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-rw-r--r--usr/kinit/run-init/Kbuild38
-rw-r--r--usr/kinit/run-init/run-init.c114
-rw-r--r--usr/kinit/run-init/run-init.h38
-rw-r--r--usr/kinit/run-init/runinitlib.c232
4 files changed, 422 insertions, 0 deletions
diff --git a/usr/kinit/run-init/Kbuild b/usr/kinit/run-init/Kbuild
new file mode 100644
index 0000000..eeff906
--- /dev/null
+++ b/usr/kinit/run-init/Kbuild
@@ -0,0 +1,38 @@
+#
+# Kbuild file for run-init
+#
+
+static-y := static/run-init
+shared-y := shared/run-init
+
+# common .o files
+objs := run-init.o runinitlib.o
+
+# TODO - do we want a stripped version
+# TODO - do we want the static.g + shared.g directories?
+
+# Create built-in.o with all object files (used by kinit)
+lib-y := $(objs)
+
+# force run-init to not have an executable stack (to keep READ_IMPLIES_EXEC
+# personality(2) flag from getting set and passed to init).
+EXTRA_KLIBCLDFLAGS += -z noexecstack
+
+# Additional include paths files
+KLIBCCFLAGS += -I$(srctree)/$(src)/..
+
+# .o files used to built executables
+static/run-init-y := $(objs)
+static/run-init-lib := ../lib.a
+shared/run-init-y := $(objs)
+shared/run-init-lib := ../lib.a
+
+# Cleaning
+clean-dirs := static shared
+
+# install binary
+ifdef KLIBCSHAREDFLAGS
+install-y := $(shared-y)
+else
+install-y := $(static-y)
+endif
diff --git a/usr/kinit/run-init/run-init.c b/usr/kinit/run-init/run-init.c
new file mode 100644
index 0000000..6a4ad3e
--- /dev/null
+++ b/usr/kinit/run-init/run-init.c
@@ -0,0 +1,114 @@
+/* ----------------------------------------------------------------------- *
+ *
+ * Copyright 2004-2006 H. Peter Anvin - All Rights Reserved
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom
+ * the Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall
+ * be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * Usage: exec run-init [-d caps] [-c /dev/console] [-n] [-p] /real-root /sbin/init "$@"
+ *
+ * This program should be called as the last thing in a shell script
+ * acting as /init in an initramfs; it does the following:
+ *
+ * 1. Delete all files in the initramfs;
+ * 2. Remounts /real-root onto the root filesystem;
+ * 3. Drops comma-separated list of capabilities;
+ * 4. Chroots;
+ * 5. Opens /dev/console;
+ * 6. Spawns the specified init program (with arguments.)
+ *
+ * With the -p option, it skips step 1 in order to allow the initramfs to
+ * be persisted into the running system.
+ *
+ * With the -n option, it skips steps 1, 2 and 6 and can be used to check
+ * whether the given root and init are likely to work.
+ */
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include "run-init.h"
+
+static const char *program;
+
+static void __attribute__ ((noreturn)) usage(void)
+{
+ fprintf(stderr,
+ "Usage: exec %s [-d caps] [-c consoledev] [-n] [-p] /real-root /sbin/init [args]\n",
+ program);
+ exit(1);
+}
+
+int main(int argc, char *argv[])
+{
+ /* Command-line options and defaults */
+ const char *console = "/dev/console";
+ const char *realroot;
+ const char *init;
+ const char *error;
+ const char *drop_caps = NULL;
+ bool dry_run = false;
+ bool persist_initramfs = false;
+ char **initargs;
+
+ /* Variables... */
+ int o;
+
+ /* Parse the command line */
+ program = argv[0];
+
+ while ((o = getopt(argc, argv, "c:d:pn")) != -1) {
+ if (o == 'c') {
+ console = optarg;
+ } else if (o == 'd') {
+ drop_caps = optarg;
+ } else if (o == 'n') {
+ dry_run = true;
+ } else if (o == 'p') {
+ persist_initramfs = true;
+ } else {
+ usage();
+ }
+ }
+
+ if (argc - optind < 2)
+ usage();
+
+ realroot = argv[optind];
+ init = argv[optind + 1];
+ initargs = argv + optind + 1;
+
+ error = run_init(realroot, console, drop_caps, dry_run, persist_initramfs, init, initargs);
+
+ if (error) {
+ fprintf(stderr, "%s: %s: %s\n", program, error, strerror(errno));
+ return 1;
+ } else {
+ /* Must have been a dry run */
+ return 0;
+ }
+}
diff --git a/usr/kinit/run-init/run-init.h b/usr/kinit/run-init/run-init.h
new file mode 100644
index 0000000..5240ce7
--- /dev/null
+++ b/usr/kinit/run-init/run-init.h
@@ -0,0 +1,38 @@
+/* ----------------------------------------------------------------------- *
+ *
+ * Copyright 2004-2006 H. Peter Anvin - All Rights Reserved
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom
+ * the Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall
+ * be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * ----------------------------------------------------------------------- */
+
+#ifndef RUN_INIT_H
+#define RUN_INIT_H
+
+#include <stdbool.h>
+
+const char *run_init(const char *realroot, const char *console,
+ const char *drop_caps, bool dry_run,
+ bool persist_initramfs, const char *init,
+ char **initargs);
+
+#endif
diff --git a/usr/kinit/run-init/runinitlib.c b/usr/kinit/run-init/runinitlib.c
new file mode 100644
index 0000000..1c2e56a
--- /dev/null
+++ b/usr/kinit/run-init/runinitlib.c
@@ -0,0 +1,232 @@
+/* ----------------------------------------------------------------------- *
+ *
+ * Copyright 2004-2006 H. Peter Anvin - All Rights Reserved
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom
+ * the Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall
+ * be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * run_init(realroot, consoledev, drop_caps, persist_initramfs, init, initargs)
+ *
+ * This function should be called as the last thing in kinit,
+ * from initramfs, it does the following:
+ *
+ * - Delete all files in the initramfs;
+ * - Remounts /real-root onto the root filesystem;
+ * - Chroots;
+ * - Drops comma-separated list of capabilities;
+ * - Opens /dev/console;
+ * - Spawns the specified init program (with arguments.)
+ *
+ * On failure, returns a human-readable error message.
+ */
+
+#include <assert.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/vfs.h>
+#include "run-init.h"
+#include "capabilities.h"
+
+/* Make it possible to compile on glibc by including constants that the
+ always-behind shipped glibc headers may not include. Classic example
+ on why the lack of ABI headers screw us up. */
+#ifndef TMPFS_MAGIC
+# define TMPFS_MAGIC 0x01021994
+#endif
+#ifndef RAMFS_MAGIC
+# define RAMFS_MAGIC 0x858458f6
+#endif
+#ifndef MS_MOVE
+# define MS_MOVE 8192
+#endif
+
+static int nuke(const char *what);
+
+static int nuke_dirent(int len, const char *dir, const char *name, dev_t me)
+{
+ int bytes = len + strlen(name) + 2;
+ char path[bytes];
+ int xlen;
+ struct stat st;
+
+ xlen = snprintf(path, bytes, "%s/%s", dir, name);
+ assert(xlen < bytes);
+
+ if (lstat(path, &st))
+ return ENOENT; /* Return 0 since already gone? */
+
+ if (st.st_dev != me)
+ return 0; /* DO NOT recurse down mount points!!!!! */
+
+ return nuke(path);
+}
+
+/* Wipe the contents of a directory, but not the directory itself */
+static int nuke_dir(const char *what)
+{
+ int len = strlen(what);
+ DIR *dir;
+ struct dirent *d;
+ int err = 0;
+ struct stat st;
+
+ if (lstat(what, &st))
+ return errno;
+
+ if (!S_ISDIR(st.st_mode))
+ return ENOTDIR;
+
+ if (!(dir = opendir(what))) {
+ /* EACCES means we can't read it. Might be empty and removable;
+ if not, the rmdir() in nuke() will trigger an error. */
+ return (errno == EACCES) ? 0 : errno;
+ }
+
+ while ((d = readdir(dir))) {
+ /* Skip . and .. */
+ if (d->d_name[0] == '.' &&
+ (d->d_name[1] == '\0' ||
+ (d->d_name[1] == '.' && d->d_name[2] == '\0')))
+ continue;
+
+ err = nuke_dirent(len, what, d->d_name, st.st_dev);
+ if (err) {
+ closedir(dir);
+ return err;
+ }
+ }
+
+ closedir(dir);
+
+ return 0;
+}
+
+static int nuke(const char *what)
+{
+ int rv;
+ int err = 0;
+
+ rv = unlink(what);
+ if (rv < 0) {
+ if (errno == EISDIR) {
+ /* It's a directory. */
+ err = nuke_dir(what);
+ if (!err)
+ err = rmdir(what) ? errno : err;
+ } else {
+ err = errno;
+ }
+ }
+
+ if (err) {
+ errno = err;
+ return err;
+ } else {
+ return 0;
+ }
+}
+
+const char *run_init(const char *realroot, const char *console,
+ const char *drop_caps, bool dry_run,
+ bool persist_initramfs, const char *init, char **initargs)
+{
+ struct stat rst, cst, ist;
+ struct statfs sfs;
+ int confd;
+
+ /* First, change to the new root directory */
+ if (chdir(realroot))
+ return "chdir to new root";
+
+ /* This is a potentially highly destructive program. Take some
+ extra precautions. */
+
+ /* Make sure the current directory is not on the same filesystem
+ as the root directory */
+ if (stat("/", &rst) || stat(".", &cst))
+ return "stat";
+
+ if (rst.st_dev == cst.st_dev)
+ return "current directory on the same filesystem as the root";
+
+ /* Make sure we're on a ramfs */
+ if (statfs("/", &sfs))
+ return "statfs /";
+ if (sfs.f_type != RAMFS_MAGIC && sfs.f_type != TMPFS_MAGIC)
+ return "rootfs not a ramfs or tmpfs";
+
+ /* Okay, I think we should be safe... */
+
+ if (!dry_run) {
+ if (!persist_initramfs) {
+ /* Delete rootfs contents */
+ if (nuke_dir("/"))
+ return "nuking initramfs contents";
+ }
+
+ /* Overmount the root */
+ if (mount(".", "/", NULL, MS_MOVE, NULL))
+ return "overmounting root";
+ }
+
+ /* chroot, chdir */
+ if (chroot(".") || chdir("/"))
+ return "chroot";
+
+ /* Drop capabilities */
+ if (drop_capabilities(drop_caps) < 0)
+ return "dropping capabilities";
+
+ /* Open /dev/console */
+ if ((confd = open(console, O_RDWR)) < 0)
+ return "opening console";
+ if (!dry_run) {
+ dup2(confd, 0);
+ dup2(confd, 1);
+ dup2(confd, 2);
+ }
+ close(confd);
+
+ if (!dry_run) {
+ /* Spawn init */
+ execv(init, initargs);
+ return init; /* Failed to spawn init */
+ } else {
+ if (stat(init, &ist))
+ return init;
+ if (!S_ISREG(ist.st_mode) || !(ist.st_mode & S_IXUGO)) {
+ errno = EACCES;
+ return init;
+ }
+ return NULL; /* Success */
+ }
+}
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