/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sched.h>
#include <signal.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/ptrace.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <asm/unistd.h>
#include "init.h"
#include "kern_constants.h"
#include "os.h"
#include "mem_user.h"
#include "ptrace_user.h"
#include "registers.h"
#include "skas_ptrace.h"
static int ptrace_child(void)
{
int ret;
/* Calling os_getpid because some libcs cached getpid incorrectly */
int pid = os_getpid(), ppid = getppid();
int sc_result;
change_sig(SIGWINCH, 0);
if (ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) {
perror("ptrace");
kill(pid, SIGKILL);
}
kill(pid, SIGSTOP);
/*
* This syscall will be intercepted by the parent. Don't call more than
* once, please.
*/
sc_result = os_getpid();
if (sc_result == pid)
/* Nothing modified by the parent, we are running normally. */
ret = 1;
else if (sc_result == ppid)
/*
* Expected in check_ptrace and check_sysemu when they succeed
* in modifying the stack frame
*/
ret = 0;
else
/* Serious trouble! This could be caused by a bug in host 2.6
* SKAS3/2.6 patch before release -V6, together with a bug in
* the UML code itself.
*/
ret = 2;
_exit(ret);
}
static void fatal_perror(char *str)
{
perror(str);
exit(1);
}
static void fatal(char *fmt, ...)
{
va_list list;
va_start(list, fmt);
vprintf(fmt, list);
va_end(list);
fflush(stdout);
exit(1);
}
static void non_fatal(char *fmt, ...)
{
va_list list;
va_start(list, fmt);
vprintf(fmt, list);
va_end(list);
fflush(stdout);
}
static int start_ptraced_child(void)
{
int pid, n, status;
pid = fork();
if (pid == 0)
ptrace_child();
else if (pid < 0)
fatal_perror("start_ptraced_child : fork failed");
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if (n < 0)
fatal_perror("check_ptrace : waitpid failed");
if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
fatal("check_ptrace : expected SIGSTOP, got status = %d",
status);
return pid;
}
/* When testing for SYSEMU support, if it is one of the broken versions, we
* must just avoid using sysemu, not panic, but only if SYSEMU features are
* broken.
* So only for SYSEMU features we test mustpanic, while normal host features
* must work anyway!
*/
static int stop_ptraced_child(int pid, int exitcode, int mustexit)
{
int status, n, ret = 0;
if (ptrace(PTRACE_CONT, pid, 0, 0) < 0)
fatal_perror("stop_ptraced_child : ptrace failed");
CATCH_EINTR(n = waitpid(pid, &status, 0));
if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
int exit_with = WEXITSTATUS(status);
if (exit_with == 2)
non_fatal("check_ptrace : child exited with status 2. "
"\nDisabling SYSEMU support.\n");
non_fatal("check_ptrace : child exited with exitcode %d, while "
"expecting %d; status 0x%x\n", exit_with,
exitcode, status);
if (mustexit)
exit(1);
ret = -1;
}
return ret;
}
/* Changed only during early boot */
int ptrace_faultinfo = 1;
int ptrace_ldt = 1;
int proc_mm = 1;
int skas_needs_stub = 0;
static int __init skas0_cmd_param(char *str, int* add)
{
ptrace_faultinfo = proc_mm = 0;
return 0;
}
/* The two __uml_setup would conflict, without this stupid alias. */
static int __init mode_skas0_cmd_param(char *str, int* add)
__attribute__((alias("skas0_cmd_param")));
__uml_setup("skas0", skas0_cmd_param,
"skas0\n"
" Disables SKAS3 usage, so that SKAS0 is used, unless \n"
" you specify mode=tt.\n\n");
__uml_setup("mode=skas0", mode_skas0_cmd_param,
"mode=skas0\n"
" Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
" specify mode=tt. Note that this was recently added - on \n"
" older kernels you must use simply \"skas0\".\n\n");
/* Changed only during early boot */
static int force_sysemu_disabled = 0;
static int __init nosysemu_cmd_param(char *str, int* add)
{
force_sysemu_disabled = 1;
return 0;
}
__uml_setup("nosysemu", nosysemu_cmd_param,
"nosysemu\n"
" Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
" SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
" behaviour of ptrace() and helps reducing host context switch rate.\n"
" To make it working, you need a kernel patch for your host, too.\n"
" See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
" information.\n\n");
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",
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_POKEUSR, 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_ptrace: 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_ptrace : wait failed");
if (WIFSTOPPED(status) &&
(WSTOPSIG(status) == (SIGTRAP|0x80))) {
if (!count)
fatal("check_ptrace : SYSEMU_SINGLESTEP "
"doesn't singlestep");
n = ptrace(PTRACE_POKEUSR, 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
fatal("check_ptrace : expected SIGTRAP or "
"(SIGTRAP | 0x80), got status = %d", status);
}
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");
}
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_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
0);
if (syscall == __NR_getpid) {
n = ptrace(PTRACE_POKEUSR, 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();
}
extern void check_tmpexec(void);
static void __init check_coredump_limit(void)
{
struct rlimit lim;
int err = getrlimit(RLIMIT_CORE, &lim);
if (err) {
perror("Getting core dump limit");
return;
}
printf("Core dump limits :\n\tsoft - ");
if (lim.rlim_cur == RLIM_INFINITY)
printf("NONE\n");
else printf("%lu\n", lim.rlim_cur);
printf("\thard - ");
if (lim.rlim_max == RLIM_INFINITY)
printf("NONE\n");
else printf("%lu\n", lim.rlim_max);
}
void __init os_early_checks(void)
{
/* 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();
}
static int __init noprocmm_cmd_param(char *str, int* add)
{
proc_mm = 0;
return 0;
}
__uml_setup("noprocmm", noprocmm_cmd_param,
"noprocmm\n"
" Turns off usage of /proc/mm, even if host supports it.\n"
" To support /proc/mm, the host needs to be patched using\n"
" the current skas3 patch.\n\n");
static int __init noptracefaultinfo_cmd_param(char *str, int* add)
{
ptrace_faultinfo = 0;
return 0;
}
__uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
"noptracefaultinfo\n"
" Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
" it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
" using the current skas3 patch.\n\n");
static int __init noptraceldt_cmd_param(char *str, int* add)
{
ptrace_ldt = 0;
return 0;
}
__uml_setup("noptraceldt", noptraceldt_cmd_param,
"noptraceldt\n"
" Turns off usage of PTRACE_LDT, even if host supports it.\n"
" To support PTRACE_LDT, the host needs to be patched using\n"
" the current skas3 patch.\n\n");
static inline void check_skas3_ptrace_faultinfo(void)
{
struct ptrace_faultinfo fi;
int pid, n;
non_fatal(" - PTRACE_FAULTINFO...");
pid = start_ptraced_child();
n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
if (n < 0) {
ptrace_faultinfo = 0;
if (errno == EIO)
non_fatal("not found\n");
else
perror("not found");
}
else {
if (!ptrace_faultinfo)
non_fatal("found but disabled on command line\n");
else
non_fatal("found\n");
}
init_registers(pid);
stop_ptraced_child(pid, 1, 1);
}
static inline void check_skas3_ptrace_ldt(void)
{
#ifdef PTRACE_LDT
int pid, n;
unsigned char ldtbuf[40];
struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
.func = 2, /* read default ldt */
.ptr = ldtbuf,
.bytecount = sizeof(ldtbuf)};
non_fatal(" - PTRACE_LDT...");
pid = start_ptraced_child();
n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
if (n < 0) {
if (errno == EIO)
non_fatal("not found\n");
else {
perror("not found");
}
ptrace_ldt = 0;
}
else {
if (ptrace_ldt)
non_fatal("found\n");
else
non_fatal("found, but use is disabled\n");
}
stop_ptraced_child(pid, 1, 1);
#else
/* PTRACE_LDT might be disabled via cmdline option.
* We want to override this, else we might use the stub
* without real need
*/
ptrace_ldt = 1;
#endif
}
static inline void check_skas3_proc_mm(void)
{
non_fatal(" - /proc/mm...");
if (access("/proc/mm", W_OK) < 0) {
proc_mm = 0;
perror("not found");
}
else if (!proc_mm)
non_fatal("found but disabled on command line\n");
else non_fatal("found\n");
}
int can_do_skas(void)
{
non_fatal("Checking for the skas3 patch in the host:\n");
check_skas3_proc_mm();
check_skas3_ptrace_faultinfo();
check_skas3_ptrace_ldt();
if (!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
skas_needs_stub = 1;
return 1;
}
int __init parse_iomem(char *str, int *add)
{
struct iomem_region *new;
struct stat64 buf;
char *file, *driver;
int fd, size;
driver = str;
file = strchr(str,',');
if (file == NULL) {
printf("parse_iomem : failed to parse iomem\n");
goto out;
}
*file = '\0';
file++;
fd = open(file, O_RDWR, 0);
if (fd < 0) {
perror("parse_iomem - Couldn't open io file");
goto out;
}
if (fstat64(fd, &buf) < 0) {
perror("parse_iomem - cannot stat_fd file");
goto out_close;
}
new = malloc(sizeof(*new));
if (new == NULL) {
perror("Couldn't allocate iomem_region struct");
goto out_close;
}
size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
*new = ((struct iomem_region) { .next = iomem_regions,
.driver = driver,
.fd = fd,
.size = size,
.phys = 0,
.virt = 0 });
iomem_regions = new;
iomem_size += new->size + UM_KERN_PAGE_SIZE;
return 0;
out_close:
close(fd);
out:
return 1;
}
