chiark / gitweb /
kdbus: when running in a container, don't complain that we cannot write to /sys
[elogind.git] / src / libsystemd / sd-bus / bus-kernel.c
index 79d29dc119798b0da25e319fdf65a9dd3d207dae..84fb4bdf2b4af185c8ab6f0de7523c96d5a6ce79 100644 (file)
@@ -32,6 +32,8 @@
 #include "util.h"
 #include "strv.h"
 #include "memfd-util.h"
+#include "cgroup-util.h"
+#include "fileio.h"
 
 #include "bus-internal.h"
 #include "bus-message.h"
@@ -39,7 +41,6 @@
 #include "bus-bloom.h"
 #include "bus-util.h"
 #include "bus-label.h"
-#include "cgroup-util.h"
 
 #define UNIQUE_NAME_MAX (3+DECIMAL_STR_MAX(uint64_t))
 
@@ -268,23 +269,22 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
                 ((m->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED) ? 0 : KDBUS_MSG_FLAGS_EXPECT_REPLY) |
                 ((m->header->flags & BUS_MESSAGE_NO_AUTO_START) ? KDBUS_MSG_FLAGS_NO_AUTO_START : 0);
 
-        if (well_known) {
+        if (well_known)
                 /* verify_destination_id will usually be 0, which makes the kernel driver only look
                  * at the provided well-known name. Otherwise, the kernel will make sure the provided
                  * destination id matches the owner of the provided weel-known-name, and fail if they
                  * differ. Currently, this is only needed for bus-proxyd. */
                 m->kdbus->dst_id = m->verify_destination_id;
-        } else {
+        else
                 m->kdbus->dst_id = destination ? unique : KDBUS_DST_ID_BROADCAST;
-        }
 
         m->kdbus->payload_type = KDBUS_PAYLOAD_DBUS;
         m->kdbus->cookie = (uint64_t) m->header->serial;
         m->kdbus->priority = m->priority;
 
-        if (m->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED) {
+        if (m->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED)
                 m->kdbus->cookie_reply = m->reply_cookie;
-        else {
+        else {
                 struct timespec now;
 
                 assert_se(clock_gettime(CLOCK_MONOTONIC_COARSE, &now) == 0);
@@ -349,6 +349,15 @@ fail:
         return r;
 }
 
+static void bus_message_set_sender_driver(sd_bus *bus, sd_bus_message *m) {
+        assert(bus);
+        assert(m);
+
+        m->sender = m->creds.unique_name = (char*) "org.freedesktop.DBus";
+        m->creds.well_known_names_driver = true;
+        m->creds.mask |= (SD_BUS_CREDS_UNIQUE_NAME|SD_BUS_CREDS_WELL_KNOWN_NAMES) & bus->creds_mask;
+}
+
 static void unset_memfds(struct sd_bus_message *m) {
         struct bus_body_part *part;
         unsigned i;
@@ -628,9 +637,15 @@ static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k) {
                         break;
 
                 case KDBUS_ITEM_AUDIT:
-                        m->creds.audit_session_id = (uint32_t) d->audit.sessionid;
-                        m->creds.audit_login_uid = (uid_t) d->audit.loginuid;
-                        m->creds.mask |= (SD_BUS_CREDS_AUDIT_SESSION_ID|SD_BUS_CREDS_AUDIT_LOGIN_UID) & bus->creds_mask;
+                        if ((uint32_t) d->audit.sessionid != (uint32_t) -1) {
+                                m->creds.audit_session_id = (uint32_t) d->audit.sessionid;
+                                m->creds.mask |= SD_BUS_CREDS_AUDIT_SESSION_ID & bus->creds_mask;
+                        }
+
+                        if ((uid_t) d->audit.loginuid != (uid_t) -1) {
+                                m->creds.audit_login_uid = (uid_t) d->audit.loginuid;
+                                m->creds.mask |= SD_BUS_CREDS_AUDIT_LOGIN_UID & bus->creds_mask;
+                        }
                         break;
 
                 case KDBUS_ITEM_CAPS:
@@ -640,19 +655,41 @@ static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k) {
                         break;
 
                 case KDBUS_ITEM_DST_NAME:
-                        if (!service_name_is_valid(d->str))
-                                return -EBADMSG;
+                        if (!service_name_is_valid(d->str)) {
+                                r = -EBADMSG;
+                                goto fail;
+                        }
 
                         destination = d->str;
                         break;
 
                 case KDBUS_ITEM_OWNED_NAME:
-                        if (!service_name_is_valid(d->name.name))
-                                return -EBADMSG;
-
-                        r = strv_extend(&m->creds.well_known_names, d->name.name);
-                        if (r < 0)
+                        if (!service_name_is_valid(d->name.name)) {
+                                r = -EBADMSG;
                                 goto fail;
+                        }
+
+                        if (bus->creds_mask & SD_BUS_CREDS_WELL_KNOWN_NAMES) {
+                                char **wkn;
+                                size_t n;
+
+                                /* We just extend the array here, but
+                                 * do not allocate the strings inside
+                                 * of it, instead we just point to our
+                                 * buffer directly. */
+                                n = strv_length(m->creds.well_known_names);
+                                wkn = realloc(m->creds.well_known_names, (n + 2) * sizeof(char*));
+                                if (!wkn) {
+                                        r = -ENOMEM;
+                                        goto fail;
+                                }
+
+                                wkn[n] = d->name.name;
+                                wkn[n+1] = NULL;
+                                m->creds.well_known_names = wkn;
+
+                                m->creds.mask |= SD_BUS_CREDS_WELL_KNOWN_NAMES;
+                        }
                         break;
 
                 case KDBUS_ITEM_CONN_DESCRIPTION:
@@ -660,6 +697,18 @@ static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k) {
                         m->creds.mask |= SD_BUS_CREDS_DESCRIPTION & bus->creds_mask;
                         break;
 
+                case KDBUS_ITEM_AUXGROUPS:
+
+                        if (bus->creds_mask & SD_BUS_CREDS_SUPPLEMENTARY_GIDS) {
+                                assert_cc(sizeof(gid_t) == sizeof(uint32_t));
+
+                                m->creds.n_supplementary_gids = (d->size - offsetof(struct kdbus_item, data32)) / sizeof(uint32_t);
+                                m->creds.supplementary_gids = (gid_t*) d->data32;
+                                m->creds.mask |= SD_BUS_CREDS_SUPPLEMENTARY_GIDS;
+                        }
+
+                        break;
+
                 case KDBUS_ITEM_FDS:
                 case KDBUS_ITEM_SECLABEL:
                         break;
@@ -669,13 +718,45 @@ static int bus_kernel_make_message(sd_bus *bus, struct kdbus_msg *k) {
                 }
         }
 
+        /* If we requested the list of well-known names to be appended
+         * and the sender had none no item for it will be
+         * attached. However, this does *not* mean that we the kernel
+         * didn't want to provide this information to us. Hence, let's
+         * explicitly mark this information as available if it was
+         * requested. */
+        m->creds.mask |= bus->creds_mask & SD_BUS_CREDS_WELL_KNOWN_NAMES;
+
         r = bus_message_parse_fields(m);
         if (r < 0)
                 goto fail;
 
+        /* Refuse messages if kdbus and dbus1 cookie doesn't match up */
+        if ((uint64_t) m->header->serial != k->cookie) {
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        /* Refuse messages where the reply flag doesn't match up */
+        if (!(m->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED) != !!(k->flags & KDBUS_MSG_FLAGS_EXPECT_REPLY)) {
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        /* Refuse reply messages where the reply cookie doesn't match up */
+        if ((m->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED) && m->reply_cookie != k->cookie_reply) {
+                r = -EBADMSG;
+                goto fail;
+        }
+
+        /* Refuse messages where the autostart flag doesn't match up */
+        if (!(m->header->flags & BUS_MESSAGE_NO_AUTO_START) != !(k->flags & KDBUS_MSG_FLAGS_NO_AUTO_START)) {
+                r = -EBADMSG;
+                goto fail;
+        }
+
         /* Override information from the user header with data from the kernel */
         if (k->src_id == KDBUS_SRC_ID_KERNEL)
-                m->sender = m->creds.unique_name = (char*) "org.freedesktop.DBus";
+                bus_message_set_sender_driver(bus, m);
         else {
                 snprintf(m->sender_buffer, sizeof(m->sender_buffer), ":1.%llu", (unsigned long long) k->src_id);
                 m->sender = m->creds.unique_name = m->sender_buffer;
@@ -874,13 +955,12 @@ int bus_kernel_connect(sd_bus *b) {
 }
 
 static void close_kdbus_msg(sd_bus *bus, struct kdbus_msg *k) {
-        struct kdbus_cmd_free cmd;
+        struct kdbus_cmd_free cmd = {};
         struct kdbus_item *d;
 
         assert(bus);
         assert(k);
 
-        cmd.flags = 0;
         cmd.offset = (uint8_t *)k - (uint8_t *)bus->kdbus_buffer;
 
         KDBUS_ITEM_FOREACH(d, k, items) {
@@ -1011,7 +1091,7 @@ static int push_name_owner_changed(sd_bus *bus, const char *name, const char *ol
         if (r < 0)
                 return r;
 
-        m->sender = "org.freedesktop.DBus";
+        bus_message_set_sender_driver(bus, m);
 
         r = bus_seal_synthetic_message(bus, m);
         if (r < 0)
@@ -1080,7 +1160,7 @@ static int translate_reply(sd_bus *bus, struct kdbus_msg *k, struct kdbus_item *
         if (r < 0)
                 return r;
 
-        m->sender = "org.freedesktop.DBus";
+        bus_message_set_sender_driver(bus, m);
 
         r = bus_seal_synthetic_message(bus, m);
         if (r < 0)
@@ -1149,6 +1229,11 @@ int bus_kernel_read_message(sd_bus *bus, bool hint_priority, int64_t priority) {
                 if (errno == EAGAIN)
                         return 0;
 
+                if (errno == EOVERFLOW) {
+                        log_debug("%s: kdbus reports %" PRIu64 " dropped broadcast messages, ignoring.", strna(bus->description), (uint64_t) recv.dropped_msgs);
+                        return 0;
+                }
+
                 return -errno;
         }
 
@@ -1272,11 +1357,9 @@ void bus_kernel_flush_memfd(sd_bus *b) {
                 close_and_munmap(b->memfd_cache[i].fd, b->memfd_cache[i].address, b->memfd_cache[i].mapped);
 }
 
-int kdbus_translate_request_name_flags(uint64_t flags, uint64_t *kdbus_flags) {
+uint64_t request_name_flags_to_kdbus(uint64_t flags) {
         uint64_t f = 0;
 
-        assert(kdbus_flags);
-
         if (flags & SD_BUS_NAME_ALLOW_REPLACEMENT)
                 f |= KDBUS_NAME_ALLOW_REPLACEMENT;
 
@@ -1286,15 +1369,12 @@ int kdbus_translate_request_name_flags(uint64_t flags, uint64_t *kdbus_flags) {
         if (flags & SD_BUS_NAME_QUEUE)
                 f |= KDBUS_NAME_QUEUE;
 
-        *kdbus_flags = f;
-        return 0;
+        return f;
 }
 
-int kdbus_translate_attach_flags(uint64_t mask, uint64_t *kdbus_mask) {
+uint64_t attach_flags_to_kdbus(uint64_t mask) {
         uint64_t m = 0;
 
-        assert(kdbus_mask);
-
         if (mask & (SD_BUS_CREDS_UID|SD_BUS_CREDS_EUID|SD_BUS_CREDS_SUID|SD_BUS_CREDS_FSUID|
                     SD_BUS_CREDS_GID|SD_BUS_CREDS_EGID|SD_BUS_CREDS_SGID|SD_BUS_CREDS_FSGID))
                 m |= KDBUS_ATTACH_CREDS;
@@ -1332,13 +1412,16 @@ int kdbus_translate_attach_flags(uint64_t mask, uint64_t *kdbus_mask) {
         if (mask & SD_BUS_CREDS_DESCRIPTION)
                 m |= KDBUS_ATTACH_CONN_DESCRIPTION;
 
-        *kdbus_mask = m;
-        return 0;
+        if (mask & SD_BUS_CREDS_SUPPLEMENTARY_GIDS)
+                m |= KDBUS_ATTACH_AUXGROUPS;
+
+        return m;
 }
 
 int bus_kernel_create_bus(const char *name, bool world, char **s) {
         struct kdbus_cmd_make *make;
         struct kdbus_item *n;
+        size_t l;
         int fd;
 
         assert(name);
@@ -1348,19 +1431,20 @@ int bus_kernel_create_bus(const char *name, bool world, char **s) {
         if (fd < 0)
                 return -errno;
 
-        make = alloca0_align(ALIGN8(offsetof(struct kdbus_cmd_make, items) +
-                                    offsetof(struct kdbus_item, data64) + sizeof(uint64_t) +
-                                    offsetof(struct kdbus_item, str) +
-                                    DECIMAL_STR_MAX(uid_t) + 1 + strlen(name) + 1),
+        l = strlen(name);
+        make = alloca0_align(offsetof(struct kdbus_cmd_make, items) +
+                             ALIGN8(offsetof(struct kdbus_item, bloom_parameter) + sizeof(struct kdbus_bloom_parameter)) +
+                             ALIGN8(offsetof(struct kdbus_item, data64) + sizeof(uint64_t)) +
+                             ALIGN8(offsetof(struct kdbus_item, str) + DECIMAL_STR_MAX(uid_t) + 1 + l + 1),
                              8);
 
         make->size = offsetof(struct kdbus_cmd_make, items);
 
+        /* Set the bloom parameters */
         n = make->items;
         n->size = offsetof(struct kdbus_item, bloom_parameter) +
                   sizeof(struct kdbus_bloom_parameter);
         n->type = KDBUS_ITEM_BLOOM_PARAMETER;
-
         n->bloom_parameter.size = DEFAULT_BLOOM_SIZE;
         n->bloom_parameter.n_hash = DEFAULT_BLOOM_N_HASH;
 
@@ -1369,6 +1453,15 @@ int bus_kernel_create_bus(const char *name, bool world, char **s) {
 
         make->size += ALIGN8(n->size);
 
+        /* The busses we create make no restrictions on what metadata
+         * peers can read from incoming messages. */
+        n = KDBUS_ITEM_NEXT(n);
+        n->type = KDBUS_ITEM_ATTACH_FLAGS_RECV;
+        n->size = offsetof(struct kdbus_item, data64) + sizeof(uint64_t);
+        n->data64[0] = _KDBUS_ATTACH_ANY;
+        make->size += ALIGN8(n->size);
+
+        /* Set the a good name */
         n = KDBUS_ITEM_NEXT(n);
         sprintf(n->str, UID_FMT "-%s", getuid(), name);
         n->size = offsetof(struct kdbus_item, str) + strlen(n->str) + 1;
@@ -1465,20 +1558,29 @@ int bus_kernel_open_bus_fd(const char *bus, char **path) {
         int fd;
         size_t len;
 
+        assert(bus);
+
         len = strlen("/sys/fs/kdbus/") + DECIMAL_STR_MAX(uid_t) + 1 + strlen(bus) + strlen("/bus") + 1;
 
         if (path) {
-                p = malloc(len);
+                p = new(char, len);
                 if (!p)
                         return -ENOMEM;
-                *path = p;
         } else
-                p = alloca(len);
+                p = newa(char, len);
+
         sprintf(p, "/sys/fs/kdbus/" UID_FMT "-%s/bus", getuid(), bus);
 
         fd = open(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
-        if (fd < 0)
+        if (fd < 0) {
+                if (path)
+                        free(p);
+
                 return -errno;
+        }
+
+        if (path)
+                *path = p;
 
         return fd;
 }
@@ -1487,25 +1589,25 @@ int bus_kernel_create_endpoint(const char *bus_name, const char *ep_name, char *
         _cleanup_free_ char *path = NULL;
         struct kdbus_cmd_make *make;
         struct kdbus_item *n;
-        size_t size;
+        const char *name;
         int fd;
 
         fd = bus_kernel_open_bus_fd(bus_name, &path);
         if (fd < 0)
                 return fd;
 
-        size = ALIGN8(offsetof(struct kdbus_cmd_make, items));
-        size += ALIGN8(offsetof(struct kdbus_item, str) + strlen(ep_name) + 1);
-
-        make = alloca0_align(size, 8);
-        make->size = size;
+        make = alloca0_align(ALIGN8(offsetof(struct kdbus_cmd_make, items)) +
+                             ALIGN8(offsetof(struct kdbus_item, str) + DECIMAL_STR_MAX(uid_t) + 1 + strlen(ep_name) + 1),
+                             8);
+        make->size = ALIGN8(offsetof(struct kdbus_cmd_make, items));
         make->flags = KDBUS_MAKE_ACCESS_WORLD;
 
         n = make->items;
-
+        sprintf(n->str, UID_FMT "-%s", getuid(), ep_name);
+        n->size = offsetof(struct kdbus_item, str) + strlen(n->str) + 1;
         n->type = KDBUS_ITEM_MAKE_NAME;
-        n->size = offsetof(struct kdbus_item, str) + strlen(ep_name) + 1;
-        strcpy(n->str, ep_name);
+        make->size += ALIGN8(n->size);
+        name = n->str;
 
         if (ioctl(fd, KDBUS_CMD_ENDPOINT_MAKE, make) < 0) {
                 safe_close(fd);
@@ -1515,7 +1617,7 @@ int bus_kernel_create_endpoint(const char *bus_name, const char *ep_name, char *
         if (ep_path) {
                 char *p;
 
-                p = strjoin(dirname(path), "/", ep_name, NULL);
+                p = strjoin(dirname(path), "/", name, NULL);
                 if (!p) {
                         safe_close(fd);
                         return -ENOMEM;
@@ -1595,7 +1697,7 @@ int bus_kernel_make_starter(
         if (world_policy >= 0)
                 policy_cnt++;
 
-        size = ALIGN8(offsetof(struct kdbus_cmd_hello, items)) +
+        size = offsetof(struct kdbus_cmd_hello, items) +
                ALIGN8(offsetof(struct kdbus_item, str) + strlen(name) + 1) +
                policy_cnt * ALIGN8(offsetof(struct kdbus_item, policy_access) + sizeof(struct kdbus_policy_access));
 
@@ -1631,7 +1733,7 @@ int bus_kernel_make_starter(
                 (accept_fd ? KDBUS_HELLO_ACCEPT_FD : 0);
         hello->pool_size = KDBUS_POOL_SIZE;
         hello->attach_flags_send = _KDBUS_ATTACH_ANY;
-        hello->attach_flags_recv = _KDBUS_ATTACH_ALL;
+        hello->attach_flags_recv = _KDBUS_ATTACH_ANY;
 
         if (ioctl(fd, KDBUS_CMD_HELLO, hello) < 0)
                 return -errno;
@@ -1669,3 +1771,64 @@ int bus_kernel_drop_one(int fd) {
 
         return 0;
 }
+
+int bus_kernel_realize_attach_flags(sd_bus *bus) {
+        struct kdbus_cmd_update *update;
+        struct kdbus_item *n;
+
+        assert(bus);
+        assert(bus->is_kernel);
+
+        update = alloca0_align(offsetof(struct kdbus_cmd_update, items) +
+                               ALIGN8(offsetof(struct kdbus_item, data64) + sizeof(uint64_t)),
+                               8);
+
+        n = update->items;
+        n->type = KDBUS_ITEM_ATTACH_FLAGS_RECV;
+        n->size = offsetof(struct kdbus_item, data64) + sizeof(uint64_t);
+        n->data64[0] = bus->attach_flags;
+
+        update->size =
+                offsetof(struct kdbus_cmd_update, items) +
+                ALIGN8(n->size);
+
+        if (ioctl(bus->input_fd, KDBUS_CMD_CONN_UPDATE, update) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int bus_kernel_fix_attach_mask(void) {
+        _cleanup_free_ char *mask = NULL;
+        uint64_t m = (uint64_t) -1;
+        char buf[2+16+2];
+        int r;
+
+        /* By default we don't want any kdbus metadata fields to be
+         * suppressed, hence we reset the kernel mask for it to
+         * (uint64_t) -1. This is overridable via a kernel command
+         * line option, however. */
+
+        r = get_proc_cmdline_key("systemd.kdbus_attach_flags_mask=", &mask);
+        if (r < 0)
+                return log_warning_errno(r, "Failed to read kernel command line: %m");
+
+        if (mask) {
+                const char *p = mask;
+
+                if (startswith(p, "0x"))
+                        p += 2;
+
+                if (sscanf(p, "%" PRIx64, &m) != 1)
+                        log_warning("Couldn't parse systemd.kdbus_attach_flags_mask= kernel command line parameter.");
+        }
+
+        sprintf(buf, "0x%" PRIx64 "\n", m);
+        r = write_string_file("/sys/module/kdbus/parameters/attach_flags_mask", buf);
+        if (r < 0)
+                return log_full_errno(
+                                r == -EROFS ? LOG_DEBUG : LOG_WARNING, r,
+                                "Failed to write kdbus attach mask: %m");
+
+        return 0;
+}