diff options
Diffstat (limited to 'dirmngr/crlfetch.c')
| -rw-r--r-- | dirmngr/crlfetch.c | 589 |
1 files changed, 589 insertions, 0 deletions
diff --git a/dirmngr/crlfetch.c b/dirmngr/crlfetch.c new file mode 100644 index 0000000..e355aab --- /dev/null +++ b/dirmngr/crlfetch.c @@ -0,0 +1,589 @@ +/* crlfetch.c - LDAP access + * Copyright (C) 2002 Klarälvdalens Datakonsult AB + * Copyright (C) 2003, 2004, 2005, 2006, 2007 g10 Code GmbH + * + * This file is part of DirMngr. + * + * DirMngr 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. + * + * DirMngr is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <https://www.gnu.org/licenses/>. + */ + +#include <config.h> + +#include <stdio.h> +#include <errno.h> +#include <npth.h> + +#include "crlfetch.h" +#include "dirmngr.h" +#include "misc.h" +#include "http.h" +#include "ks-engine.h" /* For ks_http_fetch. */ + +#if USE_LDAP +# include "ldap-wrapper.h" +#endif + +/* For detecting armored CRLs received via HTTP (yes, such CRLS really + exits, e.g. http://grid.fzk.de/ca/gridka-crl.pem at least in June + 2008) we need a context in the reader callback. */ +struct reader_cb_context_s +{ + estream_t fp; /* The stream used with the ksba reader. */ + int checked:1; /* PEM/binary detection ahs been done. */ + int is_pem:1; /* The file stream is PEM encoded. */ + struct b64state b64state; /* The state used for Base64 decoding. */ +}; + + +/* We need to associate a reader object with the reader callback + context. This table is used for it. */ +struct file_reader_map_s +{ + ksba_reader_t reader; + struct reader_cb_context_s *cb_ctx; +}; +#define MAX_FILE_READER 50 +static struct file_reader_map_s file_reader_map[MAX_FILE_READER]; + +/* Associate FP with READER. If the table is full wait until another + thread has removed an entry. */ +static void +register_file_reader (ksba_reader_t reader, struct reader_cb_context_s *cb_ctx) +{ + int i; + + for (;;) + { + for (i=0; i < MAX_FILE_READER; i++) + if (!file_reader_map[i].reader) + { + file_reader_map[i].reader = reader; + file_reader_map[i].cb_ctx = cb_ctx; + return; + } + log_info (_("reader to file mapping table full - waiting\n")); + npth_sleep (2); + } +} + +/* Scan the table for an entry matching READER, remove that entry and + return the associated file pointer. */ +static struct reader_cb_context_s * +get_file_reader (ksba_reader_t reader) +{ + struct reader_cb_context_s *cb_ctx = NULL; + int i; + + for (i=0; i < MAX_FILE_READER; i++) + if (file_reader_map[i].reader == reader) + { + cb_ctx = file_reader_map[i].cb_ctx; + file_reader_map[i].reader = NULL; + file_reader_map[i].cb_ctx = NULL; + break; + } + return cb_ctx; +} + + + +static int +my_es_read (void *opaque, char *buffer, size_t nbytes, size_t *nread) +{ + struct reader_cb_context_s *cb_ctx = opaque; + int result; + + result = es_read (cb_ctx->fp, buffer, nbytes, nread); + if (result) + return result; + /* Fixme we should check whether the semantics of es_read are okay + and well defined. I have some doubts. */ + if (nbytes && !*nread && es_feof (cb_ctx->fp)) + return gpg_error (GPG_ERR_EOF); + if (!nread && es_ferror (cb_ctx->fp)) + return gpg_error (GPG_ERR_EIO); + + if (!cb_ctx->checked && *nread) + { + int c = *(unsigned char *)buffer; + + cb_ctx->checked = 1; + if ( ((c & 0xc0) >> 6) == 0 /* class: universal */ + && (c & 0x1f) == 16 /* sequence */ + && (c & 0x20) /* is constructed */ ) + ; /* Binary data. */ + else + { + cb_ctx->is_pem = 1; + b64dec_start (&cb_ctx->b64state, ""); + } + } + if (cb_ctx->is_pem && *nread) + { + size_t nread2; + + if (b64dec_proc (&cb_ctx->b64state, buffer, *nread, &nread2)) + { + /* EOF from decoder. */ + *nread = 0; + result = gpg_error (GPG_ERR_EOF); + } + else + *nread = nread2; + } + + return result; +} + + +/* Fetch CRL from URL and return the entire CRL using new ksba reader + object in READER. Note that this reader object should be closed + only using ldap_close_reader. */ +gpg_error_t +crl_fetch (ctrl_t ctrl, const char *url, ksba_reader_t *reader) +{ + gpg_error_t err; + parsed_uri_t uri; + estream_t httpfp = NULL; + + *reader = NULL; + + if (!url) + return gpg_error (GPG_ERR_INV_ARG); + + err = http_parse_uri (&uri, url, 0); + http_release_parsed_uri (uri); + if (!err) /* Yes, our HTTP code groks that. */ + { + if (opt.disable_http) + { + log_error (_("CRL access not possible due to disabled %s\n"), + "HTTP"); + err = gpg_error (GPG_ERR_NOT_SUPPORTED); + } + else + { + /* Note that we also allow root certificates loaded from + * "/etc/gnupg/trusted-certs/". We also do not consult the + * CRL for the TLS connection - that may lead to a loop. + * Due to cacert.org redirecting their https URL to http we + * also allow such a downgrade. */ + err = ks_http_fetch (ctrl, url, + (KS_HTTP_FETCH_TRUST_CFG + | KS_HTTP_FETCH_NO_CRL + | KS_HTTP_FETCH_ALLOW_DOWNGRADE ), + &httpfp); + } + + if (err) + log_error (_("error retrieving '%s': %s\n"), url, gpg_strerror (err)); + else + { + struct reader_cb_context_s *cb_ctx; + + cb_ctx = xtrycalloc (1, sizeof *cb_ctx); + if (!cb_ctx) + err = gpg_error_from_syserror (); + else if (!(err = ksba_reader_new (reader))) + { + cb_ctx->fp = httpfp; + err = ksba_reader_set_cb (*reader, &my_es_read, cb_ctx); + if (!err) + { + /* The ksba reader misses a user pointer thus we + * need to come up with our own way of associating a + * file pointer (or well the callback context) with + * the reader. It is only required when closing the + * reader thus there is no performance issue doing + * it this way. FIXME: We now have a close + * notification which might be used here. */ + register_file_reader (*reader, cb_ctx); + httpfp = NULL; + } + } + + if (err) + { + log_error (_("error initializing reader object: %s\n"), + gpg_strerror (err)); + ksba_reader_release (*reader); + *reader = NULL; + xfree (cb_ctx); + } + } + } + else /* Let the LDAP code parse other schemes. */ + { + if (opt.disable_ldap) + { + log_error (_("CRL access not possible due to disabled %s\n"), + "LDAP"); + err = gpg_error (GPG_ERR_NOT_SUPPORTED); + } + else if (dirmngr_use_tor ()) + { + /* For now we do not support LDAP over Tor. */ + log_error (_("CRL access not possible due to Tor mode\n")); + err = gpg_error (GPG_ERR_NOT_SUPPORTED); + } + else + { +# if USE_LDAP + err = url_fetch_ldap (ctrl, url, reader); +# else /*!USE_LDAP*/ + err = gpg_error (GPG_ERR_NOT_IMPLEMENTED); +# endif /*!USE_LDAP*/ + } + } + + es_fclose (httpfp); + return err; +} + + +/* Fetch CRL for ISSUER using a default server. Return the entire CRL + as a newly opened stream returned in R_FP. */ +gpg_error_t +crl_fetch_default (ctrl_t ctrl, const char *issuer, ksba_reader_t *reader) +{ + if (dirmngr_use_tor ()) + { + /* For now we do not support LDAP over Tor. */ + log_error (_("CRL access not possible due to Tor mode\n")); + return gpg_error (GPG_ERR_NOT_SUPPORTED); + } + if (opt.disable_ldap) + { + log_error (_("CRL access not possible due to disabled %s\n"), + "LDAP"); + return gpg_error (GPG_ERR_NOT_SUPPORTED); + } + +#if USE_LDAP + return attr_fetch_ldap (ctrl, issuer, "certificateRevocationList", + reader); +#else + (void)ctrl; + (void)issuer; + (void)reader; + return gpg_error (GPG_ERR_NOT_IMPLEMENTED); +#endif +} + + +/* Fetch a CA certificate for DN using the default server. This + * function only initiates the fetch; fetch_next_cert must be used to + * actually read the certificate; end_cert_fetch to end the + * operation. */ +gpg_error_t +ca_cert_fetch (ctrl_t ctrl, cert_fetch_context_t *context, const char *dn) +{ + if (dirmngr_use_tor ()) + { + /* For now we do not support LDAP over Tor. */ + log_error (_("CRL access not possible due to Tor mode\n")); + return gpg_error (GPG_ERR_NOT_SUPPORTED); + } + if (opt.disable_ldap) + { + log_error (_("CRL access not possible due to disabled %s\n"), + "LDAP"); + return gpg_error (GPG_ERR_NOT_SUPPORTED); + } +#if USE_LDAP + return start_cacert_fetch_ldap (ctrl, context, dn); +#else + (void)ctrl; + (void)context; + (void)dn; + return gpg_error (GPG_ERR_NOT_IMPLEMENTED); +#endif +} + + +gpg_error_t +start_cert_fetch (ctrl_t ctrl, cert_fetch_context_t *context, + strlist_t patterns, const ldap_server_t server) +{ + if (dirmngr_use_tor ()) + { + /* For now we do not support LDAP over Tor. */ + log_error (_("CRL access not possible due to Tor mode\n")); + return gpg_error (GPG_ERR_NOT_SUPPORTED); + } + if (opt.disable_ldap) + { + log_error (_("certificate search not possible due to disabled %s\n"), + "LDAP"); + return gpg_error (GPG_ERR_NOT_SUPPORTED); + } +#if USE_LDAP + return start_cert_fetch_ldap (ctrl, context, patterns, server); +#else + (void)ctrl; + (void)context; + (void)patterns; + (void)server; + return gpg_error (GPG_ERR_NOT_IMPLEMENTED); +#endif +} + + +gpg_error_t +fetch_next_cert (cert_fetch_context_t context, + unsigned char **value, size_t * valuelen) +{ +#if USE_LDAP + return fetch_next_cert_ldap (context, value, valuelen); +#else + (void)context; + (void)value; + (void)valuelen; + return gpg_error (GPG_ERR_NOT_IMPLEMENTED); +#endif +} + + +/* Fetch the next data from CONTEXT, assuming it is a certificate and return + * it as a cert object in R_CERT. */ +gpg_error_t +fetch_next_ksba_cert (cert_fetch_context_t context, ksba_cert_t *r_cert) +{ + gpg_error_t err; + unsigned char *value; + size_t valuelen; + ksba_cert_t cert; + + *r_cert = NULL; + +#if USE_LDAP + err = fetch_next_cert_ldap (context, &value, &valuelen); + if (!err && !value) + err = gpg_error (GPG_ERR_BUG); +#else + (void)context; + err = gpg_error (GPG_ERR_NOT_IMPLEMENTED); +#endif + if (err) + return err; + + err = ksba_cert_new (&cert); + if (err) + { + xfree (value); + return err; + } + + err = ksba_cert_init_from_mem (cert, value, valuelen); + xfree (value); + if (err) + { + ksba_cert_release (cert); + return err; + } + *r_cert = cert; + return 0; +} + + +void +end_cert_fetch (cert_fetch_context_t context) +{ +#if USE_LDAP + end_cert_fetch_ldap (context); +#else + (void)context; +#endif +} + + +/* Read a certificate from an HTTP URL and return it as an estream + * memory buffer at R_FP. */ +static gpg_error_t +read_cert_via_http (ctrl_t ctrl, const char *url, estream_t *r_fp) +{ + gpg_error_t err; + estream_t fp = NULL; + estream_t httpfp = NULL; + size_t nread, nwritten; + char buffer[1024]; + + if ((err = ks_http_fetch (ctrl, url, KS_HTTP_FETCH_TRUST_CFG, &httpfp))) + goto leave; + + /* We now read the data from the web server into a memory buffer. + * To DOS we limit the certificate length to 32k. */ + fp = es_fopenmem (32*1024, "rw"); + if (!fp) + { + err = gpg_error_from_syserror (); + log_error ("error allocating memory buffer: %s\n", gpg_strerror (err)); + goto leave; + } + + for (;;) + { + if (es_read (httpfp, buffer, sizeof buffer, &nread)) + { + err = gpg_error_from_syserror (); + log_error ("error reading '%s': %s\n", + es_fname_get (httpfp), gpg_strerror (err)); + goto leave; + } + + if (!nread) + break; /* Ready. */ + if (es_write (fp, buffer, nread, &nwritten)) + { + err = gpg_error_from_syserror (); + log_error ("error writing '%s': %s\n", + es_fname_get (fp), gpg_strerror (err)); + goto leave; + } + else if (nread != nwritten) + { + err = gpg_error (GPG_ERR_EIO); + log_error ("error writing '%s': %s\n", + es_fname_get (fp), "short write"); + goto leave; + } + } + + es_rewind (fp); + *r_fp = fp; + fp = NULL; + + leave: + es_fclose (httpfp); + es_fclose (fp); + return err; +} + + +/* Lookup a cert by it's URL. */ +gpg_error_t +fetch_cert_by_url (ctrl_t ctrl, const char *url, + unsigned char **value, size_t *valuelen) +{ + const unsigned char *cert_image = NULL; + size_t cert_image_n; + ksba_reader_t reader = NULL; + ksba_cert_t cert = NULL; + gpg_error_t err; + + *value = NULL; + *valuelen = 0; + + err = ksba_cert_new (&cert); + if (err) + goto leave; + + if (url && (!strncmp (url, "http:", 5) || !strncmp (url, "https:", 6))) + { + estream_t stream; + void *der; + size_t derlen; + + err = read_cert_via_http (ctrl, url, &stream); + if (err) + goto leave; + + if (es_fclose_snatch (stream, &der, &derlen)) + { + err = gpg_error_from_syserror (); + goto leave; + } + + err = ksba_cert_init_from_mem (cert, der, derlen); + xfree (der); + if (err) + goto leave; + } + else /* Assume LDAP. */ + { +#if USE_LDAP + err = url_fetch_ldap (ctrl, url, &reader); +#else + (void)ctrl; + (void)url; + err = gpg_error (GPG_ERR_NOT_IMPLEMENTED); +#endif /*USE_LDAP*/ + if (err) + goto leave; + + err = ksba_cert_read_der (cert, reader); + if (err) + goto leave; + } + + cert_image = ksba_cert_get_image (cert, &cert_image_n); + if (!cert_image || !cert_image_n) + { + err = gpg_error (GPG_ERR_INV_CERT_OBJ); + goto leave; + } + + *value = xtrymalloc (cert_image_n); + if (!*value) + { + err = gpg_error_from_syserror (); + goto leave; + } + + memcpy (*value, cert_image, cert_image_n); + *valuelen = cert_image_n; + + leave: + ksba_cert_release (cert); +#if USE_LDAP + ldap_wrapper_release_context (reader); +#endif /*USE_LDAP*/ + + return err; +} + +/* This function is to be used to close the reader object. In + addition to running ksba_reader_release it also releases the LDAP + or HTTP contexts associated with that reader. */ +void +crl_close_reader (ksba_reader_t reader) +{ + struct reader_cb_context_s *cb_ctx; + + if (!reader) + return; + + /* Check whether this is a HTTP one. */ + cb_ctx = get_file_reader (reader); + if (cb_ctx) + { + /* This is an HTTP context. */ + if (cb_ctx->fp) + es_fclose (cb_ctx->fp); + /* Release the base64 decoder state. */ + if (cb_ctx->is_pem) + b64dec_finish (&cb_ctx->b64state); + /* Release the callback context. */ + xfree (cb_ctx); + } + else /* This is an ldap wrapper context (Currently not used). */ + { +#if USE_LDAP + ldap_wrapper_release_context (reader); +#endif /*USE_LDAP*/ + } + + /* Now get rid of the reader object. */ + ksba_reader_release (reader); +} |