int can_do_skas(void)
{
#ifdef UML_CONFIG_MODE_SKAS
struct ptrace_faultinfo fi;
void *stack;
int pid, n, ret = 1;
printf("Checking for the skas3 patch in the host...");
pid = start_ptraced_child(&stack);
n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
if(n < 0){
if(errno == EIO)
printf("not found\n");
else printf("No (unexpected errno - %d)\n", errno);
ret = 0;
}
else printf("found\n");
init_registers(pid);
stop_ptraced_child(pid, stack, 1, 1);
printf("Checking for /proc/mm...");
if(os_access("/proc/mm", OS_ACC_W_OK) < 0){
printf("not found\n");
ret = 0;
}
else printf("found\n");
return(ret);
#else
return(0);
#endif
}
void __init check_ptrace(void)
{
void *stack;
int pid, syscall, n, status;
printk("Checking that ptrace can change system call numbers...");
pid = start_ptraced_child(&stack);
while(1){
if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
panic("check_ptrace : ptrace failed, errno = %d",
errno);
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0)
panic("check_ptrace : wait failed, errno = %d", errno);
if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
panic("check_ptrace : expected SIGTRAP, "
"got status = %d", status);
syscall = ptrace(PTRACE_PEEKUSER, pid, PT_SYSCALL_NR_OFFSET,
0);
if(syscall == __NR_getpid){
n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
__NR_getppid);
if(n < 0)
panic("check_ptrace : failed to modify system "
"call, errno = %d", errno);
break;
}
}
stop_ptraced_child(pid, stack, 0, 1);
printk("OK\n");
check_sysemu();
}
void __init os_early_checks(void)
{
int pid;
/* Print out the core dump limits early */
check_coredump_limit();
check_ptrace();
/* Need to check this early because mmapping happens before the
* kernel is running.
*/
check_tmpexec();
pid = start_ptraced_child();
if (init_registers(pid))
fatal("Failed to initialize default registers");
stop_ptraced_child(pid, 1, 1);
}
static void __init check_sysemu(void)
{
void *stack;
int pid, n, status;
printk("Checking syscall emulation patch for ptrace...");
sysemu_supported = 0;
pid = start_ptraced_child(&stack);
if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
goto fail;
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if (n < 0)
panic("check_sysemu : wait failed, errno = %d", errno);
if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
panic("check_sysemu : expected SIGTRAP, "
"got status = %d", status);
n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET,
os_getpid());
if(n < 0)
panic("check_sysemu : failed to modify system "
"call return, errno = %d", errno);
if (stop_ptraced_child(pid, stack, 0, 0) < 0)
goto fail_stopped;
sysemu_supported = 1;
printk("OK\n");
set_using_sysemu(!force_sysemu_disabled);
return;
fail:
stop_ptraced_child(pid, stack, 1, 0);
fail_stopped:
sysemu_supported = 0;
printk("missing\n");
}
static void __init check_ptrace(void)
{
int pid, syscall, n, status;
non_fatal("Checking that ptrace can change system call numbers...");
pid = start_ptraced_child();
if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
(void *) PTRACE_O_TRACESYSGOOD) < 0))
fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
while (1) {
if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
fatal_perror("check_ptrace : ptrace failed");
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if (n < 0)
fatal_perror("check_ptrace : wait failed");
if (!WIFSTOPPED(status) ||
(WSTOPSIG(status) != (SIGTRAP | 0x80)))
fatal("check_ptrace : expected (SIGTRAP|0x80), "
"got status = %d", status);
syscall = ptrace(PTRACE_PEEKUSER, pid, PT_SYSCALL_NR_OFFSET,
0);
if (syscall == __NR_getpid) {
n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
__NR_getppid);
if (n < 0)
fatal_perror("check_ptrace : failed to modify "
"system call");
break;
}
}
stop_ptraced_child(pid, 0, 1);
non_fatal("OK\n");
check_sysemu();
}
static void __init check_sysemu(void)
{
unsigned long regs[MAX_REG_NR];
int pid, n, status, count=0;
non_fatal("Checking syscall emulation patch for ptrace...");
sysemu_supported = 0;
pid = start_ptraced_child();
if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
goto fail;
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if (n < 0)
fatal_perror("check_sysemu : wait failed");
if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
fatal("check_sysemu : expected SIGTRAP, got status = %d\n",
status);
if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
fatal_perror("check_sysemu : PTRACE_GETREGS failed");
if (PT_SYSCALL_NR(regs) != __NR_getpid) {
non_fatal("check_sysemu got system call number %d, "
"expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
goto fail;
}
n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
if (n < 0) {
non_fatal("check_sysemu : failed to modify system call "
"return");
goto fail;
}
if (stop_ptraced_child(pid, 0, 0) < 0)
goto fail_stopped;
sysemu_supported = 1;
non_fatal("OK\n");
set_using_sysemu(!force_sysemu_disabled);
non_fatal("Checking advanced syscall emulation patch for ptrace...");
pid = start_ptraced_child();
if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
(void *) PTRACE_O_TRACESYSGOOD) < 0))
fatal_perror("check_sysemu: PTRACE_OLDSETOPTIONS failed");
while (1) {
count++;
if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
goto fail;
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if (n < 0)
fatal_perror("check_sysemu: wait failed");
if (WIFSTOPPED(status) &&
(WSTOPSIG(status) == (SIGTRAP|0x80))) {
if (!count) {
non_fatal("check_sysemu: SYSEMU_SINGLESTEP "
"doesn't singlestep");
goto fail;
}
n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET,
os_getpid());
if (n < 0)
fatal_perror("check_sysemu : failed to modify "
"system call return");
break;
}
else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
count++;
else {
non_fatal("check_sysemu: expected SIGTRAP or "
"(SIGTRAP | 0x80), got status = %d\n",
status);
goto fail;
}
}
if (stop_ptraced_child(pid, 0, 0) < 0)
goto fail_stopped;
sysemu_supported = 2;
non_fatal("OK\n");
if (!force_sysemu_disabled)
set_using_sysemu(sysemu_supported);
return;
fail:
stop_ptraced_child(pid, 1, 0);
fail_stopped:
non_fatal("missing\n");
}
