Merge pull request #15804 from poettering/hostnamed-instant-part1

four likely safe commits split out of #15624

man/sd_bus_add_object.xml

@@ -544,6 +544,25 @@
           This corresponds to the <constant>org.freedesktop.systemd1.Explicit</constant> annotation
           in introspection data.</para></listitem>
         </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_VTABLE_SENSITIVE</constant></term>
+
+          <listitem><para>Mark this vtable method entry as processing sensitive data. When set,
+          incoming method call messages and their outgoing reply messages are marked as sensitive using
+          <citerefentry><refentrytitle>sd_bus_message_sensitive</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+          so that they are erased from memory when freed.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>SD_BUS_VTABLE_ABSOLUTE_OFFSET</constant></term>
+
+          <listitem><para>Mark this vtable method or property entry so that the user data pointer passed to
+          its associated handler functions is determined slightly differently: instead of adding the offset
+          parameter of the entry to the user data pointer specified during vtable registration, the offset is
+          passed directly, converted to a pointer, without taking the user data pointer specified during
+          vtable registration into account.</para></listitem>
+        </varlistentry>
       </variablelist>
     </refsect2>
   </refsect1>

src/basic/stat-util.c

@@ -388,3 +388,24 @@ int proc_mounted(void) {
 
         return r;
 }
+
+bool stat_inode_unmodified(const struct stat *a, const struct stat *b) {
+
+        /* Returns if the specified stat structures reference the same, unmodified inode. This check tries to
+         * be reasonably careful when detecting changes: we check both inode and mtime, to cater for file
+         * systems where mtimes are fixed to 0 (think: ostree/nixos type installations). We also check file
+         * size, backing device, inode type and if this refers to a device not the major/minor.
+         *
+         * Note that we don't care if file attributes such as ownership or access mode change, this here is
+         * about contents of the file. The purpose here is to detect file contents changes, and nothing
+         * else. */
+
+        return a && b &&
+                (a->st_mode & S_IFMT) != 0 && /* We use the check for .st_mode if the structure was ever initialized */
+                ((a->st_mode ^ b->st_mode) & S_IFMT) == 0 &&  /* same inode type */
+                a->st_mtime == b->st_mtime &&
+                (!S_ISREG(a->st_mode) || a->st_size == b->st_size) && /* if regular file, compare file size */
+                a->st_dev == b->st_dev &&
+                a->st_ino == b->st_ino &&
+                (!(S_ISCHR(a->st_mode) || S_ISBLK(a->st_mode)) || a->st_rdev == b->st_rdev); /* if device node, also compare major/minor, because we can */
+}

src/basic/stat-util.h

@@ -89,3 +89,5 @@ int device_path_make_canonical(mode_t mode, dev_t devno, char **ret);
 int device_path_parse_major_minor(const char *path, mode_t *ret_mode, dev_t *ret_devno);
 
 int proc_mounted(void);
+
+bool stat_inode_unmodified(const struct stat *a, const struct stat *b);

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

@@ -56,7 +56,7 @@ static int node_vtable_get_userdata(
 static void *vtable_method_convert_userdata(const sd_bus_vtable *p, void *u) {
         assert(p);
 
-        if (!u)
+        if (!u || FLAGS_SET(p->flags, SD_BUS_VTABLE_ABSOLUTE_OFFSET))
                 return SIZE_TO_PTR(p->x.method.offset); /* don't add offset on NULL, to make ubsan happy */
 
         return (uint8_t*) u + p->x.method.offset;
@@ -65,7 +65,7 @@ static void *vtable_method_convert_userdata(const sd_bus_vtable *p, void *u) {
 static void *vtable_property_convert_userdata(const sd_bus_vtable *p, void *u) {
         assert(p);
 
-        if (!u)
+        if (!u || FLAGS_SET(p->flags, SD_BUS_VTABLE_ABSOLUTE_OFFSET))
                 return SIZE_TO_PTR(p->x.property.offset); /* as above */
 
         return (uint8_t*) u + p->x.property.offset;

src/resolve/resolved-manager.h

@@ -1,6 +1,8 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 #pragma once
 
+#include <sys/stat.h>
+
 #include "sd-event.h"
 #include "sd-netlink.h"
 #include "sd-network.h"
@@ -71,7 +73,7 @@ struct Manager {
         bool need_builtin_fallbacks:1;
 
         bool read_resolv_conf:1;
-        usec_t resolv_conf_mtime;
+        struct stat resolv_conf_stat;
 
         DnsTrustAnchor trust_anchor;
 

src/resolve/resolved-resolv-conf.c

@@ -14,6 +14,7 @@
 #include "resolved-conf.h"
 #include "resolved-dns-server.h"
 #include "resolved-resolv-conf.h"
+#include "stat-util.h"
 #include "string-util.h"
 #include "strv.h"
 #include "tmpfile-util-label.h"
@@ -93,7 +94,7 @@ int manager_read_resolv_conf(Manager *m) {
         }
 
         /* Have we already seen the file? */
-        if (timespec_load(&st.st_mtim) == m->resolv_conf_mtime)
+        if (stat_inode_unmodified(&st, &m->resolv_conf_stat))
                 return 0;
 
         if (file_is_our_own(&st))
@@ -159,7 +160,7 @@ int manager_read_resolv_conf(Manager *m) {
                 log_syntax(NULL, LOG_DEBUG, "/etc/resolv.conf", n, 0, "Ignoring resolv.conf line: %s", l);
         }
 
-        m->resolv_conf_mtime = timespec_load(&st.st_mtim);
+        m->resolv_conf_stat = st;
 
         /* Flush out all servers and search domains that are still
          * marked. Those are then ones that didn't appear in the new

src/systemd/sd-bus-vtable.h

@@ -44,6 +44,7 @@ enum {
         SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION  = 1ULL << 6,
         SD_BUS_VTABLE_PROPERTY_EXPLICIT            = 1ULL << 7,
         SD_BUS_VTABLE_SENSITIVE                    = 1ULL << 8, /* covers both directions: method call + reply */
+        SD_BUS_VTABLE_ABSOLUTE_OFFSET              = 1ULL << 9,
         _SD_BUS_VTABLE_CAPABILITY_MASK             = 0xFFFFULL << 40
 };