From 9029b54e9f2a3173391e630c8cff5758f2d56321 Mon Sep 17 00:00:00 2001 From: Vsevolod Stakhov Date: Wed, 23 Sep 2020 11:58:33 +0100 Subject: [PATCH] [Fix] Use strict IDNA for utf8 DNS names + add sanity checks for DNS names --- src/libserver/dns.c | 121 +++++++++++++++++++++++++++++++++++++++++++- src/libserver/dns.h | 15 ++++++ 2 files changed, 134 insertions(+), 2 deletions(-) diff --git a/src/libserver/dns.c b/src/libserver/dns.c index 8fe0c6f92..cbbed4aa8 100644 --- a/src/libserver/dns.c +++ b/src/libserver/dns.c @@ -15,7 +15,7 @@ */ -#include +#include "contrib/librdns/rdns.h" #include "config.h" #include "dns.h" #include "rspamd.h" @@ -25,6 +25,8 @@ #include "contrib/librdns/rdns_ev.h" #include "unix-std.h" +#include + static const gchar *M = "rspamd dns"; static struct rdns_upstream_elt* rspamd_dns_select_upstream (const char *name, @@ -66,6 +68,22 @@ struct rspamd_dns_fail_cache_entry { enum rdns_request_type type; }; +static const gint8 ascii_dns_table[128]={ + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + /* HYPHEN-MINUS..FULL STOP */ + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 1, -1, + /* 0..9 digits */ + 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, + /* LATIN CAPITAL LETTER A..LATIN CAPITAL LETTER Z */ + -1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, + /* _ */ + 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, 1, + /* LATIN SMALL LETTER A..LATIN SMALL LETTER Z */ + -1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, + 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1 +}; + static guint rspamd_dns_fail_hash (gconstpointer ptr) { @@ -189,6 +207,8 @@ rspamd_dns_resolver_request (struct rspamd_dns_resolver *resolver, { struct rdns_request *req; struct rspamd_dns_request_ud *reqdata = NULL; + guint nlen = strlen (name); + gchar *real_name = NULL; g_assert (resolver != NULL); @@ -196,13 +216,42 @@ rspamd_dns_resolver_request (struct rspamd_dns_resolver *resolver, return NULL; } + if (nlen == 0 || nlen > DNS_D_MAXNAME) { + return NULL; + } + if (session && rspamd_session_blocked (session)) { return NULL; } + if (rspamd_str_has_8bit (name, nlen)) { + /* Convert to idna using libicu as it follows all the standards */ + real_name = rspamd_dns_resolver_idna_convert_utf8 (resolver, pool, + name, nlen, &nlen); + + if (real_name == NULL) { + return NULL; + } + + name = real_name; + } + + /* Name is now in ASCII only */ + for (gsize i = 0; i < nlen; i ++) { + if (ascii_dns_table[((unsigned int)name[i]) & 0x7F] == -1) { + /* Invalid DNS name requested */ + + if (!pool) { + g_free (real_name); + } + + return NULL; + } + } + if (pool != NULL) { reqdata = - rspamd_mempool_alloc0 (pool, sizeof (struct rspamd_dns_request_ud)); + rspamd_mempool_alloc0 (pool, sizeof (struct rspamd_dns_request_ud)); } else { reqdata = g_malloc0 (sizeof (struct rspamd_dns_request_ud)); @@ -230,11 +279,16 @@ rspamd_dns_resolver_request (struct rspamd_dns_resolver *resolver, if (req == NULL) { if (pool == NULL) { g_free (reqdata); + g_free (real_name); } return NULL; } + if (real_name && pool == NULL) { + g_free (real_name); + } + return reqdata; } @@ -820,6 +874,7 @@ rspamd_dns_resolver_init (rspamd_logger_t *logger, dns_resolver = g_malloc0 (sizeof (struct rspamd_dns_resolver)); dns_resolver->event_loop = ev_base; + if (cfg != NULL) { dns_resolver->request_timeout = cfg->dns_timeout; dns_resolver->max_retransmits = cfg->dns_retransmits; @@ -830,6 +885,11 @@ rspamd_dns_resolver_init (rspamd_logger_t *logger, } dns_resolver->r = rdns_resolver_new (); + + UErrorCode uc_err = U_ZERO_ERROR; + + dns_resolver->uidna = uidna_openUTS46 (UIDNA_DEFAULT, &uc_err); + g_assert (!U_FAILURE (uc_err)); rdns_bind_libev (dns_resolver->r, dns_resolver->event_loop); if (cfg != NULL) { @@ -924,6 +984,8 @@ rspamd_dns_resolver_deinit (struct rspamd_dns_resolver *resolver) rspamd_lru_hash_destroy (resolver->fails_cache); } + uidna_close (resolver->uidna); + g_free (resolver); } } @@ -999,3 +1061,58 @@ rspamd_dns_upstream_count (void *ups_data) return rspamd_upstreams_alive (ups); } + +gchar* +rspamd_dns_resolver_idna_convert_utf8 (struct rspamd_dns_resolver *resolver, + rspamd_mempool_t *pool, + const char *name, + gint namelen, + guint *outlen) +{ + if (resolver == NULL || resolver->uidna == NULL || name == NULL + || namelen > DNS_D_MAXNAME) { + return NULL; + } + + guint dest_len; + UErrorCode uc_err = U_ZERO_ERROR; + UIDNAInfo info = UIDNA_INFO_INITIALIZER; + /* Calculate length required */ + dest_len = uidna_nameToASCII_UTF8 (resolver->uidna, name, namelen, + NULL, 0, &info, &uc_err); + + if (uc_err == U_BUFFER_OVERFLOW_ERROR) { + gchar *dest; + + if (pool) { + dest = rspamd_mempool_alloc (pool, dest_len + 1); + } + else { + dest = g_malloc (dest_len + 1); + } + + uc_err = U_ZERO_ERROR; + + dest_len = uidna_nameToASCII_UTF8 (resolver->uidna, name, namelen, + dest, dest_len + 1, &info, &uc_err); + + if (U_FAILURE (uc_err)) { + + if (!pool) { + g_free (dest); + } + + return NULL; + } + + dest[dest_len] = '\0'; + + if (outlen) { + *outlen = dest_len; + } + + return dest; + } + + return NULL; +} \ No newline at end of file diff --git a/src/libserver/dns.h b/src/libserver/dns.h index 367053ef4..50db8c891 100644 --- a/src/libserver/dns.h +++ b/src/libserver/dns.h @@ -36,6 +36,7 @@ struct rspamd_dns_resolver { struct rdns_resolver *r; struct ev_loop *event_loop; rspamd_lru_hash_t *fails_cache; + void *uidna; ev_tstamp fails_cache_time; struct upstream_list *ups; struct rspamd_config *cfg; @@ -87,6 +88,20 @@ gboolean rspamd_dns_resolver_request_task_forced (struct rspamd_task *task, enum rdns_request_type type, const char *name); +/** + * Converts a name into idna from UTF8 + * @param resolver resolver (must be initialised) + * @param pool optional memory pool (can be NULL, then you need to g_free) the result + * @param name input name + * @param namelen length of input (-1 for zero terminated) + * @return encoded string + */ +gchar* rspamd_dns_resolver_idna_convert_utf8 (struct rspamd_dns_resolver *resolver, + rspamd_mempool_t *pool, + const char *name, + gint namelen, + guint *outlen); + #ifdef __cplusplus } #endif -- 2.39.5