Merge pull request #16705 from bluca/verity_udev_wait

Verity: use udev to wait for symlink creation on concurrent activations

src/cryptsetup/cryptsetup.c

@@ -839,10 +839,7 @@ static int run(int argc, char *argv[]) {
 
         log_setup_service();
 
-        crypt_set_log_callback(NULL, cryptsetup_log_glue, NULL);
-        if (DEBUG_LOGGING)
-                /* libcryptsetup won't even consider debug messages by default */
-                crypt_set_debug_level(CRYPT_DEBUG_ALL);
+        cryptsetup_enable_logging(cd);
 
         umask(0022);
 
@@ -906,7 +903,7 @@ static int run(int argc, char *argv[]) {
                 if (r < 0)
                         return log_error_errno(r, "crypt_init() failed: %m");
 
-                crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+                cryptsetup_enable_logging(cd);
 
                 status = crypt_status(cd, argv[2]);
                 if (IN_SET(status, CRYPT_ACTIVE, CRYPT_BUSY)) {
@@ -1032,7 +1029,7 @@ static int run(int argc, char *argv[]) {
                 if (r < 0)
                         return log_error_errno(r, "crypt_init_by_name() failed: %m");
 
-                crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+                cryptsetup_enable_logging(cd);
 
                 r = crypt_deactivate(cd, argv[2]);
                 if (r < 0)

src/home/homework-luks.c

@@ -238,7 +238,7 @@ static int luks_setup(
         if (r < 0)
                 return log_error_errno(r, "Failed to allocate libcryptsetup context: %m");
 
-        crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+        cryptsetup_enable_logging(cd);
 
         r = crypt_load(cd, CRYPT_LUKS2, NULL);
         if (r < 0)
@@ -338,7 +338,7 @@ static int luks_open(
         if (r < 0)
                 return log_error_errno(r, "Failed to initialize cryptsetup context for %s: %m", dm_name);
 
-        crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+        cryptsetup_enable_logging(cd);
 
         r = crypt_load(cd, CRYPT_LUKS2, NULL);
         if (r < 0)
@@ -1335,7 +1335,7 @@ int home_deactivate_luks(UserRecord *h) {
         else {
                 log_info("Discovered used LUKS device %s.", dm_node);
 
-                crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+                cryptsetup_enable_logging(cd);
 
                 r = crypt_deactivate(cd, dm_name);
                 if (IN_SET(r, -ENODEV, -EINVAL, -ENOENT)) {
@@ -1494,7 +1494,7 @@ static int luks_format(
         if (r < 0)
                 return log_error_errno(r, "Failed to allocate libcryptsetup context: %m");
 
-        crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+        cryptsetup_enable_logging(cd);
 
         /* Normally we'd, just leave volume key generation to libcryptsetup. However, we can't, since we
          * can't extract the volume key from the library again, but we need it in order to encrypt the JSON
@@ -2971,7 +2971,7 @@ int home_lock_luks(UserRecord *h) {
                 return log_error_errno(r, "Failed to initialize cryptsetup context for %s: %m", dm_name);
 
         log_info("Discovered used LUKS device %s.", dm_node);
-        crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+        cryptsetup_enable_logging(cd);
 
         if (syncfs(root_fd) < 0) /* Snake oil, but let's better be safe than sorry */
                 return log_error_errno(errno, "Failed to synchronize file system %s: %m", p);
@@ -3036,7 +3036,7 @@ int home_unlock_luks(UserRecord *h, PasswordCache *cache) {
                 return log_error_errno(r, "Failed to initialize cryptsetup context for %s: %m", dm_name);
 
         log_info("Discovered used LUKS device %s.", dm_node);
-        crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+        cryptsetup_enable_logging(cd);
 
         r = -ENOKEY;
         FOREACH_POINTER(list, cache->pkcs11_passwords, cache->fido2_passwords, h->password) {

src/partition/growfs.c

@@ -56,7 +56,7 @@ static int resize_crypt_luks_device(dev_t devno, const char *fstype, dev_t main_
         if (r < 0)
                 return log_error_errno(r, "crypt_init(\"%s\") failed: %m", devpath);
 
-        crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+        cryptsetup_enable_logging(cd);
 
         r = crypt_load(cd, CRYPT_LUKS, NULL);
         if (r < 0)
@@ -85,9 +85,7 @@ static int maybe_resize_underlying_device(const char *mountpath, dev_t main_devn
         int r;
 
 #if HAVE_LIBCRYPTSETUP
-        crypt_set_log_callback(NULL, cryptsetup_log_glue, NULL);
-        if (DEBUG_LOGGING)
-                crypt_set_debug_level(CRYPT_DEBUG_ALL);
+        cryptsetup_enable_logging(NULL);
 #endif
 
         r = get_block_device_harder(mountpath, &devno);

src/shared/crypt-util.c

@@ -4,7 +4,7 @@
 #include "crypt-util.h"
 #include "log.h"
 
-void cryptsetup_log_glue(int level, const char *msg, void *usrptr) {
+static void cryptsetup_log_glue(int level, const char *msg, void *usrptr) {
         switch (level) {
         case CRYPT_LOG_NORMAL:
                 level = LOG_NOTICE;
@@ -25,4 +25,10 @@ void cryptsetup_log_glue(int level, const char *msg, void *usrptr) {
 
         log_full(level, "%s", msg);
 }
+
+void cryptsetup_enable_logging(struct crypt_device *cd) {
+        crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+        crypt_set_debug_level(DEBUG_LOGGING ? CRYPT_DEBUG_ALL : CRYPT_DEBUG_NONE);
+}
+
 #endif

src/shared/crypt-util.h

@@ -8,5 +8,5 @@
 
 DEFINE_TRIVIAL_CLEANUP_FUNC(struct crypt_device *, crypt_free);
 
-void cryptsetup_log_glue(int level, const char *msg, void *usrptr);
+void cryptsetup_enable_logging(struct crypt_device *cd);
 #endif

src/shared/dissect-image.c

@@ -1277,7 +1277,7 @@ static int decrypt_partition(
         if (r < 0)
                 return log_debug_errno(r, "Failed to initialize dm-crypt: %m");
 
-        crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+        cryptsetup_enable_logging(cd);
 
         r = crypt_load(cd, CRYPT_LUKS, NULL);
         if (r < 0)
@@ -1399,7 +1399,7 @@ static int verity_partition(
         if (r < 0)
                 return r;
 
-        crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+        cryptsetup_enable_logging(cd);
 
         r = crypt_load(cd, CRYPT_VERITY, NULL);
         if (r < 0)
@@ -1430,28 +1430,44 @@ static int verity_partition(
                  * Improvements in libcrypsetup can ensure this never happens: https://gitlab.com/cryptsetup/cryptsetup/-/merge_requests/96 */
                 if (r == -EINVAL && FLAGS_SET(flags, DISSECT_IMAGE_VERITY_SHARE))
                         return verity_partition(m, v, root_hash, root_hash_size, verity_data, NULL, root_hash_sig ?: hash_sig_from_file, root_hash_sig_size, flags & ~DISSECT_IMAGE_VERITY_SHARE, d);
-                if (!IN_SET(r, 0, -EEXIST, -ENODEV))
+                if (!IN_SET(r,
+                            0, /* Success */
+                            -EEXIST, /* Volume is already open and ready to be used */
+                            -EBUSY, /* Volume is being opened but not ready, crypt_init_by_name can fetch details */
+                            -ENODEV /* Volume is being opened but not ready, crypt_init_by_name would fail, try to open again */))
                         return r;
-                if (r == -EEXIST) {
+                if (IN_SET(r, -EEXIST, -EBUSY)) {
                         struct crypt_device *existing_cd = NULL;
 
                         if (!restore_deferred_remove){
                                 /* To avoid races, disable automatic removal on umount while setting up the new device. Restore it on failure. */
                                 r = dm_deferred_remove_cancel(name);
-                                if (r < 0)
+                                /* If activation returns EBUSY there might be no deferred removal to cancel, that's fine */
+                                if (r < 0 && r != -ENXIO)
                                         return log_debug_errno(r, "Disabling automated deferred removal for verity device %s failed: %m", node);
+                                if (r == 0) {
                                         restore_deferred_remove = strdup(name);
                                         if (!restore_deferred_remove)
                                                 return -ENOMEM;
                                 }
+                        }
 
                         r = verity_can_reuse(root_hash, root_hash_size, !!root_hash_sig || !!hash_sig_from_file, name, &existing_cd);
                         /* Same as above, -EINVAL can randomly happen when it actually means -EEXIST */
                         if (r == -EINVAL && FLAGS_SET(flags, DISSECT_IMAGE_VERITY_SHARE))
                                 return verity_partition(m, v, root_hash, root_hash_size, verity_data, NULL, root_hash_sig ?: hash_sig_from_file, root_hash_sig_size, flags & ~DISSECT_IMAGE_VERITY_SHARE, d);
-                        if (!IN_SET(r, 0, -ENODEV, -ENOENT))
+                        if (!IN_SET(r, 0, -ENODEV, -ENOENT, -EBUSY))
                                 return log_debug_errno(r, "Checking whether existing verity device %s can be reused failed: %m", node);
                         if (r == 0) {
+                                /* devmapper might say that the device exists, but the devlink might not yet have been
+                                 * created. Check and wait for the udev event in that case. */
+                                r = device_wait_for_devlink(node, "block", 100 * USEC_PER_MSEC, NULL);
+                                /* Fallback to activation with a unique device if it's taking too long */
+                                if (r == -ETIMEDOUT)
+                                        break;
+                                if (r < 0)
+                                        return r;
+
                                 if (cd)
                                         crypt_free(cd);
                                 cd = existing_cd;
@@ -1459,12 +1475,11 @@ static int verity_partition(
                 }
                 if (r == 0)
                         break;
+
+                /* Device is being opened by another process, but it has not finished yet, yield for 2ms */
+                (void) usleep(2 * USEC_PER_MSEC);
         }
 
-        /* Sanity check: libdevmapper is known to report that the device already exists and is active,
-        * but it's actually not there, so the later filesystem probe or mount would fail. */
-        if (r == 0)
-                r = access(node, F_OK);
         /* An existing verity device was reported by libcryptsetup/libdevmapper, but we can't use it at this time.
          * Fall back to activating it with a unique device name. */
         if (r != 0 && FLAGS_SET(flags, DISSECT_IMAGE_VERITY_SHARE))

src/shared/udev-util.c

@@ -1,12 +1,14 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
 #include <errno.h>
+#include <unistd.h>
 
 #include "alloc-util.h"
 #include "device-util.h"
 #include "env-file.h"
 #include "log.h"
 #include "parse-util.h"
+#include "path-util.h"
 #include "signal-util.h"
 #include "string-table.h"
 #include "string-util.h"
@@ -108,48 +110,108 @@ int udev_parse_config_full(
         return 0;
 }
 
+/* Note that if -ENOENT is returned, it will be logged at debug level rather than error,
+ * because it's an expected, common occurrence that the caller will handle with a fallback */
+static int device_new_from_dev_path(const char *devlink, sd_device **ret_device) {
+        struct stat st;
+        int r;
+
+        assert(devlink);
+
+        r = stat(devlink, &st);
+        if (r < 0)
+                return log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_ERR, errno, "Failed to stat() %s: %m", devlink);
+
+        if (!S_ISBLK(st.st_mode))
+                return log_error_errno(SYNTHETIC_ERRNO(ENOTBLK), "%s does not point to a block device: %m", devlink);
+
+        r = sd_device_new_from_devnum(ret_device, 'b', st.st_rdev);
+        if (r < 0)
+                return log_error_errno(r, "Failed to initialize device from %s: %m", devlink);
+
+        return 0;
+}
+
 struct DeviceMonitorData {
         const char *sysname;
+        const char *devlink;
         sd_device *device;
 };
 
+static void device_monitor_data_free(struct DeviceMonitorData *d) {
+        assert(d);
+
+        sd_device_unref(d->device);
+}
+
 static int device_monitor_handler(sd_device_monitor *monitor, sd_device *device, void *userdata) {
         struct DeviceMonitorData *data = userdata;
         const char *sysname;
 
         assert(device);
         assert(data);
-        assert(data->sysname);
+        assert(data->sysname || data->devlink);
         assert(!data->device);
 
-        if (sd_device_get_sysname(device, &sysname) >= 0 && streq(sysname, data->sysname)) {
-                data->device = sd_device_ref(device);
-                return sd_event_exit(sd_device_monitor_get_event(monitor), 0);
+        if (data->sysname && sd_device_get_sysname(device, &sysname) >= 0 && streq(sysname, data->sysname))
+                goto found;
+
+        if (data->devlink) {
+                const char *devlink;
+
+                FOREACH_DEVICE_DEVLINK(device, devlink)
+                        if (path_equal(devlink, data->devlink))
+                                goto found;
+
+                if (sd_device_get_devname(device, &devlink) >= 0 && path_equal(devlink, data->devlink))
+                        goto found;
         }
 
         return 0;
+
+found:
+        data->device = sd_device_ref(device);
+        return sd_event_exit(sd_device_monitor_get_event(monitor), 0);
 }
 
 static int device_timeout_handler(sd_event_source *s, uint64_t usec, void *userdata) {
         return sd_event_exit(sd_event_source_get_event(s), -ETIMEDOUT);
 }
 
-int device_wait_for_initialization(sd_device *device, const char *subsystem, usec_t timeout, sd_device **ret) {
+static int device_wait_for_initialization_internal(
+                sd_device *_device,
+                const char *devlink,
+                const char *subsystem,
+                usec_t timeout,
+                sd_device **ret) {
         _cleanup_(sd_device_monitor_unrefp) sd_device_monitor *monitor = NULL;
         _cleanup_(sd_event_source_unrefp) sd_event_source *timeout_source = NULL;
         _cleanup_(sd_event_unrefp) sd_event *event = NULL;
-        struct DeviceMonitorData data = {};
+        /* Ensure that if !_device && devlink, device gets unrefd on errors since it will be new */
+        _cleanup_(sd_device_unrefp) sd_device *device = sd_device_ref(_device);
+        _cleanup_(device_monitor_data_free) struct DeviceMonitorData data = {
+                .devlink = devlink,
+        };
         int r;
 
-        assert(device);
+        assert(device || (subsystem && devlink));
 
+        /* Devlink might already exist, if it does get the device to use the sysname filtering */
+        if (!device && devlink) {
+                r = device_new_from_dev_path(devlink, &device);
+                if (r < 0 && r != -ENOENT)
+                        return r;
+        }
+
+        if (device) {
                 if (sd_device_get_is_initialized(device) > 0) {
                         if (ret)
                                 *ret = sd_device_ref(device);
                         return 0;
                 }
-
-        assert_se(sd_device_get_sysname(device, &data.sysname) >= 0);
+                /* We need either the sysname or the devlink for filtering */
+                assert_se(sd_device_get_sysname(device, &data.sysname) >= 0 || devlink);
+        }
 
         /* Wait until the device is initialized, so that we can get access to the ID_PATH property */
 
@@ -161,7 +223,7 @@ int device_wait_for_initialization(sd_device *device, const char *subsystem, use
         if (r < 0)
                 return log_error_errno(r, "Failed to acquire monitor: %m");
 
-        if (!subsystem) {
+        if (device && !subsystem) {
                 r = sd_device_get_subsystem(device, &subsystem);
                 if (r < 0 && r != -ENOENT)
                         return log_device_error_errno(device, r, "Failed to get subsystem: %m");
@@ -192,7 +254,12 @@ int device_wait_for_initialization(sd_device *device, const char *subsystem, use
 
         /* Check again, maybe things changed. Udev will re-read the db if the device wasn't initialized
          * yet. */
-        if (sd_device_get_is_initialized(device) > 0) {
+        if (!device && devlink) {
+                r = device_new_from_dev_path(devlink, &device);
+                if (r < 0 && r != -ENOENT)
+                        return r;
+        }
+        if (device && sd_device_get_is_initialized(device) > 0) {
                 if (ret)
                         *ret = sd_device_ref(device);
                 return 0;
@@ -207,6 +274,14 @@ int device_wait_for_initialization(sd_device *device, const char *subsystem, use
         return 0;
 }
 
+int device_wait_for_initialization(sd_device *device, const char *subsystem, usec_t timeout, sd_device **ret) {
+        return device_wait_for_initialization_internal(device, NULL, subsystem, timeout, ret);
+}
+
+int device_wait_for_devlink(const char *devlink, const char *subsystem, usec_t timeout, sd_device **ret) {
+        return device_wait_for_initialization_internal(NULL, devlink, subsystem, timeout, ret);
+}
+
 int device_is_renaming(sd_device *dev) {
         int r;
 

src/shared/udev-util.h

@@ -29,5 +29,6 @@ static inline int udev_parse_config(void) {
 }
 
 int device_wait_for_initialization(sd_device *device, const char *subsystem, usec_t timeout, sd_device **ret);
+int device_wait_for_devlink(const char *path, const char *subsystem, usec_t timeout, sd_device **ret);
 int device_is_renaming(sd_device *dev);
 bool device_for_action(sd_device *dev, DeviceAction action);

src/veritysetup/veritysetup.c

@@ -73,7 +73,7 @@ static int run(int argc, char *argv[]) {
                 if (r < 0)
                         return log_error_errno(r, "Failed to open verity device %s: %m", argv[4]);
 
-                crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+                cryptsetup_enable_logging(cd);
 
                 status = crypt_status(cd, argv[2]);
                 if (IN_SET(status, CRYPT_ACTIVE, CRYPT_BUSY)) {
@@ -124,7 +124,7 @@ static int run(int argc, char *argv[]) {
                 if (r < 0)
                         return log_error_errno(r, "crypt_init_by_name() failed: %m");
 
-                crypt_set_log_callback(cd, cryptsetup_log_glue, NULL);
+                cryptsetup_enable_logging(cd);
 
                 r = crypt_deactivate(cd, argv[2]);
                 if (r < 0)