diff options
Diffstat (limited to 'util-linux')
| -rw-r--r-- | util-linux/switch_root.c | 77 |
1 files changed, 43 insertions, 34 deletions
diff --git a/util-linux/switch_root.c b/util-linux/switch_root.c index fe9ab68..16abcb6 100644 --- a/util-linux/switch_root.c +++ b/util-linux/switch_root.c @@ -24,6 +24,8 @@ //config: * Because the Linux kernel uses rootfs internally as the starting //config: and ending point for searching through the kernel's doubly linked //config: list of active mount points. That's why. +//config: +// RUN_INIT config item is in klibc-utils //applet:IF_SWITCH_ROOT(APPLET(switch_root, BB_DIR_SBIN, BB_SUID_DROP)) // APPLET_ODDNAME:name main location suid_type help @@ -32,23 +34,6 @@ //kbuild:lib-$(CONFIG_SWITCH_ROOT) += switch_root.o //kbuild:lib-$(CONFIG_RUN_INIT) += switch_root.o -//usage:#define switch_root_trivial_usage -//usage: "[-c CONSOLE_DEV] NEW_ROOT NEW_INIT [ARGS]" -//usage:#define switch_root_full_usage "\n\n" -//usage: "Free initramfs and switch to another root fs:\n" -//usage: "chroot to NEW_ROOT, delete all in /, move NEW_ROOT to /,\n" -//usage: "execute NEW_INIT. PID must be 1. NEW_ROOT must be a mountpoint.\n" -//usage: "\n -c DEV Reopen stdio to DEV after switch" - -//usage:#define run_init_trivial_usage -//usage: "[-d CAP,CAP...] [-c CONSOLE_DEV] NEW_ROOT NEW_INIT [ARGS]" -//usage:#define run_init_full_usage "\n\n" -//usage: "Free initramfs and switch to another root fs:\n" -//usage: "chroot to NEW_ROOT, delete all in /, move NEW_ROOT to /,\n" -//usage: "execute NEW_INIT. PID must be 1. NEW_ROOT must be a mountpoint.\n" -//usage: "\n -c DEV Reopen stdio to DEV after switch" -//usage: "\n -d CAPS Drop capabilities" - #include <sys/vfs.h> #include <sys/mount.h> #if ENABLE_RUN_INIT @@ -122,13 +107,8 @@ static void drop_capset(int cap_idx) { struct caps caps; - /* Get the current capability mask */ getcaps(&caps); - - /* Drop the bit */ caps.data[CAP_TO_INDEX(cap_idx)].inheritable &= ~CAP_TO_MASK(cap_idx); - - /* And drop the capability. */ if (capset(&caps.header, caps.data) != 0) bb_perror_msg_and_die("capset"); } @@ -199,10 +179,18 @@ int switch_root_main(int argc UNUSED_PARAM, char **argv) char *newroot, *console = NULL; struct stat st; struct statfs stfs; + unsigned dry_run = 0; dev_t rootdev; - // Parse args (-c console). '+': stop at first non-option + // Parse args. '+': stop at first non-option if (ENABLE_SWITCH_ROOT && (!ENABLE_RUN_INIT || applet_name[0] == 's')) { +//usage:#define switch_root_trivial_usage +//usage: "[-c CONSOLE_DEV] NEW_ROOT NEW_INIT [ARGS]" +//usage:#define switch_root_full_usage "\n\n" +//usage: "Free initramfs and switch to another root fs:\n" +//usage: "chroot to NEW_ROOT, delete all in /, move NEW_ROOT to /,\n" +//usage: "execute NEW_INIT. PID must be 1. NEW_ROOT must be a mountpoint.\n" +//usage: "\n -c DEV Reopen stdio to DEV after switch" getopt32(argv, "^+" "c:" "\0" "-2" /* minimum 2 args */, @@ -210,13 +198,23 @@ int switch_root_main(int argc UNUSED_PARAM, char **argv) ); } else { #if ENABLE_RUN_INIT +//usage:#define run_init_trivial_usage +//usage: "[-d CAP,CAP...] [-n] [-c CONSOLE_DEV] NEW_ROOT NEW_INIT [ARGS]" +//usage:#define run_init_full_usage "\n\n" +//usage: "Free initramfs and switch to another root fs:\n" +//usage: "chroot to NEW_ROOT, delete all in /, move NEW_ROOT to /,\n" +//usage: "execute NEW_INIT. PID must be 1. NEW_ROOT must be a mountpoint.\n" +//usage: "\n -c DEV Reopen stdio to DEV after switch" +//usage: "\n -d CAPS Drop capabilities" +//usage: "\n -n Dry run" char *cap_list = NULL; - getopt32(argv, "^+" - "c:d:" + dry_run = getopt32(argv, "^+" + "c:d:n" "\0" "-2" /* minimum 2 args */, &console, &cap_list ); + dry_run >>= 2; // -n if (cap_list) drop_capabilities(cap_list); #endif @@ -239,7 +237,7 @@ int switch_root_main(int argc UNUSED_PARAM, char **argv) // we mean it. I could make this a CONFIG option, but I would get email // from all the people who WILL destroy their filesystems. if (stat("/init", &st) != 0 || !S_ISREG(st.st_mode)) { - bb_error_msg_and_die("/init is not a regular file"); + bb_error_msg_and_die("'%s' is not a regular file", "/init"); } statfs("/", &stfs); // this never fails if ((unsigned)stfs.f_type != RAMFS_MAGIC @@ -248,13 +246,15 @@ int switch_root_main(int argc UNUSED_PARAM, char **argv) bb_error_msg_and_die("root filesystem is not ramfs/tmpfs"); } - // Zap everything out of rootdev - delete_contents("/", rootdev); + if (!dry_run) { + // Zap everything out of rootdev + delete_contents("/", rootdev); - // Overmount / with newdir and chroot into it - if (mount(".", "/", NULL, MS_MOVE, NULL)) { - // For example, fails when newroot is not a mountpoint - bb_perror_msg_and_die("error moving root"); + // Overmount / with newdir and chroot into it + if (mount(".", "/", NULL, MS_MOVE, NULL)) { + // For example, fails when newroot is not a mountpoint + bb_perror_msg_and_die("error moving root"); + } } xchroot("."); // The chdir is needed to recalculate "." and ".." links @@ -270,8 +270,17 @@ int switch_root_main(int argc UNUSED_PARAM, char **argv) } } - // Exec real init - execv(argv[0], argv); + if (dry_run) { + // Does NEW_INIT look like it can be executed? + //xstat(argv[0], &st); + //if (!S_ISREG(st.st_mode)) + // bb_perror_msg_and_die("'%s' is not a regular file", argv[0]); + if (access(argv[0], X_OK) == 0) + return 0; + } else { + // Exec NEW_INIT + execv(argv[0], argv); + } bb_perror_msg_and_die("can't execute '%s'", argv[0]); } |