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APE fexecve - attempt *-safety, tame strace

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This commit is contained in:
Gavin Hayes 2023-02-06 10:58:54 -05:00
parent 3b2b724ac7
commit 181afad089
1 changed files with 15 additions and 15 deletions
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30
libc/calls/fexecve.c
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@ -18,6 +18,7 @@
╚─────────────────────────────────────────────────────────────────────────────*/ ╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h" #include "libc/assert.h"
#include "libc/calls/blockcancel.internal.h" #include "libc/calls/blockcancel.internal.h"
#include "libc/calls/blocksigs.internal.h"
#include "libc/calls/calls.h" #include "libc/calls/calls.h"
#include "libc/calls/cp.internal.h" #include "libc/calls/cp.internal.h"
#include "libc/calls/execve-sysv.internal.h" #include "libc/calls/execve-sysv.internal.h"
@ -41,11 +42,7 @@
static bool IsAPEFd(const int fd) { static bool IsAPEFd(const int fd) {
char buf[8]; char buf[8];
bool res; bool res;
// TODO(jart): Should we block signals too? return (sys_pread(fd, buf, 8, 0, 0) == 8) && IsAPEMagic(buf);
BLOCK_CANCELLATIONS;
res = (sys_pread(fd, buf, 8, 0, 0) == 8) && IsAPEMagic(buf);
ALLOW_CANCELLATIONS;
return res;
} }
static int fexecve_impl(const int fd, char *const argv[], char *const envp[]) { static int fexecve_impl(const int fd, char *const argv[], char *const envp[]) {
@ -109,7 +106,7 @@ static bool ape_to_elf(void *ape, const size_t apesize) {
} }
static int ape_fd_to_mem_elf_fd(const int infd, char *path) { static int ape_fd_to_mem_elf_fd(const int infd, char *path) {
if (!IsLinux() && !IsFreebsd()) { if (!IsLinux() && !IsFreebsd() || !_weaken(mmap) || !_weaken(munmap)) {
return enosys(); return enosys();
} }
@ -132,17 +129,11 @@ static int ape_fd_to_mem_elf_fd(const int infd, char *path) {
return -1; return -1;
} }
void *space; void *space;
int rc; if ((sys_ftruncate(fd, st.st_size, st.st_size) != -1) &&
BEGIN_CANCELLATION_POINT;
rc = sys_ftruncate(fd, st.st_size, st.st_size);
END_CANCELLATION_POINT;
if ((rc != -1) &&
((space = _weaken(mmap)(0, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, ((space = _weaken(mmap)(0, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED,
fd, 0)) != MAP_FAILED)) { fd, 0)) != MAP_FAILED)) {
ssize_t readRc; ssize_t readRc;
BEGIN_CANCELLATION_POINT;
readRc = sys_pread(infd, space, st.st_size, 0, 0); readRc = sys_pread(infd, space, st.st_size, 0, 0);
END_CANCELLATION_POINT;
bool success = readRc != -1; bool success = readRc != -1;
if (success && (st.st_size > 8) && IsAPEMagic(space)) { if (success && (st.st_size > 8) && IsAPEMagic(space)) {
success = ape_to_elf(space, st.st_size); success = ape_to_elf(space, st.st_size);
@ -182,8 +173,17 @@ int fexecve(int fd, char *const argv[], char *const envp[]) {
STRACE("fexecve(%d, %s, %s) → ...", fd, DescribeStringList(argv), STRACE("fexecve(%d, %s, %s) → ...", fd, DescribeStringList(argv),
DescribeStringList(envp)); DescribeStringList(envp));
rc = fexecve_impl(fd, argv, envp); rc = fexecve_impl(fd, argv, envp);
if ((errno == ENOEXEC) && (IsLinux() || IsFreebsd()) && IsAPEFd(fd)) { if ((errno == ENOEXEC) && (IsLinux() || IsFreebsd())) {
const int newfd = ape_fd_to_mem_elf_fd(fd, NULL); int newfd = -1;
BEGIN_CANCELLATION_POINT;
BLOCK_SIGNALS;
strace_enabled(-1);
if (IsAPEFd(fd)) {
newfd = ape_fd_to_mem_elf_fd(fd, NULL);
}
strace_enabled(+1);
ALLOW_SIGNALS;
END_CANCELLATION_POINT;
if (newfd != -1) { if (newfd != -1) {
rc = fexecve_impl(newfd, argv, envp); rc = fexecve_impl(newfd, argv, envp);
} }