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
39 extern "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 || (defined(__mips__) && _MIPS_SIM == _ABIN32))
58 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 1
59 #else
60 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 0
61 #endif
62
63 namespace safestack {
64
65 #if SANITIZER_NETBSD
GetRealLibcAddress(const char * symbol)66 static void *GetRealLibcAddress(const char *symbol) {
67 void *real = dlsym(RTLD_NEXT, symbol);
68 if (!real)
69 real = dlsym(RTLD_DEFAULT, symbol);
70 if (!real) {
71 fprintf(stderr, "safestack GetRealLibcAddress failed for symbol=%s",
72 symbol);
73 abort();
74 }
75 return real;
76 }
77
78 #define _REAL(func, ...) real##_##func(__VA_ARGS__)
79 #define DEFINE__REAL(ret_type, func, ...) \
80 static ret_type (*real_##func)(__VA_ARGS__) = NULL; \
81 if (!real_##func) { \
82 real_##func = (ret_type(*)(__VA_ARGS__))GetRealLibcAddress(#func); \
83 } \
84 SFS_CHECK(real_##func);
85 #endif
86
87 #if SANITIZER_SOLARIS
88 # define _REAL(func) _##func
89 # define DEFINE__REAL(ret_type, func, ...) \
90 extern "C" ret_type _REAL(func)(__VA_ARGS__)
91
92 # if !defined(_LP64) && _FILE_OFFSET_BITS == 64
93 # define _REAL64(func) _##func##64
94 # else
95 # define _REAL64(func) _REAL(func)
96 # endif
97 # define DEFINE__REAL64(ret_type, func, ...) \
98 extern "C" ret_type _REAL64(func)(__VA_ARGS__)
99
100 DEFINE__REAL64(void *, mmap, void *a, size_t b, int c, int d, int e, off_t f);
101 DEFINE__REAL(int, munmap, void *a, size_t b);
102 DEFINE__REAL(int, mprotect, void *a, size_t b, int c);
103 #endif
104
105 using ThreadId = uint64_t;
106
GetTid()107 inline ThreadId GetTid() {
108 #if SANITIZER_NETBSD
109 DEFINE__REAL(int, _lwp_self);
110 return _REAL(_lwp_self);
111 #elif SANITIZER_FREEBSD
112 long Tid;
113 thr_self(&Tid);
114 return Tid;
115 #elif SANITIZER_SOLARIS
116 return thr_self();
117 #else
118 return syscall(SYS_gettid);
119 #endif
120 }
121
TgKill(pid_t pid,ThreadId tid,int sig)122 inline int TgKill(pid_t pid, ThreadId tid, int sig) {
123 #if SANITIZER_NETBSD
124 DEFINE__REAL(int, _lwp_kill, int a, int b);
125 (void)pid;
126 return _REAL(_lwp_kill, tid, sig);
127 #elif SANITIZER_SOLARIS
128 (void)pid;
129 errno = thr_kill(tid, sig);
130 // TgKill is expected to return -1 on error, not an errno.
131 return errno != 0 ? -1 : 0;
132 #elif SANITIZER_FREEBSD
133 return syscall(SYS_thr_kill2, pid, tid, sig);
134 #else
135 // tid is pid_t (int), not ThreadId (uint64_t).
136 return syscall(SYS_tgkill, pid, (pid_t)tid, sig);
137 #endif
138 }
139
Mmap(void * addr,size_t length,int prot,int flags,int fd,off_t offset)140 inline void *Mmap(void *addr, size_t length, int prot, int flags, int fd,
141 off_t offset) {
142 #if SANITIZER_NETBSD
143 return __mmap(addr, length, prot, flags, fd, 0, offset);
144 #elif SANITIZER_FREEBSD && (defined(__aarch64__) || defined(__x86_64__))
145 return (void *)__syscall(SYS_mmap, addr, length, prot, flags, fd, offset);
146 #elif SANITIZER_FREEBSD && (defined(__i386__))
147 return (void *)syscall(SYS_mmap, addr, length, prot, flags, fd, offset);
148 #elif SANITIZER_SOLARIS
149 return _REAL64(mmap)(addr, length, prot, flags, fd, offset);
150 #elif SANITIZER_LINUX_USES_64BIT_SYSCALLS
151 return (void *)syscall(SYS_mmap, addr, length, prot, flags, fd, offset);
152 #else
153 // mmap2 specifies file offset in 4096-byte units.
154 SFS_CHECK(IsAligned(offset, 4096));
155 return (void *)syscall(SYS_mmap2, addr, length, prot, flags, fd,
156 offset / 4096);
157 #endif
158 }
159
Munmap(void * addr,size_t length)160 inline int Munmap(void *addr, size_t length) {
161 #if SANITIZER_NETBSD
162 DEFINE__REAL(int, munmap, void *a, size_t b);
163 return _REAL(munmap, addr, length);
164 #elif SANITIZER_SOLARIS
165 return _REAL(munmap)(addr, length);
166 #else
167 return syscall(SYS_munmap, addr, length);
168 #endif
169 }
170
Mprotect(void * addr,size_t length,int prot)171 inline int Mprotect(void *addr, size_t length, int prot) {
172 #if SANITIZER_NETBSD
173 DEFINE__REAL(int, mprotect, void *a, size_t b, int c);
174 return _REAL(mprotect, addr, length, prot);
175 #elif SANITIZER_SOLARIS
176 return _REAL(mprotect)(addr, length, prot);
177 #else
178 return syscall(SYS_mprotect, addr, length, prot);
179 #endif
180 }
181
182 } // namespace safestack
183
184 #endif // SAFESTACK_PLATFORM_H
185