/*  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com) * Licensed under the GPL */ #include <stdio.h>#include <unistd.h>#include <signal.h>#include <sched.h>#include <errno.h>#include <stdarg.h>#include <stdlib.h>#include <setjmp.h>#include <sys/time.h>#include <sys/wait.h>#include <sys/mman.h>#include <asm/unistd.h>#include <asm/page.h>#include "user_util.h"#include "kern_util.h"#include "user.h"#include "process.h"#include "signal_kern.h"#include "signal_user.h"#include "sysdep/ptrace.h"#include "sysdep/sigcontext.h"#include "irq_user.h"#include "ptrace_user.h"#include "time_user.h"#include "init.h"#include "os.h"#include "uml-config.h"#include "choose-mode.h"#include "mode.h"#include "tempfile.h"#ifdef UML_CONFIG_MODE_SKAS#include "skas.h"#include "skas_ptrace.h"#include "registers.h"#endif void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int)){	int flags = 0, pages; 	if(sig_stack != NULL){		pages = (1 << UML_CONFIG_KERNEL_STACK_ORDER);		set_sigstack(sig_stack, pages * page_size());		flags = SA_ONSTACK;	}	if(usr1_handler) set_handler(SIGUSR1, usr1_handler, flags, -1);} void init_new_thread_signals(int altstack){	int flags = altstack ? SA_ONSTACK : 0; 	set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags,		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);	set_handler(SIGTRAP, (__sighandler_t) sig_handler, flags, 		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);	set_handler(SIGFPE, (__sighandler_t) sig_handler, flags, 		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);	set_handler(SIGILL, (__sighandler_t) sig_handler, flags, 		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);	set_handler(SIGBUS, (__sighandler_t) sig_handler, flags, 		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);	set_handler(SIGUSR2, (__sighandler_t) sig_handler, 		    flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);	signal(SIGHUP, SIG_IGN); 	init_irq_signals(altstack);} struct tramp {	int (*tramp)(void *);	void *tramp_data;	unsigned long temp_stack;	int flags;	int pid;}; /* See above for why sigkill is here */ int sigkill = SIGKILL; int outer_tramp(void *arg){	struct tramp *t;	int sig = sigkill; 	t = arg;	t->pid = clone(t->tramp, (void *) t->temp_stack + page_size()/2,		       t->flags, t->tramp_data);	if(t->pid > 0) wait_for_stop(t->pid, SIGSTOP, PTRACE_CONT, NULL);	kill(os_getpid(), sig);	_exit(0);} int start_fork_tramp(void *thread_arg, unsigned long temp_stack, 		     int clone_flags, int (*tramp)(void *)){	struct tramp arg;	unsigned long sp;	int new_pid, status, err; 	/* The trampoline will run on the temporary stack */	sp = stack_sp(temp_stack); 	clone_flags |= CLONE_FILES | SIGCHLD; 	arg.tramp = tramp;	arg.tramp_data = thread_arg;	arg.temp_stack = temp_stack;	arg.flags = clone_flags; 	/* Start the process and wait for it to kill itself */	new_pid = clone(outer_tramp, (void *) sp, clone_flags, &arg);	if(new_pid < 0)		return(new_pid); 	CATCH_EINTR(err = waitpid(new_pid, &status, 0));	if(err < 0)		panic("Waiting for outer trampoline failed - errno = %d",		      errno); 	if(!WIFSIGNALED(status) || (WTERMSIG(status) != SIGKILL))		panic("outer trampoline didn't exit with SIGKILL, "		      "status = %d", status); 	return(arg.pid);} static int ptrace_child(void *arg){	int ret;	int pid = os_getpid(), ppid = getppid();	int sc_result; 	if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){		perror("ptrace");		os_kill_process(pid, 0);	}	os_stop_process(pid); 	/*This syscall will be intercepted by the parent. Don't call more than	 * once, please.*/	sc_result = os_getpid(); 	if (sc_result == pid)		ret = 1; /*Nothing modified by the parent, we are running			   normally.*/	else if (sc_result == ppid)		ret = 0; /*Expected in check_ptrace and check_sysemu when they			   succeed in modifying the stack frame*/	else		ret = 2; /*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.*/	_exit(ret);} static int start_ptraced_child(void **stack_out){	void *stack;	unsigned long sp;	int pid, n, status;		stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);	if(stack == MAP_FAILED)		panic("check_ptrace : mmap failed, errno = %d", errno);	sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);	pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);	if(pid < 0)		panic("check_ptrace : clone 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) != SIGSTOP))		panic("check_ptrace : expected SIGSTOP, got status = %d",		      status); 	*stack_out = stack;	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, void *stack, int exitcode, int mustpanic){	int status, n, ret = 0; 	if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)		panic("check_ptrace : ptrace failed, errno = %d", errno);	CATCH_EINTR(n = waitpid(pid, &status, 0));	if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {		int exit_with = WEXITSTATUS(status);		if (exit_with == 2)			printk("check_ptrace : child exited with status 2. "			       "Serious trouble happening! Try updating your "			       "host skas patch!\nDisabling SYSEMU support.");		printk("check_ptrace : child exited with exitcode %d, while "		      "expecting %d; status 0x%x", exit_with,		      exitcode, status);		if (mustpanic)			panic("\n");		else			printk("\n");		ret = -1;	} 	if(munmap(stack, PAGE_SIZE) < 0)		panic("check_ptrace : munmap failed, errno = %d", errno);	return ret;} static int force_sysemu_disabled = 0; int ptrace_faultinfo = 1;int proc_mm = 1; static int __init skas0_cmd_param(char *str, int* add){	ptrace_faultinfo = proc_mm = 0;	return 0;} static int __init nosysemu_cmd_param(char *str, int* add){	force_sysemu_disabled = 1;	return 0;} __uml_setup("skas0", skas0_cmd_param,		"skas0\n"		"    Disables SKAS3 usage, so that SKAS0 is used, unless you \n"		"    specify mode=tt.\n\n"); __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 information.\n\n"); static void __init check_sysemu(void){	void *stack;	int pid, syscall, n, status, count=0; 	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_POKEUSR, 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); 	printk("Checking advanced syscall emulation patch for ptrace...");	pid = start_ptraced_child(&stack);	while(1){		count++;		if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)			goto fail;		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|SYSCALL_TRAP), "			      "got status = %d", status); 		syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,				 0);		if(syscall == __NR_getpid){			if (!count)				panic("check_ptrace : SYSEMU_SINGLESTEP doesn't singlestep");			n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,				   os_getpid());			if(n < 0)				panic("check_sysemu : failed to modify system "				      "call return, errno = %d", errno);			break;		}	}	if (stop_ptraced_child(pid, stack, 0, 0) < 0)		goto fail_stopped; 	sysemu_supported = 2;	printk("OK\n"); 	if ( !force_sysemu_disabled )		set_using_sysemu(sysemu_supported);	return; fail:	stop_ptraced_child(pid, stack, 1, 0);fail_stopped:	printk("missing\n");} 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); 	if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)		panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno); 	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 + 0x80))			panic("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)				panic("check_ptrace : failed to modify system "				      "call, errno = %d", errno);			break;		}	}	stop_ptraced_child(pid, stack, 0, 1);	printk("OK\n");	check_sysemu();} int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr){	sigjmp_buf buf;	int n; 	*jmp_ptr = &buf;	n = sigsetjmp(buf, 1);	if(n != 0)		return(n);	(*fn)(arg);	return(0);} void forward_pending_sigio(int target){	sigset_t sigs; 	if(sigpending(&sigs)) 		panic("forward_pending_sigio : sigpending failed");	if(sigismember(&sigs, SIGIO))		kill(target, SIGIO);} extern void *__syscall_stub_start, __syscall_stub_end; #ifdef UML_CONFIG_MODE_SKAS static inline void check_skas3_ptrace_support(void){	struct ptrace_faultinfo fi;	void *stack;	int pid, n; 	printf("Checking for the skas3 patch in the host...");	pid = start_ptraced_child(&stack); 	n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);	if (n < 0) {		ptrace_faultinfo = 0;		if(errno == EIO)			printf("not found\n");		else {			perror("not found");		}	}	else {		if (!ptrace_faultinfo)			printf("found but disabled on command line\n");		else			printf("found\n");	} 	init_registers(pid);	stop_ptraced_child(pid, stack, 1, 1);} int can_do_skas(void){	printf("Checking for /proc/mm...");	if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {		proc_mm = 0;		printf("not found\n");	} else {		if (!proc_mm)			printf("found but disabled on command line\n");		else			printf("found\n");	} 	check_skas3_ptrace_support();	return 1;}#elseint can_do_skas(void){	return(0);}#endif