extend sysctl functions to shadow values

Pass to all the sysctl_* functions a hashmap which can be used to
optionally save the value written in the sysctl.

6 files changed, 76 insertions, 38 deletions

diff --git a/src/basic/sysctl-util.c b/src/basic/sysctl-util.c
index b284c9ccd2..dfb99e1896 100644
--- a/src/basic/sysctl-util.c
+++ b/src/basic/sysctl-util.c
@@ -44,8 +44,39 @@ char* sysctl_normalize(char *s) {
         return s;
 }
 
-int sysctl_write(const char *property, const char *value) {
+static int shadow_update(Hashmap **shadow, const char *property, const char *value) {
+        _cleanup_free_ char *k = NULL, *v = NULL, *cur_k = NULL, *cur_v = NULL;
+        int r;
+
+        assert(property);
+        assert(value);
+
+        if (!shadow)
+                return 0;
+
+        k = strdup(property);
+        if (!k)
+                return -ENOMEM;
+
+        v = strdup(value);
+        if (!v)
+                return -ENOMEM;
+
+        cur_v = hashmap_remove2(*shadow, k, (void**)&cur_k);
+
+        r = hashmap_ensure_put(shadow, &path_hash_ops_free_free, k, v);
+        if (r < 0)
+                return r;
+
+        TAKE_PTR(k);
+        TAKE_PTR(v);
+
+        return 0;
+}
+
+int sysctl_write_full(const char *property, const char *value, Hashmap **shadow) {
         char *p;
+        int r;
 
         assert(property);
         assert(value);
@@ -58,6 +89,10 @@ int sysctl_write(const char *property, const char *value) {
 
         log_debug("Setting '%s' to '%s'", p, value);
 
+        r = shadow_update(shadow, p, value);
+        if (r < 0)
+                return r;
+
         return write_string_file(p, value, WRITE_STRING_FILE_VERIFY_ON_FAILURE | WRITE_STRING_FILE_DISABLE_BUFFER | WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL);
 }
 
@@ -76,7 +111,7 @@ int sysctl_writef(const char *property, const char *format, ...) {
         return sysctl_write(property, v);
 }
 
-int sysctl_write_ip_property(int af, const char *ifname, const char *property, const char *value) {
+int sysctl_write_ip_property(int af, const char *ifname, const char *property, const char *value, Hashmap **shadow) {
         const char *p;
 
         assert(property);
@@ -93,10 +128,10 @@ int sysctl_write_ip_property(int af, const char *ifname, const char *property, c
         } else
                 p = strjoina("net/", af_to_ipv4_ipv6(af), "/", property);
 
-        return sysctl_write(p, value);
+        return sysctl_write_full(p, value, shadow);
 }
 
-int sysctl_write_ip_neighbor_property(int af, const char *ifname, const char *property, const char *value) {
+int sysctl_write_ip_neighbor_property(int af, const char *ifname, const char *property, const char *value, Hashmap **shadow) {
         const char *p;
 
         assert(property);
@@ -113,7 +148,7 @@ int sysctl_write_ip_neighbor_property(int af, const char *ifname, const char *pr
         } else
                 p = strjoina("net/", af_to_ipv4_ipv6(af), "/neigh/default/", property);
 
-        return sysctl_write(p, value);
+        return sysctl_write_full(p, value, shadow);
 }
 
 int sysctl_read(const char *property, char **ret) {
diff --git a/src/basic/sysctl-util.h b/src/basic/sysctl-util.h
index 2bf5491703..041292f693 100644
--- a/src/basic/sysctl-util.h
+++ b/src/basic/sysctl-util.h
@@ -10,27 +10,30 @@
 
 char* sysctl_normalize(char *s);
 int sysctl_read(const char *property, char **value);
-int sysctl_write(const char *property, const char *value);
+int sysctl_write_full(const char *property, const char *value, Hashmap **shadow);
 int sysctl_writef(const char *property, const char *format, ...) _printf_(2, 3);
+static inline int sysctl_write(const char *property, const char *value) {
+        return sysctl_write_full(property, value, NULL);
+}
 
 int sysctl_read_ip_property(int af, const char *ifname, const char *property, char **ret);
-int sysctl_write_ip_property(int af, const char *ifname, const char *property, const char *value);
-static inline int sysctl_write_ip_property_boolean(int af, const char *ifname, const char *property, bool value) {
-        return sysctl_write_ip_property(af, ifname, property, one_zero(value));
+int sysctl_write_ip_property(int af, const char *ifname, const char *property, const char *value, Hashmap **shadow);
+static inline int sysctl_write_ip_property_boolean(int af, const char *ifname, const char *property, bool value, Hashmap **shadow) {
+        return sysctl_write_ip_property(af, ifname, property, one_zero(value), shadow);
 }
 
-int sysctl_write_ip_neighbor_property(int af, const char *ifname, const char *property, const char *value);
-static inline int sysctl_write_ip_neighbor_property_uint32(int af, const char *ifname, const char *property, uint32_t value) {
+int sysctl_write_ip_neighbor_property(int af, const char *ifname, const char *property, const char *value, Hashmap **shadow);
+static inline int sysctl_write_ip_neighbor_property_uint32(int af, const char *ifname, const char *property, uint32_t value, Hashmap **shadow) {
         char buf[DECIMAL_STR_MAX(uint32_t)];
         xsprintf(buf, "%u", value);
-        return sysctl_write_ip_neighbor_property(af, ifname, property, buf);
+        return sysctl_write_ip_neighbor_property(af, ifname, property, buf, shadow);
 }
 
 #define DEFINE_SYSCTL_WRITE_IP_PROPERTY(name, type, format)           \
-        static inline int sysctl_write_ip_property_##name(int af, const char *ifname, const char *property, type value) { \
+        static inline int sysctl_write_ip_property_##name(int af, const char *ifname, const char *property, type value, Hashmap **shadow) { \
                 char buf[DECIMAL_STR_MAX(type)];                        \
                 xsprintf(buf, format, value);                           \
-                return sysctl_write_ip_property(af, ifname, property, buf); \
+                return sysctl_write_ip_property(af, ifname, property, buf, shadow); \
         }
 
 DEFINE_SYSCTL_WRITE_IP_PROPERTY(int, int, "%i");
diff --git a/src/network/networkd-ipv6ll.c b/src/network/networkd-ipv6ll.c
index cd23cc94aa..66705e6a79 100644
--- a/src/network/networkd-ipv6ll.c
+++ b/src/network/networkd-ipv6ll.c
@@ -219,7 +219,7 @@ int link_set_ipv6ll_stable_secret(Link *link) {
         }
 
         return sysctl_write_ip_property(AF_INET6, link->ifname, "stable_secret",
-                                        IN6_ADDR_TO_STRING(&a));
+                                        IN6_ADDR_TO_STRING(&a), NULL);
 }
 
 int link_set_ipv6ll_addrgen_mode(Link *link, IPv6LinkLocalAddressGenMode mode) {
@@ -229,7 +229,7 @@ int link_set_ipv6ll_addrgen_mode(Link *link, IPv6LinkLocalAddressGenMode mode) {
         if (mode == link->ipv6ll_address_gen_mode)
                 return 0;
 
-        return sysctl_write_ip_property_uint32(AF_INET6, link->ifname, "addr_gen_mode", mode);
+        return sysctl_write_ip_property_uint32(AF_INET6, link->ifname, "addr_gen_mode", mode, NULL);
 }
 
 static const char* const ipv6_link_local_address_gen_mode_table[_IPV6_LINK_LOCAL_ADDRESS_GEN_MODE_MAX] = {
diff --git a/src/network/networkd-ndisc.c b/src/network/networkd-ndisc.c
index f44f03365c..253ca585aa 100644
--- a/src/network/networkd-ndisc.c
+++ b/src/network/networkd-ndisc.c
@@ -986,7 +986,7 @@ static int ndisc_router_process_reachable_time(Link *link, sd_ndisc_router *rt)
         }
 
         /* Set the reachable time for Neighbor Solicitations. */
-        r = sysctl_write_ip_neighbor_property_uint32(AF_INET6, link->ifname, "base_reachable_time_ms", (uint32_t) msec);
+        r = sysctl_write_ip_neighbor_property_uint32(AF_INET6, link->ifname, "base_reachable_time_ms", (uint32_t) msec, NULL);
         if (r < 0)
                 log_link_warning_errno(link, r, "Failed to apply neighbor reachable time (%"PRIu64"), ignoring: %m", msec);
 
@@ -1019,7 +1019,7 @@ static int ndisc_router_process_retransmission_time(Link *link, sd_ndisc_router
         }
 
         /* Set the retransmission time for Neighbor Solicitations. */
-        r = sysctl_write_ip_neighbor_property_uint32(AF_INET6, link->ifname, "retrans_time_ms", (uint32_t) msec);
+        r = sysctl_write_ip_neighbor_property_uint32(AF_INET6, link->ifname, "retrans_time_ms", (uint32_t) msec, NULL);
         if (r < 0)
                 log_link_warning_errno(link, r, "Failed to apply neighbor retransmission time (%"PRIu64"), ignoring: %m", msec);
 
@@ -1054,7 +1054,7 @@ static int ndisc_router_process_hop_limit(Link *link, sd_ndisc_router *rt) {
         if (hop_limit <= 0)
                 return 0;
 
-        r = sysctl_write_ip_property_uint32(AF_INET6, link->ifname, "hop_limit", (uint32_t) hop_limit);
+        r = sysctl_write_ip_property_uint32(AF_INET6, link->ifname, "hop_limit", (uint32_t) hop_limit, NULL);
         if (r < 0)
                 log_link_warning_errno(link, r, "Failed to apply hop_limit (%u), ignoring: %m", hop_limit);
 
diff --git a/src/network/networkd-sysctl.c b/src/network/networkd-sysctl.c
index 2027a29f27..23c2878359 100644
--- a/src/network/networkd-sysctl.c
+++ b/src/network/networkd-sysctl.c
@@ -30,13 +30,13 @@ static void manager_set_ip_forwarding(Manager *manager, int family) {
                 return; /* keep */
 
         /* First, set the default value. */
-        r = sysctl_write_ip_property_boolean(family, "default", "forwarding", t);
+        r = sysctl_write_ip_property_boolean(family, "default", "forwarding", t, NULL);
         if (r < 0)
                 log_warning_errno(r, "Failed to %s the default %s forwarding: %m",
                                   enable_disable(t), af_to_ipv4_ipv6(family));
 
         /* Then, set the value to all interfaces. */
-        r = sysctl_write_ip_property_boolean(family, "all", "forwarding", t);
+        r = sysctl_write_ip_property_boolean(family, "all", "forwarding", t, NULL);
         if (r < 0)
                 log_warning_errno(r, "Failed to %s %s forwarding for all interfaces: %m",
                                   enable_disable(t), af_to_ipv4_ipv6(family));
@@ -80,7 +80,7 @@ static int link_update_ipv6_sysctl(Link *link) {
         if (!link_ipv6_enabled(link))
                 return 0;
 
-        return sysctl_write_ip_property_boolean(AF_INET6, link->ifname, "disable_ipv6", false);
+        return sysctl_write_ip_property_boolean(AF_INET6, link->ifname, "disable_ipv6", false, NULL);
 }
 
 static int link_set_proxy_arp(Link *link) {
@@ -92,7 +92,7 @@ static int link_set_proxy_arp(Link *link) {
         if (link->network->proxy_arp < 0)
                 return 0;
 
-        return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "proxy_arp", link->network->proxy_arp > 0);
+        return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "proxy_arp", link->network->proxy_arp > 0, NULL);
 }
 
 static int link_set_proxy_arp_pvlan(Link *link) {
@@ -104,7 +104,7 @@ static int link_set_proxy_arp_pvlan(Link *link) {
         if (link->network->proxy_arp_pvlan < 0)
                 return 0;
 
-        return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "proxy_arp_pvlan", link->network->proxy_arp_pvlan > 0);
+        return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "proxy_arp_pvlan", link->network->proxy_arp_pvlan > 0, NULL);
 }
 
 int link_get_ip_forwarding(Link *link, int family) {
@@ -145,7 +145,7 @@ static int link_set_ip_forwarding_impl(Link *link, int family) {
         if (t < 0)
                 return 0; /* keep */
 
-        r = sysctl_write_ip_property_boolean(family, link->ifname, "forwarding", t);
+        r = sysctl_write_ip_property_boolean(family, link->ifname, "forwarding", t, NULL);
         if (r < 0)
                 return log_link_warning_errno(link, r, "Failed to %s %s forwarding, ignoring: %m",
                                               enable_disable(t), af_to_ipv4_ipv6(family));
@@ -221,7 +221,7 @@ static int link_set_ipv4_rp_filter(Link *link) {
         if (link->network->ipv4_rp_filter < 0)
                 return 0;
 
-        return sysctl_write_ip_property_int(AF_INET, link->ifname, "rp_filter", link->network->ipv4_rp_filter);
+        return sysctl_write_ip_property_int(AF_INET, link->ifname, "rp_filter", link->network->ipv4_rp_filter, NULL);
 }
 
 static int link_set_ipv6_privacy_extensions(Link *link) {
@@ -241,7 +241,7 @@ static int link_set_ipv6_privacy_extensions(Link *link) {
         if (val == IPV6_PRIVACY_EXTENSIONS_KERNEL)
                 return 0;
 
-        return sysctl_write_ip_property_int(AF_INET6, link->ifname, "use_tempaddr", (int) val);
+        return sysctl_write_ip_property_int(AF_INET6, link->ifname, "use_tempaddr", (int) val, NULL);
 }
 
 static int link_set_ipv6_accept_ra(Link *link) {
@@ -250,7 +250,7 @@ static int link_set_ipv6_accept_ra(Link *link) {
         if (!link_is_configured_for_family(link, AF_INET6))
                 return 0;
 
-        return sysctl_write_ip_property(AF_INET6, link->ifname, "accept_ra", "0");
+        return sysctl_write_ip_property(AF_INET6, link->ifname, "accept_ra", "0", NULL);
 }
 
 static int link_set_ipv6_dad_transmits(Link *link) {
@@ -262,7 +262,7 @@ static int link_set_ipv6_dad_transmits(Link *link) {
         if (link->network->ipv6_dad_transmits < 0)
                 return 0;
 
-        return sysctl_write_ip_property_int(AF_INET6, link->ifname, "dad_transmits", link->network->ipv6_dad_transmits);
+        return sysctl_write_ip_property_int(AF_INET6, link->ifname, "dad_transmits", link->network->ipv6_dad_transmits, NULL);
 }
 
 static int link_set_ipv6_hop_limit(Link *link) {
@@ -274,7 +274,7 @@ static int link_set_ipv6_hop_limit(Link *link) {
         if (link->network->ipv6_hop_limit <= 0)
                 return 0;
 
-        return sysctl_write_ip_property_int(AF_INET6, link->ifname, "hop_limit", link->network->ipv6_hop_limit);
+        return sysctl_write_ip_property_int(AF_INET6, link->ifname, "hop_limit", link->network->ipv6_hop_limit, NULL);
 }
 
 static int link_set_ipv6_retransmission_time(Link *link) {
@@ -292,7 +292,7 @@ static int link_set_ipv6_retransmission_time(Link *link) {
          if (retrans_time_ms <= 0 || retrans_time_ms > UINT32_MAX)
                 return 0;
 
-        return sysctl_write_ip_neighbor_property_uint32(AF_INET6, link->ifname, "retrans_time_ms", retrans_time_ms);
+        return sysctl_write_ip_neighbor_property_uint32(AF_INET6, link->ifname, "retrans_time_ms", retrans_time_ms, NULL);
 }
 
 static int link_set_ipv6_proxy_ndp(Link *link) {
@@ -308,7 +308,7 @@ static int link_set_ipv6_proxy_ndp(Link *link) {
         else
                 v = !set_isempty(link->network->ipv6_proxy_ndp_addresses);
 
-        return sysctl_write_ip_property_boolean(AF_INET6, link->ifname, "proxy_ndp", v);
+        return sysctl_write_ip_property_boolean(AF_INET6, link->ifname, "proxy_ndp", v, NULL);
 }
 
 int link_set_ipv6_mtu(Link *link, int log_level) {
@@ -335,7 +335,7 @@ int link_set_ipv6_mtu(Link *link, int log_level) {
                 mtu = link->mtu;
         }
 
-        return sysctl_write_ip_property_uint32(AF_INET6, link->ifname, "mtu", mtu);
+        return sysctl_write_ip_property_uint32(AF_INET6, link->ifname, "mtu", mtu, NULL);
 }
 
 static int link_set_ipv4_accept_local(Link *link) {
@@ -347,7 +347,7 @@ static int link_set_ipv4_accept_local(Link *link) {
         if (link->network->ipv4_accept_local < 0)
                 return 0;
 
-        return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "accept_local", link->network->ipv4_accept_local > 0);
+        return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "accept_local", link->network->ipv4_accept_local > 0, NULL);
 }
 
 static int link_set_ipv4_route_localnet(Link *link) {
@@ -359,7 +359,7 @@ static int link_set_ipv4_route_localnet(Link *link) {
         if (link->network->ipv4_route_localnet < 0)
                 return 0;
 
-        return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "route_localnet", link->network->ipv4_route_localnet > 0);
+        return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "route_localnet", link->network->ipv4_route_localnet > 0, NULL);
 }
 
 static int link_set_ipv4_promote_secondaries(Link *link) {
@@ -373,7 +373,7 @@ static int link_set_ipv4_promote_secondaries(Link *link) {
          * otherwise. The way systemd-networkd works is that the new IP of a lease is added as a
          * secondary IP and when the primary one expires it relies on the kernel to promote the
          * secondary IP. See also https://github.com/systemd/systemd/issues/7163 */
-        return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "promote_secondaries", true);
+        return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "promote_secondaries", true, NULL);
 }
 
 int link_set_sysctl(Link *link) {
diff --git a/src/test/test-sysctl-util.c b/src/test/test-sysctl-util.c
index e94099605c..83d6c9036c 100644
--- a/src/test/test-sysctl-util.c
+++ b/src/test/test-sysctl-util.c
@@ -53,14 +53,14 @@ TEST(sysctl_read) {
         assert_se(sysctl_read_ip_property(AF_INET, "lo", "forwarding", &s));
         assert_se(STR_IN_SET(s, "0", "1"));
 
-        r = sysctl_write_ip_property(AF_INET, "lo", "forwarding", s);
+        r = sysctl_write_ip_property(AF_INET, "lo", "forwarding", s, NULL);
         assert_se(r >= 0 || ERRNO_IS_PRIVILEGE(r) || r == -EROFS);
         s = mfree(s);
 
         assert_se(sysctl_read_ip_property(AF_INET, NULL, "ip_forward", &s));
         assert_se(STR_IN_SET(s, "0", "1"));
 
-        r = sysctl_write_ip_property(AF_INET, NULL, "ip_forward", s);
+        r = sysctl_write_ip_property(AF_INET, NULL, "ip_forward", s, NULL);
         assert_se(r >= 0 || ERRNO_IS_PRIVILEGE(r) || r == -EROFS);
         s = mfree(s);