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Make ZipOS mmap safer (#735)

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- It now runs entirely under __mmi_lock
- Hide implementation strace
This commit is contained in:
Gavin Hayes 2023-02-22 21:57:36 -05:00 • committed by GitHub
parent e323527ffa
commit b275e664ec
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GPG key ID: 4AEE18F83AFDEB23
6 changed files with 44 additions and 29 deletions
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41
libc/zipos/mmap.c
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@ -22,6 +22,7 @@
#include "libc/errno.h"
#include "libc/intrin/likely.h"
#include "libc/intrin/strace.internal.h"
#include "libc/runtime/internal.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/prot.h"
#include "libc/sysv/errfuns.h"
@ -46,8 +47,8 @@
* it does not need to be 64kb aligned.
* @return virtual base address of new mapping, or MAP_FAILED w/ errno
*/
void *__zipos_mmap(void *addr, size_t size, int prot, int flags,
struct ZiposHandle *h, int64_t off) {
noasan void *__zipos_Mmap(void *addr, size_t size, int prot, int flags,
struct ZiposHandle *h, int64_t off) {
if (!(flags & MAP_PRIVATE) ||
(flags & ~(MAP_PRIVATE | MAP_FILE | MAP_FIXED | MAP_FIXED_NOREPLACE)) ||
(!!(flags & MAP_FIXED) ^ !!(flags & MAP_FIXED_NOREPLACE))) {
@ -56,21 +57,33 @@ void *__zipos_mmap(void *addr, size_t size, int prot, int flags,
return VIP(einval());
}
if (VERY_UNLIKELY(off < 0)) {
STRACE("neg off");
return VIP(einval());
}
const int tempProt = !IsXnu() ? prot | PROT_WRITE : PROT_WRITE;
void *outAddr =
mmap(addr, size, tempProt, (flags & (~MAP_FILE)) | MAP_ANONYMOUS, -1, 0);
Mmap(addr, size, tempProt, (flags & (~MAP_FILE)) | MAP_ANONYMOUS, -1, 0);
if (outAddr == MAP_FAILED) {
return MAP_FAILED;
}
const int64_t beforeOffset = __zipos_lseek(h, 0, SEEK_CUR);
if ((beforeOffset == -1) ||
(__zipos_read(h, &(struct iovec){outAddr, size}, 1, off) == -1) ||
(__zipos_lseek(h, beforeOffset, SEEK_SET) == -1) ||
((prot != tempProt) && (mprotect(outAddr, size, prot) == -1))) {
const int e = errno;
munmap(outAddr, size);
errno = e;
return MAP_FAILED;
}
return outAddr;
do {
if (__zipos_read(h, &(struct iovec){outAddr, size}, 1, off) == -1) {
strace_enabled(-1);
break;
} else if (prot != tempProt) {
strace_enabled(-1);
if (mprotect(outAddr, size, prot) == -1) {
break;
}
strace_enabled(+1);
}
return outAddr;
} while (0);
const int e = errno;
Munmap(outAddr, size);
errno = e;
strace_enabled(+1);
return MAP_FAILED;
}