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
| //===-- linux.cpp -----------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "platform.h"
#if SCUDO_LINUX
#include "common.h"
#include "linux.h"
#include "mutex.h"
#include "string_utils.h"
#include <errno.h>
#include <fcntl.h>
#include <linux/futex.h>
#include <sched.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#if SCUDO_ANDROID
#include <sys/prctl.h>
// Definitions of prctl arguments to set a vma name in Android kernels.
#define ANDROID_PR_SET_VMA 0x53564d41
#define ANDROID_PR_SET_VMA_ANON_NAME 0
#endif
namespace scudo {
uptr getPageSize() { return static_cast<uptr>(sysconf(_SC_PAGESIZE)); }
void NORETURN die() { abort(); }
void *map(void *Addr, uptr Size, UNUSED const char *Name, uptr Flags,
UNUSED MapPlatformData *Data) {
int MmapFlags = MAP_PRIVATE | MAP_ANONYMOUS;
int MmapProt;
if (Flags & MAP_NOACCESS) {
MmapFlags |= MAP_NORESERVE;
MmapProt = PROT_NONE;
} else {
MmapProt = PROT_READ | PROT_WRITE;
}
if (Addr) {
// Currently no scenario for a noaccess mapping with a fixed address.
DCHECK_EQ(Flags & MAP_NOACCESS, 0);
MmapFlags |= MAP_FIXED;
}
void *P = mmap(Addr, Size, MmapProt, MmapFlags, -1, 0);
if (P == MAP_FAILED) {
if (!(Flags & MAP_ALLOWNOMEM) || errno != ENOMEM)
dieOnMapUnmapError(errno == ENOMEM);
return nullptr;
}
#if SCUDO_ANDROID
if (!(Flags & MAP_NOACCESS))
prctl(ANDROID_PR_SET_VMA, ANDROID_PR_SET_VMA_ANON_NAME, P, Size, Name);
#endif
return P;
}
void unmap(void *Addr, uptr Size, UNUSED uptr Flags,
UNUSED MapPlatformData *Data) {
if (munmap(Addr, Size) != 0)
dieOnMapUnmapError();
}
void releasePagesToOS(uptr BaseAddress, uptr Offset, uptr Size,
UNUSED MapPlatformData *Data) {
void *Addr = reinterpret_cast<void *>(BaseAddress + Offset);
while (madvise(Addr, Size, MADV_DONTNEED) == -1 && errno == EAGAIN) {
}
}
// Calling getenv should be fine (c)(tm) at any time.
const char *getEnv(const char *Name) { return getenv(Name); }
namespace {
enum State : u32 { Unlocked = 0, Locked = 1, Sleeping = 2 };
}
bool HybridMutex::tryLock() {
return atomic_compare_exchange(&M, Unlocked, Locked) == Unlocked;
}
// The following is based on https://akkadia.org/drepper/futex.pdf.
void HybridMutex::lockSlow() {
u32 V = atomic_compare_exchange(&M, Unlocked, Locked);
if (V == Unlocked)
return;
if (V != Sleeping)
V = atomic_exchange(&M, Sleeping, memory_order_acquire);
while (V != Unlocked) {
syscall(SYS_futex, reinterpret_cast<uptr>(&M), FUTEX_WAIT_PRIVATE, Sleeping,
nullptr, nullptr, 0);
V = atomic_exchange(&M, Sleeping, memory_order_acquire);
}
}
void HybridMutex::unlock() {
if (atomic_fetch_sub(&M, 1U, memory_order_release) != Locked) {
atomic_store(&M, Unlocked, memory_order_release);
syscall(SYS_futex, reinterpret_cast<uptr>(&M), FUTEX_WAKE_PRIVATE, 1,
nullptr, nullptr, 0);
}
}
u64 getMonotonicTime() {
timespec TS;
clock_gettime(CLOCK_MONOTONIC, &TS);
return static_cast<u64>(TS.tv_sec) * (1000ULL * 1000 * 1000) +
static_cast<u64>(TS.tv_nsec);
}
u32 getNumberOfCPUs() {
cpu_set_t CPUs;
CHECK_EQ(sched_getaffinity(0, sizeof(cpu_set_t), &CPUs), 0);
return static_cast<u32>(CPU_COUNT(&CPUs));
}
// Blocking is possibly unused if the getrandom block is not compiled in.
bool getRandom(void *Buffer, uptr Length, UNUSED bool Blocking) {
if (!Buffer || !Length || Length > MaxRandomLength)
return false;
ssize_t ReadBytes;
#if defined(SYS_getrandom)
#if !defined(GRND_NONBLOCK)
#define GRND_NONBLOCK 1
#endif
// Up to 256 bytes, getrandom will not be interrupted.
ReadBytes =
syscall(SYS_getrandom, Buffer, Length, Blocking ? 0 : GRND_NONBLOCK);
if (ReadBytes == static_cast<ssize_t>(Length))
return true;
#endif // defined(SYS_getrandom)
// Up to 256 bytes, a read off /dev/urandom will not be interrupted.
// Blocking is moot here, O_NONBLOCK has no effect when opening /dev/urandom.
const int FileDesc = open("/dev/urandom", O_RDONLY);
if (FileDesc == -1)
return false;
ReadBytes = read(FileDesc, Buffer, Length);
close(FileDesc);
return (ReadBytes == static_cast<ssize_t>(Length));
}
void outputRaw(const char *Buffer) {
static HybridMutex Mutex;
ScopedLock L(Mutex);
write(2, Buffer, strlen(Buffer));
}
extern "C" WEAK void android_set_abort_message(const char *);
void setAbortMessage(const char *Message) {
if (&android_set_abort_message)
android_set_abort_message(Message);
}
} // namespace scudo
#endif // SCUDO_LINUX
|