gpt-auto-generator: add basic auto-discovery of GPT partitions

This adds a simple generator that is capable of automatically
discovering certain GPT partitions by their type UUID and mount/enable
them. This currently covers swap partitions and /home partitions, but is
expected to grow more features soon.

This currently doesn't handle LUKS encrypted /home.

This enables all swap partitions of type
0657fd6da4ab43c484e50933c84b4f4f, if found.

This mounts the first partition of type 933ac7e12eb44f13b8440e14e2aef915
as /home, if it is found.

1 files changed, 492 insertions, 0 deletions

diff --git a/src/gpt-auto-generator/gpt-auto-generator.c b/src/gpt-auto-generator/gpt-auto-generator.c
new file mode 100644
index 0000000000..0c7635bfe4
--- /dev/null
+++ b/src/gpt-auto-generator/gpt-auto-generator.c
@@ -0,0 +1,492 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <linux/btrfs.h>
+#include <sys/ioctl.h>
+#include <sys/statfs.h>
+#include <blkid.h>
+
+#include "path-util.h"
+#include "util.h"
+#include "mkdir.h"
+#include "missing.h"
+#include "sd-id128.h"
+#include "libudev.h"
+#include "special.h"
+#include "unit-name.h"
+
+/* TODO:
+ *
+ * - Properly handle cryptsetup partitions
+ * - Define new partition type for encrypted swap
+ *
+ */
+
+static const char *arg_dest = "/tmp";
+
+static int verify_gpt_partition(dev_t dev, sd_id128_t *type, unsigned *nr, char **fstype) {
+        _cleanup_free_ char *t = NULL;
+        blkid_probe b = NULL;
+        const char *v;
+        int r;
+
+        r = asprintf(&t, "/dev/block/%u:%u", major(dev), minor(dev));
+        if (r < 0)
+                return -ENOMEM;
+
+        errno = 0;
+        b = blkid_new_probe_from_filename(t);
+        if (!b) {
+                if (errno != 0)
+                        return -errno;
+
+                return -ENOMEM;
+        }
+
+        blkid_probe_enable_superblocks(b, 1);
+        blkid_probe_set_superblocks_flags(b, BLKID_SUBLKS_TYPE);
+        blkid_probe_enable_partitions(b, 1);
+        blkid_probe_set_partitions_flags(b, BLKID_PARTS_ENTRY_DETAILS);
+
+        errno = 0;
+        r = blkid_do_safeprobe(b);
+        if (r == -2) {
+                r = -ENODEV;
+                goto finish;
+        } else if (r == 1) {
+                r = -ENODEV;
+                goto finish;
+        } else if (r != 0) {
+                r = errno ? -errno : -EIO;
+                goto finish;
+        }
+
+        errno = 0;
+        r = blkid_probe_lookup_value(b, "PART_ENTRY_SCHEME", &v, NULL);
+        if (r != 0) {
+                r = errno ? -errno : -EIO;
+                goto finish;
+        }
+
+        if (strcmp(v, "gpt") != 0) {
+                r = 0;
+                goto finish;
+        }
+
+        if (type) {
+                errno = 0;
+                r = blkid_probe_lookup_value(b, "PART_ENTRY_TYPE", &v, NULL);
+                if (r != 0) {
+                        r = errno ? -errno : -EIO;
+                        goto finish;
+                }
+
+                r = sd_id128_from_string(v, type);
+                if (r < 0)
+                        return r;
+        }
+
+        if (nr) {
+                errno = 0;
+                r = blkid_probe_lookup_value(b, "PART_ENTRY_NUMBER", &v, NULL);
+                if (r != 0) {
+                        r = errno ? -errno : -EIO;
+                        goto finish;
+                }
+
+                r = safe_atou(v, nr);
+                if (r < 0)
+                        return r;
+        }
+
+
+        if (fstype) {
+                char *fst;
+
+                errno = 0;
+                r = blkid_probe_lookup_value(b, "TYPE", &v, NULL);
+                if (r != 0)
+                        *fstype = NULL;
+                else {
+                        fst = strdup(v);
+                        if (!fst) {
+                                r = -ENOMEM;
+                                goto finish;
+                        }
+
+                        *fstype = fst;
+                }
+        }
+
+        return 1;
+
+finish:
+        if (b)
+                blkid_free_probe(b);
+
+        return r;
+}
+
+static int add_swap(const char *path, const char *fstype) {
+        _cleanup_free_ char *name = NULL, *unit = NULL, *lnk = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+
+        log_debug("Adding swap: %s %s", path, fstype);
+
+        name = unit_name_from_path(path, ".swap");
+        if (!name)
+                return log_oom();
+
+        unit = strjoin(arg_dest, "/", name, NULL);
+        if (!unit)
+                return log_oom();
+
+        f = fopen(unit, "wxe");
+        if (!f) {
+                log_error("Failed to create unit file %s: %m", unit);
+                return -errno;
+        }
+
+        fprintf(f,
+                "# Automatically generated by systemd-gpt-auto-generator\n\n"
+                "[Unit]\n"
+                "DefaultDependencies=no\n"
+                "Conflicts=" SPECIAL_UMOUNT_TARGET "\n"
+                "Before=" SPECIAL_UMOUNT_TARGET " " SPECIAL_SWAP_TARGET "\n\n"
+                "[Mount]\n"
+                "What=%s\n",
+                path);
+
+        fflush(f);
+        if (ferror(f)) {
+                log_error("Failed to write unit file %s: %m", unit);
+                return -errno;
+        }
+
+        lnk = strjoin(arg_dest, "/" SPECIAL_SWAP_TARGET ".wants/", name, NULL);
+        if (!lnk)
+                return log_oom();
+
+        mkdir_parents_label(lnk, 0755);
+        if (symlink(unit, lnk) < 0) {
+                log_error("Failed to create symlink %s: %m", lnk);
+                return -errno;
+        }
+
+        return 0;
+}
+
+static int add_home(const char *path, const char *fstype) {
+        _cleanup_free_ char *unit = NULL, *lnk = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+
+        log_debug("Adding home: %s %s", path, fstype);
+
+        unit = strappend(arg_dest, "/home.mount");
+        if (!unit)
+                return log_oom();
+
+        f = fopen(unit, "wxe");
+        if (!f) {
+                log_error("Failed to create unit file %s: %m", unit);
+                return -errno;
+        }
+
+        fprintf(f,
+                "# Automatically generated by systemd-gpt-auto-generator\n\n"
+                "[Unit]\n"
+                "DefaultDependencies=no\n"
+                "After=" SPECIAL_LOCAL_FS_PRE_TARGET "\n"
+                "Conflicts=" SPECIAL_UMOUNT_TARGET "\n"
+                "Before=" SPECIAL_UMOUNT_TARGET " " SPECIAL_LOCAL_FS_TARGET "\n\n"
+                "[Mount]\n"
+                "What=%s\n"
+                "Where=/home\n"
+                "Type=%s\n"
+                "FsckPassNo=2\n",
+                path, fstype);
+
+        fflush(f);
+        if (ferror(f)) {
+                log_error("Failed to write unit file %s: %m", unit);
+                return -errno;
+        }
+
+        lnk = strjoin(arg_dest, "/" SPECIAL_LOCAL_FS_TARGET ".requires/home.mount", NULL);
+        if (!lnk)
+                return log_oom();
+
+
+        mkdir_parents_label(lnk, 0755);
+        if (symlink(unit, lnk) < 0) {
+                log_error("Failed to create symlink %s: %m", lnk);
+                return -errno;
+        }
+
+        return 0;
+}
+
+static int enumerate_partitions(dev_t dev) {
+        struct udev *udev;
+        struct udev_enumerate *e = NULL;
+        struct udev_device *parent = NULL, *d = NULL;
+        struct udev_list_entry *first, *item;
+        unsigned home_nr = (unsigned) -1;
+        _cleanup_free_ char *home = NULL, *home_fstype = NULL;
+        int r;
+
+        udev = udev_new();
+        if (!udev)
+                return log_oom();
+
+        e = udev_enumerate_new(udev);
+        if (!e) {
+                r = log_oom();
+                goto finish;
+        }
+
+        d = udev_device_new_from_devnum(udev, 'b', dev);
+        if (!d) {
+                r = log_oom();
+                goto finish;
+        }
+
+        parent = udev_device_get_parent(d);
+        if (!parent) {
+                r = log_oom();
+                goto finish;
+        }
+
+        r = udev_enumerate_add_match_parent(e, parent);
+        if (r < 0) {
+                r = log_oom();
+                goto finish;
+        }
+
+        r = udev_enumerate_add_match_subsystem(e, "block");
+        if (r < 0) {
+                r = log_oom();
+                goto finish;
+        }
+
+        r = udev_enumerate_scan_devices(e);
+        if (r < 0) {
+                log_error("Failed to enumerate partitions: %s", strerror(-r));
+                goto finish;
+        }
+
+        first = udev_enumerate_get_list_entry(e);
+        udev_list_entry_foreach(item, first) {
+                _cleanup_free_ char *fstype = NULL;
+                const char *node = NULL;
+                struct udev_device *q;
+                sd_id128_t type_id;
+                unsigned nr;
+
+                q = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
+                if (!q) {
+                        r = log_oom();
+                        goto finish;
+                }
+
+                if (udev_device_get_devnum(q) == udev_device_get_devnum(d))
+                        goto skip;
+
+                if (udev_device_get_devnum(q) == udev_device_get_devnum(parent))
+                        goto skip;
+
+                node = udev_device_get_devnode(q);
+                if (!node) {
+                        r = log_oom();
+                        goto finish;
+                }
+
+                r = verify_gpt_partition(udev_device_get_devnum(q), &type_id, &nr, &fstype);
+                if (r < 0) {
+                        log_error("Failed to verify GPT partition: %s", strerror(-r));
+                        udev_device_unref(q);
+                        goto finish;
+                }
+                if (r == 0)
+                        goto skip;
+
+                if (sd_id128_equal(type_id, SD_ID128_MAKE(06,57,fd,6d,a4,ab,43,c4,84,e5,09,33,c8,4b,4f,4f)))
+                        add_swap(node, fstype);
+                else if (sd_id128_equal(type_id, SD_ID128_MAKE(93,3a,c7,e1,2e,b4,4f,13,b8,44,0e,14,e2,ae,f9,15))) {
+
+                        if (!home || nr < home_nr) {
+                                free(home);
+                                home = strdup(node);
+                                if (!home) {
+                                        r = log_oom();
+                                        goto finish;
+                                }
+
+                                home_nr = nr;
+
+                                free(home_fstype);
+                                home_fstype = fstype;
+                                fstype = NULL;
+                        }
+                }
+
+        skip:
+                udev_device_unref(q);
+        }
+
+        if (home && home_fstype)
+                add_home(home, home_fstype);
+
+finish:
+        if (d)
+                udev_device_unref(d);
+
+        if (e)
+                udev_enumerate_unref(e);
+
+        if (udev)
+                udev_unref(udev);
+
+        return r;
+}
+
+static int get_btrfs_block_device(const char *path, dev_t *dev) {
+        struct btrfs_ioctl_fs_info_args fsi;
+        _cleanup_close_ int fd = -1;
+        uint64_t id;
+
+        assert(path);
+        assert(dev);
+
+        fd = open(path, O_DIRECTORY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        zero(fsi);
+        if (ioctl(fd, BTRFS_IOC_FS_INFO, &fsi) < 0)
+                return -errno;
+
+        /* We won't do this for btrfs RAID */
+        if (fsi.num_devices != 1)
+                return 0;
+
+        for (id = 1; id <= fsi.max_id; id++) {
+                struct btrfs_ioctl_dev_info_args di;
+                struct stat st;
+
+                zero(di);
+                di.devid = id;
+
+                if (ioctl(fd, BTRFS_IOC_DEV_INFO, &di) < 0) {
+                        if (errno == ENODEV)
+                                continue;
+
+                        return -errno;
+                }
+
+                if (stat((char*) di.path, &st) < 0)
+                        return -errno;
+
+                if (!S_ISBLK(st.st_mode))
+                        return -ENODEV;
+
+                if (major(st.st_rdev) == 0)
+                        return -ENODEV;
+
+                *dev = st.st_rdev;
+                return 1;
+        }
+
+        return -ENODEV;
+}
+
+static int get_block_device(const char *path, dev_t *dev) {
+        struct stat st;
+        struct statfs sfs;
+
+        assert(path);
+        assert(dev);
+
+        if (lstat("/", &st))
+                return -errno;
+
+        if (major(st.st_dev) != 0) {
+                *dev = st.st_dev;
+                return 1;
+        }
+
+        if (statfs("/", &sfs) < 0)
+                return -errno;
+
+        if (F_TYPE_CMP(sfs.f_type, BTRFS_SUPER_MAGIC))
+                return get_btrfs_block_device(path, dev);
+
+        return 0;
+}
+
+int main(int argc, char *argv[]) {
+        dev_t dev;
+        int r;
+
+        if (argc > 1 && argc != 4) {
+                log_error("This program takes three or no arguments.");
+                return EXIT_FAILURE;
+        }
+
+        if (argc > 1)
+                arg_dest = argv[3];
+
+        log_set_target(LOG_TARGET_SAFE);
+        log_parse_environment();
+        log_open();
+
+        umask(0022);
+
+        if (in_initrd())
+                return EXIT_SUCCESS;
+
+        r = get_block_device("/", &dev);
+        if (r < 0) {
+                log_error("Failed to determine block device of root file system: %s", strerror(-r));
+                return EXIT_FAILURE;
+        }
+        if (r == 0) {
+                log_debug("Root file system not on a (single) block device.");
+                return EXIT_SUCCESS;
+        }
+
+        log_debug("Root device %u:%u.", major(dev), minor(dev));
+
+        r = verify_gpt_partition(dev, NULL, NULL, NULL);
+        if (r < 0) {
+                log_error("Failed to verify GPT partition: %s", strerror(-r));
+                return EXIT_FAILURE;
+        }
+        if (r == 0)
+                return EXIT_SUCCESS;
+
+        r = enumerate_partitions(dev);
+
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}