Merge pull request #34026 from DaanDeMeyer/tests

Handle unprivileged user namespaces gracefully in tests

src/shared/tests.c

@@ -29,6 +29,7 @@
 #include "strv.h"
 #include "tests.h"
 #include "tmpfile-util.h"
+#include "uid-range.h"
 
 char* setup_fake_runtime_dir(void) {
         char t[] = "/tmp/fake-xdg-runtime-XXXXXX", *p;
@@ -166,6 +167,24 @@ bool have_namespaces(void) {
         assert_not_reached();
 }
 
+bool userns_has_single_user(void) {
+        _cleanup_(uid_range_freep) UIDRange *uidrange = NULL, *gidrange = NULL;
+
+        /* Check if we're in a user namespace with only a single user mapped in. We special case this
+         * scenario in a few tests because it's the only kind of namespace that can be created unprivileged
+         * and as such happens more often than not, so we make sure to deal with it so that all tests pass
+         * in such environments. */
+
+        if (uid_range_load_userns(NULL, UID_RANGE_USERNS_INSIDE, &uidrange) < 0)
+                return false;
+
+        if (uid_range_load_userns(NULL, GID_RANGE_USERNS_INSIDE, &gidrange) < 0)
+                return false;
+
+        return uidrange->n_entries == 1 && uidrange->entries[0].nr == 1 &&
+                gidrange->n_entries == 1 && gidrange->entries[0].nr == 1;
+}
+
 bool can_memlock(void) {
         /* Let's see if we can mlock() a larger blob of memory. BPF programs are charged against
          * RLIMIT_MEMLOCK, hence let's first make sure we can lock memory at all, and skip the test if we

src/shared/tests.h

@@ -76,6 +76,7 @@ void test_setup_logging(int level);
 int write_tmpfile(char *pattern, const char *contents);
 
 bool have_namespaces(void);
+bool userns_has_single_user(void);
 
 /* We use the small but non-trivial limit here */
 #define CAN_MEMLOCK_SIZE (512 * 1024U)