File dns-Apply-a-default-TTL-to-records-obtained-from-get.patch of Package keyutils.25279
From 75e7568dc516db698093b33ea273e1b4a30b70be Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Tue, 14 Apr 2020 16:07:26 +0100
Subject: [PATCH] dns: Apply a default TTL to records obtained from
getaddrinfo()
[ ematsumiya: the patch has been modified from upstream version to
accomodate the missing files/context in this older version ]
Address records obtained from getaddrinfo() don't come with any TTL
information, even if they're obtained from the DNS, with the result that
key.dns_resolver upcall program doesn't set an expiry time on dns_resolver
records unless they include a component obtained directly from the DNS,
such as an SRV or AFSDB record.
Fix this to apply a default TTL of 10mins in the event that we haven't got
one. This can be configured in /etc/keyutils/key.dns_resolver.conf by
adding the line:
default_ttl = <number-of-seconds>
to the file.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Ben Boeckel <me@benboeckel.net>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
--- a/Makefile
+++ b/Makefile
@@ -168,6 +168,7 @@ endif
$(INSTALL) -D key.dns_resolver $(DESTDIR)$(SBINDIR)/key.dns_resolver
$(INSTALL) -D -m 0644 request-key.conf $(DESTDIR)$(ETCDIR)/request-key.conf
mkdir -p $(DESTDIR)$(ETCDIR)/request-key.d
+ mkdir -p $(DESTDIR)$(ETCDIR)/keyutils
mkdir -p $(DESTDIR)$(MAN1)
$(INSTALL) -m 0644 $(wildcard man/*.1) $(DESTDIR)$(MAN1)
mkdir -p $(DESTDIR)$(MAN3)
--- a/key.dns_resolver.c
+++ b/key.dns_resolver.c
@@ -56,6 +56,8 @@
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
+#include <stdbool.h>
+#include <ctype.h>
static const char *DNS_PARSE_VERSION = "1.0";
static const char prog[] = "key.dns_resolver";
@@ -63,9 +65,12 @@ static const char key_type[] = "dns_reso
static const char a_query_type[] = "a";
static const char aaaa_query_type[] = "aaaa";
static const char afsdb_query_type[] = "afsdb";
+static const char *config_file = "/etc/keyutils/key.dns_resolver.conf";
+static bool config_specified = false;
static key_serial_t key;
static int verbose;
static int debug_mode;
+unsigned int key_expiry = 5;
#define MAX_VLS 15 /* Max Volume Location Servers Per-Cell */
@@ -287,6 +292,7 @@ static void dump_payload(void)
}
info("The key instantiation data is '%s'", buf);
+ info("The key expiry time is %us", key_expiry);
free(buf);
}
@@ -363,8 +369,7 @@ dns_resolver(const char *server_name, un
*/
static void afsdb_hosts_to_addrs(ns_msg handle,
ns_sect section,
- unsigned mask,
- unsigned long *_ttl)
+ unsigned mask)
{
char *vllist[MAX_VLS]; /* list of name servers */
int vlsnum = 0; /* number of name servers in list */
@@ -436,8 +441,8 @@ static void afsdb_hosts_to_addrs(ns_msg
}
}
- *_ttl = ttl;
- info("ttl: %u", ttl);
+ key_expiry = ttl;
+ info("ttl: %u", key_expiry);
}
/*
@@ -453,7 +458,6 @@ int dns_query_afsdb(const char *cell, ch
unsigned mask = INET_ALL;
int response_len; /* buffer length */
ns_msg handle; /* handle for response message */
- unsigned long ttl = ULONG_MAX;
union {
HEADER hdr;
u_char buf[NS_PACKETSZ];
@@ -482,13 +486,13 @@ int dns_query_afsdb(const char *cell, ch
mask = INET_IP6_ONLY;
/* look up the hostnames we've obtained to get the actual addresses */
- afsdb_hosts_to_addrs(handle, ns_s_an, mask, &ttl);
+ afsdb_hosts_to_addrs(handle, ns_s_an, mask);
- info("DNS query AFSDB RR results:%u ttl:%lu", payload_index, ttl);
+ info("DNS query AFSDB RR results:%u ttl:%u", payload_index, key_expiry);
/* set the key's expiry time from the minimum TTL encountered */
if (!debug_mode) {
- ret = keyctl_set_timeout(key, ttl);
+ ret = keyctl_set_timeout(key, key_expiry);
if (ret == -1)
error("%s: keyctl_set_timeout: %m", __func__);
}
@@ -583,6 +587,9 @@ int dns_query_a_or_aaaa(const char *host
/* load the key with data key */
if (!debug_mode) {
+ ret = keyctl_set_timeout(key, key_expiry);
+ if (ret == -1)
+ error("%s: keyctl_set_timeout: %m", __func__);
ret = keyctl_instantiate_iov(key, payload, payload_index, 0);
if (ret == -1)
error("%s: keyctl_instantiate: %m", __func__);
@@ -592,6 +599,157 @@ int dns_query_a_or_aaaa(const char *host
}
/*
+ * Read the config file.
+ */
+static void read_config(void)
+{
+ FILE *f;
+ char buf[4096], *b, *p, *k, *v;
+ unsigned int line = 0, u;
+ int n;
+
+ info("READ CONFIG %s", config_file);
+
+ f = fopen(config_file, "r");
+ if (!f) {
+ if (errno == ENOENT && !config_specified) {
+ debug("%s: %m", config_file);
+ return;
+ }
+ error("%s: %m", config_file);
+ }
+
+ while (fgets(buf, sizeof(buf) - 1, f)) {
+ line++;
+
+ /* Trim off leading and trailing spaces and discard whole-line
+ * comments.
+ */
+ b = buf;
+ while (isspace(*b))
+ b++;
+ if (!*b || *b == '#')
+ continue;
+ p = strchr(b, '\n');
+ if (!p)
+ error("%s:%u: line missing newline or too long", config_file, line);
+ while (p > buf && isspace(p[-1]))
+ p--;
+ *p = 0;
+
+ /* Split into key[=value] pairs and trim spaces. */
+ k = b;
+ v = NULL;
+ b = strchr(b, '=');
+ if (b) {
+ char quote = 0;
+ bool esc = false;
+
+ if (b == k)
+ error("%s:%u: Unspecified key",
+ config_file, line);
+
+ /* NUL-terminate the key. */
+ for (p = b - 1; isspace(*p); p--)
+ ;
+ p[1] = 0;
+
+ /* Strip leading spaces */
+ b++;
+ while (isspace(*b))
+ b++;
+ if (!*b)
+ goto missing_value;
+
+ if (*b == '"' || *b == '\'') {
+ quote = *b;
+ b++;
+ }
+ v = p = b;
+ while (*b) {
+ if (esc) {
+ switch (*b) {
+ case ' ':
+ case '\t':
+ case '"':
+ case '\'':
+ case '\\':
+ break;
+ default:
+ goto invalid_escape_char;
+ }
+ esc = false;
+ *p++ = *b++;
+ continue;
+ }
+ if (*b == '\\') {
+ esc = true;
+ b++;
+ continue;
+ }
+ if (*b == quote) {
+ b++;
+ if (*b)
+ goto post_quote_data;
+ quote = 0;
+ break;
+ }
+ if (!quote && *b == '#')
+ break; /* Terminal comment */
+ *p++ = *b++;
+ }
+
+ if (esc)
+ error("%s:%u: Incomplete escape", config_file, line);
+ if (quote)
+ error("%s:%u: Unclosed quotes", config_file, line);
+ *p = 0;
+ }
+
+ if (strcmp(k, "default_ttl") == 0) {
+ if (!v)
+ goto missing_value;
+ if (sscanf(v, "%u%n", &u, &n) != 1)
+ goto bad_value;
+ if (v[n])
+ goto extra_data;
+ if (u < 1 || u > INT_MAX)
+ goto out_of_range;
+ key_expiry = u;
+ } else {
+ error("%s:%u: Unknown option '%s'", config_file, line, k);
+ }
+ }
+
+ if (ferror(f) || fclose(f) == EOF)
+ error("%s: %m", config_file);
+ return;
+
+missing_value:
+ error("%s:%u: %s: Missing value", config_file, line, k);
+invalid_escape_char:
+ error("%s:%u: %s: Invalid char in escape", config_file, line, k);
+post_quote_data:
+ error("%s:%u: %s: Data after closing quote", config_file, line, k);
+bad_value:
+ error("%s:%u: %s: Bad value", config_file, line, k);
+extra_data:
+ error("%s:%u: %s: Extra data supplied", config_file, line, k);
+out_of_range:
+ error("%s:%u: %s: Value out of range", config_file, line, k);
+}
+
+/*
+ * Dump the configuration after parsing the config file.
+ */
+static __attribute__((noreturn))
+void config_dumper(void)
+{
+ printf("default_ttl = %u\n", key_expiry);
+ exit(0);
+}
+
+/*
* Print usage details,
*/
static __attribute__((noreturn))
@@ -599,22 +757,24 @@ void usage(void)
{
if (isatty(2)) {
fprintf(stderr,
- "Usage: %s [-vv] key_serial\n",
+ "Usage: %s [-vv] [-c config] key_serial\n",
prog);
fprintf(stderr,
- "Usage: %s -D [-vv] <desc> <calloutinfo>\n",
+ "Usage: %s -D [-vv] [-c config] <desc> <calloutinfo>\n",
prog);
} else {
- info("Usage: %s [-vv] key_serial", prog);
+ info("Usage: %s [-vv] [-c config] key_serial", prog);
}
exit(2);
}
const struct option long_options[] = {
- { "debug", 0, NULL, 'D' },
- { "verbose", 0, NULL, 'v' },
- { "version", 0, NULL, 'V' },
- { NULL, 0, NULL, 0 }
+ { "config", 0, NULL, 'c' },
+ { "debug", 0, NULL, 'D' },
+ { "dump-config", 0, NULL, 2 },
+ { "verbose", 0, NULL, 'v' },
+ { "version", 0, NULL, 'V' },
+ { NULL, 0, NULL, 0 }
};
/*
@@ -626,11 +786,19 @@ int main(int argc, char *argv[])
char *keyend, *p;
char *callout_info = NULL;
char *buf = NULL, *name;
+ bool dump_config = false;
openlog(prog, 0, LOG_DAEMON);
- while ((ret = getopt_long(argc, argv, "vD", long_options, NULL)) != -1) {
+ while ((ret = getopt_long(argc, argv, "c:vD", long_options, NULL)) != -1) {
switch (ret) {
+ case 'c':
+ config_file = optarg;
+ config_specified = true;
+ continue;
+ case 2:
+ dump_config = true;
+ continue;
case 'D':
debug_mode = 1;
continue;
@@ -652,6 +820,9 @@ int main(int argc, char *argv[])
argc -= optind;
argv += optind;
+ read_config();
+ if (dump_config)
+ config_dumper();
if (!debug_mode) {
if (argc != 1)
--- a/man/key.dns_resolver.8
+++ b/man/key.dns_resolver.8
@@ -13,18 +13,29 @@ key.dns_resolver - Upcall for request-ke
.SH SYNOPSIS
\fB/sbin/key.dns_resolver \fR<key>
.br
-\fB/sbin/key.dns_resolver \fR-D [-v] [-v] <keydesc> <calloutinfo>
+\fB/sbin/key.dns_resolver \fR--dump-config [\-c <configfile>]
+\fB/sbin/key.dns_resolver \fR\-D [-v] [-v] [\-c <configfile>] <keydesc>
+.br
+<calloutinfo>
.SH DESCRIPTION
This program is invoked by request-key on behalf of the kernel when kernel
services (such as NFS, CIFS and AFS) want to perform a hostname lookup and the
kernel does not have the key cached. It is not ordinarily intended to be
called directly.
.P
-It can be called in debugging mode to test its functionality by passing a
-\fB-D\fR flag on the command line. For this to work, the key description and
-the callout information must be supplied. Verbosity can be increased by
-supplying one or more \fB-v\fR flags.
+There program has internal parameters that can be changed with a configuration
+file (see key.dns_resolver.conf(5) for more information). The default
+configuration file is in /etc, but this can be overridden with the \fB-c\fR
+flag.
+.P
+The program can be called in debugging mode to test its functionality by
+passing a \fB\-D\fR or \fB\--debug\fR flag on the command line. For this to
+work, the key description and the callout information must be supplied.
+Verbosity can be increased by supplying one or more \fB\-v\fR flags.
+.P
+The program may also be called with \fB--dump-config\fR to show the values that
+configurable parameters will have after parsing the config file.
.SH ERRORS
All errors will be logged to the syslog.
.SH SEE ALSO
-\fBrequest-key\fR(8), \fBrequest-key.conf\fR(5)
+\fBrequest-key\fR(8), \fBrequest-key.conf\fR(5), \fBkey.dns_resolver.conf\fR(5)
--- /dev/null
+++ b/man/key.dns_resolver.conf.5
@@ -0,0 +1,48 @@
+.\" -*- nroff -*-
+.\" Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
+.\" Written by David Howells (dhowells@redhat.com)
+.\"
+.\" This program is free software; you can redistribute it and/or
+.\" modify it under the terms of the GNU General Public License
+.\" as published by the Free Software Foundation; either version
+.\" 2 of the License, or (at your option) any later version.
+.\"
+.TH KEY.DNS_RESOLVER.CONF 5 "18 May 2020" Linux "Linux Key Management Utilities"
+.SH NAME
+key.dns_resolver.conf \- Kernel DNS resolver config
+.SH DESCRIPTION
+This file is used by the key.dns_resolver(5) program to set parameters.
+Unless otherwise overridden with the \fB\-c\fR flag, the program reads:
+.IP
+/etc/key.dns_resolver.conf
+.P
+Configuration options are given in \fBkey[=value]\fR form, where \fBvalue\fR is
+optional. If present, the value may be surrounded by a pair of single ('') or
+double quotes ("") which will be stripped off. The special characters in the
+value may be escaped with a backslash to turn them into ordinary characters.
+.P
+Lines beginning with a '#' are considered comments and ignored. A '#' symbol
+anywhere after the '=' makes the rest of the line into a comment unless the '#'
+is inside a quoted section or is escaped.
+.P
+Leading and trailing spaces and spaces around the '=' symbol will be stripped
+off.
+.P
+Available options include:
+.TP
+.B default_ttl=<number>
+The number of seconds to set as the expiration on a cached record. This will
+be overridden if the program manages to retrieve TTL information along with
+the addresses (if, for example, it accesses the DNS directly). The default is
+5 seconds. The value must be in the range 1 to INT_MAX.
+.P
+The file can also include comments beginning with a '#' character unless
+otherwise suppressed by being inside a quoted value or being escaped with a
+backslash.
+
+.SH FILES
+.ul
+/etc/key.dns_resolver.conf
+.ul 0
+.SH SEE ALSO
+\fBkey.dns_resolver\fR(8)
