Merge pull request #34026 from DaanDeMeyer/tests

Handle unprivileged user namespaces gracefully in tests

src/libsystemd/sd-netlink/test-netlink.c

@@ -92,18 +92,24 @@ TEST(message_address) {
         struct in_addr in_data;
         struct ifa_cacheinfo cache;
         const char *label;
+        int r;
 
         assert_se(sd_netlink_open(&rtnl) >= 0);
         ifindex = (int) if_nametoindex("lo");
 
         assert_se(sd_rtnl_message_new_addr(rtnl, &message, RTM_GETADDR, ifindex, AF_INET) >= 0);
         assert_se(sd_netlink_message_set_request_dump(message, true) >= 0);
-        assert_se(sd_netlink_call(rtnl, message, 0, &reply) == 1);
 
-        assert_se(sd_netlink_message_read_in_addr(reply, IFA_LOCAL, &in_data) >= 0);
-        assert_se(sd_netlink_message_read_in_addr(reply, IFA_ADDRESS, &in_data) >= 0);
-        assert_se(sd_netlink_message_read_string(reply, IFA_LABEL, &label) >= 0);
-        assert_se(sd_netlink_message_read_cache_info(reply, IFA_CACHEINFO, &cache) == 0);
+        r = sd_netlink_call(rtnl, message, 0, &reply);
+        assert_se(r >= 0);
+
+        /* If the loopback device is down we won't get any results. */
+        if (r > 0) {
+                assert_se(sd_netlink_message_read_in_addr(reply, IFA_LOCAL, &in_data) >= 0);
+                assert_se(sd_netlink_message_read_in_addr(reply, IFA_ADDRESS, &in_data) >= 0);
+                assert_se(sd_netlink_message_read_string(reply, IFA_LABEL, &label) >= 0);
+                assert_se(sd_netlink_message_read_cache_info(reply, IFA_CACHEINFO, &cache) == 0);
+        }
 }
 
 TEST(message_route) {

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)

src/test/test-acl-util.c

@@ -41,7 +41,7 @@ TEST_RET(add_acls_for_user) {
         cmd = strjoina("getfacl -p ", fn);
         assert_se(system(cmd) == 0);
 
-        if (getuid() == 0) {
+        if (getuid() == 0 && !userns_has_single_user()) {
                 const char *nobody = NOBODY_USER_NAME;
                 r = get_user_creds(&nobody, &uid, NULL, NULL, NULL, 0);
                 if (r < 0)

src/test/test-capability.c

@@ -318,10 +318,13 @@ int main(int argc, char *argv[]) {
 
         show_capabilities();
 
-        test_drop_privileges();
+        if (!userns_has_single_user())
+                test_drop_privileges();
+
         test_update_inherited_set();
 
-        fork_test(test_have_effective_cap);
+        if (!userns_has_single_user())
+                fork_test(test_have_effective_cap);
 
         if (run_ambient)
                 fork_test(test_apply_ambient_caps);

src/test/test-chase.c

@@ -183,7 +183,7 @@ TEST(chase) {
 
         /* Paths underneath the "root" with different UIDs while using CHASE_SAFE */
 
-        if (geteuid() == 0) {
+        if (geteuid() == 0 && !userns_has_single_user()) {
                 p = strjoina(temp, "/user");
                 ASSERT_OK(mkdir(p, 0755));
                 ASSERT_OK(chown(p, UID_NOBODY, GID_NOBODY));
@@ -313,7 +313,7 @@ TEST(chase) {
         r = chase(p, NULL, 0, &result, NULL);
         assert_se(r == -ENOENT);
 
-        if (geteuid() == 0) {
+        if (geteuid() == 0 && !userns_has_single_user()) {
                 p = strjoina(temp, "/priv1");
                 ASSERT_OK(mkdir(p, 0755));
 

src/test/test-chown-rec.c

@@ -153,8 +153,8 @@ TEST(chown_recursive) {
 }
 
 static int intro(void) {
-        if (geteuid() != 0)
-                return log_tests_skipped("not running as root");
+        if (geteuid() != 0 || userns_has_single_user())
+                return log_tests_skipped("not running as root or in userns with single user");
 
         return EXIT_SUCCESS;
 }

src/test/test-condition.c

@@ -1003,6 +1003,13 @@ TEST(condition_test_group) {
         condition_free(condition);
         free(gid);
 
+        /* In an unprivileged user namespace with the current user mapped to root, all the auxiliary groups
+         * of the user will be mapped to the nobody group, which means the user in the user namespace is in
+         * both the root and the nobody group, meaning the next test can't work, so let's skip it in that
+         * case. */
+        if (in_group(NOBODY_GROUP_NAME) && in_group("root"))
+                return (void) log_tests_skipped("user is in both root and nobody group");
+
         groupname = (char*)(getegid() == 0 ? NOBODY_GROUP_NAME : "root");
         condition = condition_new(CONDITION_GROUP, groupname, false, false);
         assert_se(condition);

src/test/test-fs-util.c

@@ -368,8 +368,8 @@ TEST(chmod_and_chown) {
         struct stat st;
         const char *p;
 
-        if (geteuid() != 0)
-                return;
+        if (geteuid() != 0 || userns_has_single_user())
+                return (void) log_tests_skipped("not running as root or in userns with single user");
 
         BLOCK_WITH_UMASK(0000);
 

src/test/test-rm-rf.c

@@ -89,6 +89,9 @@ static void test_rm_rf_chmod_inner(void) {
 TEST(rm_rf_chmod) {
         int r;
 
+        if (getuid() == 0 && userns_has_single_user())
+                return (void) log_tests_skipped("running as root or in userns with single user");
+
         if (getuid() == 0) {
                 /* This test only works unpriv (as only then the access mask for the owning user matters),
                  * hence drop privs here */

src/test/test-socket-util.c

@@ -170,7 +170,7 @@ TEST(getpeercred_getpeergroups) {
                 struct ucred ucred;
                 int pair[2] = EBADF_PAIR;
 
-                if (geteuid() == 0) {
+                if (geteuid() == 0 && !userns_has_single_user()) {
                         test_uid = 1;
                         test_gid = 2;
                         test_gids = (gid_t*) gids;