diff options
Diffstat (limited to 'src/udev/udev-worker.c')
| -rw-r--r-- | src/udev/udev-worker.c | 352 |
1 files changed, 352 insertions, 0 deletions
diff --git a/src/udev/udev-worker.c b/src/udev/udev-worker.c new file mode 100644 index 0000000..53722b2 --- /dev/null +++ b/src/udev/udev-worker.c @@ -0,0 +1,352 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include <sys/file.h> +#include <sys/ioctl.h> +#include <sys/mount.h> + +#include "alloc-util.h" +#include "blockdev-util.h" +#include "common-signal.h" +#include "device-monitor-private.h" +#include "device-private.h" +#include "device-util.h" +#include "errno-util.h" +#include "fd-util.h" +#include "io-util.h" +#include "path-util.h" +#include "process-util.h" +#include "signal-util.h" +#include "string-util.h" +#include "udev-event.h" +#include "udev-spawn.h" +#include "udev-trace.h" +#include "udev-util.h" +#include "udev-watch.h" +#include "udev-worker.h" + +void udev_worker_done(UdevWorker *worker) { + assert(worker); + + sd_event_unref(worker->event); + sd_netlink_unref(worker->rtnl); + sd_device_monitor_unref(worker->monitor); + hashmap_free(worker->properties); + udev_rules_free(worker->rules); + safe_close(worker->pipe_fd); +} + +int udev_get_whole_disk(sd_device *dev, sd_device **ret_device, const char **ret_devname) { + const char *val; + int r; + + assert(dev); + + if (device_for_action(dev, SD_DEVICE_REMOVE)) + goto irrelevant; + + r = sd_device_get_sysname(dev, &val); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get sysname: %m"); + + /* Exclude the following devices: + * For "dm-", see the comment added by e918a1b5a94f270186dca59156354acd2a596494. + * For "md", see the commit message of 2e5b17d01347d3c3118be2b8ad63d20415dbb1f0, + * but not sure the assumption is still valid even when partitions are created on the md + * devices, surprisingly which seems to be possible, see PR #22973. + * For "drbd", see the commit message of fee854ee8ccde0cd28e0f925dea18cce35f3993d. */ + if (STARTSWITH_SET(val, "dm-", "md", "drbd")) + goto irrelevant; + + r = block_device_get_whole_disk(dev, &dev); + if (IN_SET(r, + -ENOTBLK, /* The device is not a block device. */ + -ENODEV /* The whole disk device was not found, it may already be removed. */)) + goto irrelevant; + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get whole disk device: %m"); + + r = sd_device_get_devname(dev, &val); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get devname: %m"); + + if (ret_device) + *ret_device = dev; + if (ret_devname) + *ret_devname = val; + return 1; + +irrelevant: + if (ret_device) + *ret_device = NULL; + if (ret_devname) + *ret_devname = NULL; + return 0; +} + +static int worker_lock_whole_disk(sd_device *dev, int *ret_fd) { + _cleanup_close_ int fd = -EBADF; + sd_device *dev_whole_disk; + const char *val; + int r; + + assert(dev); + assert(ret_fd); + + /* Take a shared lock on the device node; this establishes a concept of device "ownership" to + * serialize device access. External processes holding an exclusive lock will cause udev to skip the + * event handling; in the case udev acquired the lock, the external process can block until udev has + * finished its event handling. */ + + r = udev_get_whole_disk(dev, &dev_whole_disk, &val); + if (r < 0) + return r; + if (r == 0) + goto nolock; + + fd = sd_device_open(dev_whole_disk, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY); + if (fd < 0) { + bool ignore = ERRNO_IS_DEVICE_ABSENT(fd); + + log_device_debug_errno(dev, fd, "Failed to open '%s'%s: %m", val, ignore ? ", ignoring" : ""); + if (!ignore) + return fd; + + goto nolock; + } + + if (flock(fd, LOCK_SH|LOCK_NB) < 0) + return log_device_debug_errno(dev, errno, "Failed to flock(%s): %m", val); + + *ret_fd = TAKE_FD(fd); + return 1; + +nolock: + *ret_fd = -EBADF; + return 0; +} + +static int worker_mark_block_device_read_only(sd_device *dev) { + _cleanup_close_ int fd = -EBADF; + const char *val; + int state = 1, r; + + assert(dev); + + /* Do this only once, when the block device is new. If the device is later retriggered let's not + * toggle the bit again, so that people can boot up with full read-only mode and then unset the bit + * for specific devices only. */ + if (!device_for_action(dev, SD_DEVICE_ADD)) + return 0; + + r = sd_device_get_subsystem(dev, &val); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get subsystem: %m"); + + if (!streq(val, "block")) + return 0; + + r = sd_device_get_sysname(dev, &val); + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get sysname: %m"); + + /* Exclude synthetic devices for now, this is supposed to be a safety feature to avoid modification + * of physical devices, and what sits on top of those doesn't really matter if we don't allow the + * underlying block devices to receive changes. */ + if (STARTSWITH_SET(val, "dm-", "md", "drbd", "loop", "nbd", "zram")) + return 0; + + fd = sd_device_open(dev, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY); + if (fd < 0) + return log_device_debug_errno(dev, fd, "Failed to open '%s', ignoring: %m", val); + + if (ioctl(fd, BLKROSET, &state) < 0) + return log_device_warning_errno(dev, errno, "Failed to mark block device '%s' read-only: %m", val); + + log_device_info(dev, "Successfully marked block device '%s' read-only.", val); + return 0; +} + +static int worker_process_device(UdevWorker *worker, sd_device *dev) { + _cleanup_(udev_event_freep) UdevEvent *udev_event = NULL; + _cleanup_close_ int fd_lock = -EBADF; + int r; + + assert(worker); + assert(dev); + + log_device_uevent(dev, "Processing device"); + + udev_event = udev_event_new(dev, worker->exec_delay_usec, worker->rtnl, worker->log_level); + if (!udev_event) + return -ENOMEM; + + /* If this is a block device and the device is locked currently via the BSD advisory locks, + * someone else is using it exclusively. We don't run our udev rules now to not interfere. + * Instead of processing the event, we requeue the event and will try again after a delay. + * + * The user-facing side of this: https://systemd.io/BLOCK_DEVICE_LOCKING */ + r = worker_lock_whole_disk(dev, &fd_lock); + if (r == -EAGAIN) + return EVENT_RESULT_TRY_AGAIN; + if (r < 0) + return r; + + if (worker->blockdev_read_only) + (void) worker_mark_block_device_read_only(dev); + + /* apply rules, create node, symlinks */ + r = udev_event_execute_rules( + udev_event, + worker->inotify_fd, + worker->timeout_usec, + worker->timeout_signal, + worker->properties, + worker->rules); + if (r < 0) + return r; + + udev_event_execute_run(udev_event, worker->timeout_usec, worker->timeout_signal); + + if (!worker->rtnl) + /* in case rtnl was initialized */ + worker->rtnl = sd_netlink_ref(udev_event->rtnl); + + if (udev_event->inotify_watch) { + r = udev_watch_begin(worker->inotify_fd, dev); + if (r < 0 && r != -ENOENT) /* The device may be already removed, ignore -ENOENT. */ + log_device_warning_errno(dev, r, "Failed to add inotify watch, ignoring: %m"); + } + + log_device_uevent(dev, "Device processed"); + return 0; +} + +void udev_broadcast_result(sd_device_monitor *monitor, sd_device *dev, EventResult result) { + int r; + + assert(dev); + + /* On exit, manager->monitor is already NULL. */ + if (!monitor) + return; + + if (result != EVENT_RESULT_SUCCESS) { + (void) device_add_property(dev, "UDEV_WORKER_FAILED", "1"); + + switch (result) { + case EVENT_RESULT_NERRNO_MIN ... EVENT_RESULT_NERRNO_MAX: { + const char *str; + + (void) device_add_propertyf(dev, "UDEV_WORKER_ERRNO", "%i", -result); + + str = errno_to_name(result); + if (str) + (void) device_add_property(dev, "UDEV_WORKER_ERRNO_NAME", str); + break; + } + case EVENT_RESULT_EXIT_STATUS_BASE ... EVENT_RESULT_EXIT_STATUS_MAX: + (void) device_add_propertyf(dev, "UDEV_WORKER_EXIT_STATUS", "%i", result - EVENT_RESULT_EXIT_STATUS_BASE); + break; + + case EVENT_RESULT_TRY_AGAIN: + assert_not_reached(); + break; + + case EVENT_RESULT_SIGNAL_BASE ... EVENT_RESULT_SIGNAL_MAX: { + const char *str; + + (void) device_add_propertyf(dev, "UDEV_WORKER_SIGNAL", "%i", result - EVENT_RESULT_SIGNAL_BASE); + + str = signal_to_string(result - EVENT_RESULT_SIGNAL_BASE); + if (str) + (void) device_add_property(dev, "UDEV_WORKER_SIGNAL_NAME", str); + break; + } + default: + log_device_warning(dev, "Unknown event result \"%i\", ignoring.", result); + } + } + + r = device_monitor_send_device(monitor, NULL, dev); + if (r < 0) + log_device_warning_errno(dev, r, + "Failed to broadcast event to libudev listeners, ignoring: %m"); +} + +static int worker_send_result(UdevWorker *worker, EventResult result) { + assert(worker); + assert(worker->pipe_fd >= 0); + + return loop_write(worker->pipe_fd, &result, sizeof(result)); +} + +static int worker_device_monitor_handler(sd_device_monitor *monitor, sd_device *dev, void *userdata) { + UdevWorker *worker = ASSERT_PTR(userdata); + int r; + + assert(dev); + + r = worker_process_device(worker, dev); + if (r == EVENT_RESULT_TRY_AGAIN) + /* if we couldn't acquire the flock(), then requeue the event */ + log_device_debug(dev, "Block device is currently locked, requeueing the event."); + else { + if (r < 0) + log_device_warning_errno(dev, r, "Failed to process device, ignoring: %m"); + + /* send processed event back to libudev listeners */ + udev_broadcast_result(monitor, dev, r); + } + + /* send udevd the result of the event execution */ + r = worker_send_result(worker, r); + if (r < 0) + log_device_warning_errno(dev, r, "Failed to send signal to main daemon, ignoring: %m"); + + /* Reset the log level, as it might be changed by "OPTIONS=log_level=". */ + log_set_max_level(worker->log_level); + + return 1; +} + +int udev_worker_main(UdevWorker *worker, sd_device *dev) { + int r; + + assert(worker); + assert(worker->monitor); + assert(dev); + + DEVICE_TRACE_POINT(worker_spawned, dev, getpid_cached()); + + assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, -1) >= 0); + + /* Reset OOM score, we only protect the main daemon. */ + r = set_oom_score_adjust(0); + if (r < 0) + log_debug_errno(r, "Failed to reset OOM score, ignoring: %m"); + + r = sd_event_new(&worker->event); + if (r < 0) + return log_error_errno(r, "Failed to allocate event loop: %m"); + + r = sd_event_add_signal(worker->event, NULL, SIGTERM, NULL, NULL); + if (r < 0) + return log_error_errno(r, "Failed to set SIGTERM event: %m"); + + r = sd_device_monitor_attach_event(worker->monitor, worker->event); + if (r < 0) + return log_error_errno(r, "Failed to attach event loop to device monitor: %m"); + + r = sd_device_monitor_start(worker->monitor, worker_device_monitor_handler, worker); + if (r < 0) + return log_error_errno(r, "Failed to start device monitor: %m"); + + /* Process first device */ + (void) worker_device_monitor_handler(worker->monitor, dev, worker); + + r = sd_event_loop(worker->event); + if (r < 0) + return log_error_errno(r, "Event loop failed: %m"); + + return 0; +} |