From 2da7d0bc92e2423a5c7225c5d24b99d5d52a0bc6 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>

Date: Wed, 7 Jul 2021 18:02:50 +0200

Subject: [PATCH] sd-bus: allow numerical uids in -M user@.host

UIDs don't work well over ssh, but locally or with containers they are OK.

In particular, user@.service uses UIDs as identifiers, and it's nice to be

able to copy&paste that UID for interaction with the user's managers.

---

 src/libsystemd/sd-bus/sd-bus.c | 27 ++++++++++++++++++---------

 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/libsystemd/sd-bus/sd-bus.c b/src/libsystemd/sd-bus/sd-bus.c

index a32e2f5e2085..6960161c3658 100644

--- a/src/libsystemd/sd-bus/sd-bus.c

+++ b/src/libsystemd/sd-bus/sd-bus.c

@@ -39,6 +39,7 @@

 #include "parse-util.h"

 #include "path-util.h"

 #include "process-util.h"

+#include "stdio-util.h"

 #include "string-util.h"

 #include "strv.h"

 #include "user-util.h"

@@ -1617,7 +1618,7 @@ static int user_and_machine_valid(const char *user_and_machine) {

                 if (!user)

                         return -ENOMEM;

-                if (!isempty(user) && !valid_user_group_name(user, VALID_USER_RELAX))

+                if (!isempty(user) && !valid_user_group_name(user, VALID_USER_RELAX | VALID_USER_ALLOW_NUMERIC))

                         return false;

                 h++;

@@ -1648,17 +1649,25 @@ static int user_and_machine_equivalent(const char *user_and_machine) {

         /* Otherwise, if we are root, then we can also allow the ".host" syntax, as that's the user this

          * would connect to. */

-        if (geteuid() == 0 && STR_IN_SET(user_and_machine, ".host", "root@.host"))

+        uid_t uid = geteuid();

+

+        if (uid == 0 && STR_IN_SET(user_and_machine, ".host", "root@.host", "0@.host"))

                 return true;

-        /* Otherwise, we have to figure our user name, and compare things with that. */

-        un = getusername_malloc();

-        if (!un)

-                return -ENOMEM;

+        /* Otherwise, we have to figure out our user id and name, and compare things with that. */

+        char buf[DECIMAL_STR_MAX(uid_t)];

+        xsprintf(buf, UID_FMT, uid);

+

+        f = startswith(user_and_machine, buf);

+        if (!f) {

+                un = getusername_malloc();

+                if (!un)

+                        return -ENOMEM;

-        f = startswith(user_and_machine, un);

-        if (!f)

-                return false;

+                f = startswith(user_and_machine, un);

+                if (!f)

+                        return false;

+        }

         return STR_IN_SET(f, "@", "@.host");

 }