1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #undef _FORTIFY_SOURCE
30
31 #include <errno.h>
32 #include <fcntl.h>
33 #include <stdarg.h>
34 #include <stdint.h>
35 #include <sys/mman.h>
36 #include <sys/resource.h>
37 #include <sys/types.h>
38 #include <unistd.h>
39
40 #include "platform/bionic/macros.h"
41 #include "platform/bionic/page.h"
42 #include "private/ErrnoRestorer.h"
43 #include "private/bionic_fdtrack.h"
44
45 #if defined(__LP64__)
46 #error This code is only needed on 32-bit systems!
47 #endif
48
49 // To implement lseek64() on ILP32, we need to use the _llseek() system call
50 // which splits the off64_t into two 32-bit arguments and returns the off64_t
51 // result via a pointer because 32-bit kernels can't accept 64-bit arguments
52 // or return 64-bit results. (Our symbol is __llseek with two underscores for
53 // historical reasons, but it's exposed as ABI so we can't fix it.)
54 extern "C" int __llseek(int, unsigned long, unsigned long, off64_t*, int);
55
lseek64(int fd,off64_t off,int whence)56 off64_t lseek64(int fd, off64_t off, int whence) {
57 off64_t result;
58 unsigned long off_hi = static_cast<unsigned long>(off >> 32);
59 unsigned long off_lo = static_cast<unsigned long>(off);
60 if (__llseek(fd, off_hi, off_lo, &result, whence) < 0) {
61 return -1;
62 }
63 return result;
64 }
65
66 // There is no pread for 32-bit off_t, so we need to widen and call pread64.
pread(int fd,void * buf,size_t byte_count,off_t offset)67 ssize_t pread(int fd, void* buf, size_t byte_count, off_t offset) {
68 return pread64(fd, buf, byte_count, static_cast<off64_t>(offset));
69 }
70
71 // There is no pwrite for 32-bit off_t, so we need to widen and call pwrite64.
pwrite(int fd,const void * buf,size_t byte_count,off_t offset)72 ssize_t pwrite(int fd, const void* buf, size_t byte_count, off_t offset) {
73 return pwrite64(fd, buf, byte_count, static_cast<off64_t>(offset));
74 }
75
76 // There is no fallocate for 32-bit off_t, so we need to widen and call fallocate64.
fallocate(int fd,int mode,off_t offset,off_t length)77 int fallocate(int fd, int mode, off_t offset, off_t length) {
78 return fallocate64(fd, mode, static_cast<off64_t>(offset), static_cast<off64_t>(length));
79 }
80
81 // There is no getrlimit64 system call, so we need to use prlimit64.
getrlimit64(int resource,rlimit64 * limits64)82 int getrlimit64(int resource, rlimit64* limits64) {
83 return prlimit64(0, resource, nullptr, limits64);
84 }
85
86 // There is no setrlimit64 system call, so we need to use prlimit64.
setrlimit64(int resource,const rlimit64 * limits64)87 int setrlimit64(int resource, const rlimit64* limits64) {
88 return prlimit64(0, resource, limits64, nullptr);
89 }
90
91 // There is no prlimit system call, so we need to use prlimit64.
prlimit(pid_t pid,int resource,const rlimit * n32,rlimit * o32)92 int prlimit(pid_t pid, int resource, const rlimit* n32, rlimit* o32) {
93 rlimit64 n64;
94 if (n32 != nullptr) {
95 n64.rlim_cur = (n32->rlim_cur == RLIM_INFINITY) ? RLIM64_INFINITY : n32->rlim_cur;
96 n64.rlim_max = (n32->rlim_max == RLIM_INFINITY) ? RLIM64_INFINITY : n32->rlim_max;
97 }
98
99 rlimit64 o64;
100 int result = prlimit64(pid, resource,
101 (n32 != nullptr) ? &n64 : nullptr,
102 (o32 != nullptr) ? &o64 : nullptr);
103 if (result != -1 && o32 != nullptr) {
104 o32->rlim_cur = (o64.rlim_cur == RLIM64_INFINITY) ? RLIM_INFINITY : o64.rlim_cur;
105 o32->rlim_max = (o64.rlim_max == RLIM64_INFINITY) ? RLIM_INFINITY : o64.rlim_max;
106 }
107 return result;
108 }
109
110 // mmap2(2) is like mmap(2), but the offset is in 4096-byte blocks (regardless
111 // of page size), not bytes, to enable mapping parts of large files past the
112 // 4GiB limit but without the inconvenience of dealing with 64-bit values, with
113 // no down side since mappings need to be page aligned anyway, and the 32-bit
114 // architectures that support this system call all have 4KiB pages.
115 extern "C" void* __mmap2(void*, size_t, int, int, int, size_t);
116
mmap64(void * addr,size_t size,int prot,int flags,int fd,off64_t offset)117 void* mmap64(void* addr, size_t size, int prot, int flags, int fd, off64_t offset) {
118 static constexpr size_t MMAP2_SHIFT = 12;
119
120 if (offset < 0 || (offset & ((1UL << MMAP2_SHIFT) - 1)) != 0) {
121 errno = EINVAL;
122 return MAP_FAILED;
123 }
124
125 // Prevent allocations large enough for `end - start` to overflow,
126 // to avoid security bugs.
127 size_t rounded = __BIONIC_ALIGN(size, page_size());
128 if (rounded < size || rounded > PTRDIFF_MAX) {
129 errno = ENOMEM;
130 return MAP_FAILED;
131 }
132
133 return __mmap2(addr, size, prot, flags, fd, offset >> MMAP2_SHIFT);
134 }
135
mmap(void * addr,size_t size,int prot,int flags,int fd,off_t offset)136 void* mmap(void* addr, size_t size, int prot, int flags, int fd, off_t offset) {
137 return mmap64(addr, size, prot, flags, fd, static_cast<off64_t>(offset));
138 }
139
140 // The only difference here is that the libc API uses varargs for the
141 // optional `new_address` argument that's only used by MREMAP_FIXED.
142 extern "C" void* __mremap(void*, size_t, size_t, int, void*);
143
mremap(void * old_address,size_t old_size,size_t new_size,int flags,...)144 void* mremap(void* old_address, size_t old_size, size_t new_size, int flags, ...) {
145 // Prevent allocations large enough for `end - start` to overflow,
146 // to avoid security bugs.
147 size_t rounded = __BIONIC_ALIGN(new_size, page_size());
148 if (rounded < new_size || rounded > PTRDIFF_MAX) {
149 errno = ENOMEM;
150 return MAP_FAILED;
151 }
152
153 // The optional argument is only valid if the MREMAP_FIXED flag is set,
154 // so we assume it's not present otherwise.
155 void* new_address = nullptr;
156 if ((flags & MREMAP_FIXED) != 0) {
157 va_list ap;
158 va_start(ap, flags);
159 new_address = va_arg(ap, void*);
160 va_end(ap);
161 }
162 return __mremap(old_address, old_size, new_size, flags, new_address);
163 }
164