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Implements (untested not debuged) child embeding

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Yann Weber 2023-03-08 19:49:32 +01:00
commit ff6aa5c8e0
4 changed files with 43 additions and 10 deletions
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42
asm_env.c
View file

@ -15,8 +15,15 @@
*/
#include "asm_env.h"
static int _asmsh_env_spawn(asmsh_env_t *asmenv, const char *childpath);
static int _asmsh_env_spawn(asmsh_env_t *asmenv);
static void _asmsh_env_child(const char *childpath);
/** Return a path (that should be freed) of a temporary executable
* child that can be exec on */
static char *asmsh_env_tmpexec();
/* binary buffer of the child elf */
extern unsigned char _binary_child_start;
extern unsigned char _binary_child_end;
asmsh_env_t* asmsh_env(const char *childpath)
{
@ -32,12 +39,13 @@ asmsh_env_t* asmsh_env(const char *childpath)
}
child_mmap_init(&(res->mmap));
if((res->childpath = strdup(childpath)) == NULL)
res->childpath = NULL;
if(childpath && (res->childpath = strdup(childpath)) == NULL)
{
goto err_pathdup;
}
if(_asmsh_env_spawn(res, childpath) < 0)
if(_asmsh_env_spawn(res) < 0)
{
err = errno;
goto err;
@ -249,11 +257,13 @@ int asmsh_env_update_regs(asmsh_env_t *asmenv)
}
static int _asmsh_env_spawn(asmsh_env_t *env, const char *childpath)
static int _asmsh_env_spawn(asmsh_env_t *env)
{
int err;
int wstatus;
const char *childpath = env->childpath?env->childpath:asmsh_env_tmpexec();
if((env->pid = fork()) == -1)
{
err = errno;
@ -263,7 +273,7 @@ static int _asmsh_env_spawn(asmsh_env_t *env, const char *childpath)
else if(env->pid == 0)
{
free(env);
_asmsh_env_child(childpath?childpath:ASMSH_CHILD_PATH_DEFAULT);
_asmsh_env_child(childpath);
}
if(ptrace(PTRACE_ATTACH, env->pid, 0, 0) == -1)
@ -347,6 +357,8 @@ static int _asmsh_env_spawn(asmsh_env_t *env, const char *childpath)
}
}
if(!env->childpath) { unlink(childpath); } // rm tmp child exec
return 0;
/// TODO replace by an utility function that logs ?
@ -378,6 +390,9 @@ err_wstatus:
err:
kill(env->pid, SIGKILL);
err_fork:
if(!env->childpath) { unlink(childpath); } // rm tmp child exec
errno = err;
return -1;
}
@ -399,3 +414,20 @@ static void _asmsh_env_child(const char *childpath)
exit(err?err:-1);
}
static char *asmsh_env_tmpexec()
{
char *ret = strdup("asmsh_child_XXXXXXXXX");
int tmpfd = mkstemp(ret);
const int sz = &_binary_child_end - &_binary_child_start;
int rsz = write(tmpfd, &_binary_child_start, sz);
if(rsz<sz)
{
perror("Unable to write the child executable");
free(ret);
return NULL;
}
fchmod(tmpfd, 0555);
close(tmpfd);
return ret;
}

2
asm_env.h
View file

@ -31,8 +31,6 @@
///! Initial size of the child's memory map with PROT_EXEC permission
#define ASMSH_CHILD_TEXT_MAP_SZ 0x1000 // defined in child.s
#define ASMSH_CHILD_PATH_DEFAULT "./child"
typedef struct asmsh_env_s asmsh_env_t;
struct asmsh_env_s

7
config.h.in
View file

@ -9,8 +9,8 @@
/* Define to 1 if you have the `fork' function. */
#undef HAVE_FORK
/* Define to 1 if you have the `gmtime_r' function. */
#undef HAVE_GMTIME_R
/* Define to 1 if you have the `gmtime_r,' function. */
#undef HAVE_GMTIME_R_
/* Define to 1 if you have the <inttypes.h> header file. */
#undef HAVE_INTTYPES_H
@ -28,6 +28,9 @@
/* Define to 1 if you have the <memory.h> header file. */
#undef HAVE_MEMORY_H
/* Define to 1 if you have the `ptrace' function. */
#undef HAVE_PTRACE
/* Define to 1 if your system has a GNU libc compatible `realloc' function,
and to 0 otherwise. */
#undef HAVE_REALLOC

2
configure.ac
View file

@ -73,7 +73,7 @@ AC_TYPE_SIZE_T
AC_FUNC_FORK
AC_FUNC_MALLOC
AC_FUNC_REALLOC
AC_CHECK_FUNCS([bzero strtoull, gmtime_r])
AC_CHECK_FUNCS([bzero strtoull, gmtime_r, ptrace])
AC_CONFIG_FILES([Makefile tests/Makefile tests/samples/Makefile])
AC_OUTPUT