bus: add new sd_bus_creds object to encapsulate process credentials

This way we can unify handling of credentials that are attached to
messages, or can be queried for bus name owners or connection peers.

This also adds the ability to extend incomplete credential information
with data from /proc,

Also, provide a convenience call that will automatically determine the
most appropriate credential object for an incoming message, by using the
the attached information if possible, the sending name information if
available and otherwise the peer's credentials.

1 files changed, 94 insertions, 60 deletions

diff --git a/src/libsystemd-bus/bus-control.c b/src/libsystemd-bus/bus-control.c
index f217269f79..43e2848ecc 100644
--- a/src/libsystemd-bus/bus-control.c
+++ b/src/libsystemd-bus/bus-control.c
@@ -260,80 +260,114 @@ _public_ int sd_bus_get_owner(sd_bus *bus, const char *name, char **owner) {
         return 0;
 }
 
-_public_ int sd_bus_get_owner_uid(sd_bus *bus, const char *name, uid_t *uid) {
+_public_ int sd_bus_get_owner_creds(sd_bus *bus, const char *name, uint64_t mask, sd_bus_creds **creds) {
         _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
-        uint32_t u;
+        _cleanup_bus_creds_unref_ sd_bus_creds *c = NULL;
+        pid_t pid = 0;
         int r;
 
-        if (!bus)
-                return -EINVAL;
-        if (!name)
-                return -EINVAL;
-        if (!uid)
-                return -EINVAL;
-        if (!BUS_IS_OPEN(bus->state))
-                return -ENOTCONN;
-        if (bus_pid_changed(bus))
-                return -ECHILD;
+        assert_return(bus, -EINVAL);
+        assert_return(name, -EINVAL);
+        assert_return(mask <= _SD_BUS_CREDS_MAX, -ENOTSUP);
+        assert_return(creds, -EINVAL);
+        assert_return(BUS_IS_OPEN(bus->state), -ENOTCONN);
+        assert_return(!bus_pid_changed(bus), -ECHILD);
 
-        r = sd_bus_call_method(
-                        bus,
-                        "org.freedesktop.DBus",
-                        "/",
-                        "org.freedesktop.DBus",
-                        "GetConnectionUnixUser",
-                        NULL,
-                        &reply,
-                        "s",
-                        name);
-        if (r < 0)
-                return r;
+        c = bus_creds_new();
+        if (!c)
+                return -ENOMEM;
 
-        r = sd_bus_message_read(reply, "u", &u);
-        if (r < 0)
-                return r;
+        if ((mask & SD_BUS_CREDS_PID) ||
+            mask & ~(SD_BUS_CREDS_PID|SD_BUS_CREDS_UID|SD_BUS_CREDS_SELINUX_CONTEXT)) {
+                uint32_t u;
 
-        *uid = (uid_t) u;
-        return 0;
-}
+                r = sd_bus_call_method(
+                                bus,
+                                "org.freedesktop.DBus",
+                                "/",
+                                "org.freedesktop.DBus",
+                                "GetConnectionUnixProcessID",
+                                NULL,
+                                &reply,
+                                "s",
+                                name);
+                if (r < 0)
+                        return r;
 
-_public_ int sd_bus_get_owner_pid(sd_bus *bus, const char *name, pid_t *pid) {
-        _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
-        uint32_t u;
-        int r;
+                r = sd_bus_message_read(reply, "u", &u);
+                if (r < 0)
+                        return r;
 
-        if (!bus)
-                return -EINVAL;
-        if (!name)
-                return -EINVAL;
-        if (!pid)
-                return -EINVAL;
-        if (!BUS_IS_OPEN(bus->state))
-                return -ENOTCONN;
-        if (bus_pid_changed(bus))
-                return -ECHILD;
+                pid = u;
+                if (mask & SD_BUS_CREDS_PID) {
+                        c->pid = u;
+                        c->mask |= SD_BUS_CREDS_PID;
+                }
 
-        r = sd_bus_call_method(
-                        bus,
-                        "org.freedesktop.DBus",
-                        "/",
-                        "org.freedesktop.DBus",
-                        "GetConnectionUnixProcessID",
-                        NULL,
-                        &reply,
-                        "s",
-                        name);
-        if (r < 0)
-                return r;
+                reply = sd_bus_message_unref(reply);
+        }
+
+        if (mask & SD_BUS_CREDS_UID) {
+                uint32_t u;
+
+                r = sd_bus_call_method(
+                                bus,
+                                "org.freedesktop.DBus",
+                                "/",
+                                "org.freedesktop.DBus",
+                                "GetConnectionUnixUser",
+                                NULL,
+                                &reply,
+                                "s",
+                                name);
+                if (r < 0)
+                        return r;
+
+                r = sd_bus_message_read(reply, "u", &u);
+                if (r < 0)
+                        return r;
+
+                c->uid = u;
+                c->mask |= SD_BUS_CREDS_UID;
+
+                reply = sd_bus_message_unref(reply);
+        }
+
+        if (mask & SD_BUS_CREDS_SELINUX_CONTEXT) {
+                const void *p;
+                size_t sz;
+
+                r = sd_bus_call_method(
+                                bus,
+                                "org.freedesktop.DBus",
+                                "/",
+                                "org.freedesktop.DBus",
+                                "GetConnectionSELinuxSecurityContext",
+                                NULL,
+                                &reply,
+                                "s",
+                                name);
+                if (r < 0)
+                        return r;
+
+                r = sd_bus_message_read_array(reply, 'y', &p, &sz);
+                if (r < 0)
+                        return r;
+
+                c->label = strndup(p, sz);
+                if (!c->label)
+                        return -ENOMEM;
+
+                c->mask |= SD_BUS_CREDS_SELINUX_CONTEXT;
+        }
 
-        r = sd_bus_message_read(reply, "u", &u);
+        r = bus_creds_add_more(c, mask, pid, 0);
         if (r < 0)
                 return r;
 
-        if (u == 0)
-                return -EIO;
+        *creds = c;
+        c = NULL;
 
-        *pid = (uid_t) u;
         return 0;
 }