98fdffccea
Convert the boot-time host ptrace testing from clone to fork. They were essentially doing fork anyway. This cleans up the code a bit, and makes valgrind a bit happier about grinding it. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
411 lines
10 KiB
C
411 lines
10 KiB
C
/*
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* Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
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* Licensed under the GPL
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <signal.h>
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#include <sched.h>
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#include <errno.h>
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#include <stdarg.h>
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#include <stdlib.h>
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#include <setjmp.h>
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#include <sys/time.h>
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#include <sys/wait.h>
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#include <sys/mman.h>
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#include <asm/unistd.h>
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#include <asm/page.h>
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#include "user_util.h"
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#include "kern_util.h"
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#include "user.h"
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#include "process.h"
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#include "signal_kern.h"
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#include "signal_user.h"
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#include "sysdep/ptrace.h"
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#include "sysdep/sigcontext.h"
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#include "irq_user.h"
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#include "ptrace_user.h"
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#include "time_user.h"
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#include "init.h"
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#include "os.h"
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#include "uml-config.h"
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#include "choose-mode.h"
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#include "mode.h"
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#ifdef UML_CONFIG_MODE_SKAS
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#include "skas.h"
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#include "skas_ptrace.h"
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#include "registers.h"
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#endif
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void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int))
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{
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int flags = 0, pages;
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if(sig_stack != NULL){
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pages = (1 << UML_CONFIG_KERNEL_STACK_ORDER);
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set_sigstack(sig_stack, pages * page_size());
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flags = SA_ONSTACK;
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}
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if(usr1_handler) set_handler(SIGUSR1, usr1_handler, flags, -1);
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}
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void init_new_thread_signals(int altstack)
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{
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int flags = altstack ? SA_ONSTACK : 0;
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set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags,
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SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
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set_handler(SIGTRAP, (__sighandler_t) sig_handler, flags,
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SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
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set_handler(SIGFPE, (__sighandler_t) sig_handler, flags,
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SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
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set_handler(SIGILL, (__sighandler_t) sig_handler, flags,
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SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
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set_handler(SIGBUS, (__sighandler_t) sig_handler, flags,
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SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
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set_handler(SIGUSR2, (__sighandler_t) sig_handler,
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flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
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signal(SIGHUP, SIG_IGN);
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init_irq_signals(altstack);
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}
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struct tramp {
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int (*tramp)(void *);
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void *tramp_data;
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unsigned long temp_stack;
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int flags;
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int pid;
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};
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/* See above for why sigkill is here */
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int sigkill = SIGKILL;
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int outer_tramp(void *arg)
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{
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struct tramp *t;
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int sig = sigkill;
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t = arg;
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t->pid = clone(t->tramp, (void *) t->temp_stack + page_size()/2,
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t->flags, t->tramp_data);
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if(t->pid > 0) wait_for_stop(t->pid, SIGSTOP, PTRACE_CONT, NULL);
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kill(os_getpid(), sig);
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_exit(0);
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}
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int start_fork_tramp(void *thread_arg, unsigned long temp_stack,
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int clone_flags, int (*tramp)(void *))
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{
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struct tramp arg;
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unsigned long sp;
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int new_pid, status, err;
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/* The trampoline will run on the temporary stack */
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sp = stack_sp(temp_stack);
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clone_flags |= CLONE_FILES | SIGCHLD;
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arg.tramp = tramp;
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arg.tramp_data = thread_arg;
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arg.temp_stack = temp_stack;
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arg.flags = clone_flags;
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/* Start the process and wait for it to kill itself */
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new_pid = clone(outer_tramp, (void *) sp, clone_flags, &arg);
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if(new_pid < 0)
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return(new_pid);
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CATCH_EINTR(err = waitpid(new_pid, &status, 0));
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if(err < 0)
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panic("Waiting for outer trampoline failed - errno = %d",
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errno);
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if(!WIFSIGNALED(status) || (WTERMSIG(status) != SIGKILL))
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panic("outer trampoline didn't exit with SIGKILL, "
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"status = %d", status);
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return(arg.pid);
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}
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static int ptrace_child(void)
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{
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int ret;
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int pid = os_getpid(), ppid = getppid();
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int sc_result;
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if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
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perror("ptrace");
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os_kill_process(pid, 0);
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}
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os_stop_process(pid);
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/*This syscall will be intercepted by the parent. Don't call more than
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* once, please.*/
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sc_result = os_getpid();
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if (sc_result == pid)
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ret = 1; /*Nothing modified by the parent, we are running
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normally.*/
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else if (sc_result == ppid)
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ret = 0; /*Expected in check_ptrace and check_sysemu when they
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succeed in modifying the stack frame*/
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else
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ret = 2; /*Serious trouble! This could be caused by a bug in
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host 2.6 SKAS3/2.6 patch before release -V6, together
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with a bug in the UML code itself.*/
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_exit(ret);
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}
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static int start_ptraced_child(void)
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{
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int pid, n, status;
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pid = fork();
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if(pid == 0)
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ptrace_child();
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if(pid < 0)
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panic("check_ptrace : fork failed, errno = %d", errno);
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
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if(n < 0)
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panic("check_ptrace : wait failed, errno = %d", errno);
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if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
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panic("check_ptrace : expected SIGSTOP, got status = %d",
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status);
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return(pid);
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}
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/* When testing for SYSEMU support, if it is one of the broken versions, we must
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* just avoid using sysemu, not panic, but only if SYSEMU features are broken.
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* So only for SYSEMU features we test mustpanic, while normal host features
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* must work anyway!*/
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static int stop_ptraced_child(int pid, int exitcode, int mustexit)
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{
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int status, n, ret = 0;
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if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
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panic("stop_ptraced_child : ptrace failed, errno = %d", errno);
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CATCH_EINTR(n = waitpid(pid, &status, 0));
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if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
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int exit_with = WEXITSTATUS(status);
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if (exit_with == 2)
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printk("check_ptrace : child exited with status 2. "
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"Serious trouble happening! Try updating your "
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"host skas patch!\nDisabling SYSEMU support.");
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printk("check_ptrace : child exited with exitcode %d, while "
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"expecting %d; status 0x%x", exit_with,
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exitcode, status);
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if (mustexit)
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panic("\n");
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else
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printk("\n");
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ret = -1;
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}
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return ret;
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}
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static int force_sysemu_disabled = 0;
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static int __init nosysemu_cmd_param(char *str, int* add)
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{
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force_sysemu_disabled = 1;
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return 0;
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}
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__uml_setup("nosysemu", nosysemu_cmd_param,
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"nosysemu\n"
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" Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
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" SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
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" behaviour of ptrace() and helps reducing host context switch rate.\n"
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" To make it working, you need a kernel patch for your host, too.\n"
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" See http://perso.wanadoo.fr/laurent.vivier/UML/ for further information.\n\n");
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static void __init check_sysemu(void)
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{
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int pid, syscall, n, status, count=0;
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printk("Checking syscall emulation patch for ptrace...");
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sysemu_supported = 0;
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pid = start_ptraced_child();
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if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
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goto fail;
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
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if (n < 0)
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panic("check_sysemu : wait failed, errno = %d", errno);
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if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
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panic("check_sysemu : expected SIGTRAP, "
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"got status = %d", status);
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n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
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os_getpid());
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if(n < 0)
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panic("check_sysemu : failed to modify system "
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"call return, errno = %d", errno);
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if (stop_ptraced_child(pid, 0, 0) < 0)
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goto fail_stopped;
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sysemu_supported = 1;
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printk("OK\n");
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set_using_sysemu(!force_sysemu_disabled);
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printk("Checking advanced syscall emulation patch for ptrace...");
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pid = start_ptraced_child();
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while(1){
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count++;
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if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
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goto fail;
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
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if(n < 0)
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panic("check_ptrace : wait failed, errno = %d", errno);
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if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
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panic("check_ptrace : expected (SIGTRAP|SYSCALL_TRAP), "
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"got status = %d", status);
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syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
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0);
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if(syscall == __NR_getpid){
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if (!count)
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panic("check_ptrace : SYSEMU_SINGLESTEP doesn't singlestep");
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n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
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os_getpid());
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if(n < 0)
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panic("check_sysemu : failed to modify system "
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"call return, errno = %d", errno);
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break;
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}
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}
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if (stop_ptraced_child(pid, 0, 0) < 0)
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goto fail_stopped;
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sysemu_supported = 2;
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printk("OK\n");
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if ( !force_sysemu_disabled )
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set_using_sysemu(sysemu_supported);
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return;
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fail:
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stop_ptraced_child(pid, 1, 0);
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fail_stopped:
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printk("missing\n");
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}
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void __init check_ptrace(void)
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{
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int pid, syscall, n, status;
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printk("Checking that ptrace can change system call numbers...");
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pid = start_ptraced_child();
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if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
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panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno);
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while(1){
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if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
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panic("check_ptrace : ptrace failed, errno = %d",
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errno);
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CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
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if(n < 0)
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panic("check_ptrace : wait failed, errno = %d", errno);
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if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP + 0x80))
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panic("check_ptrace : expected SIGTRAP + 0x80, "
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"got status = %d", status);
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syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
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0);
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if(syscall == __NR_getpid){
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n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
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__NR_getppid);
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if(n < 0)
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panic("check_ptrace : failed to modify system "
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"call, errno = %d", errno);
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break;
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}
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}
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stop_ptraced_child(pid, 0, 1);
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printk("OK\n");
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check_sysemu();
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}
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int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr)
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{
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sigjmp_buf buf;
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int n;
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*jmp_ptr = &buf;
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n = sigsetjmp(buf, 1);
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if(n != 0)
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return(n);
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(*fn)(arg);
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return(0);
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}
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void forward_pending_sigio(int target)
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{
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sigset_t sigs;
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if(sigpending(&sigs))
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panic("forward_pending_sigio : sigpending failed");
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if(sigismember(&sigs, SIGIO))
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kill(target, SIGIO);
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}
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#ifdef UML_CONFIG_MODE_SKAS
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static inline int check_skas3_ptrace_support(void)
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{
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struct ptrace_faultinfo fi;
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int pid, n, ret = 1;
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printf("Checking for the skas3 patch in the host...");
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pid = start_ptraced_child();
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n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
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if (n < 0) {
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if(errno == EIO)
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printf("not found\n");
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else {
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perror("not found");
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}
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ret = 0;
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} else {
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printf("found\n");
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}
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init_registers(pid);
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stop_ptraced_child(pid, 1, 1);
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return(ret);
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}
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int can_do_skas(void)
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{
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int ret = 1;
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printf("Checking for /proc/mm...");
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if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {
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printf("not found\n");
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ret = 0;
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goto out;
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} else {
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printf("found\n");
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}
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ret = check_skas3_ptrace_support();
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out:
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return ret;
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}
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#else
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int can_do_skas(void)
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{
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return(0);
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}
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#endif
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