From 2a7ea306e35a35296314484eec9eff5d8e38f02a Mon Sep 17 00:00:00 2001 From: Simo Sorce Date: Thu, 30 Mar 2017 11:27:09 -0400 Subject: [PATCH] Add support to query the SSF of a GSS context Cyrus SASL provides a Security Strength Factor number to assess the relative "strength" of the negotiated mechanism, and applications sometimes make access control decisions based on it. Add a call that allows us to query the mechanism that established the GSS security context to ask what is the current SSF, based on the enctype of the session key. ticket: 8569 (new) (cherry picked from commit 7feb7da54c0321b5a3eeb6c3797846a3cf7eda28) [rharwood@redhat.com: hide GSS_KRB5_GET_CRED_IMPERSONATOR symbol] --- src/include/k5-int.h | 1 + src/lib/crypto/krb/crypto_int.h | 1 + src/lib/crypto/krb/enctype_util.c | 16 ++++++++++++++++ src/lib/crypto/krb/etypes.c | 33 ++++++++++++++++++--------------- src/lib/crypto/libk5crypto.exports | 1 + src/lib/gssapi/generic/gssapi_ext.h | 11 +++++++++++ src/lib/gssapi/generic/gssapi_generic.c | 9 +++++++++ src/lib/gssapi/krb5/gssapiP_krb5.h | 6 ++++++ src/lib/gssapi/krb5/gssapi_krb5.c | 4 ++++ src/lib/gssapi/krb5/inq_context.c | 27 +++++++++++++++++++++++++++ src/lib/gssapi/libgssapi_krb5.exports | 1 + src/lib/gssapi32.def | 3 +++ src/lib/krb5_32.def | 3 +++ src/tests/gssapi/t_enctypes.c | 14 ++++++++++++++ 14 files changed, 115 insertions(+), 15 deletions(-) diff --git a/src/include/k5-int.h b/src/include/k5-int.h index cea644d0a..06ca2b66d 100644 --- a/src/include/k5-int.h +++ b/src/include/k5-int.h @@ -2114,6 +2114,7 @@ krb5_get_tgs_ktypes(krb5_context, krb5_const_principal, krb5_enctype **); krb5_boolean krb5_is_permitted_enctype(krb5_context, krb5_enctype); krb5_boolean KRB5_CALLCONV krb5int_c_weak_enctype(krb5_enctype); +krb5_error_code k5_enctype_to_ssf(krb5_enctype enctype, unsigned int *ssf_out); krb5_error_code krb5_kdc_rep_decrypt_proc(krb5_context, const krb5_keyblock *, krb5_const_pointer, krb5_kdc_rep *); diff --git a/src/lib/crypto/krb/crypto_int.h b/src/lib/crypto/krb/crypto_int.h index d75b49c69..e5099291e 100644 --- a/src/lib/crypto/krb/crypto_int.h +++ b/src/lib/crypto/krb/crypto_int.h @@ -111,6 +111,7 @@ struct krb5_keytypes { prf_func prf; krb5_cksumtype required_ctype; krb5_flags flags; + unsigned int ssf; }; #define ETYPE_WEAK 1 diff --git a/src/lib/crypto/krb/enctype_util.c b/src/lib/crypto/krb/enctype_util.c index 0ed74bd6e..b1b40e7ec 100644 --- a/src/lib/crypto/krb/enctype_util.c +++ b/src/lib/crypto/krb/enctype_util.c @@ -131,3 +131,19 @@ krb5_enctype_to_name(krb5_enctype enctype, krb5_boolean shortest, return ENOMEM; return 0; } + +/* The security of a mechanism cannot be summarized with a simple integer + * value, but we provide a per-enctype value for Cyrus SASL's SSF. */ +krb5_error_code +k5_enctype_to_ssf(krb5_enctype enctype, unsigned int *ssf_out) +{ + const struct krb5_keytypes *ktp; + + *ssf_out = 0; + + ktp = find_enctype(enctype); + if (ktp == NULL) + return EINVAL; + *ssf_out = ktp->ssf; + return 0; +} diff --git a/src/lib/crypto/krb/etypes.c b/src/lib/crypto/krb/etypes.c index 0e5e977d4..53d4a5c79 100644 --- a/src/lib/crypto/krb/etypes.c +++ b/src/lib/crypto/krb/etypes.c @@ -42,7 +42,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_des_string_to_key, k5_rand2key_des, krb5int_des_prf, CKSUMTYPE_RSA_MD5_DES, - ETYPE_WEAK }, + ETYPE_WEAK, 56 }, { ENCTYPE_DES_CBC_MD4, "des-cbc-md4", { 0 }, "DES cbc mode with RSA-MD4", &krb5int_enc_des, &krb5int_hash_md4, @@ -51,7 +51,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_des_string_to_key, k5_rand2key_des, krb5int_des_prf, CKSUMTYPE_RSA_MD4_DES, - ETYPE_WEAK }, + ETYPE_WEAK, 56 }, { ENCTYPE_DES_CBC_MD5, "des-cbc-md5", { "des" }, "DES cbc mode with RSA-MD5", &krb5int_enc_des, &krb5int_hash_md5, @@ -60,7 +60,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_des_string_to_key, k5_rand2key_des, krb5int_des_prf, CKSUMTYPE_RSA_MD5_DES, - ETYPE_WEAK }, + ETYPE_WEAK, 56 }, { ENCTYPE_DES_CBC_RAW, "des-cbc-raw", { 0 }, "DES cbc mode raw", &krb5int_enc_des, NULL, @@ -69,7 +69,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_des_string_to_key, k5_rand2key_des, krb5int_des_prf, 0, - ETYPE_WEAK }, + ETYPE_WEAK, 56 }, { ENCTYPE_DES3_CBC_RAW, "des3-cbc-raw", { 0 }, "Triple DES cbc mode raw", &krb5int_enc_des3, NULL, @@ -78,7 +78,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_dk_string_to_key, k5_rand2key_des3, NULL, /*PRF*/ 0, - ETYPE_WEAK }, + ETYPE_WEAK, 112 }, { ENCTYPE_DES3_CBC_SHA1, "des3-cbc-sha1", { "des3-hmac-sha1", "des3-cbc-sha1-kd" }, @@ -89,7 +89,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_dk_string_to_key, k5_rand2key_des3, krb5int_dk_prf, CKSUMTYPE_HMAC_SHA1_DES3, - 0 /*flags*/ }, + 0 /*flags*/, 112 }, { ENCTYPE_DES_HMAC_SHA1, "des-hmac-sha1", { 0 }, "DES with HMAC/sha1", @@ -99,7 +99,10 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_dk_string_to_key, k5_rand2key_des, NULL, /*PRF*/ 0, - ETYPE_WEAK }, + ETYPE_WEAK, 56 }, + + /* rc4-hmac uses a 128-bit key, but due to weaknesses in the RC4 cipher, we + * consider its strength degraded and assign it an SSF value of 64. */ { ENCTYPE_ARCFOUR_HMAC, "arcfour-hmac", { "rc4-hmac", "arcfour-hmac-md5" }, "ArcFour with HMAC/md5", @@ -110,7 +113,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_arcfour_decrypt, krb5int_arcfour_string_to_key, k5_rand2key_direct, krb5int_arcfour_prf, CKSUMTYPE_HMAC_MD5_ARCFOUR, - 0 /*flags*/ }, + 0 /*flags*/, 64 }, { ENCTYPE_ARCFOUR_HMAC_EXP, "arcfour-hmac-exp", { "rc4-hmac-exp", "arcfour-hmac-md5-exp" }, "Exportable ArcFour with HMAC/md5", @@ -121,7 +124,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_arcfour_decrypt, krb5int_arcfour_string_to_key, k5_rand2key_direct, krb5int_arcfour_prf, CKSUMTYPE_HMAC_MD5_ARCFOUR, - ETYPE_WEAK + ETYPE_WEAK, 40 }, { ENCTYPE_AES128_CTS_HMAC_SHA1_96, @@ -133,7 +136,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_aes_string_to_key, k5_rand2key_direct, krb5int_dk_prf, CKSUMTYPE_HMAC_SHA1_96_AES128, - 0 /*flags*/ }, + 0 /*flags*/, 128 }, { ENCTYPE_AES256_CTS_HMAC_SHA1_96, "aes256-cts-hmac-sha1-96", { "aes256-cts", "aes256-sha1" }, "AES-256 CTS mode with 96-bit SHA-1 HMAC", @@ -143,7 +146,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_aes_string_to_key, k5_rand2key_direct, krb5int_dk_prf, CKSUMTYPE_HMAC_SHA1_96_AES256, - 0 /*flags*/ }, + 0 /*flags*/, 256 }, { ENCTYPE_CAMELLIA128_CTS_CMAC, "camellia128-cts-cmac", { "camellia128-cts" }, @@ -155,7 +158,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_camellia_string_to_key, k5_rand2key_direct, krb5int_dk_cmac_prf, CKSUMTYPE_CMAC_CAMELLIA128, - 0 /*flags*/ }, + 0 /*flags*/, 128 }, { ENCTYPE_CAMELLIA256_CTS_CMAC, "camellia256-cts-cmac", { "camellia256-cts" }, "Camellia-256 CTS mode with CMAC", @@ -166,7 +169,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_camellia_string_to_key, k5_rand2key_direct, krb5int_dk_cmac_prf, CKSUMTYPE_CMAC_CAMELLIA256, - 0 /*flags */ }, + 0 /*flags */, 256 }, { ENCTYPE_AES128_CTS_HMAC_SHA256_128, "aes128-cts-hmac-sha256-128", { "aes128-sha2" }, @@ -177,7 +180,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_aes2_string_to_key, k5_rand2key_direct, krb5int_aes2_prf, CKSUMTYPE_HMAC_SHA256_128_AES128, - 0 /*flags*/ }, + 0 /*flags*/, 128 }, { ENCTYPE_AES256_CTS_HMAC_SHA384_192, "aes256-cts-hmac-sha384-192", { "aes256-sha2" }, "AES-256 CTS mode with 192-bit SHA-384 HMAC", @@ -187,7 +190,7 @@ const struct krb5_keytypes krb5int_enctypes_list[] = { krb5int_aes2_string_to_key, k5_rand2key_direct, krb5int_aes2_prf, CKSUMTYPE_HMAC_SHA384_192_AES256, - 0 /*flags*/ }, + 0 /*flags*/, 256 }, }; const int krb5int_enctypes_length = diff --git a/src/lib/crypto/libk5crypto.exports b/src/lib/crypto/libk5crypto.exports index 447e45644..82eb5f30c 100644 --- a/src/lib/crypto/libk5crypto.exports +++ b/src/lib/crypto/libk5crypto.exports @@ -108,3 +108,4 @@ krb5int_nfold k5_allow_weak_pbkdf2iter krb5_c_prfplus krb5_c_derive_prfplus +k5_enctype_to_ssf diff --git a/src/lib/gssapi/generic/gssapi_ext.h b/src/lib/gssapi/generic/gssapi_ext.h index 9ad44216d..9d3a7e736 100644 --- a/src/lib/gssapi/generic/gssapi_ext.h +++ b/src/lib/gssapi/generic/gssapi_ext.h @@ -575,4 +575,15 @@ gss_import_cred( } #endif +/* + * When used with gss_inquire_sec_context_by_oid(), return a buffer set with + * the first member containing an unsigned 32-bit integer in network byte + * order. This is the Security Strength Factor (SSF) associated with the + * secure channel established by the security context. NOTE: This value is + * made available solely as an indication for use by APIs like Cyrus SASL that + * classify the strength of a secure channel via this number. The strength of + * a channel cannot necessarily be represented by a simple number. + */ +GSS_DLLIMP extern gss_OID GSS_C_SEC_CONTEXT_SASL_SSF; + #endif /* GSSAPI_EXT_H_ */ diff --git a/src/lib/gssapi/generic/gssapi_generic.c b/src/lib/gssapi/generic/gssapi_generic.c index 5496aa335..fa144c2bf 100644 --- a/src/lib/gssapi/generic/gssapi_generic.c +++ b/src/lib/gssapi/generic/gssapi_generic.c @@ -157,6 +157,13 @@ static const gss_OID_desc const_oids[] = { {7, (void *)"\x2b\x06\x01\x05\x05\x0d\x19"}, {7, (void *)"\x2b\x06\x01\x05\x05\x0d\x1a"}, {7, (void *)"\x2b\x06\x01\x05\x05\x0d\x1b"}, + + /* + * GSS_SEC_CONTEXT_SASL_SSF_OID 1.2.840.113554.1.2.2.5.15 + * iso(1) member-body(2) United States(840) mit(113554) + * infosys(1) gssapi(2) krb5(2) krb5-gssapi-ext(5) sasl-ssf(15) + */ + {11, (void *)"\x2a\x86\x48\x86\xf7\x12\x01\x02\x02\x05\x0f"}, }; /* Here are the constants which point to the static structure above. @@ -218,6 +225,8 @@ GSS_DLLIMP gss_const_OID GSS_C_MA_PFS = oids+33; GSS_DLLIMP gss_const_OID GSS_C_MA_COMPRESS = oids+34; GSS_DLLIMP gss_const_OID GSS_C_MA_CTX_TRANS = oids+35; +GSS_DLLIMP gss_OID GSS_C_SEC_CONTEXT_SASL_SSF = oids+36; + static gss_OID_set_desc gss_ma_known_attrs_desc = { 27, oids+9 }; gss_OID_set gss_ma_known_attrs = &gss_ma_known_attrs_desc; diff --git a/src/lib/gssapi/krb5/gssapiP_krb5.h b/src/lib/gssapi/krb5/gssapiP_krb5.h index d7bdef7e2..ef030707e 100644 --- a/src/lib/gssapi/krb5/gssapiP_krb5.h +++ b/src/lib/gssapi/krb5/gssapiP_krb5.h @@ -1144,6 +1144,12 @@ gss_krb5int_extract_authtime_from_sec_context(OM_uint32 *, const gss_OID, gss_buffer_set_t *); +#define GET_SEC_CONTEXT_SASL_SSF_OID_LENGTH 11 +#define GET_SEC_CONTEXT_SASL_SSF_OID "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02\x05\x0f" +OM_uint32 +gss_krb5int_sec_context_sasl_ssf(OM_uint32 *, const gss_ctx_id_t, + const gss_OID, gss_buffer_set_t *); + #define GSS_KRB5_IMPORT_CRED_OID_LENGTH 11 #define GSS_KRB5_IMPORT_CRED_OID "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02\x05\x0d" diff --git a/src/lib/gssapi/krb5/gssapi_krb5.c b/src/lib/gssapi/krb5/gssapi_krb5.c index 99092ccab..de4131980 100644 --- a/src/lib/gssapi/krb5/gssapi_krb5.c +++ b/src/lib/gssapi/krb5/gssapi_krb5.c @@ -352,6 +352,10 @@ static struct { { {GSS_KRB5_EXTRACT_AUTHTIME_FROM_SEC_CONTEXT_OID_LENGTH, GSS_KRB5_EXTRACT_AUTHTIME_FROM_SEC_CONTEXT_OID}, gss_krb5int_extract_authtime_from_sec_context + }, + { + {GET_SEC_CONTEXT_SASL_SSF_OID_LENGTH, GET_SEC_CONTEXT_SASL_SSF_OID}, + gss_krb5int_sec_context_sasl_ssf } }; diff --git a/src/lib/gssapi/krb5/inq_context.c b/src/lib/gssapi/krb5/inq_context.c index 9024b3c7e..d2e466e60 100644 --- a/src/lib/gssapi/krb5/inq_context.c +++ b/src/lib/gssapi/krb5/inq_context.c @@ -310,3 +310,30 @@ gss_krb5int_extract_authtime_from_sec_context(OM_uint32 *minor_status, return generic_gss_add_buffer_set_member(minor_status, &rep, data_set); } + +OM_uint32 +gss_krb5int_sec_context_sasl_ssf(OM_uint32 *minor_status, + const gss_ctx_id_t context_handle, + const gss_OID desired_object, + gss_buffer_set_t *data_set) +{ + krb5_gss_ctx_id_rec *ctx; + krb5_key key; + krb5_error_code code; + gss_buffer_desc ssfbuf; + unsigned int ssf; + uint8_t buf[4]; + + ctx = (krb5_gss_ctx_id_rec *)context_handle; + key = ctx->have_acceptor_subkey ? ctx->acceptor_subkey : ctx->subkey; + + code = k5_enctype_to_ssf(key->keyblock.enctype, &ssf); + if (code) + return GSS_S_FAILURE; + + store_32_be(ssf, buf); + ssfbuf.value = buf; + ssfbuf.length = sizeof(buf); + + return generic_gss_add_buffer_set_member(minor_status, &ssfbuf, data_set); +} diff --git a/src/lib/gssapi/libgssapi_krb5.exports b/src/lib/gssapi/libgssapi_krb5.exports index 9facb3f42..936540e41 100644 --- a/src/lib/gssapi/libgssapi_krb5.exports +++ b/src/lib/gssapi/libgssapi_krb5.exports @@ -37,6 +37,7 @@ GSS_C_MA_CBINDINGS GSS_C_MA_PFS GSS_C_MA_COMPRESS GSS_C_MA_CTX_TRANS +GSS_C_SEC_CONTEXT_SASL_SSF gss_accept_sec_context gss_acquire_cred gss_acquire_cred_with_password diff --git a/src/lib/gssapi32.def b/src/lib/gssapi32.def index 362b9bce8..dff057754 100644 --- a/src/lib/gssapi32.def +++ b/src/lib/gssapi32.def @@ -182,3 +182,6 @@ EXPORTS gss_verify_mic_iov @146 ; Added in 1.14 GSS_KRB5_CRED_NO_CI_FLAGS_X @147 DATA +; Added in 1.16 +; GSS_KRB5_GET_CRED_IMPERSONATOR @148 DATA + GSS_C_SEC_CONTEXT_SASL_SSF @149 DATA diff --git a/src/lib/krb5_32.def b/src/lib/krb5_32.def index e5b560dfc..f7b428e16 100644 --- a/src/lib/krb5_32.def +++ b/src/lib/krb5_32.def @@ -470,3 +470,6 @@ EXPORTS krb5_get_init_creds_opt_set_pac_request @435 krb5int_trace @436 ; PRIVATE GSSAPI krb5_expand_hostname @437 + +; new in 1.16 + k5_enctype_to_ssf @438 ; PRIVATE GSSAPI diff --git a/src/tests/gssapi/t_enctypes.c b/src/tests/gssapi/t_enctypes.c index a2ad18f47..3fd31e2f8 100644 --- a/src/tests/gssapi/t_enctypes.c +++ b/src/tests/gssapi/t_enctypes.c @@ -32,6 +32,7 @@ #include "k5-int.h" #include "common.h" +#include "gssapi_ext.h" /* * This test program establishes contexts with the krb5 mech, the default @@ -86,6 +87,9 @@ main(int argc, char *argv[]) gss_krb5_lucid_context_v1_t *ilucid, *alucid; gss_krb5_rfc1964_keydata_t *i1964, *a1964; gss_krb5_cfx_keydata_t *icfx, *acfx; + gss_buffer_set_t bufset = GSS_C_NO_BUFFER_SET; + gss_OID ssf_oid = GSS_C_SEC_CONTEXT_SASL_SSF; + unsigned int ssf; size_t count; void *lptr; int c; @@ -139,6 +143,16 @@ main(int argc, char *argv[]) establish_contexts(&mech_krb5, icred, acred, tname, flags, &ictx, &actx, NULL, NULL, NULL); + /* Query the SSF value and range-check the result. */ + major = gss_inquire_sec_context_by_oid(&minor, ictx, ssf_oid, &bufset); + check_gsserr("gss_inquire_sec_context_by_oid(ssf)", major, minor); + if (bufset->elements[0].length != 4) + errout("SSF buffer has unexpected length"); + ssf = load_32_be(bufset->elements[0].value); + if (ssf < 56 || ssf > 256) + errout("SSF value not within acceptable range (56-256)"); + (void)gss_release_buffer_set(&minor, &bufset); + /* Export to lucid contexts. */ major = gss_krb5_export_lucid_sec_context(&minor, &ictx, 1, &lptr); check_gsserr("gss_export_lucid_sec_context(initiator)", major, minor);