X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Flibsystemd-bus%2Fbus-message.c;h=7acab50979336b4e464dc9f0b403bac6a221af05;hp=5f3dbdb75de8a55d2a41076b045b7de9af0b9507;hb=917b5dc7075a15bded4948efba8e686dba4509f8;hpb=fbfa72b0a1276366d50dce223c06efe9db9d6585

diff --git a/src/libsystemd-bus/bus-message.c b/src/libsystemd-bus/bus-message.c
index 5f3dbdb75..7acab5097 100644
--- a/src/libsystemd-bus/bus-message.c
+++ b/src/libsystemd-bus/bus-message.c
@@ -20,9 +20,11 @@
 ***/
 
 #include <errno.h>
+#include <fcntl.h>
 
 #include "util.h"
 #include "utf8.h"
+#include "strv.h"
 
 #include "sd-bus.h"
 #include "bus-message.h"
@@ -49,8 +51,6 @@ static void reset_containers(sd_bus_message *m) {
 }
 
 static void message_free(sd_bus_message *m) {
-        unsigned i;
-
         assert(m);
 
         if (m->free_header)
@@ -62,8 +62,10 @@ static void message_free(sd_bus_message *m) {
         if (m->free_body)
                 free(m->body);
 
-        for (i = 0; i < m->n_fds; i++)
-                close_nointr_nofail(m->fds[i]);
+        if (m->free_fds) {
+                close_many(m->fds, m->n_fds);
+                free(m->fds);
+        }
 
         reset_containers(m);
         free(m->root_container.signature);
@@ -223,13 +225,22 @@ static int message_append_field_uint32(sd_bus_message *m, uint8_t h, uint32_t x)
         return 0;
 }
 
-int bus_message_from_malloc(void *buffer, size_t length, sd_bus_message **ret) {
+int bus_message_from_malloc(
+                void *buffer,
+                size_t length,
+                int *fds,
+                unsigned n_fds,
+                const struct ucred *ucred,
+                const char *label,
+                sd_bus_message **ret) {
+
         sd_bus_message *m;
         struct bus_header *h;
-        size_t total, fs, bs;
+        size_t total, fs, bs, label_sz, a;
         int r;
 
         assert(buffer || length <= 0);
+        assert(fds || n_fds <= 0);
         assert(ret);
 
         if (length < sizeof(struct bus_header))
@@ -258,29 +269,55 @@ int bus_message_from_malloc(void *buffer, size_t length, sd_bus_message **ret) {
         if (length != total)
                 return -EBADMSG;
 
-        m = new0(sd_bus_message, 1);
+        if (label) {
+                label_sz = strlen(label);
+                a = ALIGN(sizeof(sd_bus_message)) + label_sz + 1;
+        } else
+                a = sizeof(sd_bus_message);
+
+        m = malloc0(a);
         if (!m)
                 return -ENOMEM;
 
         m->n_ref = 1;
+        m->sealed = true;
         m->header = h;
-        m->free_header = true;
         m->fields = (uint8_t*) buffer + sizeof(struct bus_header);
         m->body = (uint8_t*) buffer + sizeof(struct bus_header) + ALIGN_TO(fs, 8);
-        m->sealed = true;
+        m->fds = fds;
+        m->n_fds = n_fds;
+
+        if (ucred) {
+                m->uid = ucred->uid;
+                m->pid = ucred->pid;
+                m->gid = ucred->gid;
+                m->uid_valid = m->gid_valid = true;
+        }
+
+        if (label) {
+                m->label = (char*) m + ALIGN(sizeof(sd_bus_message));
+                memcpy(m->label, label, label_sz + 1);
+        }
 
         m->n_iovec = 1;
         m->iovec[0].iov_base = buffer;
         m->iovec[0].iov_len = length;
+        m->size = length;
 
         r = message_parse_fields(m);
-        if (r < 0) {
-                message_free(m);
-                return r;
-        }
+        if (r < 0)
+                goto fail;
+
+        /* We take possession of the memory and fds now */
+        m->free_header = true;
+        m->free_fds = true;
 
         *ret = m;
         return 0;
+
+fail:
+        message_free(m);
+        return r;
 }
 
 static sd_bus_message *message_new(sd_bus *bus, uint8_t type) {
@@ -295,6 +332,7 @@ static sd_bus_message *message_new(sd_bus *bus, uint8_t type) {
         m->header->endian = SD_BUS_NATIVE_ENDIAN;
         m->header->type = type;
         m->header->version = bus ? bus->message_version : 1;
+        m->allow_fds = !bus || bus->can_fds || (bus->state != BUS_HELLO && bus->state != BUS_RUNNING);
 
         return m;
 }
@@ -317,11 +355,15 @@ int sd_bus_message_new_signal(
                 return -EINVAL;
         if (!m)
                 return -EINVAL;
+        if (bus && bus->state == BUS_UNSET)
+                return -ENOTCONN;
 
         t = message_new(bus, SD_BUS_MESSAGE_TYPE_SIGNAL);
         if (!t)
                 return -ENOMEM;
 
+        t->header->flags |= SD_BUS_MESSAGE_NO_REPLY_EXPECTED;
+
         r = message_append_field_string(t, SD_BUS_MESSAGE_HEADER_PATH, SD_BUS_TYPE_OBJECT_PATH, path, &t->path);
         if (r < 0)
                 goto fail;
@@ -357,6 +399,8 @@ int sd_bus_message_new_method_call(
                 return -EINVAL;
         if (!m)
                 return -EINVAL;
+        if (bus && bus->state == BUS_UNSET)
+                return -ENOTCONN;
 
         t = message_new(bus, SD_BUS_MESSAGE_TYPE_METHOD_CALL);
         if (!t)
@@ -400,15 +444,20 @@ static int message_new_reply(
 
         if (!call)
                 return -EINVAL;
+        if (!call->sealed)
+                return -EPERM;
         if (call->header->type != SD_BUS_MESSAGE_TYPE_METHOD_CALL)
                 return -EINVAL;
         if (!m)
                 return -EINVAL;
+        if (bus && bus->state == BUS_UNSET)
+                return -ENOTCONN;
 
         t = message_new(bus, type);
         if (!t)
                 return -ENOMEM;
 
+        t->header->flags |= SD_BUS_MESSAGE_NO_REPLY_EXPECTED;
         t->reply_serial = BUS_MESSAGE_SERIAL(call);
 
         r = message_append_field_uint32(t, SD_BUS_MESSAGE_HEADER_REPLY_SERIAL, t->reply_serial);
@@ -424,6 +473,7 @@ static int message_new_reply(
         t->dont_send = !!(call->header->flags & SD_BUS_MESSAGE_NO_REPLY_EXPECTED);
 
         *m = t;
+        return 0;
 
 fail:
         message_free(t);
@@ -622,6 +672,13 @@ int sd_bus_message_get_tid(sd_bus_message *m, pid_t *tid) {
         return 0;
 }
 
+const char *sd_bus_message_get_label(sd_bus_message *m) {
+        if (!m)
+                return NULL;
+
+        return m->label;
+}
+
 int sd_bus_message_is_signal(sd_bus_message *m, const char *interface, const char *member) {
         if (!m)
                 return -EINVAL;
@@ -728,13 +785,18 @@ static void *message_extend_body(sd_bus_message *m, size_t align, size_t sz) {
 
 int message_append_basic(sd_bus_message *m, char type, const void *p, const void **stored) {
         struct bus_container *c;
-        size_t sz, align;
+        ssize_t align, sz;
         uint32_t k;
         void *a;
         char *e = NULL;
+        int fd = -1;
+        uint32_t fdi = 0;
+        int r;
 
         if (!m)
                 return -EINVAL;
+        if (!p)
+                return -EINVAL;
         if (m->sealed)
                 return -EPERM;
         if (!bus_type_is_basic(type))
@@ -761,11 +823,13 @@ int message_append_basic(sd_bus_message *m, char type, const void *p, const void
 
         case SD_BUS_TYPE_STRING:
         case SD_BUS_TYPE_OBJECT_PATH:
+
                 align = 4;
                 sz = 4 + strlen(p) + 1;
                 break;
 
         case SD_BUS_TYPE_SIGNATURE:
+
                 align = 1;
                 sz = 1 + strlen(p) + 1;
                 break;
@@ -779,6 +843,41 @@ int message_append_basic(sd_bus_message *m, char type, const void *p, const void
                 p = &k;
                 break;
 
+        case SD_BUS_TYPE_UNIX_FD: {
+                int z, *f;
+
+                if (!m->allow_fds) {
+                        r = -ENOTSUP;
+                        goto fail;
+                }
+
+                align = sz = 4;
+
+                z = *(int*) p;
+                if (z < 0) {
+                        r = -EINVAL;
+                        goto fail;
+                }
+
+                fd = fcntl(z, F_DUPFD_CLOEXEC, 3);
+                if (fd < 0) {
+                        r = -errno;
+                        goto fail;
+                }
+
+                f = realloc(m->fds, sizeof(int) * (m->n_fds + 1));
+                if (!f) {
+                        r = -ENOMEM;
+                        goto fail;
+                }
+
+                fdi = m->n_fds;
+                f[fdi] = fd;
+                m->fds = f;
+                m->free_fds = true;
+                break;
+        }
+
         default:
                 align = bus_type_get_alignment(type);
                 sz = bus_type_get_size(type);
@@ -790,11 +889,8 @@ int message_append_basic(sd_bus_message *m, char type, const void *p, const void
 
         a = message_extend_body(m, align, sz);
         if (!a) {
-                /* Truncate extended signature again */
-                if (e)
-                        c->signature[c->index] = 0;
-
-                return -ENOMEM;
+                r = -ENOMEM;
+                goto fail;
         }
 
         if (type == SD_BUS_TYPE_STRING || type == SD_BUS_TYPE_OBJECT_PATH) {
@@ -810,6 +906,13 @@ int message_append_basic(sd_bus_message *m, char type, const void *p, const void
 
                 if (stored)
                         *stored = (const uint8_t*) a + 1;
+        } else if (type == SD_BUS_TYPE_UNIX_FD) {
+                *(uint32_t*) a = fdi;
+
+                if (stored)
+                        *stored = a;
+
+                m->n_fds ++;
 
         } else {
                 memcpy(a, p, sz);
@@ -822,6 +925,16 @@ int message_append_basic(sd_bus_message *m, char type, const void *p, const void
                 c->index++;
 
         return 0;
+
+fail:
+        /* Truncate extended signature again */
+        if (e)
+                c->signature[c->index] = 0;
+
+        if (fd >= 0)
+                close_nointr_nofail(fd);
+
+        return r;
 }
 
 int sd_bus_message_append_basic(sd_bus_message *m, char type, const void *p) {
@@ -1128,7 +1241,7 @@ int sd_bus_message_close_container(sd_bus_message *m) {
         return 0;
 }
 
-static int message_append_ap(
+int bus_message_append_ap(
                 sd_bus_message *m,
                 const char *types,
                 va_list ap) {
@@ -1214,7 +1327,7 @@ static int message_append_ap(
 
                                 n = va_arg(ap, unsigned);
                                 for (i = 0; i < n; i++) {
-                                        r = message_append_ap(m, s, ap);
+                                        r = bus_message_append_ap(m, s, ap);
                                         if (r < 0)
                                                 return r;
                                 }
@@ -1236,7 +1349,7 @@ static int message_append_ap(
                         if (r < 0)
                                 return r;
 
-                        r = message_append_ap(m, s, ap);
+                        r = bus_message_append_ap(m, s, ap);
                         if (r < 0)
                                 return r;
 
@@ -1264,7 +1377,7 @@ static int message_append_ap(
 
                                 t += k - 1;
 
-                                r = message_append_ap(m, s, ap);
+                                r = bus_message_append_ap(m, s, ap);
                                 if (r < 0)
                                         return r;
 
@@ -1294,10 +1407,10 @@ int sd_bus_message_append(sd_bus_message *m, const char *types, ...) {
         if (m->sealed)
                 return -EPERM;
         if (!types)
-                return -EINVAL;
+                return 0;
 
         va_start(ap, types);
-        r = message_append_ap(m, types, ap);
+        r = bus_message_append_ap(m, types, ap);
         va_end(ap);
 
         return r;
@@ -1351,8 +1464,7 @@ static int message_peek_body(sd_bus_message *m, size_t *rindex, size_t align, si
         return buffer_peek(m->body, BUS_MESSAGE_BODY_SIZE(m), rindex, align, nbytes, ret);
 }
 
-static bool validate_string(const char *s, size_t l) {
-        assert(s);
+static bool validate_nul(const char *s, size_t l) {
 
         /* Check for NUL chars in the string */
         if (memchr(s, 0, l))
@@ -1362,6 +1474,14 @@ static bool validate_string(const char *s, size_t l) {
         if (s[l] != 0)
                 return false;
 
+        return true;
+}
+
+static bool validate_string(const char *s, size_t l) {
+
+        if (!validate_nul(s, l))
+                return false;
+
         /* Check if valid UTF8 */
         if (!utf8_is_valid(s))
                 return false;
@@ -1370,12 +1490,8 @@ static bool validate_string(const char *s, size_t l) {
 }
 
 static bool validate_signature(const char *s, size_t l) {
-        /* Check for NUL chars in the signature */
-        if (memchr(s, 0, l))
-                return false;
 
-        /* Check for NUL termination */
-        if (s[l] != 0)
+        if (!validate_nul(s, l))
                 return false;
 
         /* Check if valid signature */
@@ -1385,6 +1501,17 @@ static bool validate_signature(const char *s, size_t l) {
         return true;
 }
 
+static bool validate_object_path(const char *s, size_t l) {
+
+        if (!validate_nul(s, l))
+                return false;
+
+        if (!object_path_is_valid(s))
+                return false;
+
+        return true;
+}
+
 int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
         struct bus_container *c;
         int r;
@@ -1396,6 +1523,8 @@ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
                 return -EPERM;
         if (!bus_type_is_basic(type))
                 return -EINVAL;
+        if (!p)
+                return -EINVAL;
 
         c = message_get_container(m);
 
@@ -1424,8 +1553,13 @@ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
                 if (r == 0)
                         return -EBADMSG;
 
-                if (!validate_string(q, l))
-                        return -EBADMSG;
+                if (type == SD_BUS_TYPE_OBJECT_PATH) {
+                        if (!validate_object_path(q, l))
+                                return -EBADMSG;
+                } else {
+                        if (!validate_string(q, l))
+                                return -EBADMSG;
+                }
 
                 m->rindex = rindex;
                 *(const char**) p = q;
@@ -1457,12 +1591,15 @@ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
         }
 
         default: {
-                size_t sz, align;
+                ssize_t sz, align;
+                size_t rindex;
 
                 align = bus_type_get_alignment(type);
                 sz = bus_type_get_size(type);
+                assert(align > 0 && sz > 0);
 
-                r = message_peek_body(m, &m->rindex, align, sz, &q);
+                rindex = m->rindex;
+                r = message_peek_body(m, &rindex, align, sz, &q);
                 if (r <= 0)
                         return r;
 
@@ -1492,10 +1629,28 @@ int sd_bus_message_read_basic(sd_bus_message *m, char type, void *p) {
                         *(uint64_t*) p = BUS_MESSAGE_BSWAP64(m, *(uint64_t*) q);
                         break;
 
+                case SD_BUS_TYPE_UNIX_FD: {
+                        int copy;
+                        uint32_t j;
+
+                        j = BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q);
+                        if (j >= m->n_fds)
+                                return -EBADMSG;
+
+                        copy = fcntl(m->fds[j], F_DUPFD_CLOEXEC, 3);
+                        if (copy < 0)
+                                return -errno;
+
+                        *(int*) p = copy;
+                        break;
+                }
+
                 default:
                         assert_not_reached("Unknown basic type...");
                 }
 
+                        m->rindex = rindex;
+
                 break;
         }
         }
@@ -1542,7 +1697,7 @@ static int bus_message_enter_array(
         if (r <= 0)
                 return r;
 
-        if (BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q) > 67108864)
+        if (BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q) > BUS_ARRAY_MAX_SIZE)
                 return -EBADMSG;
 
         r = message_peek_body(m, &rindex, alignment, 0, NULL);
@@ -1699,6 +1854,25 @@ int sd_bus_message_enter_container(sd_bus_message *m, char type, const char *con
         if (!contents)
                 return -EINVAL;
 
+        /*
+         * We enforce a global limit on container depth, that is much
+         * higher than the 32 structs and 32 arrays the specification
+         * mandates. This is simpler to implement for us, and we need
+         * this only to ensure our container array doesn't grow
+         * without bounds. We are happy to return any data from a
+         * message as long as the data itself is valid, even if the
+         * overall message might be not.
+         *
+         * Note that the message signature is validated when
+         * parsing the headers, and that validation does check the
+         * 32/32 limit.
+         *
+         * Note that the specification defines no limits on the depth
+         * of stacked variants, but we do.
+         */
+        if (m->n_containers >= BUS_CONTAINER_DEPTH)
+                return -EBADMSG;
+
         w = realloc(m->containers, sizeof(struct bus_container) * (m->n_containers + 1));
         if (!w)
                 return -ENOMEM;
@@ -1891,7 +2065,7 @@ eof:
         return 0;
 }
 
-int sd_bus_message_rewind(sd_bus_message *m, bool complete) {
+int sd_bus_message_rewind(sd_bus_message *m, int complete) {
         struct bus_container *c;
 
         if (!m)
@@ -1936,7 +2110,8 @@ static int message_read_ap(sd_bus_message *m, const char *types, va_list ap) {
                 case SD_BUS_TYPE_DOUBLE:
                 case SD_BUS_TYPE_STRING:
                 case SD_BUS_TYPE_OBJECT_PATH:
-                case SD_BUS_TYPE_SIGNATURE: {
+                case SD_BUS_TYPE_SIGNATURE:
+                case SD_BUS_TYPE_UNIX_FD: {
                         void *p;
 
                         p = va_arg(ap, void*);
@@ -2079,12 +2254,11 @@ static int message_peek_fields(
         return buffer_peek(m->fields, BUS_MESSAGE_FIELDS_SIZE(m), rindex, align, nbytes, ret);
 }
 
-static int message_peek_field_string(
+static int message_peek_field_uint32(
                 sd_bus_message *m,
                 size_t *ri,
-                const char **ret) {
+                uint32_t *ret) {
 
-        size_t l;
         int r;
         void *q;
 
@@ -2095,43 +2269,43 @@ static int message_peek_field_string(
         if (r < 0)
                 return r;
 
-        l = BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q);
-        r = message_peek_fields(m, ri, 1, l+1, &q);
-        if (r < 0)
-                return r;
-
-        if (!validate_string(q, l))
-                return -EBADMSG;
-
         if (ret)
-                *ret = q;
+                *ret = BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q);
 
         return 0;
 }
 
-static int message_peek_field_signature(
+static int message_peek_field_string(
                 sd_bus_message *m,
+                bool (*validate)(const char *p),
                 size_t *ri,
                 const char **ret) {
 
-        size_t l;
+        uint32_t l;
         int r;
         void *q;
 
         assert(m);
         assert(ri);
 
-        r = message_peek_fields(m, ri, 1, 1, &q);
+        r = message_peek_field_uint32(m, ri, &l);
         if (r < 0)
                 return r;
 
-        l = *(uint8_t*) q;
         r = message_peek_fields(m, ri, 1, l+1, &q);
         if (r < 0)
                 return r;
 
-        if (!validate_signature(q, l))
-                return -EBADMSG;
+        if (validate) {
+                if (!validate_nul(q, l))
+                        return -EBADMSG;
+
+                if (!validate(q))
+                        return -EBADMSG;
+        } else {
+                if (!validate_string(q, l))
+                        return -EBADMSG;
+        }
 
         if (ret)
                 *ret = q;
@@ -2139,23 +2313,32 @@ static int message_peek_field_signature(
         return 0;
 }
 
-static int message_peek_field_uint32(
+static int message_peek_field_signature(
                 sd_bus_message *m,
                 size_t *ri,
-                uint32_t *ret) {
+                const char **ret) {
 
+        size_t l;
         int r;
         void *q;
 
         assert(m);
         assert(ri);
 
-        r = message_peek_fields(m, ri, 4, 4, &q);
+        r = message_peek_fields(m, ri, 1, 1, &q);
+        if (r < 0)
+                return r;
+
+        l = *(uint8_t*) q;
+        r = message_peek_fields(m, ri, 1, l+1, &q);
         if (r < 0)
                 return r;
 
+        if (!validate_signature(q, l))
+                return -EBADMSG;
+
         if (ret)
-                *ret = BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q);
+                *ret = q;
 
         return 0;
 }
@@ -2177,7 +2360,6 @@ static int message_skip_fields(
 
         for (;;) {
                 char t;
-                void *q;
                 size_t l;
 
                 if (array_size != (uint32_t) -1 &&
@@ -2188,10 +2370,17 @@ static int message_skip_fields(
                 if (!t)
                         return 0;
 
-                if (t == SD_BUS_TYPE_STRING ||
-                    t == SD_BUS_TYPE_OBJECT_PATH) {
+                if (t == SD_BUS_TYPE_STRING) {
+
+                        r = message_peek_field_string(m, NULL, ri, NULL);
+                        if (r < 0)
+                                return r;
+
+                        (*signature)++;
 
-                        r = message_peek_field_string(m, ri, NULL);
+                } else if (t == SD_BUS_TYPE_OBJECT_PATH) {
+
+                        r = message_peek_field_string(m, object_path_is_valid, ri, NULL);
                         if (r < 0)
                                 return r;
 
@@ -2206,10 +2395,11 @@ static int message_skip_fields(
                         (*signature)++;
 
                 } else if (bus_type_is_basic(t)) {
-                        size_t align, k;
+                        ssize_t align, k;
 
-                        align = bus_type_get_alignment(align);
-                        k = bus_type_get_size(align);
+                        align = bus_type_get_alignment(t);
+                        k = bus_type_get_size(t);
+                        assert(align > 0 && k > 0);
 
                         r = message_peek_fields(m, ri, align, k, NULL);
                         if (r < 0)
@@ -2226,7 +2416,7 @@ static int message_skip_fields(
                         assert(l >= 1);
                         {
                                 char sig[l-1], *s;
-                                size_t nas;
+                                uint32_t nas;
                                 int alignment;
 
                                 strncpy(sig, *signature + 1, l-1);
@@ -2236,12 +2426,10 @@ static int message_skip_fields(
                                 if (alignment < 0)
                                         return alignment;
 
-                                r = message_peek_fields(m, ri, 4, 4, &q);
+                                r = message_peek_field_uint32(m, ri, &nas);
                                 if (r < 0)
                                         return r;
-
-                                nas = BUS_MESSAGE_BSWAP32(m, *(uint32_t*) q);
-                                if (nas > 67108864)
+                                if (nas > BUS_ARRAY_MAX_SIZE)
                                         return -EBADMSG;
 
                                 r = message_peek_fields(m, ri, alignment, 0, NULL);
@@ -2295,6 +2483,7 @@ static int message_skip_fields(
 static int message_parse_fields(sd_bus_message *m) {
         size_t ri;
         int r;
+        uint32_t unix_fds = 0;
 
         assert(m);
 
@@ -2315,45 +2504,69 @@ static int message_parse_fields(sd_bus_message *m) {
                         return -EBADMSG;
 
                 case SD_BUS_MESSAGE_HEADER_PATH:
+
+                        if (m->path)
+                                return -EBADMSG;
+
                         if (!streq(signature, "o"))
                                 return -EBADMSG;
 
-                        r = message_peek_field_string(m, &ri, &m->path);
+                        r = message_peek_field_string(m, object_path_is_valid, &ri, &m->path);
                         break;
 
                 case SD_BUS_MESSAGE_HEADER_INTERFACE:
+
+                        if (m->interface)
+                                return -EBADMSG;
+
                         if (!streq(signature, "s"))
                                 return -EBADMSG;
 
-                        r = message_peek_field_string(m, &ri, &m->interface);
+                        r = message_peek_field_string(m, interface_name_is_valid, &ri, &m->interface);
                         break;
 
                 case SD_BUS_MESSAGE_HEADER_MEMBER:
+
+                        if (m->member)
+                                return -EBADMSG;
+
                         if (!streq(signature, "s"))
                                 return -EBADMSG;
 
-                        r = message_peek_field_string(m, &ri, &m->member);
+                        r = message_peek_field_string(m, member_name_is_valid, &ri, &m->member);
                         break;
 
                 case SD_BUS_MESSAGE_HEADER_ERROR_NAME:
+
+                        if (m->error.name)
+                                return -EBADMSG;
+
                         if (!streq(signature, "s"))
                                 return -EBADMSG;
 
-                        r = message_peek_field_string(m, &ri, &m->error.name);
+                        r = message_peek_field_string(m, error_name_is_valid, &ri, &m->error.name);
                         break;
 
                 case SD_BUS_MESSAGE_HEADER_DESTINATION:
+
+                        if (m->destination)
+                                return -EBADMSG;
+
                         if (!streq(signature, "s"))
                                 return -EBADMSG;
 
-                        r = message_peek_field_string(m, &ri, &m->destination);
+                        r = message_peek_field_string(m, service_name_is_valid, &ri, &m->destination);
                         break;
 
                 case SD_BUS_MESSAGE_HEADER_SENDER:
+
+                        if (m->sender)
+                                return -EBADMSG;
+
                         if (!streq(signature, "s"))
                                 return -EBADMSG;
 
-                        r = message_peek_field_string(m, &ri, &m->sender);
+                        r = message_peek_field_string(m, service_name_is_valid, &ri, &m->sender);
                         break;
 
 
@@ -2361,6 +2574,9 @@ static int message_parse_fields(sd_bus_message *m) {
                         const char *s;
                         char *c;
 
+                        if (m->root_container.signature)
+                                return -EBADMSG;
+
                         if (!streq(signature, "g"))
                                 return -EBADMSG;
 
@@ -2374,16 +2590,39 @@ static int message_parse_fields(sd_bus_message *m) {
 
                         free(m->root_container.signature);
                         m->root_container.signature = c;
-
-                        r = 0;
                         break;
                 }
 
                 case SD_BUS_MESSAGE_HEADER_REPLY_SERIAL:
+                        if (m->reply_serial != 0)
+                                return -EBADMSG;
+
                         if (!streq(signature, "u"))
                                 return -EBADMSG;
 
                         r = message_peek_field_uint32(m, &ri, &m->reply_serial);
+                        if (r < 0)
+                                return r;
+
+                        if (m->reply_serial == 0)
+                                return -EBADMSG;
+
+                        break;
+
+                case SD_BUS_MESSAGE_HEADER_UNIX_FDS:
+                        if (unix_fds != 0)
+                                return -EBADMSG;
+
+                        if (!streq(signature, "u"))
+                                return -EBADMSG;
+
+                        r = message_peek_field_uint32(m, &ri, &unix_fds);
+                        if (r < 0)
+                                return -EBADMSG;
+
+                        if (unix_fds == 0)
+                                return -EBADMSG;
+
                         break;
 
                 default:
@@ -2394,6 +2633,9 @@ static int message_parse_fields(sd_bus_message *m) {
                         return r;
         }
 
+        if (m->n_fds != unix_fds)
+                return -EBADMSG;
+
         if (isempty(m->root_container.signature) != (BUS_MESSAGE_BODY_SIZE(m) == 0))
                 return -EBADMSG;
 
@@ -2424,6 +2666,10 @@ static int message_parse_fields(sd_bus_message *m) {
                 break;
         }
 
+        /* Try to read the error message, but if we can't it's a non-issue */
+        if (m->header->type == SD_BUS_MESSAGE_TYPE_METHOD_ERROR)
+                sd_bus_message_read(m, "s", &m->error.message);
+
         return 0;
 }
 
@@ -2432,14 +2678,17 @@ static void setup_iovec(sd_bus_message *m) {
         assert(m->sealed);
 
         m->n_iovec = 0;
+        m->size = 0;
 
         m->iovec[m->n_iovec].iov_base = m->header;
         m->iovec[m->n_iovec].iov_len = sizeof(*m->header);
+        m->size += m->iovec[m->n_iovec].iov_len;
         m->n_iovec++;
 
         if (m->fields) {
                 m->iovec[m->n_iovec].iov_base = m->fields;
                 m->iovec[m->n_iovec].iov_len = m->header->fields_size;
+                m->size += m->iovec[m->n_iovec].iov_len;
                 m->n_iovec++;
 
                 if (m->header->fields_size % 8 != 0) {
@@ -2447,6 +2696,7 @@ static void setup_iovec(sd_bus_message *m) {
 
                         m->iovec[m->n_iovec].iov_base = (void*) padding;
                         m->iovec[m->n_iovec].iov_len = 8 - m->header->fields_size % 8;
+                        m->size += m->iovec[m->n_iovec].iov_len;
                         m->n_iovec++;
                 }
         }
@@ -2454,6 +2704,7 @@ static void setup_iovec(sd_bus_message *m) {
         if (m->body) {
                 m->iovec[m->n_iovec].iov_base = m->body;
                 m->iovec[m->n_iovec].iov_len = m->header->body_size;
+                m->size += m->iovec[m->n_iovec].iov_len;
                 m->n_iovec++;
         }
 }
@@ -2724,3 +2975,69 @@ int bus_message_get_blob(sd_bus_message *m, void **buffer, size_t *sz) {
 
         return 0;
 }
+
+int bus_message_read_strv_extend(sd_bus_message *m, char ***l) {
+        int r;
+
+        assert(m);
+        assert(l);
+
+        r = sd_bus_message_enter_container(m, 'a', "s");
+        if (r < 0)
+                return r;
+
+        for (;;) {
+                const char *s;
+
+                r = sd_bus_message_read_basic(m, 's', &s);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        break;
+
+                r = strv_extend(l, s);
+                if (r < 0)
+                        return r;
+        }
+
+        r = sd_bus_message_exit_container(m);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+const char* bus_message_get_arg(sd_bus_message *m, unsigned i) {
+        int r;
+        const char *t;
+        char type;
+
+        assert(m);
+
+        r = sd_bus_message_rewind(m, true);
+        if (r < 0)
+                return NULL;
+
+        while (i > 0) {
+                r = sd_bus_message_peek_type(m, &type, NULL);
+                if (r < 0)
+                        return NULL;
+
+                if (type != SD_BUS_TYPE_STRING &&
+                    type != SD_BUS_TYPE_OBJECT_PATH &&
+                    type != SD_BUS_TYPE_SIGNATURE)
+                        return NULL;
+
+                r = sd_bus_message_read_basic(m, type, &t);
+                if (r < 0)
+                        return NULL;
+
+                i--;
+        }
+
+        r = sd_bus_message_rewind(m, true);
+        if (r < 0)
+                return NULL;
+
+        return t;
+}