udev: do not try to rename interface if it is already up

See dev_change_name() in kernel's net/core/dev.c.

Fixes #21105.

src/basic/missing_syscall.h

@@ -465,10 +465,18 @@ struct mount_attr;
 #define MOUNT_ATTR_IDMAP 0x00100000
 #endif
 
+#ifndef MOUNT_ATTR_NOSYMFOLLOW
+#define MOUNT_ATTR_NOSYMFOLLOW 0x00200000
+#endif
+
 #ifndef AT_RECURSIVE
 #define AT_RECURSIVE 0x8000
 #endif
 
+#ifndef MOUNT_ATTR_SIZE_VER0
+#define MOUNT_ATTR_SIZE_VER0 32
+#endif
+
 static inline int missing_mount_setattr(
                 int dfd,
                 const char *path,

src/core/cgroup.c

@@ -3043,12 +3043,15 @@ int unit_check_oom(Unit *u) {
                 return 0;
 
         r = cg_get_keyed_attribute("memory", u->cgroup_path, "memory.events", STRV_MAKE("oom_kill"), &oom_kill);
-        if (r < 0)
+        if (IN_SET(r, -ENOENT, -ENXIO)) /* Handle gracefully if cgroup or oom_kill attribute don't exist */
+                c = 0;
+        else if (r < 0)
                 return log_unit_debug_errno(u, r, "Failed to read oom_kill field of memory.events cgroup attribute: %m");
-
-        r = safe_atou64(oom_kill, &c);
-        if (r < 0)
-                return log_unit_debug_errno(u, r, "Failed to parse oom_kill field: %m");
+        else {
+                r = safe_atou64(oom_kill, &c);
+                if (r < 0)
+                        return log_unit_debug_errno(u, r, "Failed to parse oom_kill field: %m");
+        }
 
         increased = c > u->oom_kill_last;
         u->oom_kill_last = c;

src/core/core-varlink.c

@@ -562,6 +562,9 @@ static int manager_varlink_init_user(Manager *m) {
         if (m->managed_oom_varlink)
                 return 1;
 
+        if (MANAGER_IS_TEST_RUN(m))
+                return 0;
+
         r = varlink_connect_address(&link, VARLINK_ADDR_PATH_MANAGED_OOM_USER);
         if (r == -ENOENT || ERRNO_IS_DISCONNECT(r)) {
                 log_debug("systemd-oomd varlink unix socket not found, skipping user manager varlink setup");

src/shared/mount-util.c

@@ -134,6 +134,31 @@ int umount_recursive(const char *prefix, int flags) {
         return n;
 }
 
+#define MS_CONVERTIBLE_FLAGS (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_NOSYMFOLLOW)
+
+static uint64_t ms_flags_to_mount_attr(unsigned long a) {
+        uint64_t f = 0;
+
+        if (FLAGS_SET(a, MS_RDONLY))
+                f |= MOUNT_ATTR_RDONLY;
+
+        if (FLAGS_SET(a, MS_NOSUID))
+                f |= MOUNT_ATTR_NOSUID;
+
+        if (FLAGS_SET(a, MS_NODEV))
+                f |= MOUNT_ATTR_NODEV;
+
+        if (FLAGS_SET(a, MS_NOEXEC))
+                f |= MOUNT_ATTR_NOEXEC;
+
+        if (FLAGS_SET(a, MS_NOSYMFOLLOW))
+                f |= MOUNT_ATTR_NOSYMFOLLOW;
+
+        return f;
+}
+
+static bool skip_mount_set_attr = false;
+
 /* Use this function only if you do not have direct access to /proc/self/mountinfo but the caller can open it
  * for you. This is the case when /proc is masked or not mounted. Otherwise, use bind_remount_recursive. */
 int bind_remount_recursive_with_mountinfo(
@@ -143,12 +168,44 @@ int bind_remount_recursive_with_mountinfo(
                 char **deny_list,
                 FILE *proc_self_mountinfo) {
 
+        _cleanup_fclose_ FILE *proc_self_mountinfo_opened = NULL;
         _cleanup_set_free_ Set *done = NULL;
         unsigned n_tries = 0;
         int r;
 
         assert(prefix);
-        assert(proc_self_mountinfo);
+
+        if ((flags_mask & ~MS_CONVERTIBLE_FLAGS) == 0 && strv_isempty(deny_list) && !skip_mount_set_attr) {
+                /* Let's take a shortcut for all the flags we know how to convert into mount_setattr() flags */
+
+                if (mount_setattr(AT_FDCWD, prefix, AT_SYMLINK_NOFOLLOW|AT_RECURSIVE,
+                                  &(struct mount_attr) {
+                                          .attr_set = ms_flags_to_mount_attr(new_flags & flags_mask),
+                                          .attr_clr = ms_flags_to_mount_attr(~new_flags & flags_mask),
+                                  }, MOUNT_ATTR_SIZE_VER0) < 0) {
+
+                        log_debug_errno(errno, "mount_setattr() failed, falling back to classic remounting: %m");
+
+                        /* We fall through to classic behaviour if not supported (i.e. kernel < 5.12). We
+                         * also do this for all other kinds of errors since they are so many different, and
+                         * mount_setattr() has no graceful mode where it continues despite seeing errors one
+                         * some mounts, but we want that. Moreover mount_setattr() only works on the mount
+                         * point inode itself, not a non-mount point inode, and we want to support arbitrary
+                         * prefixes here. */
+
+                        if (ERRNO_IS_NOT_SUPPORTED(errno)) /* if not supported, then don't bother at all anymore */
+                                skip_mount_set_attr = true;
+                } else
+                        return 0; /* Nice, this worked! */
+        }
+
+        if (!proc_self_mountinfo) {
+                r = fopen_unlocked("/proc/self/mountinfo", "re", &proc_self_mountinfo_opened);
+                if (r < 0)
+                        return r;
+
+                proc_self_mountinfo = proc_self_mountinfo_opened;
+        }
 
         /* Recursively remount a directory (and all its submounts) with desired flags (MS_READONLY,
          * MS_NOSUID, MS_NOEXEC). If the directory is already mounted, we reuse the mount and simply mark it
@@ -343,22 +400,6 @@ int bind_remount_recursive_with_mountinfo(
         }
 }
 
-int bind_remount_recursive(
-                const char *prefix,
-                unsigned long new_flags,
-                unsigned long flags_mask,
-                char **deny_list) {
-
-        _cleanup_fclose_ FILE *proc_self_mountinfo = NULL;
-        int r;
-
-        r = fopen_unlocked("/proc/self/mountinfo", "re", &proc_self_mountinfo);
-        if (r < 0)
-                return r;
-
-        return bind_remount_recursive_with_mountinfo(prefix, new_flags, flags_mask, deny_list, proc_self_mountinfo);
-}
-
 int bind_remount_one_with_mountinfo(
                 const char *path,
                 unsigned long new_flags,
@@ -374,6 +415,23 @@ int bind_remount_one_with_mountinfo(
         assert(path);
         assert(proc_self_mountinfo);
 
+        if ((flags_mask & ~MS_CONVERTIBLE_FLAGS) == 0 && !skip_mount_set_attr) {
+                /* Let's take a shortcut for all the flags we know how to convert into mount_setattr() flags */
+
+                if (mount_setattr(AT_FDCWD, path, AT_SYMLINK_NOFOLLOW,
+                                  &(struct mount_attr) {
+                                          .attr_set = ms_flags_to_mount_attr(new_flags & flags_mask),
+                                          .attr_clr = ms_flags_to_mount_attr(~new_flags & flags_mask),
+                                  }, MOUNT_ATTR_SIZE_VER0) < 0) {
+
+                        log_debug_errno(errno, "mount_setattr() didn't work, falling back to classic remounting: %m");
+
+                        if (ERRNO_IS_NOT_SUPPORTED(errno)) /* if not supported, then don't bother at all anymore */
+                                skip_mount_set_attr = true;
+                } else
+                        return 0; /* Nice, this worked! */
+        }
+
         rewind(proc_self_mountinfo);
 
         table = mnt_new_table();

src/shared/mount-util.h

@@ -40,8 +40,12 @@ int mount_nofollow(const char *source, const char *target, const char *filesyste
 
 int repeat_unmount(const char *path, int flags);
 int umount_recursive(const char *target, int flags);
-int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list);
+
 int bind_remount_recursive_with_mountinfo(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list, FILE *proc_self_mountinfo);
+static inline int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **deny_list) {
+        return bind_remount_recursive_with_mountinfo(prefix, new_flags, flags_mask, deny_list, NULL);
+}
+
 int bind_remount_one_with_mountinfo(const char *path, unsigned long new_flags, unsigned long flags_mask, FILE *proc_self_mountinfo);
 
 int mount_move_root(const char *path);

src/test/test-mount-util.c

@@ -169,7 +169,7 @@ static void test_bind_remount_recursive(void) {
                         assert_se(!FLAGS_SET(svfs.f_flag, ST_RDONLY));
 
                         /* Now mark the path we currently run for read-only */
-                        assert_se(bind_remount_recursive(p, MS_RDONLY, MS_RDONLY, STRV_MAKE("/sys/kernel")) >= 0);
+                        assert_se(bind_remount_recursive(p, MS_RDONLY, MS_RDONLY, path_equal(p, "/sys") ? STRV_MAKE("/sys/kernel") : NULL) >= 0);
 
                         /* Ensure that this worked on the top-level */
                         assert_se(statvfs(p, &svfs) >= 0);
@@ -209,6 +209,7 @@ static void test_bind_remount_one(void) {
                 assert_se(fopen_unlocked("/proc/self/mountinfo", "re", &proc_self_mountinfo) >= 0);
 
                 assert_se(bind_remount_one_with_mountinfo("/run", MS_RDONLY, MS_RDONLY, proc_self_mountinfo) >= 0);
+                assert_se(bind_remount_one_with_mountinfo("/run", MS_NOEXEC, MS_RDONLY|MS_NOEXEC, proc_self_mountinfo) >= 0);
                 assert_se(bind_remount_one_with_mountinfo("/proc/idontexist", MS_RDONLY, MS_RDONLY, proc_self_mountinfo) == -ENOENT);
                 assert_se(bind_remount_one_with_mountinfo("/proc/self", MS_RDONLY, MS_RDONLY, proc_self_mountinfo) == -EINVAL);
                 assert_se(bind_remount_one_with_mountinfo("/", MS_RDONLY, MS_RDONLY, proc_self_mountinfo) >= 0);

src/udev/udev-event.c

@@ -827,6 +827,7 @@ int udev_event_spawn(UdevEvent *event,
 static int rename_netif(UdevEvent *event) {
         sd_device *dev = event->dev;
         const char *oldname;
+        unsigned flags;
         int ifindex, r;
 
         if (!event->name)
@@ -854,6 +855,16 @@ static int rename_netif(UdevEvent *event) {
                 return 0;
         }
 
+        r = rtnl_get_link_info(&event->rtnl, ifindex, NULL, &flags);
+        if (r < 0)
+                return log_device_warning_errno(dev, r, "Failed to get link flags: %m");
+
+        if (FLAGS_SET(flags, IFF_UP)) {
+                log_device_info(dev, "Network interface '%s' is already up, refusing to rename to '%s'.",
+                                oldname, event->name);
+                return 0;
+        }
+
         /* Set ID_RENAMING boolean property here, and drop it in the corresponding move uevent later. */
         r = device_add_property(dev, "ID_RENAMING", "1");
         if (r < 0)

test/TEST-10-ISSUE-2467/test.sh

@@ -7,4 +7,16 @@ TEST_DESCRIPTION="https://github.com/systemd/systemd/issues/2467"
 # shellcheck source=test/test-functions
 . "${TEST_BASE_DIR:?}/test-functions"
 
+test_append_files() {
+    (
+        # Collecting coverage slows this particular test quite a bit, causing
+        # it to fail with the default settings (20 triggers per 2 secs)
+        # to trip over the default limit. Let's help it a bit in such case.
+        if get_bool "$IS_BUILT_WITH_COVERAGE"; then
+            mkdir -p "${initdir:?}/etc/systemd/system/test10.socket.d"
+            printf "[Socket]\nTriggerLimitIntervalSec=10\n" >"${initdir:?}/etc/systemd/system/test10.socket.d/coverage-override.conf"
+        fi
+    )
+}
+
 do_test "$@"

test/test-functions

@@ -1316,8 +1316,19 @@ check_coverage_reports() {
 
     # Create a coverage report that will later be uploaded. Remove info about
     # system libraries/headers, as we don't really care about them.
-    lcov --directory "${root}/${BUILD_DIR:?}" --capture --output-file "${dest}"
-    lcov --remove "${dest}" -o "${dest}" '/usr/include/*' '/usr/lib/*'
+    if [[ -f "$dest" ]]; then
+        # If the destination report file already exists, don't overwrite it, but
+        # dump the new report in a temporary file and then merge it with the already
+        # present one - this usually happens when running both "parts" of a test
+        # in one run (the qemu and the nspawn part).
+        lcov --directory "${root}/${BUILD_DIR:?}" --capture --output-file "${dest}.new"
+        lcov --remove "${dest}.new" -o "${dest}.new" '/usr/include/*' '/usr/lib/*'
+        lcov --add-tracefile "${dest}" --add-tracefile "${dest}.new" -o "${dest}"
+        rm -f "${dest}.new"
+    else
+        lcov --directory "${root}/${BUILD_DIR:?}" --capture --output-file "${dest}"
+        lcov --remove "${dest}" -o "${dest}" '/usr/include/*' '/usr/lib/*'
+    fi
 
     return 0
 }