cosmopolitan/libc/runtime/mmap.c
Justine Tunney 7166679620 Fix bugs and add security features to redbean
- Fix a regression with the previous change that broke redbean
- Add chroot(), resource limit, seccomp, and other stuff to redbean
- Write lots and lots of documentation
- Iron out more system call issues
2022-04-18 00:01:26 -07:00

324 lines
12 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/bits/likely.h"
#include "libc/bits/weaken.h"
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/strace.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/asan.internal.h"
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/kprintf.h"
#include "libc/log/backtrace.internal.h"
#include "libc/log/libfatal.internal.h"
#include "libc/log/log.h"
#include "libc/macros.internal.h"
#include "libc/nt/process.h"
#include "libc/nt/runtime.h"
#include "libc/nt/struct/processmemorycounters.h"
#include "libc/rand/rand.h"
#include "libc/runtime/directmap.internal.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/memtrack.internal.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/consts/prot.h"
#include "libc/sysv/errfuns.h"
#define IP(X) (intptr_t)(X)
#define VIP(X) (void *)IP(X)
#define ALIGNED(p) (!(IP(p) & (FRAMESIZE - 1)))
#define ADDR(x) ((int64_t)((uint64_t)(x) << 32) >> 16)
#define SHADE(x) (((intptr_t)(x) >> 3) + 0x7fff8000)
#define FRAME(x) ((int)((intptr_t)(x) >> 16))
static wontreturn void OnUnrecoverableMmapError(const char *s) {
if (weaken(__die)) weaken(__die)();
STRACE("%s %m", s);
__restorewintty();
_Exit(199);
}
noasan static bool IsMapped(char *p, size_t n) {
return OverlapsImageSpace(p, n) || IsMemtracked(FRAME(p), FRAME(p + (n - 1)));
}
noasan static bool NeedAutomap(char *p, size_t n) {
return !p || OverlapsArenaSpace(p, n) || OverlapsShadowSpace(p, n) ||
IsMapped(p, n);
}
noasan static bool ChooseMemoryInterval(int x, int n, int *res) {
int i;
if (_mmi.i) {
i = FindMemoryInterval(&_mmi, x);
if (i < _mmi.i) {
if (x + n < _mmi.p[i].x) {
*res = x;
return true;
}
while (++i < _mmi.i) {
if (_mmi.p[i].x - _mmi.p[i - 1].y > n) {
*res = _mmi.p[i - 1].y + 1;
return true;
}
}
}
if (INT_MAX - _mmi.p[i - 1].y >= n) {
*res = _mmi.p[i - 1].y + 1;
return true;
}
return false;
} else {
*res = x;
return true;
}
}
noasan static bool Automap(int n, int *res) {
*res = -1;
if (ChooseMemoryInterval(FRAME(kAutomapStart), n, res)) {
assert(*res >= FRAME(kAutomapStart));
if (*res + n <= FRAME(kAutomapStart + (kAutomapStart - 1))) {
return true;
} else {
STRACE("mmap(%.12p, %p) ENOMEM (automap interval exhausted)", ADDR(*res),
ADDR(n + 1));
return false;
}
} else {
STRACE("mmap(%.12p, %p) ENOMEM (automap failed)", ADDR(*res), ADDR(n + 1));
return false;
}
}
noasan static size_t GetMemtrackSize(struct MemoryIntervals *mm) {
size_t i, n;
for (n = i = 0; i < mm->i; ++i) {
n += ((size_t)(mm->p[i].y - mm->p[i].x) + 1) << 16;
}
return n;
}
static noasan void *MapMemory(void *addr, size_t size, int prot, int flags,
int fd, int64_t off, int f, int x, int n) {
struct DirectMap dm;
dm = sys_mmap(addr, size, prot, f, fd, off);
if (UNLIKELY(dm.addr == MAP_FAILED)) {
if (IsWindows() && (flags & MAP_FIXED)) {
OnUnrecoverableMmapError(
"can't recover from MAP_FIXED errors on Windows");
}
return MAP_FAILED;
}
if (UNLIKELY(dm.addr != addr)) {
OnUnrecoverableMmapError("KERNEL DIDN'T RESPECT MAP_FIXED");
}
if (!IsWindows() && (flags & MAP_FIXED)) {
if (UntrackMemoryIntervals(addr, size)) {
OnUnrecoverableMmapError("FIXED UNTRACK FAILED");
}
}
if (TrackMemoryInterval(&_mmi, x, x + (n - 1), dm.maphandle, prot, flags,
false, false, off, size)) {
if (sys_munmap(addr, n) == -1) {
OnUnrecoverableMmapError("TRACK MUNMAP FAILED");
}
return MAP_FAILED;
}
if (weaken(__asan_map_shadow) && !OverlapsShadowSpace(addr, size)) {
weaken(__asan_map_shadow)((intptr_t)addr, size);
}
return addr;
}
/**
* Maps memory from system, one frame at a time.
*
* This is useful on Windows since it allows us to partially unmap or
* punch holes into existing mappings.
*/
static textwindows dontinline noasan void *MapMemories(char *addr, size_t size,
int prot, int flags,
int fd, int64_t off,
int f, int x, int n) {
size_t i, m;
int64_t oi, sz;
struct DirectMap dm;
bool iscow, readonlyfile;
m = (size_t)(n - 1) << 16;
assert(m < size);
assert(m + FRAMESIZE >= size);
oi = fd == -1 ? 0 : off + m;
sz = size - m;
dm = sys_mmap(addr + m, sz, prot, f, fd, oi);
if (dm.addr == MAP_FAILED) return MAP_FAILED;
iscow = (flags & MAP_PRIVATE) && fd != -1;
readonlyfile = (flags & MAP_SHARED) && fd != -1 &&
(g_fds.p[fd].flags & O_ACCMODE) == O_RDONLY;
if (TrackMemoryInterval(&_mmi, x + (n - 1), x + (n - 1), dm.maphandle, prot,
flags, readonlyfile, iscow, oi, sz) == -1) {
OnUnrecoverableMmapError("MapMemories unrecoverable #1");
}
for (i = 0; i < m; i += FRAMESIZE) {
oi = fd == -1 ? 0 : off + i;
sz = FRAMESIZE;
dm = sys_mmap(addr + i, sz, prot, f, fd, oi);
if (dm.addr == MAP_FAILED ||
TrackMemoryInterval(&_mmi, x + i / FRAMESIZE, x + i / FRAMESIZE,
dm.maphandle, prot, flags, readonlyfile, iscow, oi,
sz) == -1) {
OnUnrecoverableMmapError("MapMemories unrecoverable #2");
}
}
if (weaken(__asan_map_shadow) && !OverlapsShadowSpace(addr, size)) {
weaken(__asan_map_shadow)((intptr_t)addr, size);
}
return addr;
}
/**
* Beseeches system for page-table entries, e.g.
*
* char *m;
* m = mmap(NULL, FRAMESIZE, PROT_READ | PROT_WRITE,
* MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
* munmap(m, FRAMESIZE);
*
* @param addr should be 0 to let your memory manager choose address;
* unless MAP_FIXED or MAP_FIXED_NOREPLACE are specified in flags
* in which case this function will do precicely as you ask, even
* if p=0 (in which you need -fno-delete-null-pointer-checks); it
* needs to be 64kb aligned because it's a wise choice that sadly
* needs to be made mandatory because of Windows although you can
* use __sys_mmap() to circumvent it on System Five in which case
* runtime support services, e.g. asan memory safety, could break
* @param size must be >0 and needn't be a multiple of FRAMESIZE, but
* will be rounded up to FRAMESIZE automatically if MAP_ANONYMOUS
* is specified
* @param prot can have PROT_READ/PROT_WRITE/PROT_EXEC/PROT_NONE/etc.
* @param flags can have MAP_ANONYMOUS, MAP_SHARED, MAP_PRIVATE, etc.
* @param fd is an open()'d file descriptor, whose contents shall be
* made available w/ automatic reading at the chosen address and
* must be -1 if MAP_ANONYMOUS is specified
* @param off specifies absolute byte index of fd's file for mapping,
* should be zero if MAP_ANONYMOUS is specified, and sadly needs
* to be 64kb aligned too
* @return virtual base address of new mapping, or MAP_FAILED w/ errno
*/
noasan void *mmap(void *addr, size_t size, int prot, int flags, int fd,
int64_t off) {
STRACE("mmap(%p, %'zu, %s, %s, %d, %'ld) → ...", addr, size,
DescribeProtFlags(prot), DescribeMapFlags(flags), fd, off);
void *res;
char *p = addr;
struct DirectMap dm;
size_t virtualused, virtualneed;
int a, b, i, f, m, n, x;
if (UNLIKELY(!size)) {
STRACE("size=0");
res = VIP(einval());
} else if (UNLIKELY(!IsLegalSize(size))) {
STRACE("size isn't 48-bit");
res = VIP(einval());
} else if (UNLIKELY(!IsLegalPointer(p))) {
STRACE("p isn't 48-bit");
res = VIP(einval());
} else if (UNLIKELY(!ALIGNED(p))) {
STRACE("p isn't 64kb aligned");
res = VIP(einval());
} else if (UNLIKELY(fd < -1)) {
STRACE("mmap(%.12p, %'zu, fd=%d) EBADF", p, size, fd);
res = VIP(ebadf());
} else if (UNLIKELY(!((fd != -1) ^ !!(flags & MAP_ANONYMOUS)))) {
STRACE("fd anonymous mismatch");
res = VIP(einval());
} else if (UNLIKELY(!(!!(flags & MAP_PRIVATE) ^ !!(flags & MAP_SHARED)))) {
STRACE("MAP_SHARED ^ MAP_PRIVATE");
res = VIP(einval());
} else if (UNLIKELY(off < 0)) {
STRACE("neg off");
res = VIP(einval());
} else if (UNLIKELY(INT64_MAX - size < off)) {
STRACE("too large");
res = VIP(einval());
} else if (UNLIKELY(!ALIGNED(off))) {
STRACE("p isn't 64kb aligned");
res = VIP(einval());
} else if ((flags & MAP_FIXED_NOREPLACE) && IsMapped(p, size)) {
#ifdef SYSDEBUG
if (OverlapsImageSpace(p, size)) {
STRACE("overlaps image");
} else {
STRACE("overlaps existing");
}
#endif
res = VIP(efault());
} else if (__isfdkind(fd, kFdZip)) {
STRACE("fd is zipos handle");
res = VIP(einval());
} else if (__virtualmax &&
(__builtin_add_overflow((virtualused = GetMemtrackSize(&_mmi)),
size, &virtualneed) ||
virtualneed > __virtualmax)) {
STRACE("%'zu size + %'zu inuse exceeds virtual memory limit %'zu", size,
virtualused, __virtualmax);
res = VIP(enomem());
} else {
if (fd == -1) {
size = ROUNDUP(size, FRAMESIZE);
if (IsWindows()) {
prot |= PROT_WRITE; /* kludge */
}
}
n = (int)(size >> 16) + !!(size & (FRAMESIZE - 1));
assert(n > 0);
f = (flags & ~MAP_FIXED_NOREPLACE) | MAP_FIXED;
if (flags & MAP_FIXED) {
x = FRAME(p);
if (IsWindows()) {
if (UntrackMemoryIntervals(p, size)) {
OnUnrecoverableMmapError("FIXED UNTRACK FAILED");
}
}
} else if (!NeedAutomap(p, size)) {
x = FRAME(p);
} else if (!Automap(n, &x)) {
STRACE("AUTOMAP OUT OF MEMORY D:");
return VIP(enomem());
}
p = (char *)ADDR(x);
if (IsOpenbsd() && (f & MAP_GROWSDOWN)) { /* openbsd:dubstack */
dm = sys_mmap(p, size, prot, f & ~MAP_GROWSDOWN, fd, off);
if (dm.addr == MAP_FAILED) res = MAP_FAILED;
}
if (!IsWindows()) {
res = MapMemory(p, size, prot, flags, fd, off, f, x, n);
} else {
res = MapMemories(p, size, prot, flags, fd, off, f, x, n);
}
}
STRACE("mmap(%p, %'zu, %s, %s, %d, %'ld) → %p% m", addr, size,
DescribeProtFlags(prot), DescribeMapFlags(flags), fd, off, res);
return res;
}