From bc41dbe55098629101fbf286755e123c9a2b6b77 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Wed, 13 Feb 2019 16:09:41 -0200 Subject: [PATCH 10/36] cifs: Allow DNS resolver key to expire This patch introduces a new '--expire' option that allows the user to set a timeout value for the dns resolver key -- which is typically useful for hostnames that may get their ip addresses changed under long running mounts. The default timeout value is set to 10 minutes. Signed-off-by: Paulo Alcantara (cherry picked from commit b101af793c8415f298072d06841a278df0368bc3) Signed-off-by: Sachin Prabhu --- cifs.upcall.c | 82 +++++++++++++++++++++++++++++++++++++++--------------- cifs.upcall.rst.in | 5 +++- 2 files changed, 64 insertions(+), 23 deletions(-) diff --git a/cifs.upcall.c b/cifs.upcall.c index 89563fd..c92ee62 100644 --- a/cifs.upcall.c +++ b/cifs.upcall.c @@ -63,6 +63,8 @@ static krb5_context context; static const char *prog = "cifs.upcall"; +#define DNS_RESOLVER_DEFAULT_TIMEOUT 600 /* 10 minutes */ + typedef enum _sectype { NONE = 0, KRB5, @@ -749,19 +751,48 @@ decode_key_description(const char *desc, struct decoded_args *arg) return retval; } -static int cifs_resolver(const key_serial_t key, const char *key_descr) +static int setup_key(const key_serial_t key, const void *data, size_t datalen) +{ + int rc; + + rc = keyctl_instantiate(key, data, datalen, 0); + if (rc) { + switch (errno) { + case ENOMEM: + case EDQUOT: + rc = keyctl_clear(key); + if (rc) { + syslog(LOG_ERR, "%s: keyctl_clear: %s", + __func__, strerror(errno)); + return rc; + } + rc = keyctl_instantiate(key, data, datalen, 0); + break; + default: + ; + } + } + if (rc) { + syslog(LOG_ERR, "%s: keyctl_instantiate: %s", + __func__, strerror(errno)); + } + return rc; +} + +static int cifs_resolver(const key_serial_t key, const char *key_descr, + const char *key_buf, unsigned expire_time) { int c; struct addrinfo *addr; char ip[INET6_ADDRSTRLEN]; void *p; - const char *keyend = key_descr; + const char *keyend = key_buf; /* skip next 4 ';' delimiters to get to description */ for (c = 1; c <= 4; c++) { keyend = index(keyend + 1, ';'); if (!keyend) { syslog(LOG_ERR, "invalid key description: %s", - key_descr); + key_buf); return 1; } } @@ -787,15 +818,21 @@ static int cifs_resolver(const key_serial_t key, const char *key_descr) return 1; } - /* setup key */ - c = keyctl_instantiate(key, ip, strlen(ip) + 1, 0); - if (c == -1) { - syslog(LOG_ERR, "%s: keyctl_instantiate: %s", __func__, + /* needed for keyctl_set_timeout() */ + request_key("keyring", key_descr, NULL, KEY_SPEC_THREAD_KEYRING); + + c = setup_key(key, ip, strlen(ip) + 1); + if (c) { + freeaddrinfo(addr); + return 1; + } + c = keyctl_set_timeout(key, expire_time); + if (c) { + syslog(LOG_ERR, "%s: keyctl_set_timeout: %s", __func__, strerror(errno)); freeaddrinfo(addr); return 1; } - freeaddrinfo(addr); return 0; } @@ -864,7 +901,7 @@ lowercase_string(char *c) static void usage(void) { - fprintf(stderr, "Usage: %s [ -K /path/to/keytab] [-k /path/to/krb5.conf] [-E] [-t] [-v] [-l] key_serial\n", prog); + fprintf(stderr, "Usage: %s [ -K /path/to/keytab] [-k /path/to/krb5.conf] [-E] [-t] [-v] [-l] [-e nsecs] key_serial\n", prog); } static const struct option long_options[] = { @@ -874,6 +911,7 @@ static const struct option long_options[] = { {"trust-dns", 0, NULL, 't'}, {"keytab", 1, NULL, 'K'}, {"version", 0, NULL, 'v'}, + {"expire", 1, NULL, 'e'}, {NULL, 0, NULL, 0} }; @@ -897,13 +935,15 @@ int main(const int argc, char *const argv[]) char *env_cachename = NULL; krb5_ccache ccache = NULL; struct passwd *pw; + unsigned expire_time = DNS_RESOLVER_DEFAULT_TIMEOUT; + const char *key_descr = NULL; hostbuf[0] = '\0'; memset(&arg, 0, sizeof(arg)); openlog(prog, 0, LOG_DAEMON); - while ((c = getopt_long(argc, argv, "cEk:K:ltv", long_options, NULL)) != -1) { + while ((c = getopt_long(argc, argv, "cEk:K:ltve:", long_options, NULL)) != -1) { switch (c) { case 'c': /* legacy option -- skip it */ @@ -931,6 +971,9 @@ int main(const int argc, char *const argv[]) rc = 0; printf("version: %s\n", VERSION); goto out; + case 'e': + expire_time = strtoul(optarg, NULL, 10); + break; default: syslog(LOG_ERR, "unknown option: %c", c); goto out; @@ -965,9 +1008,12 @@ int main(const int argc, char *const argv[]) syslog(LOG_DEBUG, "key description: %s", buf); - if ((strncmp(buf, "cifs.resolver", sizeof("cifs.resolver") - 1) == 0) || - (strncmp(buf, "dns_resolver", sizeof("dns_resolver") - 1) == 0)) { - rc = cifs_resolver(key, buf); + if (strncmp(buf, "cifs.resolver", sizeof("cifs.resolver") - 1) == 0) + key_descr = ".cifs.resolver"; + else if (strncmp(buf, "dns_resolver", sizeof("dns_resolver") - 1) == 0) + key_descr = ".dns_resolver"; + if (key_descr) { + rc = cifs_resolver(key, key_descr, buf, expire_time); goto out; } @@ -1193,16 +1239,8 @@ retry_new_hostname: memcpy(&(keydata->data) + keydata->sesskey_len, secblob.data, secblob.length); - /* setup key */ - rc = keyctl_instantiate(key, keydata, datalen, 0); - if (rc == -1) { - syslog(LOG_ERR, "keyctl_instantiate: %s", strerror(errno)); - goto out; - } + rc = setup_key(key, keydata, datalen); - /* BB: maybe we need use timeout for key: for example no more then - * ticket lifietime? */ - /* keyctl_set_timeout( key, 60); */ out: /* * on error, negatively instantiate the key ourselves so that we can diff --git a/cifs.upcall.rst.in b/cifs.upcall.rst.in index 1b8df3f..08ce324 100644 --- a/cifs.upcall.rst.in +++ b/cifs.upcall.rst.in @@ -13,7 +13,7 @@ SYNOPSIS cifs.upcall [--trust-dns|-t] [--version|-v] [--legacy-uid|-l] [--krb5conf=/path/to/krb5.conf|-k /path/to/krb5.conf] - [--keytab=/path/to/keytab|-K /path/to/keytab] {keyid} + [--keytab=/path/to/keytab|-K /path/to/keytab] [--expire|-e nsecs] {keyid} *********** DESCRIPTION @@ -85,6 +85,9 @@ OPTIONS user. Set this option if you want cifs.upcall to use the older uid= parameter instead of the creduid= parameter. +--expire|-e + Override default timeout value (600 seconds) for ``dns_resolver`` key. + --version|-v Print version number and exit. -- 1.8.3.1