
#include <sys/wait.h>
#include "../kselftest.h"
#define PAGE_SIZE 4096
static int try_to_remap(void *vdso_addr, unsigned long size)
{
void *dest_addr, *new_addr;
/* Searching for memory location where to remap */
dest_addr = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if (dest_addr == MAP_FAILED) {
ksft_print_msg("WARN: mmap failed (%d): %m\n", errno);
return 0;
}
ksft_print_msg("Moving vDSO: [%p, %#lx] -> [%p, %#lx]\n",
vdso_addr, (unsigned long)vdso_addr + size,
dest_addr, (unsigned long)dest_addr + size);
fflush(stdout);
new_addr = mremap(vdso_addr, size, size,
MREMAP_FIXED|MREMAP_MAYMOVE, dest_addr);
if ((unsigned long)new_addr == (unsigned long)-1) {
munmap(dest_addr, size);
if (errno == EINVAL) {
ksft_print_msg("vDSO partial move failed, will try with bigger size\n");
return -1; /* Retry with larger */
}
ksft_print_msg("[FAIL]\tmremap failed (%d): %m\n", errno);
return 1;
}
return 0;
}
#define VDSO_NAME "[vdso]"
#define VMFLAGS "VmFlags:"
#define MSEAL_FLAGS "sl"
#define MAX_LINE_LEN 512
bool vdso_sealed(FILE *maps)
{
char line[MAX_LINE_LEN];
bool has_vdso = false;
while (fgets(line, sizeof(line), maps)) {
if (strstr(line, VDSO_NAME))
has_vdso = true;
if (has_vdso && !strncmp(line, VMFLAGS, strlen(VMFLAGS))) {
if (strstr(line, MSEAL_FLAGS))
return true;
return false;
}
}
return false;
}
int main(int argc, char **argv, char **envp)
{
pid_t child;
FILE *maps;
ksft_print_header();
ksft_set_plan(1);
maps = fopen("/proc/self/smaps", "r");
if (!maps) {
ksft_test_result_skip(
"Could not open /proc/self/smaps, errno=%d\n",
errno);
return 0;
}
if (vdso_sealed(maps)) {
ksft_test_result_skip("vdso is sealed\n");
return 0;
}
fclose(maps);
child = fork();
if (child == -1)
ksft_exit_fail_msg("failed to fork (%d): %m\n", errno);
if (child == 0) {
unsigned long vdso_size = PAGE_SIZE;
unsigned long auxval;
int ret = -1;
auxval = getauxval(AT_SYSINFO_EHDR);
ksft_print_msg("AT_SYSINFO_EHDR is %#lx\n", auxval);
if (!auxval || auxval == -ENOENT) {
ksft_print_msg("WARN: getauxval failed\n");
return 0;
}
/* Simpler than parsing ELF header */
while (ret < 0) {
ret = try_to_remap((void *)auxval, vdso_size);
vdso_size += PAGE_SIZE;
}
#ifdef __i386__
/* Glibc is likely to explode now - exit with raw syscall */
asm volatile ("int $0x80" : : "a" (__NR_exit), "b" (!!ret));
#else /* __x86_64__ */
syscall(SYS_exit, ret);
#endif
} else {
int status;
if (waitpid(child, &status, 0) != child ||
!WIFEXITED(status))
ksft_test_result_fail("mremap() of the vDSO does not work on this kernel!\n");
else if (WEXITSTATUS(status) != 0)
ksft_test_result_fail("Child failed with %d\n", WEXITSTATUS(status));
else
ksft_test_result_pass("%s\n", __func__);
}
ksft_finished();
}
|
