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fexecve: fix running APEs with FD_CLOEXEC, avoid double fd to memfd conversion

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This commit is contained in:
Gavin Hayes 2023-02-24 10:43:28 -05:00
parent 34133019bc
commit 8b5a6ad642
3 changed files with 51 additions and 20 deletions
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2
libc/calls/execve-sysv.c
View file

@ -79,7 +79,7 @@ int sys_execve(const char *prog, char *const argv[], char *const envp[]) {
const char *ape;
struct ZiposUri uri;
if (_weaken(__zipos_parseuri) && (_weaken(__zipos_parseuri)(prog, &uri) != -1)) {
rc = _weaken(__zipos_open)(&uri, O_RDONLY, 0);
rc = _weaken(__zipos_open)(&uri, O_RDONLY | O_CLOEXEC, 0);
if (rc != -1) {
const int zipFD = rc;
strace_enabled(-1);

52
libc/calls/fexecve.c
View file

@ -33,6 +33,8 @@
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/weaken.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/f.h"
#include "libc/sysv/consts/fd.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/mfd.h"
#include "libc/sysv/consts/o.h"
@ -162,7 +164,9 @@ static int fd_to_mem_fd(const int infd, char *path) {
* Executes binary executable at file descriptor.
*
* This is only supported on Linux and FreeBSD. APE binaries are
* supported. Zipos is supported.
* supported. Zipos is supported. Zipos fds or FD_CLOEXEC APE fds or
* fds that fail fexecve with ENOEXEC are copied to a new memfd (with
* in-memory APE to ELF conversion) and fexecve is (re)attempted.
*
* @param fd is opened executable and current file position is ignored
* @return doesn't return on success, otherwise -1 w/ errno
@ -170,7 +174,7 @@ static int fd_to_mem_fd(const int infd, char *path) {
* @raise ENOSYS on Windows, XNU, OpenBSD, NetBSD, and Metal
*/
int fexecve(int fd, char *const argv[], char *const envp[]) {
int rc;
int rc = 0;
if (!argv || !envp ||
(IsAsan() &&
(!__asan_is_valid_strlist(argv) || !__asan_is_valid_strlist(envp)))) {
@ -179,41 +183,57 @@ int fexecve(int fd, char *const argv[], char *const envp[]) {
STRACE("fexecve(%d, %s, %s) → ...", fd, DescribeStringList(argv),
DescribeStringList(envp));
do {
int fexecvefd = fd;
if (__isfdkind(fd, kFdZip)) {
if(!IsLinux() && !IsFreebsd()) {
rc = enosys();
break;
}
if(!__isfdkind(fd, kFdZip)) {
bool memfdReq;
BEGIN_CANCELLATION_POINT;
BLOCK_SIGNALS;
strace_enabled(-1);
rc = fd_to_mem_fd(fd, NULL);
memfdReq = ((rc = fcntl(fd, F_GETFD)) != -1) && (rc & FD_CLOEXEC) && IsAPEFd(fd);
strace_enabled(+1);
ALLOW_SIGNALS;
END_CANCELLATION_POINT;
if (rc == -1) {
break;
}
fexecvefd = rc;
}
rc = fexecve_impl(fexecvefd, argv, envp);
if ((errno != ENOEXEC) || (!IsLinux() && !IsFreebsd())) {
} else if (!memfdReq) {
rc = fexecve_impl(fd, argv, envp);
if (errno != ENOEXEC) {
break;
}
int newfd = -1;
}
}
int newfd;
BEGIN_CANCELLATION_POINT;
BLOCK_SIGNALS;
strace_enabled(-1);
if (IsAPEFd(fexecvefd)) {
newfd = fd_to_mem_fd(fexecvefd, NULL);
}
newfd = fd_to_mem_fd(fd, NULL);
strace_enabled(+1);
ALLOW_SIGNALS;
END_CANCELLATION_POINT;
if (newfd != -1) {
rc = fexecve_impl(newfd, argv, envp);
if (newfd == -1) {
if (rc == -1) {
errno = ENOEXEC;
}
rc = -1;
break;
}
fexecve_impl(newfd, argv, envp);
if (rc == -1) {
errno = ENOEXEC;
}
rc = -1;
const int savedErr = errno;
BEGIN_CANCELLATION_POINT;
BLOCK_SIGNALS;
strace_enabled(-1);
close(newfd);
strace_enabled(+1);
ALLOW_SIGNALS;
END_CANCELLATION_POINT;
errno = savedErr;
} while (0);
}
STRACE("fexecve(%d) failed %d% m", fd, rc);

11
test/libc/calls/fexecve_test.c
View file

@ -100,6 +100,17 @@ TEST(fexecve, APE) {
EXITS(42);
}
TEST(fexecve, APE_cloexec) {
if (!IsLinux() && !IsFreebsd()) return;
testlib_extract("/zip/life-nomod.com", "life-nomod.com", 0555);
SPAWN(fork);
int fd = open("life-nomod.com", O_RDONLY | O_CLOEXEC);
ASSERT_NE(-1, fd);
if (fd == -1 && errno == ENOSYS) _Exit(42);
fexecve(fd, (char *const[]){0}, (char *const[]){0});
EXITS(42);
}
TEST(fexecve, zipos) {
if (!IsLinux() && !IsFreebsd()) return;
int fd = open("/zip/life.elf", O_RDONLY);