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
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* unwind_vdso.c - tests unwind info for AT_SYSINFO in the vDSO
* Copyright (c) 2014-2015 Andrew Lutomirski
*
* This tests __kernel_vsyscall's unwind info.
*/
#define _GNU_SOURCE
#include <features.h>
#include <stdio.h>
#include "helpers.h"
#if defined(__GLIBC__) && __GLIBC__ == 2 && __GLIBC_MINOR__ < 16
int main()
{
/* We need getauxval(). */
printf("[SKIP]\tGLIBC before 2.16 cannot compile this test\n");
return 0;
}
#else
#include <sys/time.h>
#include <stdlib.h>
#include <syscall.h>
#include <unistd.h>
#include <string.h>
#include <inttypes.h>
#include <sys/mman.h>
#include <signal.h>
#include <sys/ucontext.h>
#include <err.h>
#include <stddef.h>
#include <stdbool.h>
#include <sys/ptrace.h>
#include <sys/user.h>
#include <link.h>
#include <sys/auxv.h>
#include <dlfcn.h>
#include <unwind.h>
static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
int flags)
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = handler;
sa.sa_flags = SA_SIGINFO | flags;
sigemptyset(&sa.sa_mask);
if (sigaction(sig, &sa, 0))
err(1, "sigaction");
}
static volatile sig_atomic_t nerrs;
static unsigned long sysinfo;
static bool got_sysinfo = false;
static unsigned long return_address;
struct unwind_state {
unsigned long ip; /* trap source */
int depth; /* -1 until we hit the trap source */
};
_Unwind_Reason_Code trace_fn(struct _Unwind_Context * ctx, void *opaque)
{
struct unwind_state *state = opaque;
unsigned long ip = _Unwind_GetIP(ctx);
if (state->depth == -1) {
if (ip == state->ip)
state->depth = 0;
else
return _URC_NO_REASON; /* Not there yet */
}
printf("\t 0x%lx\n", ip);
if (ip == return_address) {
/* Here we are. */
unsigned long eax = _Unwind_GetGR(ctx, 0);
unsigned long ecx = _Unwind_GetGR(ctx, 1);
unsigned long edx = _Unwind_GetGR(ctx, 2);
unsigned long ebx = _Unwind_GetGR(ctx, 3);
unsigned long ebp = _Unwind_GetGR(ctx, 5);
unsigned long esi = _Unwind_GetGR(ctx, 6);
unsigned long edi = _Unwind_GetGR(ctx, 7);
bool ok = (eax == SYS_getpid || eax == getpid()) &&
ebx == 1 && ecx == 2 && edx == 3 &&
esi == 4 && edi == 5 && ebp == 6;
if (!ok)
nerrs++;
printf("[%s]\t NR = %ld, args = %ld, %ld, %ld, %ld, %ld, %ld\n",
(ok ? "OK" : "FAIL"),
eax, ebx, ecx, edx, esi, edi, ebp);
return _URC_NORMAL_STOP;
} else {
state->depth++;
return _URC_NO_REASON;
}
}
static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
{
ucontext_t *ctx = (ucontext_t *)ctx_void;
struct unwind_state state;
unsigned long ip = ctx->uc_mcontext.gregs[REG_EIP];
if (!got_sysinfo && ip == sysinfo) {
got_sysinfo = true;
/* Find the return address. */
return_address = *(unsigned long *)(unsigned long)ctx->uc_mcontext.gregs[REG_ESP];
printf("\tIn vsyscall at 0x%lx, returning to 0x%lx\n",
ip, return_address);
}
if (!got_sysinfo)
return; /* Not there yet */
if (ip == return_address) {
ctx->uc_mcontext.gregs[REG_EFL] &= ~X86_EFLAGS_TF;
printf("\tVsyscall is done\n");
return;
}
printf("\tSIGTRAP at 0x%lx\n", ip);
state.ip = ip;
state.depth = -1;
_Unwind_Backtrace(trace_fn, &state);
}
int main()
{
sysinfo = getauxval(AT_SYSINFO);
printf("\tAT_SYSINFO is 0x%lx\n", sysinfo);
Dl_info info;
if (!dladdr((void *)sysinfo, &info)) {
printf("[WARN]\tdladdr failed on AT_SYSINFO\n");
} else {
printf("[OK]\tAT_SYSINFO maps to %s, loaded at 0x%p\n",
info.dli_fname, info.dli_fbase);
}
sethandler(SIGTRAP, sigtrap, 0);
syscall(SYS_getpid); /* Force symbol binding without TF set. */
printf("[RUN]\tSet TF and check a fast syscall\n");
set_eflags(get_eflags() | X86_EFLAGS_TF);
syscall(SYS_getpid, 1, 2, 3, 4, 5, 6);
if (!got_sysinfo) {
set_eflags(get_eflags() & ~X86_EFLAGS_TF);
/*
* The most likely cause of this is that you're on Debian or
* a Debian-based distro, you're missing libc6-i686, and you're
* affected by libc/19006 (https://sourceware.org/PR19006).
*/
printf("[WARN]\tsyscall(2) didn't enter AT_SYSINFO\n");
}
if (get_eflags() & X86_EFLAGS_TF) {
printf("[FAIL]\tTF is still set\n");
nerrs++;
}
if (nerrs) {
printf("[FAIL]\tThere were errors\n");
return 1;
} else {
printf("[OK]\tAll is well\n");
return 0;
}
}
#endif /* New enough libc */
|
