165 lines
3.6 KiB
C
165 lines
3.6 KiB
C
/**
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* This file group all function which interact with system operation
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*/
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#ifndef _SYSTEM
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#define _SYSTEM
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#include "prototype.h"
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#include <errno.h>
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#include <unistd.h>
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#include <sys/mount.h>
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#include <sys/syscall.h>
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#include <signal.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <string.h>
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#define OLDROOT "/.old"
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/**
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* Wrapper for pivot root syscall
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*/
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int pivot_root(char *mount_dir)
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{
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char *inner_mount_dir = malloc(
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(sizeof(*(mount_dir)) * strlen(mount_dir) + 1) +
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strlen(OLDROOT));
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strcpy(inner_mount_dir, mount_dir);
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strcat(inner_mount_dir, OLDROOT);
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if (mount("/", "/", "bind", MS_REC | MS_PRIVATE, NULL))
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{
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error("error remount / with MS_PRIVATE");
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}
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if (mount(mount_dir, mount_dir, "bind", MS_BIND | MS_REC, NULL) < 0)
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{
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error("error mount");
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}
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if (mkdir(inner_mount_dir, 0755) != 0)
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{
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if (errno != EEXIST)
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{
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error("error mkdir");
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}
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}
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int syscall_result = syscall(SYS_pivot_root, mount_dir, inner_mount_dir);
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// deal with old mount directory
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if (umount2(OLDROOT, MNT_DETACH) != 0)
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{
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error("umount old directory failed");
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}
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if (rmdir(inner_mount_dir) != 0)
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{
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error("rm old directory failed");
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}
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free(inner_mount_dir);
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return syscall_result;
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}
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/**
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* Umount pivot root folder
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*/
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int clean_pivot_root(char *a)
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{
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if (umount2(a, MNT_DETACH) != 0)
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{
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error("umount pivot_root directory failed");
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return EXIT_FAILURE;
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}
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return EXIT_SUCCESS;
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}
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/**
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* Mount tmpfs into /dev and remount proc into /proc
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*/
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void remount()
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{
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// remount devtmpfs device to /dev with type devtmpfs
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if (mount(NULL, "/dev", "devtmpfs", MS_NOSUID | MS_STRICTATIME, NULL))
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{
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error("failed mount tmpfs to /dev");
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}
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// remount proc device to /proc with type proc
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if (mount(NULL, "/proc", "proc", MS_MGC_VAL, NULL))
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{
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error("failed to re mount proc into /proc");
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}
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// remount sys device to /sys with type sysfs
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if (mount(NULL, "/sys", "sysfs", MS_MGC_VAL, NULL))
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{
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error("failed to re mount proc into /proc");
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}
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}
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/**
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* Run external binary
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*/
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int run_subprocess(char *const *argv)
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{
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errno = execvp(argv[0], argv);
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return errno;
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}
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/**
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* Run external binary into new sub process
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*/
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int run_subprocess_async(char *const *argv)
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{
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pid_t pid;
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// pipe to permit child => parent comunication
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int pipefd[2];
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pipe(pipefd);
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if ((pid = fork()) == -1)
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{
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error("fork() subprocess error");
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}
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else if (pid == 0)
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{
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close(pipefd[0]); // close reading end in the child
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printf("[CHILD] : running\n");
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dup2(pipefd[1], 1); // send stdout to the pipe
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dup2(pipefd[1], 2); // send stderr to the pipe
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close(pipefd[1]); // this descriptor is no longer needed
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errno = execvp(argv[0], argv);
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return errno;
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}
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else
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{
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int child_status;
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close(pipefd[1]); // close the write end of the pipe in the parent
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waitpid(pid, &child_status, 0);
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if (WIFEXITED(child_status))
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{
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char *stdout_buffer = read_infinite_fd(pipefd[0]);
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printf("[PARENT] child stdout : \n%s\n", stdout_buffer);
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free(stdout_buffer);
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close(pipefd[0]); // close the descriptor is no longer needed
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int es = WEXITSTATUS(child_status);
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printf("[PARENT] Exit status was %d\n", es);
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return es;
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}
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}
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// reach when wait child failed
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return EXIT_FAILURE;
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}
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#endif
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