diff --git a/NEWS b/NEWS
index 238ea4a032..3383357c41 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,15 @@ systemd System and Service Manager
CHANGES WITH 243 in spe:
+ * This release enables unprivileged programs (i.e. requiring neither
+ setuid nor file capabilities) to send ICMP Echo (i.e. ping) requests
+ by turning on the net.ipv4.ping_group_range sysctl of the Linux
+ kernel for the whole UNIX group range, i.e. all processes. This
+ change should be reasonably safe, as the kernel support for it was
+ specifically implemented to allow safe access to ICMP Echo for
+ processes lacking any privileges. If this is not desirable, it can be
+ disabled again by setting the parameter to "1 0".
+
* Previously, filters defined with SystemCallFilter= would have the
effect that an calling an offending system call would terminate the
calling thread. This behaviour never made much sense, since killing
@@ -345,6 +354,9 @@ CHANGES WITH 243 in spe:
* "localectl list-locales" won't list non-UTF-8 locales anymore. It's
2019. (You can set non-UTF-8 locales though, if you know there name.)
+ * If variable assignments in sysctl.d/ files are prefixed with "-" any
+ failures to apply them are now ignored.
+
Contributions from: Aaron Barany, Adrian Bunk, Alan Jenkins, Andrej
Valek, Anita Zhang, Arian van Putten, Balint Reczey, Bastien Nocera,
Ben Boeckel, Benjamin Robin, camoz, Chen Qi, Chris Chiu, Chris Down,
diff --git a/man/sysctl.d.xml b/man/sysctl.d.xml
index 0a8eeb62a4..21ef6de97c 100644
--- a/man/sysctl.d.xml
+++ b/man/sysctl.d.xml
@@ -59,6 +59,10 @@
/proc/sys/net/ipv4/conf/enp3s0.200/forwarding.
+ If a variable assignment is prefixed with a single - character, any attempts to
+ set it that fail will be ignored (though are logged). Moreover, any access permission errors, and
+ attempts to write variables not defined on the local system are ignored (and logged) too.
+
The settings configured with sysctl.d
files will be applied early on boot. The network
interface-specific options will also be applied individually for
diff --git a/src/sysctl/sysctl.c b/src/sysctl/sysctl.c
index 9838701a3d..c67782ea8f 100644
--- a/src/sysctl/sysctl.c
+++ b/src/sysctl/sysctl.c
@@ -30,25 +30,71 @@ static PagerFlags arg_pager_flags = 0;
STATIC_DESTRUCTOR_REGISTER(arg_prefixes, strv_freep);
+typedef struct Option {
+ char *key;
+ char *value;
+ bool ignore_failure;
+} Option;
+
+static Option *option_free(Option *o) {
+ if (!o)
+ return NULL;
+
+ free(o->key);
+ free(o->value);
+
+ return mfree(o);
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(Option*, option_free);
+DEFINE_HASH_OPS_WITH_VALUE_DESTRUCTOR(option_hash_ops, char, string_hash_func, string_compare_func, Option, option_free);
+
+static Option *option_new(
+ const char *key,
+ const char *value,
+ bool ignore_failure) {
+
+ _cleanup_(option_freep) Option *o = NULL;
+
+ assert(key);
+ assert(value);
+
+ o = new(Option, 1);
+ if (!o)
+ return NULL;
+
+ *o = (Option) {
+ .key = strdup(key),
+ .value = strdup(value),
+ .ignore_failure = ignore_failure,
+ };
+
+ if (!o->key || !o->value)
+ return NULL;
+
+ return TAKE_PTR(o);
+}
+
static int apply_all(OrderedHashmap *sysctl_options) {
- char *property, *value;
+ Option *option;
Iterator i;
int r = 0;
- ORDERED_HASHMAP_FOREACH_KEY(value, property, sysctl_options, i) {
+ ORDERED_HASHMAP_FOREACH(option, sysctl_options, i) {
int k;
- k = sysctl_write(property, value);
+ k = sysctl_write(option->key, option->value);
if (k < 0) {
- /* If the sysctl is not available in the kernel or we are running with reduced privileges and
- * cannot write it, then log about the issue at LOG_NOTICE level, and proceed without
- * failing. (EROFS is treated as a permission problem here, since that's how container managers
- * usually protected their sysctls.) In all other cases log an error and make the tool fail. */
+ /* If the sysctl is not available in the kernel or we are running with reduced
+ * privileges and cannot write it, then log about the issue at LOG_NOTICE level, and
+ * proceed without failing. (EROFS is treated as a permission problem here, since
+ * that's how container managers usually protected their sysctls.) In all other cases
+ * log an error and make the tool fail. */
- if (IN_SET(k, -EPERM, -EACCES, -EROFS, -ENOENT))
- log_notice_errno(k, "Couldn't write '%s' to '%s', ignoring: %m", value, property);
+ if (IN_SET(k, -EPERM, -EACCES, -EROFS, -ENOENT) || option->ignore_failure)
+ log_notice_errno(k, "Couldn't write '%s' to '%s', ignoring: %m", option->value, option->key);
else {
- log_error_errno(k, "Couldn't write '%s' to '%s': %m", value, property);
+ log_error_errno(k, "Couldn't write '%s' to '%s': %m", option->value, option->key);
if (r == 0)
r = k;
}
@@ -94,9 +140,11 @@ static int parse_file(OrderedHashmap *sysctl_options, const char *path, bool ign
log_debug("Parsing %s", path);
for (;;) {
- char *p, *value, *new_value, *property, *existing;
+ _cleanup_(option_freep) Option *new_option = NULL;
_cleanup_free_ char *l = NULL;
- void *v;
+ bool ignore_failure;
+ Option *existing;
+ char *p, *value;
int k;
k = read_line(f, LONG_LINE_MAX, &l);
@@ -116,8 +164,7 @@ static int parse_file(OrderedHashmap *sysctl_options, const char *path, bool ign
value = strchr(p, '=');
if (!value) {
- log_error("Line is not an assignment at '%s:%u': %s", path, c, p);
-
+ log_syntax(NULL, LOG_WARNING, path, c, 0, "Line is not an assignment, ignoring: %s", p);
if (r == 0)
r = -EINVAL;
continue;
@@ -126,39 +173,37 @@ static int parse_file(OrderedHashmap *sysctl_options, const char *path, bool ign
*value = 0;
value++;
- p = sysctl_normalize(strstrip(p));
+ p = strstrip(p);
+ ignore_failure = p[0] == '-';
+ if (ignore_failure)
+ p++;
+
+ p = sysctl_normalize(p);
value = strstrip(value);
if (!test_prefix(p))
continue;
- existing = ordered_hashmap_get2(sysctl_options, p, &v);
+ existing = ordered_hashmap_get(sysctl_options, p);
if (existing) {
- if (streq(value, existing))
+ if (streq(value, existing->value)) {
+ existing->ignore_failure = existing->ignore_failure || ignore_failure;
continue;
+ }
log_debug("Overwriting earlier assignment of %s at '%s:%u'.", p, path, c);
- free(ordered_hashmap_remove(sysctl_options, p));
- free(v);
+ option_free(ordered_hashmap_remove(sysctl_options, p));
}
- property = strdup(p);
- if (!property)
+ new_option = option_new(p, value, ignore_failure);
+ if (!new_option)
return log_oom();
- new_value = strdup(value);
- if (!new_value) {
- free(property);
- return log_oom();
- }
+ k = ordered_hashmap_put(sysctl_options, new_option->key, new_option);
+ if (k < 0)
+ return log_error_errno(k, "Failed to add sysctl variable %s to hashmap: %m", p);
- k = ordered_hashmap_put(sysctl_options, property, new_value);
- if (k < 0) {
- log_error_errno(k, "Failed to add sysctl variable %s to hashmap: %m", property);
- free(property);
- free(new_value);
- return k;
- }
+ TAKE_PTR(new_option);
}
return r;
@@ -265,7 +310,7 @@ static int parse_argv(int argc, char *argv[]) {
}
static int run(int argc, char *argv[]) {
- _cleanup_(ordered_hashmap_free_free_freep) OrderedHashmap *sysctl_options = NULL;
+ _cleanup_(ordered_hashmap_freep) OrderedHashmap *sysctl_options = NULL;
int r, k;
r = parse_argv(argc, argv);
@@ -276,15 +321,15 @@ static int run(int argc, char *argv[]) {
umask(0022);
- sysctl_options = ordered_hashmap_new(&path_hash_ops);
+ sysctl_options = ordered_hashmap_new(&option_hash_ops);
if (!sysctl_options)
return log_oom();
- r = 0;
-
if (argc > optind) {
int i;
+ r = 0;
+
for (i = optind; i < argc; i++) {
k = parse_file(sysctl_options, argv[i], false);
if (k < 0 && r == 0)
diff --git a/sysctl.d/50-default.conf b/sysctl.d/50-default.conf
index 27084f6242..41bd1f9183 100644
--- a/sysctl.d/50-default.conf
+++ b/sysctl.d/50-default.conf
@@ -30,6 +30,14 @@ net.ipv4.conf.all.accept_source_route = 0
# Promote secondary addresses when the primary address is removed
net.ipv4.conf.all.promote_secondaries = 1
+# ping(8) without CAP_NET_ADMIN and CAP_NET_RAW
+# The upper limit is set to 2^31-1. Values greater than that get rejected by
+# the kernel because of this definition in linux/include/net/ping.h:
+# #define GID_T_MAX (((gid_t)~0U) >> 1)
+# That's not so bad because values between 2^31 and 2^32-1 are reserved on
+# systemd-based systems anyway: https://systemd.io/UIDS-GIDS.html#summary
+-net.ipv4.ping_group_range = 0 2147483647
+
# Fair Queue CoDel packet scheduler to fight bufferbloat
net.core.default_qdisc = fq_codel