X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fbus-proxyd%2Fbus-proxyd.c;h=bd2b0a82cb010ddecdddbab9628928a81047b5a7;hb=6d0b55c272ea31d025e8b3c311cea8cda0bfefd7;hp=d2acb788d33c9d5e46d39f4464b816988f23e250;hpb=2e43ad9ca677b1f641a30849526e2b999cb81075;p=elogind.git diff --git a/src/bus-proxyd/bus-proxyd.c b/src/bus-proxyd/bus-proxyd.c index d2acb788d..bd2b0a82c 100644 --- a/src/bus-proxyd/bus-proxyd.c +++ b/src/bus-proxyd/bus-proxyd.c @@ -44,7 +44,10 @@ #include "strv.h" #include "def.h" #include "capability.h" -#include "bus-policy.h" +#include "bus-control.h" +#include "smack-util.h" +#include "set.h" +#include "bus-xml-policy.h" static char *arg_address = NULL; static char *arg_command_line_buffer = NULL; @@ -136,9 +139,9 @@ static int parse_argv(int argc, char *argv[]) { return log_oom(); #ifdef ENABLE_KDBUS - a = strjoin("x-container-kernel:machine=", e, ";x-container-unix:machine=", e, NULL); + a = strjoin("x-machine-kernel:machine=", e, ";x-machine-unix:machine=", e, NULL); #else - a = strjoin("x-container-unix:machine=", e, NULL); + a = strjoin("x-machine-unix:machine=", e, NULL); #endif if (!a) return log_oom(); @@ -186,7 +189,7 @@ static int rename_service(sd_bus *a, sd_bus *b) { assert(a); assert(b); - r = sd_bus_get_owner_creds(b, SD_BUS_CREDS_UID|SD_BUS_CREDS_PID|SD_BUS_CREDS_CMDLINE|SD_BUS_CREDS_COMM, &creds); + r = sd_bus_get_owner_creds(b, SD_BUS_CREDS_UID|SD_BUS_CREDS_PID|SD_BUS_CREDS_CMDLINE|SD_BUS_CREDS_COMM|SD_BUS_CREDS_AUGMENT, &creds); if (r < 0) return r; @@ -342,6 +345,17 @@ static int synthetic_reply_method_error(sd_bus_message *call, const sd_bus_error return synthetic_driver_send(call->bus, m); } +static int synthetic_reply_method_errorf(sd_bus_message *call, const char *name, const char *format, ...) { + _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL; + va_list ap; + + va_start(ap, format); + bus_error_setfv(&error, name, format, ap); + va_end(ap); + + return synthetic_reply_method_error(call, &error); +} + static int synthetic_reply_method_errno(sd_bus_message *call, int error, const sd_bus_error *p) { _cleanup_bus_error_free_ sd_bus_error berror = SD_BUS_ERROR_NULL; @@ -391,6 +405,9 @@ static int synthetic_reply_return_strv(sd_bus_message *call, char **l) { assert(call); + if (call->header->flags & BUS_MESSAGE_NO_REPLY_EXPECTED) + return 0; + r = sd_bus_message_new_method_return(call, &m); if (r < 0) return synthetic_reply_method_errno(call, r, NULL); @@ -625,7 +642,7 @@ static int process_driver(sd_bus *a, sd_bus *b, sd_bus_message *m, Policy *polic if (!sd_bus_message_has_signature(m, "")) return synthetic_reply_method_error(m, &SD_BUS_ERROR_MAKE_CONST(SD_BUS_ERROR_INVALID_ARGS, "Invalid parameters")); - r = sd_bus_get_owner_id(a, &server_id); + r = sd_bus_get_bus_id(a, &server_id); if (r < 0) return synthetic_reply_method_errno(m, r, NULL); @@ -958,6 +975,13 @@ static int process_driver(sd_bus *a, sd_bus *b, sd_bus_message *m, Policy *polic } } +static int handle_policy_error(sd_bus_message *m, int r) { + if (r == -ESRCH || r == -ENXIO) + return synthetic_reply_method_errorf(m, SD_BUS_ERROR_NAME_HAS_NO_OWNER, "Name %s is currently not owned by anyone.", m->destination); + + return r; +} + static int process_policy(sd_bus *from, sd_bus *to, sd_bus_message *m, Policy *policy, const struct ucred *our_ucred, Set *owned_names) { int r; @@ -968,9 +992,25 @@ static int process_policy(sd_bus *from, sd_bus *to, sd_bus_message *m, Policy *p if (!policy) return 0; + /* + * dbus-1 distinguishes expected and non-expected replies by tracking + * method-calls and timeouts. By default, DENY rules are *NEVER* applied + * on expected replies, unless explicitly specified. But we dont track + * method-calls, thus, we cannot know whether a reply is expected. + * Fortunately, the kdbus forbids non-expected replies, so we can safely + * ignore any policy on those and let the kernel deal with it. + * + * TODO: To be correct, we should only ignore policy-tags that are + * applied on non-expected replies. However, so far we don't parse those + * tags so we let everything pass. I haven't seen a DENY policy tag on + * expected-replies, ever, so don't bother.. + */ + if (m->reply_cookie > 0) + return 0; + if (from->is_kernel) { - uid_t sender_uid = (uid_t) -1; - gid_t sender_gid = (gid_t) -1; + uid_t sender_uid = UID_INVALID; + gid_t sender_gid = GID_INVALID; char **sender_names = NULL; bool granted = false; @@ -979,38 +1019,54 @@ static int process_policy(sd_bus *from, sd_bus *to, sd_bus_message *m, Policy *p return 0; /* The message came from the kernel, and is sent to our legacy client. */ - r = sd_bus_creds_get_well_known_names(&m->creds, &sender_names); - if (r < 0) - return r; + sd_bus_creds_get_well_known_names(&m->creds, &sender_names); (void) sd_bus_creds_get_uid(&m->creds, &sender_uid); (void) sd_bus_creds_get_gid(&m->creds, &sender_gid); + if (sender_uid == UID_INVALID || sender_gid == GID_INVALID) { + _cleanup_bus_creds_unref_ sd_bus_creds *sender_creds = NULL; + + /* If the message came from another legacy + * client, then the message creds will be + * missing, simply because on legacy clients + * per-message creds were unknown. In this + * case, query the creds of the peer + * instead. */ + + r = bus_get_name_creds_kdbus(from, m->sender, SD_BUS_CREDS_UID|SD_BUS_CREDS_GID, true, &sender_creds); + if (r < 0) + return handle_policy_error(m, r); + + (void) sd_bus_creds_get_uid(sender_creds, &sender_uid); + (void) sd_bus_creds_get_gid(sender_creds, &sender_gid); + } + /* First check whether the sender can send the message to our name */ if (set_isempty(owned_names)) { - if (policy_check_send(policy, sender_uid, sender_gid, m->header->type, NULL, m->path, m->interface, m->member)) + if (policy_check_send(policy, sender_uid, sender_gid, m->header->type, NULL, m->path, m->interface, m->member, false)) granted = true; } else { Iterator i; char *n; SET_FOREACH(n, owned_names, i) - if (policy_check_send(policy, sender_uid, sender_gid, m->header->type, n, m->path, m->interface, m->member)) { + if (policy_check_send(policy, sender_uid, sender_gid, m->header->type, n, m->path, m->interface, m->member, false)) { granted = true; break; } } if (granted) { - /* Then check whether us, the recipient can recieve from the sender's name */ + /* Then check whether us (the recipient) can receive from the sender's name */ if (strv_isempty(sender_names)) { - if (policy_check_recv(policy, our_ucred->uid, our_ucred->gid, m->header->type, NULL, m->path, m->interface, m->member)) + if (policy_check_recv(policy, our_ucred->uid, our_ucred->gid, m->header->type, NULL, m->path, m->interface, m->member, false)) return 0; } else { char **n; STRV_FOREACH(n, sender_names) { - if (policy_check_recv(policy, our_ucred->uid, our_ucred->gid, m->header->type, *n, m->path, m->interface, m->member)) + if (policy_check_recv(policy, our_ucred->uid, our_ucred->gid, m->header->type, *n, m->path, m->interface, m->member, false)) return 0; } } @@ -1018,7 +1074,7 @@ static int process_policy(sd_bus *from, sd_bus *to, sd_bus_message *m, Policy *p /* Return an error back to the caller */ if (m->header->type == SD_BUS_MESSAGE_METHOD_CALL) - return sd_bus_reply_method_errorf(m, SD_BUS_ERROR_ACCESS_DENIED, "Access prohibited by XML receiver policy."); + return synthetic_reply_method_errorf(m, SD_BUS_ERROR_ACCESS_DENIED, "Access prohibited by XML receiver policy."); /* Return 1, indicating that the message shall not be processed any further */ return 1; @@ -1026,8 +1082,8 @@ static int process_policy(sd_bus *from, sd_bus *to, sd_bus_message *m, Policy *p if (to->is_kernel) { _cleanup_bus_creds_unref_ sd_bus_creds *destination_creds = NULL; - uid_t destination_uid = (uid_t) -1; - gid_t destination_gid = (gid_t) -1; + uid_t destination_uid = UID_INVALID; + gid_t destination_gid = GID_INVALID; const char *destination_unique = NULL; char **destination_names = NULL; bool granted = false; @@ -1038,33 +1094,32 @@ static int process_policy(sd_bus *from, sd_bus *to, sd_bus_message *m, Policy *p /* The message came from the legacy client, and is sent to kdbus. */ if (m->destination) { - r = sd_bus_get_name_creds(to, m->destination, - SD_BUS_CREDS_WELL_KNOWN_NAMES|SD_BUS_CREDS_UNIQUE_NAME| - SD_BUS_CREDS_UID|SD_BUS_CREDS_GID|SD_BUS_CREDS_PID, &destination_creds); - if (r < 0) - return r; - - r = sd_bus_creds_get_well_known_names(destination_creds, &destination_names); + r = bus_get_name_creds_kdbus(to, m->destination, + SD_BUS_CREDS_WELL_KNOWN_NAMES|SD_BUS_CREDS_UNIQUE_NAME| + SD_BUS_CREDS_UID|SD_BUS_CREDS_GID|SD_BUS_CREDS_PID, + true, &destination_creds); if (r < 0) - return r; + return handle_policy_error(m, r); r = sd_bus_creds_get_unique_name(destination_creds, &destination_unique); if (r < 0) - return r; + return handle_policy_error(m, r); + + sd_bus_creds_get_well_known_names(destination_creds, &destination_names); (void) sd_bus_creds_get_uid(destination_creds, &destination_uid); (void) sd_bus_creds_get_gid(destination_creds, &destination_gid); } - /* First check if we, the sender can send to this name */ + /* First check if we (the sender) can send to this name */ if (strv_isempty(destination_names)) { - if (policy_check_send(policy, our_ucred->uid, our_ucred->gid, m->header->type, NULL, m->path, m->interface, m->member)) + if (policy_check_send(policy, our_ucred->uid, our_ucred->gid, m->header->type, NULL, m->path, m->interface, m->member, true)) granted = true; } else { char **n; STRV_FOREACH(n, destination_names) { - if (policy_check_send(policy, our_ucred->uid, our_ucred->gid, m->header->type, *n, m->path, m->interface, m->member)) { + if (policy_check_send(policy, our_ucred->uid, our_ucred->gid, m->header->type, *n, m->path, m->interface, m->member, true)) { /* If we made a receiver decision, then remember which name's policy @@ -1093,22 +1148,32 @@ static int process_policy(sd_bus *from, sd_bus *to, sd_bus_message *m, Policy *p /* Then check if the recipient can receive from our name */ if (granted) { - if (set_isempty(owned_names)) { - if (policy_check_recv(policy, destination_uid, destination_gid, m->header->type, NULL, m->path, m->interface, m->member)) + if (sd_bus_message_is_signal(m, NULL, NULL)) { + /* If we forward a signal from dbus-1 to kdbus, + * we have no idea who the recipient is. + * Therefore, we cannot apply any dbus-1 + * receiver policies that match on receiver + * credentials. We know sd-bus always sets + * KDBUS_MSG_SIGNAL, so the kernel applies + * receiver policies to the message. Therefore, + * skip policy checks in this case. */ + return 0; + } else if (set_isempty(owned_names)) { + if (policy_check_recv(policy, destination_uid, destination_gid, m->header->type, NULL, m->path, m->interface, m->member, true)) return 0; } else { Iterator i; char *n; SET_FOREACH(n, owned_names, i) - if (policy_check_recv(policy, destination_uid, destination_gid, m->header->type, n, m->path, m->interface, m->member)) + if (policy_check_recv(policy, destination_uid, destination_gid, m->header->type, n, m->path, m->interface, m->member, true)) return 0; } } /* Return an error back to the caller */ if (m->header->type == SD_BUS_MESSAGE_METHOD_CALL) - return sd_bus_reply_method_errorf(m, SD_BUS_ERROR_ACCESS_DENIED, "Access prohibited by XML sender policy."); + return synthetic_reply_method_errorf(m, SD_BUS_ERROR_ACCESS_DENIED, "Access prohibited by XML sender policy."); /* Return 1, indicating that the message shall not be processed any further */ return 1; @@ -1155,34 +1220,24 @@ static int process_hello(sd_bus *a, sd_bus *b, sd_bus_message *m, bool *got_hell return 0; r = sd_bus_message_new_method_return(m, &n); - if (r < 0) { - log_error_errno(r, "Failed to generate HELLO reply: %m"); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to generate HELLO reply: %m"); r = sd_bus_message_append(n, "s", a->unique_name); - if (r < 0) { - log_error_errno(r, "Failed to append unique name to HELLO reply: %m"); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to append unique name to HELLO reply: %m"); r = bus_message_append_sender(n, "org.freedesktop.DBus"); - if (r < 0) { - log_error_errno(r, "Failed to append sender to HELLO reply: %m"); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to append sender to HELLO reply: %m"); r = bus_seal_synthetic_message(b, n); - if (r < 0) { - log_error_errno(r, "Failed to seal HELLO reply: %m"); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to seal HELLO reply: %m"); r = sd_bus_send(b, n, NULL); - if (r < 0) { - log_error_errno(r, "Failed to send HELLO reply: %m"); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to send HELLO reply: %m"); n = sd_bus_message_unref(n); r = sd_bus_message_new_signal( @@ -1191,34 +1246,24 @@ static int process_hello(sd_bus *a, sd_bus *b, sd_bus_message *m, bool *got_hell "/org/freedesktop/DBus", "org.freedesktop.DBus", "NameAcquired"); - if (r < 0) { - log_error_errno(r, "Failed to allocate initial NameAcquired message: %m"); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to allocate initial NameAcquired message: %m"); r = sd_bus_message_append(n, "s", a->unique_name); - if (r < 0) { - log_error_errno(r, "Failed to append unique name to NameAcquired message: %m"); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to append unique name to NameAcquired message: %m"); r = bus_message_append_sender(n, "org.freedesktop.DBus"); - if (r < 0) { - log_error_errno(r, "Failed to append sender to NameAcquired message: %m"); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to append sender to NameAcquired message: %m"); r = bus_seal_synthetic_message(b, n); - if (r < 0) { - log_error_errno(r, "Failed to seal NameAcquired message: %m"); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to seal NameAcquired message: %m"); r = sd_bus_send(b, n, NULL); - if (r < 0) { - log_error_errno(r, "Failed to send NameAcquired message: %m"); - return r; - } + if (r < 0) + return log_error_errno(r, "Failed to send NameAcquired message: %m"); return 1; } @@ -1253,6 +1298,23 @@ static int patch_sender(sd_bus *a, sd_bus_message *m) { return 0; } +static int mac_smack_apply_label_and_drop_cap_mac_admin(pid_t its_pid, const char *new_label) { +#ifdef HAVE_SMACK + int r = 0, k; + + if (!mac_smack_use()) + return 0; + + if (new_label && its_pid > 0) + r = mac_smack_apply_pid(its_pid, new_label); + + k = drop_capability(CAP_MAC_ADMIN); + return r < 0 ? r : k; +#else + return 0; +#endif +} + int main(int argc, char *argv[]) { _cleanup_bus_close_unref_ sd_bus *a = NULL, *b = NULL; @@ -1264,6 +1326,7 @@ int main(int argc, char *argv[]) { _cleanup_free_ char *peersec = NULL; Policy policy_buffer = {}, *policy = NULL; _cleanup_set_free_free_ Set *owned_names = NULL; + uid_t original_uid; log_set_target(LOG_TARGET_JOURNAL_OR_KMSG); log_parse_environment(); @@ -1285,6 +1348,8 @@ int main(int argc, char *argv[]) { goto finish; } + original_uid = getuid(); + is_unix = sd_is_socket(in_fd, AF_UNIX, 0, 0) > 0 && sd_is_socket(out_fd, AF_UNIX, 0, 0) > 0; @@ -1292,6 +1357,10 @@ int main(int argc, char *argv[]) { if (is_unix) { (void) getpeercred(in_fd, &ucred); (void) getpeersec(in_fd, &peersec); + + r = mac_smack_apply_label_and_drop_cap_mac_admin(getpid(), peersec); + if (r < 0) + log_warning_errno(r, "Failed to set SMACK label (%s) and drop CAP_MAC_ADMIN: %m", peersec); } if (arg_drop_privileges) { @@ -1351,13 +1420,13 @@ int main(int argc, char *argv[]) { a->fake_pids_valid = true; a->fake_creds.uid = ucred.uid; - a->fake_creds.euid = (uid_t) -1; - a->fake_creds.suid = (uid_t) -1; - a->fake_creds.fsuid = (uid_t) -1; + a->fake_creds.euid = UID_INVALID; + a->fake_creds.suid = UID_INVALID; + a->fake_creds.fsuid = UID_INVALID; a->fake_creds.gid = ucred.gid; - a->fake_creds.egid = (gid_t) -1; - a->fake_creds.sgid = (gid_t) -1; - a->fake_creds.fsgid = (gid_t) -1; + a->fake_creds.egid = GID_INVALID; + a->fake_creds.sgid = GID_INVALID; + a->fake_creds.fsgid = GID_INVALID; a->fake_creds_valid = true; } @@ -1374,7 +1443,7 @@ int main(int argc, char *argv[]) { goto finish; } - r = sd_bus_get_owner_id(a, &server_id); + r = sd_bus_get_bus_id(a, &server_id); if (r < 0) { log_error_errno(r, "Failed to get server ID: %m"); goto finish; @@ -1420,9 +1489,13 @@ int main(int argc, char *argv[]) { } policy = &policy_buffer; - policy_dump(policy); + /* policy_dump(policy); */ - if (!policy_check_hello(policy, ucred.uid, ucred.gid)) { + if (ucred.uid == original_uid) + log_debug("Permitting access, since bus owner matches bus client."); + else if (policy_check_hello(policy, ucred.uid, ucred.gid)) + log_debug("Permitting access due to XML policy."); + else { r = log_error_errno(EPERM, "Policy denied connection."); goto finish; } @@ -1583,14 +1656,26 @@ int main(int argc, char *argv[]) { if (!processed) { k = sd_bus_send(b, m, NULL); if (k < 0) { - if (k == -ECONNRESET) + if (k == -ECONNRESET) { r = 0; - else { + goto finish; + } else if (k == -EPERM && m->reply_cookie > 0) { + /* If the peer tries to send a reply and it is rejected with EPERM + * by the kernel, we ignore the error. This catches cases where the + * original method-call didn't had EXPECT_REPLY set, but the proxy-peer + * still sends a reply. This is allowed in dbus1, but not in kdbus. We + * don't want to track reply-windows in the proxy, so we simply ignore + * EPERM for all replies. The only downside is, that callers are no + * longer notified if their replies are dropped. However, this is + * equivalent to the caller's timeout to expire, so this should be + * acceptable. Nobody sane sends replies without a matching method-call, + * so nobody should care. */ + r = 1; + } else { r = k; log_error_errno(r, "Failed to send message to client: %m"); + goto finish; } - - goto finish; } else r = 1; } @@ -1660,17 +1745,20 @@ int main(int argc, char *argv[]) { k = sd_bus_send(a, m, NULL); if (k < 0) { - if (k == -EREMCHG) + if (k == -EREMCHG) { /* The name database changed since the policy check, hence let's check again */ continue; - else if (k == -ECONNRESET) + } else if (k == -ECONNRESET) { r = 0; - else { + goto finish; + } else if (k == -EPERM && m->reply_cookie > 0) { + /* see above why EPERM is ignored for replies */ + r = 1; + } else { r = k; log_error_errno(r, "Failed to send message to bus: %m"); + goto finish; } - - goto finish; } else r = 1; @@ -1739,7 +1827,7 @@ int main(int argc, char *argv[]) { r = ppoll(pollfd, 3, ts, NULL); if (r < 0) { - log_error("ppoll() failed: %m"); + log_error_errno(errno, "ppoll() failed: %m"); goto finish; } }