chiark / gitweb /
automount: implement automount unit type
[elogind.git] / automount.c
index 1192949..5d79131 100644 (file)
 ***/
 
 #include <errno.h>
+#include <limits.h>
+#include <sys/mount.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/epoll.h>
+#include <sys/stat.h>
+#include <linux/auto_fs4.h>
+#include <linux/auto_dev-ioctl.h>
 
 #include "unit.h"
 #include "automount.h"
 #include "load-fragment.h"
 #include "load-dropin.h"
+#include "unit-name.h"
 
 static const UnitActiveState state_translation_table[_AUTOMOUNT_STATE_MAX] = {
         [AUTOMOUNT_DEAD] = UNIT_INACTIVE,
@@ -40,11 +49,95 @@ static const char* const state_string_table[_AUTOMOUNT_STATE_MAX] = {
         [AUTOMOUNT_MAINTAINANCE] = "maintainance"
 };
 
+static char *automount_name_from_where(const char *where) {
+        assert(where);
+
+        if (streq(where, "/"))
+                return strdup("-.automount");
+
+        return unit_name_build_escape(where+1, NULL, ".automount");
+}
+
 static void automount_init(Unit *u) {
         Automount *a = AUTOMOUNT(u);
 
-        a->state = 0;
+        assert(u);
+        assert(u->meta.load_state == UNIT_STUB);
+
+        a->pipe_watch.fd = a->pipe_fd = -1;
+}
+
+static void repeat_unmout(const char *path) {
+        assert(path);
+
+        for (;;) {
+
+                if (umount2(path, MNT_DETACH) >= 0)
+                        continue;
+
+                if (errno != EINVAL)
+                        log_error("Failed to unmount: %m");
+
+                break;
+        }
+}
+
+static void unmount_autofs(Automount *a) {
+        assert(a);
+
+        if (a->pipe_fd < 0)
+                return;
+
+        automount_send_ready(a, -EHOSTDOWN);
+
+        unit_unwatch_fd(UNIT(a), &a->pipe_watch);
+        close_nointr_nofail(a->pipe_fd);
+        a->pipe_fd = -1;
+
+        repeat_unmout(a->where);
+}
+
+static void automount_done(Unit *u) {
+        Automount *a = AUTOMOUNT(u);
+
+        assert(a);
+
+        unmount_autofs(a);
         a->mount = NULL;
+
+        if (a->tokens) {
+                set_free(a->tokens);
+                a->tokens = NULL;
+        }
+}
+
+static int automount_verify(Automount *a) {
+        bool b;
+        char *e;
+        assert(a);
+
+        if (UNIT(a)->meta.load_state != UNIT_LOADED)
+                return 0;
+
+        if (!a->where) {
+                log_error("%s lacks Where setting. Refusing.", UNIT(a)->meta.id);
+                return -EINVAL;
+        }
+
+        path_kill_slashes(a->where);
+
+        if (!(e = automount_name_from_where(a->where)))
+                return -ENOMEM;
+
+        b = unit_has_name(UNIT(a), e);
+        free(e);
+
+        if (!b) {
+                log_error("%s's Where setting doesn't match unit name. Refusing.", UNIT(a)->meta.id);
+                return -EINVAL;
+        }
+
+        return 0;
 }
 
 static int automount_load(Unit *u) {
@@ -67,15 +160,24 @@ static int automount_load(Unit *u) {
                         return r;
         }
 
-        return 0;
+        return automount_verify(a);
 }
 
-static void automount_done(Unit *u) {
-        Automount *a = AUTOMOUNT(u);
-
+static void automount_set_state(Automount *a, AutomountState state) {
+        AutomountState old_state;
         assert(a);
 
-        a->mount = NULL;
+        old_state = a->state;
+        a->state = state;
+
+        if (state != AUTOMOUNT_WAITING &&
+            state != AUTOMOUNT_RUNNING)
+                unmount_autofs(a);
+
+        if (state != old_state)
+                log_debug("%s changed %s → %s", UNIT(a)->meta.id, state_string_table[old_state], state_string_table[state]);
+
+        unit_notify(UNIT(a), state_translation_table[old_state], state_translation_table[state]);
 }
 
 static void automount_dump(Unit *u, FILE *f, const char *prefix) {
@@ -88,6 +190,336 @@ static void automount_dump(Unit *u, FILE *f, const char *prefix) {
                 prefix, state_string_table[s->state]);
 }
 
+static void automount_enter_dead(Automount *a, bool success) {
+        assert(a);
+
+        if (!success)
+                a->failure = true;
+
+        automount_set_state(a, a->failure ? AUTOMOUNT_MAINTAINANCE : AUTOMOUNT_DEAD);
+}
+
+static int open_dev_autofs(Manager *m) {
+        struct autofs_dev_ioctl param;
+
+        assert(m);
+
+        if (m->dev_autofs_fd >= 0)
+                return m->dev_autofs_fd;
+
+        if ((m->dev_autofs_fd = open("/dev/autofs", O_RDONLY)) < 0) {
+                log_error("Failed to open /dev/autofs: %s", strerror(errno));
+                return -errno;
+        }
+
+        init_autofs_dev_ioctl(&param);
+        if (ioctl(m->dev_autofs_fd, AUTOFS_DEV_IOCTL_VERSION, &param) < 0) {
+                close_nointr_nofail(m->dev_autofs_fd);
+                m->dev_autofs_fd = -1;
+                return -errno;
+        }
+
+        log_debug("Autofs kernel version %i.%i", param.ver_major, param.ver_minor);
+
+        return m->dev_autofs_fd;
+}
+
+static int open_ioctl_fd(int dev_autofs_fd, const char *where, dev_t devid) {
+        struct autofs_dev_ioctl *param;
+        size_t l;
+        int r;
+
+        assert(dev_autofs_fd >= 0);
+        assert(where);
+
+        l = sizeof(struct autofs_dev_ioctl) + strlen(where) + 1;
+
+        if (!(param = malloc(l)))
+                return -ENOMEM;
+
+        init_autofs_dev_ioctl(param);
+        param->size = l;
+        param->ioctlfd = -1;
+        param->openmount.devid = devid;
+        strcpy(param->path, where);
+
+        if (ioctl(dev_autofs_fd, AUTOFS_DEV_IOCTL_OPENMOUNT, param) < 0) {
+                r = -errno;
+                goto finish;
+        }
+
+        if (param->ioctlfd < 0) {
+                r = -EIO;
+                goto finish;
+        }
+
+        r = param->ioctlfd;
+
+finish:
+        free(param);
+        return r;
+}
+
+static int autofs_protocol(int dev_autofs_fd, int ioctl_fd) {
+        uint32_t major, minor;
+        struct autofs_dev_ioctl param;
+
+        assert(dev_autofs_fd >= 0);
+        assert(ioctl_fd >= 0);
+
+        init_autofs_dev_ioctl(&param);
+        param.ioctlfd = ioctl_fd;
+
+        if (ioctl(dev_autofs_fd, AUTOFS_DEV_IOCTL_PROTOVER, &param) < 0)
+                return -errno;
+
+        major = param.protover.version;
+
+        init_autofs_dev_ioctl(&param);
+        param.ioctlfd = ioctl_fd;
+
+        if (ioctl(dev_autofs_fd, AUTOFS_DEV_IOCTL_PROTOSUBVER, &param) < 0)
+                return -errno;
+
+        minor = param.protosubver.sub_version;
+
+        log_debug("Autofs protocol version %i.%i", major, minor);
+        return 0;
+}
+
+static int autofs_set_timeout(int dev_autofs_fd, int ioctl_fd, time_t sec) {
+        struct autofs_dev_ioctl param;
+
+        assert(dev_autofs_fd >= 0);
+        assert(ioctl_fd >= 0);
+
+        init_autofs_dev_ioctl(&param);
+        param.ioctlfd = ioctl_fd;
+        param.timeout.timeout = sec;
+
+        if (ioctl(dev_autofs_fd, AUTOFS_DEV_IOCTL_TIMEOUT, &param) < 0)
+                return -errno;
+
+        return 0;
+}
+
+static int autofs_send_ready(int dev_autofs_fd, int ioctl_fd, uint32_t token, int status) {
+        struct autofs_dev_ioctl param;
+
+        assert(dev_autofs_fd >= 0);
+        assert(ioctl_fd >= 0);
+
+        init_autofs_dev_ioctl(&param);
+        param.ioctlfd = ioctl_fd;
+
+        if (status) {
+                param.fail.token = token;
+                param.fail.status = status;
+        } else
+                param.ready.token = token;
+
+        if (ioctl(dev_autofs_fd, status ? AUTOFS_DEV_IOCTL_FAIL : AUTOFS_DEV_IOCTL_READY, &param) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int automount_send_ready(Automount *a, int status) {
+        int ioctl_fd, r;
+        unsigned token;
+
+        assert(a);
+        assert(status <= 0);
+
+        if (set_isempty(a->tokens))
+                return 0;
+
+        if ((ioctl_fd = open_ioctl_fd(UNIT(a)->meta.manager->dev_autofs_fd, a->where, a->dev_id)) < 0) {
+                r = ioctl_fd;
+                goto fail;
+        }
+
+        if (status)
+                log_debug("Sending failure: %s", strerror(-status));
+        else
+                log_debug("Sending success.");
+
+        /* Autofs thankfully does not hand out 0 as a token */
+        while ((token = PTR_TO_UINT(set_steal_first(a->tokens)))) {
+                int k;
+
+                /* Autofs fun fact II:
+                 *
+                 * if you pass a positive status code here, the kernel will
+                 * freeze! Yay! */
+
+                if ((k = autofs_send_ready(UNIT(a)->meta.manager->dev_autofs_fd,
+                                           ioctl_fd,
+                                           token,
+                                           status)) < 0)
+                        r = k;
+        }
+
+        r = 0;
+
+fail:
+        if (ioctl_fd >= 0)
+                close_nointr_nofail(ioctl_fd);
+
+        return r;
+}
+
+static void automount_enter_waiting(Automount *a) {
+        int p[2] = { -1, -1 };
+        char name[32], options[128];
+        bool mounted = false;
+        int r, ioctl_fd = -1, dev_autofs_fd;
+        struct stat st;
+
+        assert(a);
+        assert(a->pipe_fd < 0);
+        assert(a->where);
+
+        if (a->tokens)
+                set_clear(a->tokens);
+        else if (!(a->tokens = set_new(trivial_hash_func, trivial_compare_func))) {
+                r = -ENOMEM;
+                goto fail;
+        }
+
+        if ((dev_autofs_fd = open_dev_autofs(UNIT(a)->meta.manager)) < 0) {
+                r = dev_autofs_fd;
+                goto fail;
+        }
+
+        /* We knowingly ignore the results of this call */
+        mkdir_p(a->where, 0555);
+
+        if (pipe2(p, O_NONBLOCK) < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        snprintf(options, sizeof(options), "fd=%i,pgrp=%u,minproto=5,maxproto=5,direct", p[1], (unsigned) getpgrp());
+        char_array_0(options);
+
+        snprintf(name, sizeof(name), "systemd-%u", (unsigned) getpid());
+        char_array_0(name);
+
+        if (mount(name, a->where, "autofs", 0, options) < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        mounted = true;
+
+        close_nointr_nofail(p[1]);
+        p[1] = -1;
+
+        if (stat(a->where, &st) < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        if ((ioctl_fd = open_ioctl_fd(dev_autofs_fd, a->where, st.st_dev)) < 0) {
+                r = ioctl_fd;
+                goto fail;
+        }
+
+        if ((r = autofs_protocol(dev_autofs_fd, ioctl_fd)) < 0)
+                goto fail;
+
+        if ((r = autofs_set_timeout(dev_autofs_fd, ioctl_fd, 300)) < 0)
+                goto fail;
+
+        /* Autofs fun fact:
+         *
+         * Unless we close the ioctl fd here, for some weird reason
+         * the direct mount will not receive events from the
+         * kernel. */
+
+        close_nointr_nofail(ioctl_fd);
+        ioctl_fd = -1;
+
+        if ((r = unit_watch_fd(UNIT(a), p[0], EPOLLIN, &a->pipe_watch)) < 0)
+                goto fail;
+
+        a->pipe_fd = p[0];
+        a->dev_id = st.st_dev;
+
+        automount_set_state(a, AUTOMOUNT_WAITING);
+
+        return;
+
+fail:
+        assert_se(close_pipe(p) == 0);
+
+        if (ioctl_fd >= 0)
+                close_nointr_nofail(ioctl_fd);
+
+        if (mounted)
+                repeat_unmout(a->where);
+
+        log_error("Failed to initialize automounter: %s", strerror(-r));
+        automount_enter_dead(a, false);
+}
+
+static void automount_enter_runnning(Automount *a) {
+        int r;
+        struct stat st;
+
+        assert(a);
+        assert(a->mount);
+
+        /* Before we do anything, let's see if somebody is playing games with us? */
+
+        if (stat(a->where, &st) < 0) {
+                log_warning("%s failed stat automount point: %m", a->meta.id);
+                goto fail;
+        }
+
+        if (!S_ISDIR(st.st_mode) || st.st_dev != a->dev_id)
+                log_info("%s's automount point already active?", a->meta.id);
+        else if ((r = manager_add_job(UNIT(a)->meta.manager, JOB_START, UNIT(a->mount), JOB_REPLACE, true, NULL)) < 0) {
+                log_warning("%s failed to queue mount startup job: %s", a->meta.id, strerror(-r));
+                goto fail;
+        }
+
+        automount_set_state(a, AUTOMOUNT_RUNNING);
+        return;
+
+fail:
+        automount_enter_dead(a, false);
+}
+
+static int automount_start(Unit *u) {
+        Automount *a = AUTOMOUNT(u);
+
+        assert(a);
+
+        if (path_is_mount_point(a->where)) {
+                log_error("Path %s is already a mount point, refusing start for %s", a->where, u->meta.id);
+                return -EEXIST;
+        }
+
+        assert(a->state == AUTOMOUNT_DEAD || a->state == AUTOMOUNT_MAINTAINANCE);
+
+        a->failure = false;
+        automount_enter_waiting(a);
+        return 0;
+}
+
+static int automount_stop(Unit *u) {
+        Automount *a = AUTOMOUNT(u);
+
+        assert(a);
+
+        assert(a->state == AUTOMOUNT_WAITING || a->state == AUTOMOUNT_RUNNING);
+
+        automount_enter_dead(a, true);
+        return 0;
+}
+
 static UnitActiveState automount_active_state(Unit *u) {
 
         return state_translation_table[AUTOMOUNT(u)->state];
@@ -99,10 +531,62 @@ static const char *automount_sub_state_to_string(Unit *u) {
         return state_string_table[AUTOMOUNT(u)->state];
 }
 
+static void automount_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
+        union autofs_v5_packet_union packet;
+        ssize_t l;
+        int r;
+
+        Automount *a = AUTOMOUNT(u);
+
+        assert(a);
+        assert(fd == a->pipe_fd);
+
+        if (events != EPOLLIN) {
+                log_error("Got invalid poll event on pipe.");
+                goto fail;
+        }
+
+        if ((l = loop_read(a->pipe_fd, &packet, sizeof(packet))) != sizeof(packet)) {
+                log_error("Invalid read from pipe: %s", l < 0 ? strerror(-l) : "short read");
+                goto fail;
+        }
+
+        switch (packet.hdr.type) {
+
+        case autofs_ptype_missing_direct:
+                log_debug("Got direct mount request for %s", packet.v5_packet.name);
+
+                if ((r = set_put(a->tokens, UINT_TO_PTR(packet.v5_packet.wait_queue_token))) < 0) {
+                        log_error("Failed to remember token: %s", strerror(-r));
+                        goto fail;
+                }
+
+                automount_enter_runnning(a);
+                break;
+
+        default:
+                log_error("Received unknown automount request %i", packet.hdr.type);
+                break;
+        }
+
+        return;
+
+fail:
+        automount_enter_dead(a, false);
+}
+
+static void automount_shutdown(Manager *m) {
+        assert(m);
+
+        if (m->dev_autofs_fd >= 0)
+                close_nointr_nofail(m->dev_autofs_fd);
+}
+
 const UnitVTable automount_vtable = {
-        .suffix = ".mount",
+        .suffix = ".automount",
 
         .no_alias = true,
+        .no_instances = true,
 
         .init = automount_init,
         .load = automount_load,
@@ -110,6 +594,13 @@ const UnitVTable automount_vtable = {
 
         .dump = automount_dump,
 
+        .start = automount_start,
+        .stop = automount_stop,
+
         .active_state = automount_active_state,
-        .sub_state_to_string = automount_sub_state_to_string
+        .sub_state_to_string = automount_sub_state_to_string,
+
+        .fd_event = automount_fd_event,
+
+        .shutdown = automount_shutdown
 };