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keyutils
dns-Apply-a-default-TTL-to-records-obtained-fro...
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File dns-Apply-a-default-TTL-to-records-obtained-from-get.patch of Package keyutils
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)
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