X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fcore%2Fmachine-id-setup.c;h=671003820b77b2a815ddbf37a8b60be1ec096196;hb=a2c0e528b8b5ba370527db279605e4e4135689c1;hp=146c5653c96af4b91ac12ed5b268684429136c3a;hpb=10d18763ec6f31ded1535f810be765f7fab2d97d;p=elogind.git

diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c
index 146c5653c..671003820 100644
--- a/src/core/machine-id-setup.c
+++ b/src/core/machine-id-setup.c
@@ -27,7 +27,7 @@
 #include <fcntl.h>
 #include <sys/mount.h>
 
-#include <systemd/sd-id128.h>
+#include "systemd/sd-id128.h"
 
 #include "machine-id-setup.h"
 #include "macro.h"
@@ -36,8 +36,9 @@
 #include "log.h"
 #include "virt.h"
 #include "fileio.h"
+#include "path-util.h"
 
-static int shorten_uuid(char destination[36], const char *source) {
+static int shorten_uuid(char destination[34], const char source[36]) {
         unsigned i, j;
 
         for (i = 0, j = 0; i < 36 && j < 32; i++) {
@@ -59,83 +60,89 @@ static int shorten_uuid(char destination[36], const char *source) {
         return -EINVAL;
 }
 
-static int generate(char id[34]) {
+static int generate(char id[34], const char *root) {
         int fd, r;
         unsigned char *p;
         sd_id128_t buf;
-        char *q;
+        char  *q;
         ssize_t k;
-        const char *vm_id;
+        const char *vm_id, *dbus_machine_id;
 
         assert(id);
 
+        if (isempty(root))
+                dbus_machine_id = "/var/lib/dbus/machine-id";
+        else
+                dbus_machine_id = strappenda(root, "/var/lib/dbus/machine-id");
+
         /* First, try reading the D-Bus machine id, unless it is a symlink */
-        fd = open("/var/lib/dbus/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
+        fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
         if (fd >= 0) {
+                k = loop_read(fd, id, 33, false);
+                safe_close(fd);
 
-                k = loop_read(fd, id, 32, false);
-                close_nointr_nofail(fd);
-
-                if (k >= 32) {
-                        id[32] = '\n';
-                        id[33] = 0;
+                if (k == 33 && id[32] == '\n') {
 
-                        log_info("Initializing machine ID from D-Bus machine ID.");
-                        return 0;
-                }
-        }
+                        id[32] = 0;
+                        if (id128_is_valid(id)) {
+                                id[32] = '\n';
+                                id[33] = 0;
 
-        /* If that didn't work, see if we are running in qemu/kvm and a
-         * machine ID was passed in via -uuid on the qemu/kvm command
-         * line */
-
-        r = detect_vm(&vm_id);
-        if (r > 0 && streq(vm_id, "kvm")) {
-                char uuid[37];
-
-                fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
-                if (fd >= 0) {
-                        k = loop_read(fd, uuid, 36, false);
-                        close_nointr_nofail(fd);
-
-                        if (k >= 36) {
-                                r = shorten_uuid(id, uuid);
-                                if (r >= 0) {
-                                        log_info("Initializing machine ID from KVM UUID.");
-                                        return 0;
-                                }
+                                log_info("Initializing machine ID from D-Bus machine ID.");
+                                return 0;
                         }
                 }
         }
 
-        /* If that didn't work either, see if we are running in a
-         * container, and a machine ID was passed in via
-         * $container_uuid the way libvirt/LXC does it */
-        r = detect_container(NULL);
-        if (r > 0) {
-                char *e;
-
-                r = getenv_for_pid(1, "container_uuid", &e);
+        if (isempty(root)) {
+                /* If that didn't work, see if we are running in a container,
+                 * and a machine ID was passed in via $container_uuid the way
+                 * libvirt/LXC does it */
+                r = detect_container(NULL);
                 if (r > 0) {
-                        if (strlen(e) >= 36) {
-                                r = shorten_uuid(id, e);
-                                if (r >= 0) {
-                                        log_info("Initializing machine ID from container UUID.");
-                                        free(e);
-                                        return 0;
+                        _cleanup_free_ char *e = NULL;
+
+                        r = getenv_for_pid(1, "container_uuid", &e);
+                        if (r > 0) {
+                                if (strlen(e) >= 36) {
+                                        r = shorten_uuid(id, e);
+                                        if (r >= 0) {
+                                                log_info("Initializing machine ID from container UUID.");
+                                                return 0;
+                                        }
                                 }
                         }
 
-                        free(e);
+                } else {
+                        /* If we are not running in a container, see if we are
+                         * running in qemu/kvm and a machine ID was passed in
+                         * via -uuid on the qemu/kvm command line */
+
+                        r = detect_vm(&vm_id);
+                        if (r > 0 && streq(vm_id, "kvm")) {
+                                char uuid[37];
+
+                                fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
+                                if (fd >= 0) {
+                                        k = loop_read(fd, uuid, 36, false);
+                                        safe_close(fd);
+
+                                        if (k >= 36) {
+                                                r = shorten_uuid(id, uuid);
+                                                if (r >= 0) {
+                                                        log_info("Initializing machine ID from KVM UUID.");
+                                                        return 0;
+                                                }
+                                        }
+                                }
+                        }
                 }
         }
 
         /* If that didn't work, generate a random machine id */
         r = sd_id128_randomize(&buf);
-        if (r < 0) {
-                log_error("Failed to open /dev/urandom: %s", strerror(-r));
-                return r;
-        }
+        if (r < 0)
+                return log_error_errno(r, "Failed to open /dev/urandom: %m");
 
         for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) {
                 q[0] = hexchar(*p >> 4);
@@ -150,100 +157,105 @@ static int generate(char id[34]) {
         return 0;
 }
 
-int machine_id_setup(void) {
-        int fd, r;
-        bool writable;
+int machine_id_setup(const char *root) {
+        const char *etc_machine_id, *run_machine_id;
+        _cleanup_close_ int fd = -1;
+        bool writable = true;
         struct stat st;
         char id[34]; /* 32 + \n + \0 */
-        mode_t m;
+        int r;
 
-        m = umask(0000);
+        if (isempty(root))  {
+                etc_machine_id = "/etc/machine-id";
+                run_machine_id = "/run/machine-id";
+        } else {
+                etc_machine_id = strappenda(root, "/etc/machine-id");
+                path_kill_slashes((char*) etc_machine_id);
 
-        /* We create this 0444, to indicate that this isn't really
-         * something you should ever modify. Of course, since the file
-         * will be owned by root it doesn't matter much, but maybe
-         * people look. */
+                run_machine_id = strappenda(root, "/run/machine-id");
+                path_kill_slashes((char*) run_machine_id);
+        }
+
+        RUN_WITH_UMASK(0000) {
+                /* We create this 0444, to indicate that this isn't really
+                 * something you should ever modify. Of course, since the file
+                 * will be owned by root it doesn't matter much, but maybe
+                 * people look. */
 
-        fd = open("/etc/machine-id", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
-        if (fd >= 0)
-                writable = true;
-        else {
-                fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+                mkdir_parents(etc_machine_id, 0755);
+                fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
                 if (fd < 0) {
-                        umask(m);
-                        log_error("Cannot open /etc/machine-id: %m");
-                        return -errno;
-                }
+                        int old_errno = errno;
+
+                        fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);
+                        if (fd < 0) {
+                                if (old_errno == EROFS && errno == ENOENT)
+                                        log_error("System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n"
+                                                  "Booting up is supported only when:\n"
+                                                  "1) /etc/machine-id exists and is populated.\n"
+                                                  "2) /etc/machine-id exists and is empty.\n"
+                                                  "3) /etc/machine-id is missing and /etc is writable.\n");
+                                else
+                                        log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
+                                return -errno;
+                        }
 
-                writable = false;
+                        writable = false;
+                }
         }
 
-        umask(m);
+        if (fstat(fd, &st) < 0)
+                return log_error_errno(errno, "fstat() failed: %m");
 
-        if (fstat(fd, &st) < 0) {
-                log_error("fstat() failed: %m");
-                r = -errno;
-                goto finish;
-        }
+        if (S_ISREG(st.st_mode))
+                if (loop_read(fd, id, 33, false) == 33 && id[32] == '\n') {
+                        id[32] = 0;
 
-        if (S_ISREG(st.st_mode)) {
-                if (loop_read(fd, id, 32, false) >= 32) {
-                        r = 0;
-                        goto finish;
+                        if (id128_is_valid(id))
+                                return 0;
                 }
-        }
 
         /* Hmm, so, the id currently stored is not useful, then let's
          * generate one */
 
-        r = generate(id);
+        r = generate(id, root);
         if (r < 0)
-                goto finish;
+                return r;
 
         if (S_ISREG(st.st_mode) && writable) {
                 lseek(fd, 0, SEEK_SET);
 
-                if (loop_write(fd, id, 33, false) == 33) {
-                        r = 0;
-                        goto finish;
-                }
+                if (loop_write(fd, id, 33, false) == 33)
+                        return 0;
         }
 
-        close_nointr_nofail(fd);
-        fd = -1;
+        fd = safe_close(fd);
 
         /* Hmm, we couldn't write it? So let's write it to
          * /run/machine-id as a replacement */
 
-        m = umask(0022);
-        r = write_one_line_file("/run/machine-id", id);
-        umask(m);
-
+        RUN_WITH_UMASK(0022) {
+                r = write_string_file(run_machine_id, id);
+        }
         if (r < 0) {
-                log_error("Cannot write /run/machine-id: %s", strerror(-r));
-
-                unlink("/run/machine-id");
-                goto finish;
+                log_error_errno(r, "Cannot write %s: %m", run_machine_id);
+                unlink(run_machine_id);
+                return r;
         }
 
         /* And now, let's mount it over */
-        r = mount("/run/machine-id", "/etc/machine-id", NULL, MS_BIND, NULL) < 0 ? -errno : 0;
+        r = mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL);
         if (r < 0) {
-                unlink("/run/machine-id");
-                log_error("Failed to mount /etc/machine-id: %s", strerror(-r));
-        } else {
-                log_info("Installed transient /etc/machine-id file.");
-
-                /* Mark the mount read-only */
-                if (mount(NULL, "/etc/machine-id", NULL,
-                          MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)
-                        log_warning("Failed to make transient /etc/machine-id read-only");
+                log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id);
+                unlink_noerrno(run_machine_id);
+                return -errno;
         }
 
-finish:
+        log_info("Installed transient %s file.", etc_machine_id);
 
-        if (fd >= 0)
-                close_nointr_nofail(fd);
+        /* Mark the mount read-only */
+        if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)
+                log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id);
 
-        return r;
+        return 0;
 }