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From 516fc73142e803a7a6cbd126c338e1c3c73d6843 Mon Sep 17 00:00:00 2001
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From: Jan Macku <jamacku@redhat.com>
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Date: Fri, 21 Jan 2022 12:10:45 +0100
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Subject: [PATCH] sysctl: if options are prefixed with "-" ignore write errors
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(cherry picked from commit dec02d6e1993d420a0a94c7fec294605df55e88e)
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Resolves: #2037807
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---
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 src/sysctl/sysctl.c | 115 ++++++++++++++++++++++++++++++--------------
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 1 file changed, 80 insertions(+), 35 deletions(-)
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diff --git a/src/sysctl/sysctl.c b/src/sysctl/sysctl.c
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index 0151f7dabe..7b0528877c 100644
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--- a/src/sysctl/sysctl.c
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+++ b/src/sysctl/sysctl.c
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@@ -26,25 +26,71 @@ static char **arg_prefixes = NULL;
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 static bool arg_cat_config = false;
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 static bool arg_no_pager = false;
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+typedef struct Option {
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+        char *key;
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+        char *value;
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+        bool ignore_failure;
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+} Option;
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+
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+static Option *option_free(Option *o) {
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+        if (!o)
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+                return NULL;
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+
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+        free(o->key);
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+        free(o->value);
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+
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+        return mfree(o);
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+}
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+
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+DEFINE_TRIVIAL_CLEANUP_FUNC(Option*, option_free);
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+DEFINE_HASH_OPS_WITH_VALUE_DESTRUCTOR(option_hash_ops, char, string_hash_func, string_compare_func, Option, option_free);
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+
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+static Option *option_new(
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+                const char *key,
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+                const char *value,
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+                bool ignore_failure) {
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+
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+        _cleanup_(option_freep) Option *o = NULL;
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+
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+        assert(key);
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+        assert(value);
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+
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+        o = new(Option, 1);
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+        if (!o)
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+                return NULL;
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+
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+        *o = (Option) {
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+                .key = strdup(key),
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+                .value = strdup(value),
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+                .ignore_failure = ignore_failure,
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+        };
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+
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+        if (!o->key || !o->value)
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+                return NULL;
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+
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+        return TAKE_PTR(o);
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+}
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+
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 static int apply_all(OrderedHashmap *sysctl_options) {
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-        char *property, *value;
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+        Option *option;
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         Iterator i;
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         int r = 0;
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-        ORDERED_HASHMAP_FOREACH_KEY(value, property, sysctl_options, i) {
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+        ORDERED_HASHMAP_FOREACH(option, sysctl_options, i) {
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                 int k;
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-                k = sysctl_write(property, value);
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+                k = sysctl_write(option->key, option->value);
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                 if (k < 0) {
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-                        /* If the sysctl is not available in the kernel or we are running with reduced privileges and
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-                         * cannot write it, then log about the issue at LOG_NOTICE level, and proceed without
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-                         * failing. (EROFS is treated as a permission problem here, since that's how container managers
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-                         * usually protected their sysctls.) In all other cases log an error and make the tool fail. */
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-
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-                        if (IN_SET(k, -EPERM, -EACCES, -EROFS, -ENOENT))
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-                                log_notice_errno(k, "Couldn't write '%s' to '%s', ignoring: %m", value, property);
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+                        /* If the sysctl is not available in the kernel or we are running with reduced
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+                         * privileges and cannot write it, then log about the issue at LOG_NOTICE level, and
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+                         * proceed without failing. (EROFS is treated as a permission problem here, since
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+                         * that's how container managers usually protected their sysctls.) In all other cases
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+                         * log an error and make the tool fail. */
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+
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+                        if (IN_SET(k, -EPERM, -EACCES, -EROFS, -ENOENT) || option->ignore_failure)
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+                                log_notice_errno(k, "Couldn't write '%s' to '%s', ignoring: %m", option->value, option->key);
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                         else {
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-                                log_error_errno(k, "Couldn't write '%s' to '%s': %m", value, property);
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+                                log_error_errno(k, "Couldn't write '%s' to '%s': %m", option->value, option->key);
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                                 if (r == 0)
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                                         r = k;
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                         }
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@@ -90,9 +136,11 @@ static int parse_file(OrderedHashmap *sysctl_options, const char *path, bool ign
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         log_debug("Parsing %s", path);
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         for (;;) {
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-                char *p, *value, *new_value, *property, *existing;
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+                _cleanup_(option_freep) Option *new_option = NULL;
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                 _cleanup_free_ char *l = NULL;
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-                void *v;
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+                bool ignore_failure;
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+                Option *existing;
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+                char *p, *value;
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                 int k;
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                 k = read_line(f, LONG_LINE_MAX, &l);
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@@ -122,39 +170,37 @@ static int parse_file(OrderedHashmap *sysctl_options, const char *path, bool ign
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                 *value = 0;
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                 value++;
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-                p = sysctl_normalize(strstrip(p));
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+                p = strstrip(p);
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+                ignore_failure = p[0] == '-';
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+                if (ignore_failure)
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+                        p++;
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+
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+                p = sysctl_normalize(p);
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                 value = strstrip(value);
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                 if (!test_prefix(p))
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                         continue;
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-                existing = ordered_hashmap_get2(sysctl_options, p, &v);
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+                existing = ordered_hashmap_get(sysctl_options, p);
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                 if (existing) {
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-                        if (streq(value, existing))
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+                        if (streq(value, existing->value)) {
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+                                existing->ignore_failure = existing->ignore_failure || ignore_failure;
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                                 continue;
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+                        }
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                         log_debug("Overwriting earlier assignment of %s at '%s:%u'.", p, path, c);
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-                        free(ordered_hashmap_remove(sysctl_options, p));
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-                        free(v);
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+                        option_free(ordered_hashmap_remove(sysctl_options, p));
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                 }
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-                property = strdup(p);
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-                if (!property)
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+                new_option = option_new(p, value, ignore_failure);
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+                if (!new_option)
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                         return log_oom();
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-                new_value = strdup(value);
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-                if (!new_value) {
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-                        free(property);
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-                        return log_oom();
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-                }
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+                k = ordered_hashmap_put(sysctl_options, new_option->key, new_option);
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+                if (k < 0)
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+                        return log_error_errno(k, "Failed to add sysctl variable %s to hashmap: %m", p);
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-                k = ordered_hashmap_put(sysctl_options, property, new_value);
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-                if (k < 0) {
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-                        log_error_errno(k, "Failed to add sysctl variable %s to hashmap: %m", property);
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-                        free(property);
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-                        free(new_value);
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-                        return k;
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-                }
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+                TAKE_PTR(new_option);
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         }
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         return r;
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@@ -251,7 +297,7 @@ static int parse_argv(int argc, char *argv[]) {
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 }
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 int main(int argc, char *argv[]) {
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-        OrderedHashmap *sysctl_options = NULL;
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+        _cleanup_(ordered_hashmap_freep) OrderedHashmap *sysctl_options = NULL;
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         int r = 0, k;
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         r = parse_argv(argc, argv);
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@@ -264,7 +310,7 @@ int main(int argc, char *argv[]) {
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         umask(0022);
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-        sysctl_options = ordered_hashmap_new(&path_hash_ops);
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+        sysctl_options = ordered_hashmap_new(&option_hash_ops);
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         if (!sysctl_options) {
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                 r = log_oom();
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                 goto finish;
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@@ -311,7 +357,6 @@ int main(int argc, char *argv[]) {
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 finish:
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         pager_close();
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-        ordered_hashmap_free_free_free(sysctl_options);
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         strv_free(arg_prefixes);
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         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;