From 0e6e8dd2600c699a7a02e3d11fed21b5bc49858d Mon Sep 17 00:00:00 2001 From: Alexander Bokovoy Date: Fri, 3 Mar 2017 16:14:57 +0200 Subject: [PATCH] lib/krb5_wrap: add smb_gss_krb5_import_cred wrapper Wrap gss_krb5_import_cred() to allow re-implementing it with gss_acquire_cred_from() for newer MIT versions. gss_acquire_cred_from() works fine with GSSAPI interposer (GSS-proxy) while gss_krb5_import_cred() is not interposed yet. The wrapper has additional parameter, krb5_context handle, to facilitate with credentials cache name discovery. All our callers to gss_krb5_import_cred() already have krb5 context handy. BUG: https://bugzilla.samba.org/show_bug.cgi?id=12611 Signed-off-by: Alexander Bokovoy Reviewed-by: Stefan Metzmacher --- lib/krb5_wrap/gss_samba.c | 121 ++++++++++++++++++++++++++++++++++++++ lib/krb5_wrap/gss_samba.h | 13 ++++ 2 files changed, 134 insertions(+) diff --git a/lib/krb5_wrap/gss_samba.c b/lib/krb5_wrap/gss_samba.c index b444633e280..757ffc5a33e 100644 --- a/lib/krb5_wrap/gss_samba.c +++ b/lib/krb5_wrap/gss_samba.c @@ -48,4 +48,125 @@ int smb_gss_oid_equal(const gss_OID first_oid, const gss_OID second_oid) } #endif /* !HAVE_GSS_OID_EQUAL */ + +/* wrapper around gss_krb5_import_cred() that prefers to use gss_acquire_cred_from() + * if this GSSAPI extension is available. gss_acquire_cred_from() is properly + * interposed by GSSPROXY while gss_krb5_import_cred() is not. + * + * This wrapper requires a proper krb5_context to resolve ccache name. + * All gss_krb5_import_cred() callers in Samba already have krb5_context available. */ +uint32_t smb_gss_krb5_import_cred(uint32_t *minor_status, krb5_context ctx, + krb5_ccache id, krb5_principal keytab_principal, + krb5_keytab keytab, gss_cred_id_t *cred) +{ + uint32_t major_status = 0; + +#if HAVE_GSS_ACQUIRE_CRED_FROM + uint32_t minor = 0; + gss_key_value_element_desc ccache_element = { + .key = "ccache", + .value = NULL, + }; + + gss_key_value_element_desc keytab_element = { + .key = "keytab", + .value = NULL, + }; + + gss_key_value_element_desc elements[2]; + + gss_key_value_set_desc cred_store = { + .elements = &ccache_element, + .count = 1, + }; + + gss_OID_set mech_set = GSS_C_NO_OID_SET; + gss_cred_usage_t cred_usage = GSS_C_INITIATE; + gss_name_t name = NULL; + gss_buffer_desc pr_name = { + .value = NULL, + .length = 0, + }; + + if (id != NULL) { + major_status = krb5_cc_get_full_name(ctx, + id, + discard_const(&ccache_element.value)); + if (major_status != 0) { + return major_status; + } + } + + if (keytab != NULL) { + keytab_element.value = malloc(4096); + if (!keytab_element.value) { + return ENOMEM; + } + major_status = krb5_kt_get_name(ctx, + keytab, + discard_const(keytab_element.value), 4096); + if (major_status != 0) { + free(discard_const(keytab_element.value)); + return major_status; + } + cred_usage = GSS_C_ACCEPT; + cred_store.elements = &keytab_element; + + if (keytab_principal != NULL) { + major_status = krb5_unparse_name(ctx, keytab_principal, (char**)&pr_name.value); + if (major_status != 0) { + free(discard_const(keytab_element.value)); + return major_status; + } + pr_name.length = strlen(pr_name.value); + + major_status = gss_import_name(minor_status, + &pr_name, + discard_const(GSS_KRB5_NT_PRINCIPAL_NAME), + &name); + if (major_status != 0) { + krb5_free_unparsed_name(ctx, pr_name.value); + free(discard_const(keytab_element.value)); + return major_status; + } + } + } + + if (id != NULL && keytab != NULL) { + elements[0] = ccache_element; + elements[1] = keytab_element; + + cred_store.elements = elements; + cred_store.count = 2; + cred_usage = GSS_C_BOTH; + } + + major_status = gss_acquire_cred_from(minor_status, + name, + 0, + mech_set, + cred_usage, + &cred_store, + cred, + NULL, + NULL); + + if (pr_name.value != NULL) { + (void)gss_release_name(&minor, &name); + krb5_free_unparsed_name(ctx, pr_name.value); + } + if (keytab_element.value != NULL) { + free(discard_const(keytab_element.value)); + } + krb5_free_string(ctx, discard_const(ccache_element.value)); +#else + major_status = gss_krb5_import_cred(minor_status, + id, + keytab_principal, + keytab, cred); +#endif + return major_status; +} + + #endif /* HAVE_GSSAPI */ diff --git a/lib/krb5_wrap/gss_samba.h b/lib/krb5_wrap/gss_samba.h index 531993263bb..89aee3479c5 100644 --- a/lib/krb5_wrap/gss_samba.h +++ b/lib/krb5_wrap/gss_samba.h @@ -25,6 +25,7 @@ #ifdef HAVE_GSSAPI #include "system/gssapi.h" +#include "krb5_samba.h" #if defined(HAVE_GSS_OID_EQUAL) #define smb_gss_oid_equal gss_oid_equal @@ -32,5 +33,17 @@ int smb_gss_oid_equal(const gss_OID first_oid, const gss_OID second_oid); #endif /* HAVE_GSS_OID_EQUAL */ +/* wrapper around gss_krb5_import_cred() that prefers to use gss_acquire_cred_from() + * if this GSSAPI extension is available. gss_acquire_cred_from() is properly + * interposed by GSS-proxy while gss_krb5_import_cred() is not. + * + * This wrapper requires a proper krb5_context to resolve the ccache name for + * gss_acquire_cred_from(). + * + * All gss_krb5_import_cred() callers in Samba already have krb5_context available. */ +uint32_t smb_gss_krb5_import_cred(OM_uint32 *minor_status, krb5_context ctx, + krb5_ccache id, krb5_principal keytab_principal, + krb5_keytab keytab, gss_cred_id_t *cred); + #endif /* HAVE_GSSAPI */ #endif /* _GSS_SAMBA_H */ -- 2.34.1