x509.h

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#ifndef _IPXE_X509_H
#define _IPXE_X509_H

/** @file
 *
 * X.509 certificates
 *
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <stdint.h>
#include <stddef.h>
#include <time.h>
#include <ipxe/asn1.h>
#include <ipxe/refcnt.h>
#include <ipxe/list.h>

struct image;
struct private_key;

/** An X.509 serial number */
struct x509_serial {
        /** Raw serial number */
        struct asn1_cursor raw;
};

/** An X.509 issuer */
struct x509_issuer {
        /** Raw issuer */
        struct asn1_cursor raw;
};

/** An X.509 time */
struct x509_time {
        /** Seconds since the Epoch */
        time_t time;
};

/** An X.509 certificate validity period */
struct x509_validity {
        /** Not valid before */
        struct x509_time not_before;
        /** Not valid after */
        struct x509_time not_after;
};

/** An X.509 certificate public key */
struct x509_public_key {
        /** Raw public key information */
        struct asn1_cursor raw;
        /** Public key algorithm */
        struct asn1_algorithm *algorithm;
        /** Raw public key bit string */
        struct asn1_bit_string raw_bits;
};

/** An X.509 certificate subject */
struct x509_subject {
        /** Raw subject */
        struct asn1_cursor raw;
        /** Common name */
        struct asn1_cursor common_name;
        /** Public key information */
        struct x509_public_key public_key;
};

/** An X.509 certificate signature */
struct x509_signature {
        /** Signature algorithm */
        struct asn1_algorithm *algorithm;
        /** Signature value */
        struct asn1_bit_string value;
};

/** An X.509 certificate basic constraints set */
struct x509_basic_constraints {
        /** Subject is a CA */
        int ca;
        /** Path length */
        unsigned int path_len;
};

/** Unlimited path length
 *
 * We use -2U, since this quantity represents one *fewer* than the
 * maximum number of remaining certificates in a chain.
 */
#define X509_PATH_LEN_UNLIMITED -2U

/** An X.509 certificate key usage */
struct x509_key_usage {
        /** Key usage extension is present */
        int present;
        /** Usage bits */
        unsigned int bits;
};

/** X.509 certificate key usage bits */
enum x509_key_usage_bits {
        X509_DIGITAL_SIGNATURE = 0x0080,
        X509_NON_REPUDIATION = 0x0040,
        X509_KEY_ENCIPHERMENT = 0x0020,
        X509_DATA_ENCIPHERMENT = 0x0010,
        X509_KEY_AGREEMENT = 0x0008,
        X509_KEY_CERT_SIGN = 0x0004,
        X509_CRL_SIGN = 0x0002,
        X509_ENCIPHER_ONLY = 0x0001,
        X509_DECIPHER_ONLY = 0x8000,
};

/** An X.509 certificate extended key usage */
struct x509_extended_key_usage {
        /** Usage bits */
        unsigned int bits;
};

/** X.509 certificate extended key usage bits
 *
 * Extended key usages are identified by OID; these bits are purely an
 * internal definition.
 */
enum x509_extended_key_usage_bits {
        X509_CODE_SIGNING = 0x0001,
        X509_OCSP_SIGNING = 0x0002,
};

/** X.509 certificate OCSP responder */
struct x509_ocsp_responder {
        /** URI */
        struct asn1_cursor uri;
        /** OCSP status is good */
        int good;
};

/** X.509 certificate authority information access */
struct x509_authority_info_access {
        /** OCSP responder */
        struct x509_ocsp_responder ocsp;
};

/** X.509 certificate subject alternative name */
struct x509_subject_alt_name {
        /** Names */
        struct asn1_cursor names;
};

/** X.509 certificate general name types */
enum x509_general_name_types {
        X509_GENERAL_NAME_DNS = ASN1_IMPLICIT_TAG ( 2 ),
        X509_GENERAL_NAME_URI = ASN1_IMPLICIT_TAG ( 6 ),
        X509_GENERAL_NAME_IP = ASN1_IMPLICIT_TAG ( 7 ),
};

/** An X.509 certificate extensions set */
struct x509_extensions {
        /** Basic constraints */
        struct x509_basic_constraints basic;
        /** Key usage */
        struct x509_key_usage usage;
        /** Extended key usage */
        struct x509_extended_key_usage ext_usage;
        /** Authority information access */
        struct x509_authority_info_access auth_info;
        /** Subject alternative name */
        struct x509_subject_alt_name alt_name;
};

/** A link in an X.509 certificate chain */
struct x509_link {
        /** List of links */
        struct list_head list;
        /** Certificate */
        struct x509_certificate *cert;
        /** Flags */
        unsigned int flags;
};

/** X.509 certficate chain link flags */
enum x509_link_flags {
        /** Cross-signed certificate download has been attempted
         *
         * This indicates that a cross-signature download attempt has
         * been made to find a cross-signed issuer for this link's
         * certificate.
         */
        X509_LINK_FL_CROSSED = 0x0001,
        /** OCSP has been attempted
         *
         * This indicates that an OCSP attempt has been made using
         * this link's certificate as an issuer.  (We record the flag
         * on the issuer rather than on the issued certificate, since
         * we want to retry OCSP if an issuer is replaced with a
         * downloaded cross-signed certificate.)
         */
        X509_LINK_FL_OCSPED = 0x0002,
};

/** An X.509 certificate chain */
struct x509_chain {
        /** Reference count */
        struct refcnt refcnt;
        /** List of links */
        struct list_head links;
        /** Mark certificate as found
         *
         * @v store             Certificate store
         * @v cert              X.509 certificate
         */
        void ( * found ) ( struct x509_chain *store,
                           struct x509_certificate *cert );
};

/** An X.509 certificate */
struct x509_certificate {
        /** Reference count */
        struct refcnt refcnt;

        /** Link in certificate store */
        struct x509_link store;

        /** Flags */
        unsigned int flags;
        /** Root against which certificate has been validated (if any) */
        struct x509_root *root;
        /** Maximum number of subsequent certificates in chain */
        unsigned int path_remaining;

        /** Raw certificate */
        struct asn1_cursor raw;
        /** Version */
        unsigned int version;
        /** Serial number */
        struct x509_serial serial;
        /** Raw tbsCertificate */
        struct asn1_cursor tbs;
        /** Signature algorithm */
        struct asn1_algorithm *signature_algorithm;
        /** Issuer */
        struct x509_issuer issuer;
        /** Validity */
        struct x509_validity validity;
        /** Subject */
        struct x509_subject subject;
        /** Signature */
        struct x509_signature signature;
        /** Extensions */
        struct x509_extensions extensions;
};

/** X.509 certificate flags */
enum x509_flags {
        /** Certificate was added at build time */
        X509_FL_PERMANENT = 0x0001,
        /** Certificate was added explicitly at run time */
        X509_FL_EXPLICIT = 0x0002,
};

/**
 * Get reference to X.509 certificate
 *
 * @v cert              X.509 certificate
 * @ret cert            X.509 certificate
 */
static inline __attribute__ (( always_inline )) struct x509_certificate *
x509_get ( struct x509_certificate *cert ) {
        ref_get ( &cert->refcnt );
        return cert;
}

/**
 * Drop reference to X.509 certificate
 *
 * @v cert              X.509 certificate
 */
static inline __attribute__ (( always_inline )) void
x509_put ( struct x509_certificate *cert ) {
        ref_put ( &cert->refcnt );
}

/**
 * Get reference to X.509 certificate chain
 *
 * @v chain             X.509 certificate chain
 * @ret chain           X.509 certificate chain
 */
static inline __attribute__ (( always_inline )) struct x509_chain *
x509_chain_get ( struct x509_chain *chain ) {
        ref_get ( &chain->refcnt );
        return chain;
}

/**
 * Drop reference to X.509 certificate chain
 *
 * @v chain             X.509 certificate chain
 */
static inline __attribute__ (( always_inline )) void
x509_chain_put ( struct x509_chain *chain ) {
        ref_put ( &chain->refcnt );
}

/**
 * Get first certificate in X.509 certificate chain
 *
 * @v chain             X.509 certificate chain
 * @ret cert            X.509 certificate, or NULL
 */
static inline __attribute__ (( always_inline )) struct x509_certificate *
x509_first ( struct x509_chain *chain ) {
        struct x509_link *link;

        link = list_first_entry ( &chain->links, struct x509_link, list );
        return ( link ? link->cert : NULL );
}

/**
 * Get last certificate in X.509 certificate chain
 *
 * @v chain             X.509 certificate chain
 * @ret cert            X.509 certificate, or NULL
 */
static inline __attribute__ (( always_inline )) struct x509_certificate *
x509_last ( struct x509_chain *chain ) {
        struct x509_link *link;

        link = list_last_entry ( &chain->links, struct x509_link, list );
        return ( link ? link->cert : NULL );
}

/** An X.509 extension */
struct x509_extension {
        /** Name */
        const char *name;
        /** Object identifier */
        struct asn1_cursor oid;
        /** Parse extension
         *
         * @v cert              X.509 certificate
         * @v raw               ASN.1 cursor
         * @ret rc              Return status code
         */
        int ( * parse ) ( struct x509_certificate *cert,
                          const struct asn1_cursor *raw );
};

/** An X.509 key purpose */
struct x509_key_purpose {
        /** Name */
        const char *name;
        /** Object identifier */
        struct asn1_cursor oid;
        /** Extended key usage bits */
        unsigned int bits;
};

/** An X.509 access method */
struct x509_access_method {
        /** Name */
        const char *name;
        /** Object identifier */
        struct asn1_cursor oid;
        /** Parse access method
         *
         * @v cert              X.509 certificate
         * @v raw               ASN.1 cursor
         * @ret rc              Return status code
         */
        int ( * parse ) ( struct x509_certificate *cert,
                          const struct asn1_cursor *raw );
};

/** An X.509 root certificate list */
struct x509_root {
        /** Reference count */
        struct refcnt refcnt;
        /** Fingerprint digest algorithm */
        struct digest_algorithm *digest;
        /** Number of certificates */
        unsigned int count;
        /** Certificate fingerprints */
        const void *fingerprints;
};

/**
 * Get reference to X.509 root certificate list
 *
 * @v root              X.509 root certificate list
 * @ret root            X.509 root certificate list
 */
static inline __attribute__ (( always_inline )) struct x509_root *
x509_root_get ( struct x509_root *root ) {
        ref_get ( &root->refcnt );
        return root;
}

/**
 * Drop reference to X.509 root certificate list
 *
 * @v root              X.509 root certificate list
 */
static inline __attribute__ (( always_inline )) void
x509_root_put ( struct x509_root *root ) {
        ref_put ( &root->refcnt );
}

/**
 * Check if X.509 certificate is self-signed
 *
 * @v cert              X.509 certificate
 * @ret is_self_signed  X.509 certificate is self-signed
 */
static inline int x509_is_self_signed ( struct x509_certificate *cert ) {
        return ( asn1_compare ( &cert->issuer.raw, &cert->subject.raw ) == 0 );
}

extern const char * x509_name ( struct x509_certificate *cert );
extern int x509_parse ( struct x509_certificate *cert,
                        const struct asn1_cursor *raw );
extern int x509_certificate ( const void *data, size_t len,
                              struct x509_certificate **cert );
extern int x509_is_valid ( struct x509_certificate *cert,
                           struct x509_root *root );
extern int x509_validate ( struct x509_certificate *cert,
                           struct x509_certificate *issuer,
                           time_t time, struct x509_root *root );
extern int x509_check_name ( struct x509_certificate *cert, const char *name );

extern struct x509_chain * x509_alloc_chain ( void );
extern int x509_append ( struct x509_chain *chain,
                         struct x509_certificate *cert );
extern int x509_append_raw ( struct x509_chain *chain, const void *data,
                             size_t len );
extern void x509_truncate ( struct x509_chain *chain, struct x509_link *link );
extern struct x509_certificate * x509_find ( struct x509_chain *store,
                                             const struct asn1_cursor *raw );
extern struct x509_certificate *
x509_find_subject ( struct x509_chain *store,
                    const struct asn1_cursor *subject );
extern struct x509_certificate *
x509_find_issuer_serial ( struct x509_chain *store,
                          const struct asn1_cursor *issuer,
                          const struct asn1_cursor *serial );
extern struct x509_certificate * x509_find_key ( struct x509_chain *store,
                                                 struct private_key *key );
extern int x509_auto_append ( struct x509_chain *chain,
                              struct x509_chain *store );
extern int x509_validate_chain ( struct x509_chain *chain, time_t time,
                                 struct x509_chain *store,
                                 struct x509_root *root );
extern int image_x509 ( struct image *image, size_t offset,
                        struct x509_certificate **cert );

/* Functions exposed only for unit testing */
extern int x509_check_issuer ( struct x509_certificate *cert,
                               struct x509_certificate *issuer );
extern void x509_fingerprint ( struct x509_certificate *cert,
                               struct digest_algorithm *digest,
                               void *fingerprint );
extern int x509_check_root ( struct x509_certificate *cert,
                             struct x509_root *root );
extern int x509_check_time ( struct x509_certificate *cert, time_t time );

/**
 * Invalidate X.509 certificate
 *
 * @v cert              X.509 certificate
 */
static inline void x509_invalidate ( struct x509_certificate *cert ) {
        x509_root_put ( cert->root );
        cert->root = NULL;
        cert->path_remaining = 0;
}

/**
 * Invalidate X.509 certificate chain
 *
 * @v chain             X.509 certificate chain
 */
static inline void x509_invalidate_chain ( struct x509_chain *chain ) {
        struct x509_link *link;

        list_for_each_entry ( link, &chain->links, list )
                x509_invalidate ( link->cert );
}

#endif /* _IPXE_X509_H */