source: libabac/abac_verifier.c @ da5afdf

// include the GNU extension of asprintf
#define _GNU_SOURCE

#include <assert.h>
#include <stdio.h>

#include <library.h>
#include <credentials/certificates/certificate.h>
#include <credentials/certificates/x509.h>
#include <credentials/certificates/ac.h>

#include "abac_verifier.h"

#include "abac_list.h"
#include "abac_util.h"
#include "abac_rt.h"

extern abac_role_t *abac_get_yap_head_role();
extern abac_role_t *abac_get_yap_tail_role();
extern abac_oset_t *abac_get_yap_head_oset();
extern abac_oset_t *abac_get_yap_tail_oset();
extern int abac_get_yap_is_oset();
extern abac_list_t *abac_get_yap_clauses();
extern char* abac_decode_string(char *);

/* keeping this a fixed enum is to have tighter control of
   what are acceptabletypes of keyid are we allowing */
enum keyidtype {
    e_KEYID = 1
};
/* keyidname[keyidtype] */
static char * const keyidname[] =
{
  "badidtype", "keyid", 0
};

enum credtype {
   e_CREDTYPE_ROLE =1,
   e_CREDTYPE_OSET =2
};

static int keyidname_cnt=1;

struct _abac_id_cert_t {
    char *keyid;
    char *cn;
    int type; /* keyidtype */
    certificate_t *cert;
    char *clause;

    UT_hash_handle hh;
};

/* can store either role or oset */
struct _abac_credential_t {
    int type;
    void *head;
    void *tail;
    certificate_t *cert;
    certificate_t *issuer;
    abac_list_t *clauses;

    int refcount;
};

typedef struct _abac_str_cred_t {
    char *strid;
    abac_credential_t *cred;

    UT_hash_handle hh;
} abac_str_cred_t;

abac_id_cert_t *id_certs = NULL;
abac_str_cred_t *str_creds = NULL;

static int debug=0;
static void check_id_cert(abac_id_cert_t *id_cert);
extern void abac_print_role_string_with_condition(abac_role_t *role, FILE*);

//
void abac_print_cred_info(abac_credential_t *cred, FILE *fp)
{
    if(fp == NULL)
        fp=stdout;

    if(debug) {
        fprintf(fp,"---> printing out credential info cred(%d)..\n", (int) cred);
        if(cred->head) {
            fprintf(fp,"  head cred(%d):\n",(int)cred->head);
            if(cred->type == e_CREDTYPE_ROLE)
               abac_print_role_string_with_condition((abac_role_t*)cred->head,fp);
               else
                   abac_print_oset_string_with_condition((abac_oset_t*)cred->head,fp);
        }
        if(cred->tail) {
            fprintf(fp,"\n  tail cred(%d):\n",(int)cred->tail);
            if(cred->type == e_CREDTYPE_ROLE)
                abac_print_role_string_with_condition((abac_role_t*)cred->tail,fp);
                else
                    abac_print_oset_string_with_condition((abac_oset_t*)cred->tail,fp);
        }

        abac_list_t *clauses=cred->clauses;
        if (clauses != NULL) {
            char *cur=NULL;
            abac_list_foreach(clauses, cur,
                fprintf(fp,"\n  a clause(%d):\n",(int)cur);
                if(cur)
                    fprintf(fp,"strlen(%d)loc(%d)(%s)\n", strlen(cur),(int)cur, cur);
            );
        }
        } else {
            fprintf(fp," ");
            if(cred->type == e_CREDTYPE_ROLE)
                abac_print_role_string_with_condition((abac_role_t *)cred->head,fp);
                else abac_print_oset_string_with_condition((abac_oset_t *)cred->head,fp);
            fprintf(fp," <- ");
            if(cred->type == e_CREDTYPE_ROLE)
                abac_print_role_string_with_condition((abac_role_t *)cred->tail,fp);
                else abac_print_oset_string_with_condition((abac_oset_t *)cred->tail,fp);
            fprintf(fp,"\n");
   }
}

// 
int abac_verify_keyid_type(char *type) {
    int i;

    if (type == NULL)
        return 0;

    for (i = 1; i <= keyidname_cnt ; i++)
        if(strcmp(type,keyidname[i])==0)
            return i;
    return 0;
}

char *abac_keyid_type(int i)
{
    return keyidname[i];
}

// convert a chunk to a lowercase binary string
// malloc's the string
static char *_chunk_to_string(chunk_t chunk) {
    int i;

    char *ret = abac_xmalloc(chunk.len * 2 + 1);

    for (i = 0; i < chunk.len; ++i)
        sprintf(ret + 2 * i, "%02x", chunk.ptr[i]);

    return ret;
}

// verify that cert was issued by issuer
// cert and issuer can be the same, in which case the self-sig is validated
static int _verify_signature(certificate_t *issuer, certificate_t *cert) {
    if (cert->issued_by(cert, issuer))
        if (cert->get_validity(cert, NULL, NULL, NULL))
            return 1;
    return 0;
}

/**
 * Init the verifier subsystem.
 */
void abac_verifier_init(void) {
    // silence all debugging

    if (!library_init(NULL))
        exit(SS_RC_LIBSTRONGSWAN_INTEGRITY);

    if (!lib->plugins->load(lib->plugins, NULL,
            lib->settings->get_str(lib->settings, "pki.load", PLUGINS)))
        exit(SS_RC_INITIALIZATION_FAILED);
}

/**
 * Uninitialize the system, free up any allocated memory.
 */
void abac_verifier_deinit(void) {
    abac_id_cert_t *id;
    while ((id = id_certs) != NULL) {
        HASH_DEL(id_certs, id);

        free(id->keyid);
        free(id->cn);
        id->cert->destroy(id->cert);
        free(id);
    }

    abac_str_cred_t *id2;
    while ((id2 = str_creds) != NULL) {
        HASH_DEL(str_creds, id2);

        free(id2->strid);
        free(id2);
    }

    library_deinit();
}

/**
 * Load an ID certificate.
 */
static int _load_id(certificate_t *cert, abac_id_cert_t **id_cert_ret) {
    abac_id_cert_t *id_cert = NULL;
    char *keyid = NULL;
    chunk_t id;
    int ret;
    x509_t *x509 = (x509_t *)cert;

    assert(cert != NULL);

    // get the key ID
    id = x509->get_subjectKeyIdentifier(x509);
    keyid = _chunk_to_string(id);

    char *str;
    int rv = asprintf(&str, "%Y", cert->get_issuer(cert));

    char *cn=(char *)abac_xmalloc(strlen(str)+2);
    cn[0]='p';
    int n=sscanf(str,"CN=%s", &(cn[1]));
    if ( n!=1 ) { 
        ret = ABAC_CERT_BAD_CN;
        goto error;
    }

    if(debug) {
        printf ("DEBUG:keyid %s \n", keyid);
        printf( "DEBUG:issuer '%s' \n", str);
        printf ("DEBUG:cn %s \n", cn);
    }
    free(str);

    // if we already have this cert 'error' with success
    HASH_FIND_STR(id_certs, keyid, id_cert);
    if (id_cert != NULL) {
        ret = ABAC_CERT_SUCCESS;
        goto error;
    }

    // validate sig
    ret = _verify_signature(cert, cert);
    if (!ret) {
        ret = ABAC_CERT_BAD_SIG;
        goto error;
    }

    // success, add the key to the map of certificates
    id_cert = abac_xmalloc(sizeof(abac_id_cert_t));
    id_cert->keyid = keyid;
    id_cert->cert = cert;
    id_cert->cn = cn;
    /* XXX default it to it now */
    id_cert->type = e_KEYID;
    id_cert->clause = generate_pl_type_clause(cn, id_cert->type);

    HASH_ADD_KEYPTR(hh, id_certs, id_cert->keyid, strlen(id_cert->keyid), id_cert);

    *id_cert_ret=id_cert;

    return ABAC_CERT_SUCCESS;

error:
    if (keyid != NULL) free(keyid);
    if (cn != NULL) free(cn);

    return ret;
}

static void check_id_cert(abac_id_cert_t *id_cert)
{
    if(id_cert) {
        printf("checking on this id_cert %d\n", (int)id_cert);
        printf("  --> sha is (%s)\n", id_cert->keyid);
        printf("  --> cn is (%s)\n", id_cert->cn);
    }
}

/**
 * Load an attribute cert as string.
 * have minimum syntax & validity check
 */
static int _load_attribute_string(char* attr_string) {
    printf("NOT implemented yet!!!");
    return ABAC_CERT_INVALID;
}

/**
 * Load an ID cert from a file.
 */
int abac_verifier_load_id_file(char *filename, abac_id_cert_t **id_cert_ret) {
    if (lib == NULL)
        errx(1, "looks like you didn't call libabac_init() (lib is NULL)");

    // load the cert
    certificate_t *cert = lib->creds->create(
        lib->creds, CRED_CERTIFICATE, CERT_X509,
        BUILD_FROM_FILE, filename,
        BUILD_X509_FLAG, X509_AA, // attribute authority, dumb
        BUILD_END
    );
    if (cert == NULL)
        return ABAC_CERT_INVALID;
    return _load_id(cert,id_cert_ret);
}

/**
 * Load an ID cert from a chunk.
 */
int abac_verifier_load_id_chunk(chunk_t chunk, abac_id_cert_t **id_cert_ret) {
    // load the cert
    certificate_t *cert = lib->creds->create(
        lib->creds, CRED_CERTIFICATE, CERT_X509,
        BUILD_BLOB_ASN1_DER, chunk,
        BUILD_X509_FLAG, X509_AA, // attribute authority, dumb
        BUILD_END
    );
    if (cert == NULL)
        return ABAC_CERT_INVALID;
    return _load_id(cert,id_cert_ret);
}


void abac_print_clauses(abac_list_t *clauses, FILE *fp)
{
    if (clauses != NULL) {
        char *cur;
        abac_list_foreach(clauses, cur,
            if(cur) {
                if(fp)
                    fprintf (fp,"a clause, %d(%s)\n", (int)cur,cur);
                    else printf ("a clause, %d(%s)\n", (int)cur,cur);
            }
        );
    }
}

static int _verify_valid_role_credential(certificate_t *cert,
abac_credential_t **cred_ret, char *encoded_attr_string)
{
    abac_role_t *head_role = NULL;
    abac_role_t *tail_role = NULL;
    abac_list_t *clauses=NULL;
    abac_id_cert_t *issuer;
    int ret, i;

    // get the attr
    head_role = abac_get_yap_head_role();
    tail_role = abac_get_yap_tail_role();
    clauses = abac_get_yap_clauses();

    // get the issuer based on keyid
    char *principalname = abac_role_principal(head_role);
    HASH_FIND_STR(id_certs, principalname, issuer);
    if (issuer == NULL) {
        ret = ABAC_CERT_MISSING_ISSUER;
        goto error;
    }

    // make sure the issuer's signed it
    ret = _verify_signature(issuer->cert, cert);
    if (!ret) {
        set_error_code(ABAC_RT_CERT_BAD_SIG);
        goto error;
    }

    // at this point we know we have a good attribute cert
    abac_credential_t *cred = abac_xmalloc(sizeof(abac_credential_t));
    cred->type= e_CREDTYPE_ROLE;
    cred->head = head_role;
    cred->tail = tail_role;
    cred->cert = cert;
    cred->issuer = issuer->cert->get_ref(issuer->cert);
    cred->clauses = clauses;
    cred->refcount = 1;
    *cred_ret = cred;

    // success, add the key to the map of certificates
    abac_str_cred_t *str_cred;
    str_cred=abac_xmalloc(sizeof(abac_str_cred_t));
    str_cred->strid=strdup(encoded_attr_string);
    str_cred->cred=cred;
    HASH_ADD_KEYPTR(hh, str_creds, str_cred->strid, strlen(str_cred->strid), str_cred);

    return ABAC_CERT_SUCCESS;

error:
    if (head_role) abac_role_free(head_role);
    if (tail_role) abac_role_free(tail_role);
    abac_free_yap_clauses();

    return ret;
}

static int _verify_valid_oset_credential(certificate_t *cert,
abac_credential_t **cred_ret, char *encoded_attr_string)
{
    abac_oset_t *head_oset = NULL;
    abac_oset_t *tail_oset = NULL;
    abac_list_t *clauses=NULL;
    abac_id_cert_t *issuer;
    int ret, i;

    // get the attr
    head_oset = abac_get_yap_head_oset();
    tail_oset = abac_get_yap_tail_oset();
    clauses = abac_get_yap_clauses();

    // get the issuer based on keyid
    char *principalname = abac_oset_principal(head_oset);
    HASH_FIND_STR(id_certs, principalname, issuer);
    if (issuer == NULL) {
        ret = ABAC_CERT_MISSING_ISSUER;
        goto error;
    }

    // make sure the issuer's signed it
    ret = _verify_signature(issuer->cert, cert);
    if (!ret) {
        set_error_code(ABAC_RT_CERT_BAD_SIG);
        goto error;
    }

    // at this point we know we have a good attribute cert
    abac_credential_t *cred = abac_xmalloc(sizeof(abac_credential_t));
    cred->type= e_CREDTYPE_OSET;
    cred->head = head_oset;
    cred->tail = tail_oset;
    cred->cert = cert;
    cred->issuer = issuer->cert->get_ref(issuer->cert);
    cred->clauses = clauses;
    cred->refcount = 1;
    *cred_ret = cred;

    // success, add the key to the map of certificates
    abac_str_cred_t *str_cred;
    str_cred=abac_xmalloc(sizeof(abac_str_cred_t));
    str_cred->strid=strdup(encoded_attr_string);
    str_cred->cred=cred;
    HASH_ADD_KEYPTR(hh, str_creds, str_cred->strid, strlen(str_cred->strid), str_cred);

    return ABAC_CERT_SUCCESS;

error:
    if (head_oset) abac_oset_free(head_oset);
    if (tail_oset) abac_oset_free(tail_oset);
    abac_free_yap_clauses();

    return ret;
}
/**
 * Load an attribute cert.
 * Returns true only if the certificate is valid and is issued by the proper
 * authority.
 */
static int _load_attribute_cert(certificate_t *cert, abac_credential_t **cred_ret) {
    ietf_attributes_t *attr_cert = NULL;
    abac_id_cert_t *issuer;
    int ret, i;

    // get the attr
    ac_t *ac = (ac_t *)cert;
    attr_cert = ac->get_groups(ac);
    if (attr_cert == NULL) {
        ret = ABAC_CERT_INVALID;
        goto error;
    }

    char *encoded_attr_string=attr_cert->get_string(attr_cert);
    char *attr_string = abac_decode_string(encoded_attr_string);
    if(debug)
         printf("string to be yyparse..(%s)\n",attr_string);

    if (attr_string == NULL) {
        ret = ABAC_CERT_INVALID;
        goto error;
    }

    /* call into yacc parser */
    abac_reset_yyfptr(attr_string);
    abac_yyinit();
    int rc=yyparse();
    if (rc) {
        ret = ABAC_CERT_INVALID;
        goto error;
    }

    if(abac_get_yap_is_oset()) {
        ret=_verify_valid_oset_credential(cert,cred_ret,encoded_attr_string);
        } else {
            ret=_verify_valid_role_credential(cert,cred_ret,encoded_attr_string);
    }

    // free up some crap
    attr_cert->destroy(attr_cert);

    return ABAC_CERT_SUCCESS;

error:
    if (cert) cert->destroy(cert);
    if (attr_cert) attr_cert->destroy(attr_cert);
    return ret;
}

/**
 * Load an attribute cert from a file.
 */
int abac_verifier_load_attribute_cert_file(char *filename, abac_credential_t **cred) {
    // load the cert
    certificate_t *cert = lib->creds->create(
        lib->creds, CRED_CERTIFICATE, CERT_X509_AC,
        BUILD_FROM_FILE, filename,
        BUILD_END
    );
    if (cert == NULL)
        return ABAC_CERT_INVALID;
    return _load_attribute_cert(cert, cred);
}

/**
 * Load attribute cert rules from a file. (this should only be used to test) 
 */
int abac_verifier_load_certs_file(char *filename) {
    size_t nbytes=0;
    char *input=NULL;
    FILE *fp;
    int ret;

    fp=fopen(filename, "r");

    if(fp == NULL)
        return ABAC_CERT_INVALID;

    while( (ret=getline(&input, &nbytes, fp)) != -1 ) {
        ret=_load_attribute_string(input);
        free(input);
        if(ret != ABAC_CERT_SUCCESS )
            fclose(fp);
            return ret;
    }
    fclose(fp);
    return ABAC_CERT_SUCCESS;
}


/**
 * Load an attribute cert from a chunk.
 */
int abac_verifier_load_attribute_cert_chunk(chunk_t chunk, abac_credential_t **cred) {
    // load the cert
    certificate_t *cert = lib->creds->create(
        lib->creds, CRED_CERTIFICATE, CERT_X509_AC,
        BUILD_BLOB_ASN1_DER, chunk,
        BUILD_END
    );
    if (cert == NULL)
        return ABAC_CERT_INVALID;
    return _load_attribute_cert(cert, cred);
}

/**
 * Return the encoding of the attribute cert.
 */
abac_chunk_t abac_credential_attribute_cert(abac_credential_t *cred) {
    chunk_t encoding = cred->cert->get_encoding(cred->cert);
    abac_chunk_t ret = { encoding.ptr, encoding.len };
    return ret;
}

/**
 * Return the encoding of the issuer cert.
 */
abac_chunk_t abac_credential_issuer_cert(abac_credential_t *cred) {
    chunk_t encoding = cred->issuer->get_encoding(cred->issuer);
    abac_chunk_t ret = { encoding.ptr, encoding.len };
    return ret;
}

/**
 * Return the clause of the cert
 */
abac_list_t *abac_credential_clauses(abac_credential_t *cred) {
    return cred->clauses;
}


/**
 * Increase the ref count of a credential.
 */
abac_credential_t *abac_credential_dup(abac_credential_t *cred) {
    assert(cred != NULL);

    ++cred->refcount;
    return cred;
}

/**
 *  lookup for a credential.
 */
abac_credential_t *abac_credential_lookup(char* cred_string)
{
    if(debug)
        printf("DEBUG:doing abac_crendential_lookup ... (%s)\n", cred_string);
    abac_str_cred_t *str_cred;
    HASH_FIND_STR(str_creds, cred_string, str_cred);
    if (str_cred == NULL) {
        if(debug) printf("DEBUG:NOT FOUND..\n");
        return NULL;
    }
    if(debug) printf("DEBUG:FOUND..(%d)\n", (int) str_cred->cred);
    return str_cred->cred;
}

/**
 * Decrease the reference count of a credential, freeing it when it reaches 0.
 */
void abac_credential_free(abac_credential_t *cred)
{
    if(debug)
        printf("DEBUG:freeing cred(%d)clause(%d)\n", (int)cred, (int)cred->clauses);

    if (cred == NULL)
        return;

    --cred->refcount;
    if (cred->refcount > 0)
        return;

    if(cred->type == e_CREDTYPE_ROLE) {
        abac_role_free((abac_role_t *)cred->head);
        abac_role_free((abac_role_t *)cred->tail);
        } else {
            abac_oset_free((abac_oset_t *)cred->head);
            abac_oset_free((abac_oset_t *)cred->tail);
    }
    cred->cert->destroy(cred->cert);
    cred->issuer->destroy(cred->issuer); // reference counted
    /* no need to free yap_clauses here */
    free(cred);
}

char *abac_id_clause(abac_id_cert_t *id_cert)
{
    if(id_cert)
        return id_cert->clause;
    return NULL;
}

/* retrieve the cn that is associated with this sha_string */
char *abac_cn_with_sha(char *sha_string) {

    // get the issuer based on keyid
    abac_id_cert_t *id_cert;
    HASH_FIND_STR(id_certs, sha_string, id_cert);
    if (id_cert == NULL) {
        return NULL;
    }
    if(debug)
        check_id_cert(id_cert);
    return id_cert->cn;
}

/* retrieve the cn that is associated with the principal of this role */
char *abac_cn_with_role(abac_role_t *role) {

    char *principal = abac_role_principal(role);
    return abac_cn_with_sha(principal);
}

/* retrieve the cn that is associated with the principal of this oset */
char *abac_cn_with_oset(abac_oset_t *oset) {

    char *principal = abac_oset_principal(oset);
    return abac_cn_with_sha(principal);
}