core: rework serialization
Let's be more careful with what we serialize: let's ensure we never serialize strings that are longer than LONG_LINE_MAX, so that we know we can read them back with read_line(…, LONG_LINE_MAX, …) safely. In order to implement this all serialization functions are move to serialize.[ch], and internally will do line size checks. We'd rather skip a serialization line (with a loud warning) than write an overly long line out. Of course, this is just a second level protection, after all the data we serialize shouldn't be this long in the first place. While we are at it also clean up logging: while serializing make sure to always log about errors immediately. Also, (void)ify all calls we don't expect errors in (or catch errors as part of the general fflush_and_check() at the end.
This commit is contained in:
Lennart Poettering
@@ -52,10 +52,10 @@ shared_sources = files('''
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import-util.c
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import-util.h
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initreq.h
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install.c
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install.h
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install-printf.c
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install-printf.h
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install.c
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install.h
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journal-util.c
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journal-util.h
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logs-show.c
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@@ -78,6 +78,8 @@ shared_sources = files('''
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resolve-util.c
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resolve-util.h
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seccomp-util.h
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serialize.c
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serialize.h
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sleep-config.c
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sleep-config.h
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spawn-ask-password-agent.c
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@@ -92,8 +94,8 @@ shared_sources = files('''
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sysctl-util.h
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tomoyo-util.c
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tomoyo-util.h
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udev-util.h
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udev-util.c
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udev-util.h
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uid-range.c
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uid-range.h
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utmp-wtmp.h
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@@ -0,0 +1,190 @@
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/* SPDX-License-Identifier: LGPL-2.1+ */
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#include "alloc-util.h"
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#include "def.h"
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#include "env-util.h"
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#include "escape.h"
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#include "parse-util.h"
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#include "serialize.h"
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#include "strv.h"
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int serialize_item(FILE *f, const char *key, const char *value) {
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assert(f);
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assert(key);
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if (!value)
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return 0;
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/* Make sure that anything we serialize we can also read back again with read_line() with a maximum line size
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* of LONG_LINE_MAX. This is a safety net only. All code calling us should filter this out earlier anyway. */
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if (strlen(key) + 1 + strlen(value) + 1 > LONG_LINE_MAX) {
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log_warning("Attempted to serialize overly long item '%s', refusing.", key);
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return -EINVAL;
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}
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fputs(key, f);
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fputc('=', f);
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fputs(value, f);
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fputc('\n', f);
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return 1;
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}
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int serialize_item_escaped(FILE *f, const char *key, const char *value) {
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_cleanup_free_ char *c = NULL;
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assert(f);
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assert(key);
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if (!value)
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return 0;
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c = cescape(value);
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if (!c)
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return log_oom();
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return serialize_item(f, key, c);
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}
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int serialize_item_format(FILE *f, const char *key, const char *format, ...) {
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char buf[LONG_LINE_MAX];
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va_list ap;
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int k;
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assert(f);
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assert(key);
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assert(format);
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va_start(ap, format);
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k = vsnprintf(buf, sizeof(buf), format, ap);
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va_end(ap);
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if (k < 0 || (size_t) k >= sizeof(buf) || strlen(key) + 1 + k + 1 > LONG_LINE_MAX) {
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log_warning("Attempted to serialize overly long item '%s', refusing.", key);
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return -EINVAL;
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}
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fputs(key, f);
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fputc('=', f);
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fputs(buf, f);
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fputc('\n', f);
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return 1;
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}
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int serialize_fd(FILE *f, FDSet *fds, const char *key, int fd) {
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int copy;
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assert(f);
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assert(key);
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if (fd < 0)
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return 0;
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copy = fdset_put_dup(fds, fd);
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if (copy < 0)
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return log_error_errno(copy, "Failed to add file descriptor to serialization set: %m");
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return serialize_item_format(f, key, "%i", copy);
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}
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int serialize_usec(FILE *f, const char *key, usec_t usec) {
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assert(f);
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assert(key);
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if (usec == USEC_INFINITY)
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return 0;
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return serialize_item_format(f, key, USEC_FMT, usec);
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}
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int serialize_dual_timestamp(FILE *f, const char *name, const dual_timestamp *t) {
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assert(f);
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assert(name);
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assert(t);
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if (!dual_timestamp_is_set(t))
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return 0;
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return serialize_item_format(f, name, USEC_FMT " " USEC_FMT, t->realtime, t->monotonic);
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}
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int serialize_strv(FILE *f, const char *key, char **l) {
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int ret = 0, r;
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char **i;
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/* Returns the first error */
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STRV_FOREACH(i, l) {
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r = serialize_item_escaped(f, key, *i);
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if ((ret >= 0 && r < 0) ||
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(ret == 0 && r > 0))
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ret = r;
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}
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return ret;
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}
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int deserialize_usec(const char *value, usec_t *ret) {
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int r;
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assert(value);
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r = safe_atou64(value, ret);
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if (r < 0)
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return log_debug_errno(r, "Failed to parse usec value \"%s\": %m", value);
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return 0;
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}
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int deserialize_dual_timestamp(const char *value, dual_timestamp *t) {
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uint64_t a, b;
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int r, pos;
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assert(value);
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assert(t);
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pos = strspn(value, WHITESPACE);
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if (value[pos] == '-')
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return -EINVAL;
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pos += strspn(value + pos, DIGITS);
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pos += strspn(value + pos, WHITESPACE);
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if (value[pos] == '-')
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return -EINVAL;
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r = sscanf(value, "%" PRIu64 "%" PRIu64 "%n", &a, &b, &pos);
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if (r != 2) {
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log_debug("Failed to parse dual timestamp value \"%s\".", value);
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return -EINVAL;
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}
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if (value[pos] != '\0')
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/* trailing garbage */
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return -EINVAL;
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t->realtime = a;
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t->monotonic = b;
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return 0;
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}
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int deserialize_environment(const char *value, char ***list) {
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_cleanup_free_ char *unescaped = NULL;
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int r;
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assert(value);
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assert(list);
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/* Changes the *environment strv inline. */
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r = cunescape(value, 0, &unescaped);
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if (r < 0)
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return log_error_errno(r, "Failed to unescape: %m");
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r = strv_env_replace(list, unescaped);
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if (r < 0)
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return log_error_errno(r, "Failed to append environment variable: %m");
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unescaped = NULL; /* now part of 'list' */
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return 0;
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}
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@@ -0,0 +1,23 @@
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/* SPDX-License-Identifier: LGPL-2.1+ */
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#pragma once
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#include <stdio.h>
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#include "fdset.h"
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#include "macro.h"
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int serialize_item(FILE *f, const char *key, const char *value);
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int serialize_item_escaped(FILE *f, const char *key, const char *value);
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int serialize_item_format(FILE *f, const char *key, const char *value, ...) _printf_(3,4);
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int serialize_fd(FILE *f, FDSet *fds, const char *key, int fd);
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int serialize_usec(FILE *f, const char *key, usec_t usec);
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int serialize_dual_timestamp(FILE *f, const char *key, const dual_timestamp *t);
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int serialize_strv(FILE *f, const char *key, char **l);
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static inline int serialize_bool(FILE *f, const char *key, bool b) {
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return serialize_item(f, key, yes_no(b));
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}
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int deserialize_usec(const char *value, usec_t *timestamp);
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int deserialize_dual_timestamp(const char *value, dual_timestamp *t);
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int deserialize_environment(const char *value, char ***environment);
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