6b7aaad9ba
There were some bugs in handling failures to exec helper programs. errno was passed back from the child with the wrong sign. It was also ignored. In the case where it mattered, the errno from the (successful) read in the parent was used instead. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
165 lines
3.6 KiB
C
165 lines
3.6 KiB
C
/*
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* Copyright (C) 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 <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sched.h>
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#include <sys/signal.h>
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#include <sys/wait.h>
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#include "user.h"
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#include "kern_util.h"
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#include "user_util.h"
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#include "os.h"
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struct helper_data {
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void (*pre_exec)(void*);
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void *pre_data;
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char **argv;
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int fd;
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};
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/* Debugging aid, changed only from gdb */
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int helper_pause = 0;
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static void helper_hup(int sig)
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{
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}
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static int helper_child(void *arg)
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{
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struct helper_data *data = arg;
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char **argv = data->argv;
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int errval;
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if(helper_pause){
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signal(SIGHUP, helper_hup);
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pause();
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}
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if(data->pre_exec != NULL)
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(*data->pre_exec)(data->pre_data);
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execvp(argv[0], argv);
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errval = -errno;
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printk("helper_child - execve of '%s' failed - errno = %d\n", argv[0], errno);
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os_write_file(data->fd, &errval, sizeof(errval));
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kill(os_getpid(), SIGKILL);
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return(0);
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}
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/* Returns either the pid of the child process we run or -E* on failure.
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* XXX The alloc_stack here breaks if this is called in the tracing thread */
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int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
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unsigned long *stack_out)
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{
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struct helper_data data;
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unsigned long stack, sp;
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int pid, fds[2], ret, n;
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if((stack_out != NULL) && (*stack_out != 0))
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stack = *stack_out;
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else stack = alloc_stack(0, __cant_sleep());
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if(stack == 0)
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return -ENOMEM;
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ret = os_pipe(fds, 1, 0);
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if(ret < 0){
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printk("run_helper : pipe failed, ret = %d\n", -ret);
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goto out_free;
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}
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ret = os_set_exec_close(fds[1], 1);
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if(ret < 0){
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printk("run_helper : setting FD_CLOEXEC failed, ret = %d\n",
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-ret);
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goto out_close;
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}
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sp = stack + page_size() - sizeof(void *);
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data.pre_exec = pre_exec;
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data.pre_data = pre_data;
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data.argv = argv;
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data.fd = fds[1];
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pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data);
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if(pid < 0){
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ret = -errno;
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printk("run_helper : clone failed, errno = %d\n", errno);
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goto out_close;
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}
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close(fds[1]);
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fds[1] = -1;
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/* Read the errno value from the child, if the exec failed, or get 0 if
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* the exec succeeded because the pipe fd was set as close-on-exec. */
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n = os_read_file(fds[0], &ret, sizeof(ret));
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if(n == 0)
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ret = pid;
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else {
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if(n < 0){
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printk("run_helper : read on pipe failed, ret = %d\n",
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-n);
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ret = n;
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kill(pid, SIGKILL);
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}
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CATCH_EINTR(waitpid(pid, NULL, 0));
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}
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out_close:
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if (fds[1] != -1)
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close(fds[1]);
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close(fds[0]);
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out_free:
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if(stack_out == NULL)
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free_stack(stack, 0);
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else *stack_out = stack;
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return(ret);
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}
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int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
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unsigned long *stack_out, int stack_order)
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{
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unsigned long stack, sp;
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int pid, status, err;
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stack = alloc_stack(stack_order, __cant_sleep());
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if(stack == 0) return(-ENOMEM);
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sp = stack + (page_size() << stack_order) - sizeof(void *);
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pid = clone(proc, (void *) sp, flags | SIGCHLD, arg);
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if(pid < 0){
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err = -errno;
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printk("run_helper_thread : clone failed, errno = %d\n",
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errno);
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return err;
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}
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if(stack_out == NULL){
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CATCH_EINTR(pid = waitpid(pid, &status, 0));
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if(pid < 0){
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err = -errno;
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printk("run_helper_thread - wait failed, errno = %d\n",
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errno);
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pid = err;
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}
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if(!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
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printk("run_helper_thread - thread returned status "
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"0x%x\n", status);
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free_stack(stack, stack_order);
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}
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else *stack_out = stack;
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return(pid);
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}
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int helper_wait(int pid)
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{
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int ret;
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CATCH_EINTR(ret = waitpid(pid, NULL, WNOHANG));
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if(ret < 0){
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ret = -errno;
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printk("helper_wait : waitpid failed, errno = %d\n", errno);
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}
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return(ret);
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}
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