1//===-- safestack_platform.h ----------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements platform specific parts of SafeStack runtime.
10// Don't use equivalent functionality from sanitizer_common to avoid dragging
11// a large codebase into security sensitive code.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef SAFESTACK_PLATFORM_H
16#define SAFESTACK_PLATFORM_H
17
18#include "safestack_util.h"
19#include "sanitizer_common/sanitizer_platform.h"
20
21#include <dlfcn.h>
22#include <errno.h>
23#include <stdint.h>
24#include <stdio.h>
25#include <stdlib.h>
26#include <sys/mman.h>
27#include <sys/syscall.h>
28#include <sys/types.h>
29#include <unistd.h>
30
31#if !(SANITIZER_NETBSD || SANITIZER_FREEBSD || SANITIZER_LINUX || \
32 SANITIZER_SOLARIS)
33# error "Support for your platform has not been implemented"
34#endif
35
36#if SANITIZER_NETBSD
37#include <lwp.h>
38
39extern "C" void *__mmap(void *, size_t, int, int, int, int, off_t);
40#endif
41
42#if SANITIZER_FREEBSD
43#include <sys/thr.h>
44#endif
45
46#if SANITIZER_SOLARIS
47# include <thread.h>
48#endif
49
50// Keep in sync with sanitizer_linux.cpp.
51//
52// Are we using 32-bit or 64-bit Linux syscalls?
53// x32 (which defines __x86_64__) has SANITIZER_WORDSIZE == 32
54// but it still needs to use 64-bit syscalls.
55#if SANITIZER_LINUX && \
56 (defined(__x86_64__) || defined(__powerpc64__) || \
57 SANITIZER_WORDSIZE == 64 || \
58 (defined(__mips__) && defined(_ABIN32) && _MIPS_SIM == _ABIN32))
59# define SANITIZER_LINUX_USES_64BIT_SYSCALLS 1
60#else
61# define SANITIZER_LINUX_USES_64BIT_SYSCALLS 0
62#endif
63
64namespace safestack {
65
66#if SANITIZER_NETBSD
67static void *GetRealLibcAddress(const char *symbol) {
68 void *real = dlsym(RTLD_NEXT, symbol);
69 if (!real)
70 real = dlsym(RTLD_DEFAULT, symbol);
71 if (!real) {
72 fprintf(stderr, "safestack GetRealLibcAddress failed for symbol=%s",
73 symbol);
74 abort();
75 }
76 return real;
77}
78
79#define _REAL(func, ...) real##_##func(__VA_ARGS__)
80#define DEFINE__REAL(ret_type, func, ...) \
81 static ret_type (*real_##func)(__VA_ARGS__) = NULL; \
82 if (!real_##func) { \
83 real_##func = (ret_type(*)(__VA_ARGS__))GetRealLibcAddress(#func); \
84 } \
85 SFS_CHECK(real_##func);
86#endif
87
88#if SANITIZER_SOLARIS
89# define _REAL(func) _##func
90# define DEFINE__REAL(ret_type, func, ...) \
91 extern "C" ret_type _REAL(func)(__VA_ARGS__)
92
93# if !defined(_LP64) && _FILE_OFFSET_BITS == 64
94# define _REAL64(func) _##func##64
95# else
96# define _REAL64(func) _REAL(func)
97# endif
98# define DEFINE__REAL64(ret_type, func, ...) \
99 extern "C" ret_type _REAL64(func)(__VA_ARGS__)
100
101DEFINE__REAL64(void *, mmap, void *a, size_t b, int c, int d, int e, off_t f);
102DEFINE__REAL(int, munmap, void *a, size_t b);
103DEFINE__REAL(int, mprotect, void *a, size_t b, int c);
104#endif
105
106using ThreadId = uint64_t;
107
108inline ThreadId GetTid() {
109#if SANITIZER_NETBSD
110 DEFINE__REAL(int, _lwp_self);
111 return _REAL(_lwp_self);
112#elif SANITIZER_FREEBSD
113 long Tid;
114 thr_self(&Tid);
115 return Tid;
116#elif SANITIZER_SOLARIS
117 return thr_self();
118#else
119 return syscall(SYS_gettid);
120#endif
121}
122
123inline int TgKill(pid_t pid, ThreadId tid, int sig) {
124#if SANITIZER_NETBSD
125 DEFINE__REAL(int, _lwp_kill, int a, int b);
126 (void)pid;
127 return _REAL(_lwp_kill, tid, sig);
128#elif SANITIZER_SOLARIS
129 (void)pid;
130 errno = thr_kill(tid, sig);
131 // TgKill is expected to return -1 on error, not an errno.
132 return errno != 0 ? -1 : 0;
133#elif SANITIZER_FREEBSD
134 return syscall(SYS_thr_kill2, pid, tid, sig);
135#else
136 // tid is pid_t (int), not ThreadId (uint64_t).
137 return syscall(SYS_tgkill, pid, (pid_t)tid, sig);
138#endif
139}
140
141inline void *Mmap(void *addr, size_t length, int prot, int flags, int fd,
142 off_t offset) {
143#if SANITIZER_NETBSD
144 return __mmap(addr, length, prot, flags, fd, 0, offset);
145#elif SANITIZER_FREEBSD && (defined(__aarch64__) || defined(__x86_64__))
146 return (void *)__syscall(SYS_mmap, addr, length, prot, flags, fd, offset);
147#elif SANITIZER_FREEBSD && (defined(__i386__))
148 return (void *)syscall(SYS_mmap, addr, length, prot, flags, fd, offset);
149#elif SANITIZER_SOLARIS
150 return _REAL64(mmap)(addr, length, prot, flags, fd, offset);
151#elif SANITIZER_LINUX_USES_64BIT_SYSCALLS
152 return (void *)syscall(SYS_mmap, addr, length, prot, flags, fd, offset);
153#else
154 // mmap2 specifies file offset in 4096-byte units.
155 SFS_CHECK(IsAligned(offset, 4096));
156 return (void *)syscall(SYS_mmap2, addr, length, prot, flags, fd,
157 offset / 4096);
158#endif
159}
160
161inline int Munmap(void *addr, size_t length) {
162#if SANITIZER_NETBSD
163 DEFINE__REAL(int, munmap, void *a, size_t b);
164 return _REAL(munmap, addr, length);
165#elif SANITIZER_SOLARIS
166 return _REAL(munmap)(addr, length);
167#else
168 return syscall(SYS_munmap, addr, length);
169#endif
170}
171
172inline int Mprotect(void *addr, size_t length, int prot) {
173#if SANITIZER_NETBSD
174 DEFINE__REAL(int, mprotect, void *a, size_t b, int c);
175 return _REAL(mprotect, addr, length, prot);
176#elif SANITIZER_SOLARIS
177 return _REAL(mprotect)(addr, length, prot);
178#else
179 return syscall(SYS_mprotect, addr, length, prot);
180#endif
181}
182
183} // namespace safestack
184
185#endif // SAFESTACK_PLATFORM_H
186