1 /* 2 * Copyright (C) 2014 John Crispin <blogic@openwrt.org> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU Lesser General Public License version 2.1 6 * as published by the Free Software Foundation 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 */ 13 14 #include <unistd.h> 15 #include <stdlib.h> 16 #include <stdio.h> 17 #include <string.h> 18 #include <sys/mount.h> 19 #include <sys/types.h> 20 #include <sys/stat.h> 21 #include <sys/wait.h> 22 #include <libgen.h> 23 24 #include "libfstools.h" 25 26 /* 27 * This will execute "block extroot" and make use of mounted extroot or return 28 * an error. 29 */ 30 int mount_extroot(char const *extroot_prefix) 31 { 32 char ldlib_path[32]; 33 char block_path[32]; 34 char kmod_loader[64]; 35 struct stat s; 36 pid_t pid; 37 38 /* try finding the library directory */ 39 snprintf(ldlib_path, sizeof(ldlib_path), "%s/upper/lib", extroot_prefix); 40 41 if (stat(ldlib_path, &s) || !S_ISDIR(s.st_mode)) 42 snprintf(ldlib_path, sizeof(ldlib_path), "%s/lib", extroot_prefix); 43 44 /* try finding the block executable */ 45 snprintf(block_path, sizeof(block_path), "%s/upper/sbin/block", extroot_prefix); 46 47 if (stat(block_path, &s) || !S_ISREG(s.st_mode)) 48 snprintf(block_path, sizeof(block_path), "%s/sbin/block", extroot_prefix); 49 50 if (stat(block_path, &s) || !S_ISREG(s.st_mode)) 51 snprintf(block_path, sizeof(block_path), "/sbin/block"); 52 53 if (stat(block_path, &s) || !S_ISREG(s.st_mode)) 54 return -1; 55 56 /* set LD_LIBRARY_PATH env var and load kmods from overlay if we found a lib directory there */ 57 if (!stat(ldlib_path, &s) && S_ISDIR(s.st_mode)) { 58 ULOG_INFO("loading kmods from internal overlay\n"); 59 setenv("LD_LIBRARY_PATH", ldlib_path, 1); 60 snprintf(kmod_loader, sizeof(kmod_loader), 61 "/sbin/kmodloader %s/etc/modules-boot.d/", dirname(ldlib_path)); 62 if (system(kmod_loader)) 63 ULOG_ERR("failed to launch kmodloader from internal overlay\n"); 64 } 65 66 pid = fork(); 67 if (!pid) { 68 mkdir("/tmp/extroot", 0755); 69 execl(block_path, block_path, "extroot", NULL); 70 exit(-1); 71 } else if (pid > 0) { 72 int status; 73 74 waitpid(pid, &status, 0); 75 if (!WEXITSTATUS(status)) { 76 if (find_mount("/tmp/extroot/mnt")) { 77 mount("/dev/root", "/", NULL, MS_NOATIME | MS_REMOUNT | MS_RDONLY, 0); 78 79 mkdir("/tmp/extroot/mnt/proc", 0755); 80 mkdir("/tmp/extroot/mnt/dev", 0755); 81 mkdir("/tmp/extroot/mnt/sys", 0755); 82 mkdir("/tmp/extroot/mnt/tmp", 0755); 83 mkdir("/tmp/extroot/mnt/rom", 0755); 84 85 if (mount_move("/tmp/extroot", "", "/mnt")) { 86 ULOG_ERR("moving pivotroot failed - continue normal boot\n"); 87 umount("/tmp/extroot/mnt"); 88 } else if (pivot("/mnt", "/rom")) { 89 ULOG_ERR("switching to pivotroot failed - continue normal boot\n"); 90 umount("/mnt"); 91 } else { 92 umount("/tmp/overlay"); 93 rmdir("/tmp/overlay"); 94 rmdir("/tmp/extroot/mnt"); 95 rmdir("/tmp/extroot"); 96 return 0; 97 } 98 } else if (find_mount("/tmp/extroot/overlay")) { 99 if (mount_move("/tmp/extroot", "", "/overlay")) { 100 ULOG_ERR("moving extroot failed - continue normal boot\n"); 101 umount("/tmp/extroot/overlay"); 102 } else if (fopivot("/overlay", "/rom")) { 103 ULOG_ERR("switching to extroot failed - continue normal boot\n"); 104 umount("/overlay"); 105 } else { 106 umount("/tmp/overlay"); 107 rmdir("/tmp/overlay"); 108 rmdir("/tmp/extroot/overlay"); 109 rmdir("/tmp/extroot"); 110 return 0; 111 } 112 } 113 } 114 } 115 return -1; 116 } 117
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