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File _service:tar_scm_kernel_repo:backport-0003-CVE-2022-2031-CVE-2022-32744.patch of Package samba
From eadd3b8844d1e4162558f443e5cd4905f12667e6 Mon Sep 17 00:00:00 2001 From: Joseph Sutton <josephsutton@catalyst.net.nz> Date: Fri, 8 Oct 2021 16:08:39 +1300 Subject: [PATCH] s4:kdc: Check ticket signature BUG: https://bugzilla.samba.org/show_bug.cgi?id=14642 BUG: https://bugzilla.samba.org/show_bug.cgi?id=14881 Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz> Reviewed-by: Andrew Bartlett <abartlet@samba.org> (cherry picked from commit 02fa69c6c73c01d82807be4370e838f3e7c66f35) Conflict: remove selftest/knownfail_heimdal_kdc --- source4/kdc/wdc-samba4.c | 270 ++++++++++++++++++++++++++------- 2 files changed, 215 insertions(+), 64 deletions(-) diff --git a/source4/kdc/wdc-samba4.c b/source4/kdc/wdc-samba4.c index 037db40ce46..589df8a651d 100644 --- a/source4/kdc/wdc-samba4.c +++ b/source4/kdc/wdc-samba4.c @@ -23,7 +23,10 @@ #include "includes.h" #include "kdc/kdc-glue.h" +#include "kdc/db-glue.h" #include "kdc/pac-glue.h" +#include "sdb.h" +#include "sdb_hdb.h" /* * Given the right private pointer from hdb_samba4, @@ -94,15 +97,13 @@ static krb5_error_code samba_wdc_get_pac_compat(void *priv, krb5_context context return samba_wdc_get_pac(priv, context, client, NULL, pac); } -/* Resign (and reform, including possibly new groups) a PAC */ - -static krb5_error_code samba_wdc_reget_pac(void *priv, krb5_context context, - const krb5_principal client_principal, - const krb5_principal delegated_proxy_principal, - struct hdb_entry_ex *client, - struct hdb_entry_ex *server, - struct hdb_entry_ex *krbtgt, - krb5_pac *pac) +static krb5_error_code samba_wdc_reget_pac2(krb5_context context, + const krb5_principal delegated_proxy_principal, + struct hdb_entry_ex *client, + struct hdb_entry_ex *server, + struct hdb_entry_ex *krbtgt, + krb5_pac *pac, + krb5_cksumtype ctype) { struct samba_kdc_entry *p = talloc_get_type_abort(server->ctx, @@ -110,15 +111,13 @@ static krb5_error_code samba_wdc_reget_pac(void *priv, krb5_context context, struct samba_kdc_entry *krbtgt_skdc_entry = talloc_get_type_abort(krbtgt->ctx, struct samba_kdc_entry); - TALLOC_CTX *mem_ctx = talloc_named(p, 0, "samba_kdc_reget_pac context"); + TALLOC_CTX *mem_ctx = talloc_named(p, 0, "samba_kdc_reget_pac2 context"); krb5_pac new_pac = NULL; DATA_BLOB *pac_blob = NULL; DATA_BLOB *upn_blob = NULL; DATA_BLOB *deleg_blob = NULL; krb5_error_code ret; NTSTATUS nt_status; - struct PAC_SIGNATURE_DATA *pac_srv_sig; - struct PAC_SIGNATURE_DATA *pac_kdc_sig; bool is_in_db, is_untrusted; size_t num_types = 0; uint32_t *types = NULL; @@ -130,6 +129,7 @@ static krb5_error_code samba_wdc_reget_pac(void *priv, krb5_context context, ssize_t upn_dns_info_idx = -1; ssize_t srv_checksum_idx = -1; ssize_t kdc_checksum_idx = -1; + ssize_t tkt_checksum_idx = -1; if (!mem_ctx) { return ENOMEM; @@ -150,6 +150,71 @@ static krb5_error_code samba_wdc_reget_pac(void *priv, krb5_context context, return ret; } + if (delegated_proxy_principal != NULL) { + krb5_enctype etype; + Key *key = NULL; + + if (!is_in_db) { + /* + * The RODC-issued PAC was signed by a KDC entry that we + * don't have a key for. The server signature is not + * trustworthy, since it could have been created by the + * server we got the ticket from. We must not proceed as + * otherwise the ticket signature is unchecked. + */ + talloc_free(mem_ctx); + return HDB_ERR_NOT_FOUND_HERE; + } + + /* Fetch the correct key depending on the checksum type. */ + if (ctype == CKSUMTYPE_HMAC_MD5) { + etype = ENCTYPE_ARCFOUR_HMAC; + } else { + ret = krb5_cksumtype_to_enctype(context, + ctype, + &etype); + if (ret != 0) { + talloc_free(mem_ctx); + return ret; + } + } + ret = hdb_enctype2key(context, &krbtgt->entry, etype, &key); + if (ret != 0) { + return ret; + } + + /* Check the KDC and ticket signatures. */ + ret = krb5_pac_verify(context, + *pac, + 0, + NULL, + NULL, + &key->key); + if (ret != 0) { + DEBUG(1, ("PAC KDC signature failed to verify\n")); + talloc_free(mem_ctx); + return ret; + } + + deleg_blob = talloc_zero(mem_ctx, DATA_BLOB); + if (!deleg_blob) { + talloc_free(mem_ctx); + return ENOMEM; + } + + nt_status = samba_kdc_update_delegation_info_blob(mem_ctx, + context, *pac, + server->entry.principal, + delegated_proxy_principal, + deleg_blob); + if (!NT_STATUS_IS_OK(nt_status)) { + DEBUG(0, ("Building PAC failed: %s\n", + nt_errstr(nt_status))); + talloc_free(mem_ctx); + return EINVAL; + } + } + if (is_untrusted) { struct samba_kdc_entry *client_skdc_entry = NULL; @@ -173,52 +238,10 @@ static krb5_error_code samba_wdc_reget_pac(void *priv, krb5_context context, return ENOMEM; } - pac_srv_sig = talloc_zero(mem_ctx, struct PAC_SIGNATURE_DATA); - if (!pac_srv_sig) { - talloc_free(mem_ctx); - return ENOMEM; - } - - pac_kdc_sig = talloc_zero(mem_ctx, struct PAC_SIGNATURE_DATA); - if (!pac_kdc_sig) { - talloc_free(mem_ctx); - return ENOMEM; - } - nt_status = samba_kdc_update_pac_blob(mem_ctx, context, krbtgt_skdc_entry->kdc_db_ctx->samdb, *pac, pac_blob, - pac_srv_sig, pac_kdc_sig); - if (!NT_STATUS_IS_OK(nt_status)) { - DEBUG(0, ("Building PAC failed: %s\n", - nt_errstr(nt_status))); - talloc_free(mem_ctx); - return EINVAL; - } - - if (is_in_db) { - /* Now check the KDC signature, fetching the correct key based on the enc type */ - ret = kdc_check_pac(context, pac_srv_sig->signature, pac_kdc_sig, krbtgt); - if (ret != 0) { - DEBUG(1, ("PAC KDC signature failed to verify\n")); - talloc_free(mem_ctx); - return ret; - } - } - } - - if (delegated_proxy_principal) { - deleg_blob = talloc_zero(mem_ctx, DATA_BLOB); - if (!deleg_blob) { - talloc_free(mem_ctx); - return ENOMEM; - } - - nt_status = samba_kdc_update_delegation_info_blob(mem_ctx, - context, *pac, - server->entry.principal, - delegated_proxy_principal, - deleg_blob); + NULL, NULL); if (!NT_STATUS_IS_OK(nt_status)) { DEBUG(0, ("Building PAC failed: %s\n", nt_errstr(nt_status))); @@ -308,6 +331,18 @@ static krb5_error_code samba_wdc_reget_pac(void *priv, krb5_context context, } kdc_checksum_idx = i; break; + case PAC_TYPE_TICKET_CHECKSUM: + if (tkt_checksum_idx != -1) { + DEBUG(1, ("ticket checksum type[%"PRIu32"] twice [%zd] and [%zu]: \n", + types[i], + tkt_checksum_idx, + i)); + SAFE_FREE(types); + talloc_free(mem_ctx); + return EINVAL; + } + tkt_checksum_idx = i; + break; default: continue; } @@ -471,6 +506,131 @@ static krb5_error_code samba_wdc_reget_pac(void *priv, krb5_context context, return ret; } +/* Resign (and reform, including possibly new groups) a PAC */ + +static krb5_error_code samba_wdc_reget_pac(void *priv, krb5_context context, + const krb5_principal client_principal, + const krb5_principal delegated_proxy_principal, + struct hdb_entry_ex *client, + struct hdb_entry_ex *server, + struct hdb_entry_ex *krbtgt, + krb5_pac *pac) +{ + struct samba_kdc_entry *krbtgt_skdc_entry = + talloc_get_type_abort(krbtgt->ctx, + struct samba_kdc_entry); + krb5_error_code ret; + krb5_cksumtype ctype = CKSUMTYPE_NONE; + struct hdb_entry_ex signing_krbtgt_hdb; + + if (delegated_proxy_principal) { + uint16_t rodc_id; + unsigned int my_krbtgt_number; + + /* + * We're using delegated_proxy_principal for the moment to + * indicate cases where the ticket was encrypted with the server + * key, and not a krbtgt key. This cannot be trusted, so we need + * to find a krbtgt key that signs the PAC in order to trust the + * ticket. + * + * The krbtgt passed in to this function refers to the krbtgt + * used to decrypt the ticket of the server requesting + * S4U2Proxy. + * + * When we implement service ticket renewal, we need to check + * the PAC, and this will need to be updated. + */ + ret = krb5_pac_get_kdc_checksum_info(context, + *pac, + &ctype, + &rodc_id); + if (ret != 0) { + DEBUG(1, ("Failed to get PAC checksum info\n")); + return ret; + } + + /* + * We need to check the KDC and ticket signatures, fetching the + * correct key based on the enctype. + */ + + my_krbtgt_number = krbtgt_skdc_entry->kdc_db_ctx->my_krbtgt_number; + + if (my_krbtgt_number != 0) { + /* + * If we are an RODC, and we are not the KDC that signed + * the evidence ticket, then we need to proxy the + * request. + */ + if (rodc_id != my_krbtgt_number) { + return HDB_ERR_NOT_FOUND_HERE; + } + } else { + /* + * If we are a DC, the ticket may have been signed by a + * different KDC than the one that issued the header + * ticket. + */ + if (rodc_id != krbtgt->entry.kvno >> 16) { + struct sdb_entry_ex signing_krbtgt_sdb; + + /* + * If we didn't sign the ticket, then return an + * error. + */ + if (rodc_id != 0) { + return KRB5KRB_AP_ERR_MODIFIED; + } + + /* + * Fetch our key from the database. To support + * key rollover, we're going to need to try + * multiple keys by trial and error. For now, + * krbtgt keys aren't assumed to change. + */ + ret = samba_kdc_fetch(context, + krbtgt_skdc_entry->kdc_db_ctx, + krbtgt->entry.principal, + SDB_F_GET_KRBTGT | SDB_F_CANON, + 0, + &signing_krbtgt_sdb); + if (ret != 0) { + return ret; + } + + ret = sdb_entry_ex_to_hdb_entry_ex(context, + &signing_krbtgt_sdb, + &signing_krbtgt_hdb); + sdb_free_entry(&signing_krbtgt_sdb); + if (ret != 0) { + return ret; + } + + /* + * Replace the krbtgt entry with our own entry + * for further processing. + */ + krbtgt = &signing_krbtgt_hdb; + } + } + } + + ret = samba_wdc_reget_pac2(context, + delegated_proxy_principal, + client, + server, + krbtgt, + pac, + ctype); + + if (krbtgt == &signing_krbtgt_hdb) { + hdb_free_entry(context, &signing_krbtgt_hdb); + } + + return ret; +} + static char *get_netbios_name(TALLOC_CTX *mem_ctx, HostAddresses *addrs) { char *nb_name = NULL; -- 2.33.0
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