/** * \file asn1.h * * \brief Generic ASN.1 parsing */ /* * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later */ #ifndef MBEDTLS_ASN1_H #define MBEDTLS_ASN1_H #include "mbedtls/private_access.h" #include "mbedtls/build_info.h" #include "mbedtls/platform_util.h" #include <stddef.h> #if defined(MBEDTLS_BIGNUM_C) #include "mbedtls/bignum.h" #endif /** * \addtogroup asn1_module * \{ */ /** * \name ASN1 Error codes * These error codes are combined with other error codes for * higher error granularity. * e.g. X.509 and PKCS #7 error codes * ASN1 is a standard to specify data structures. * \{ */ /** Out of data when parsing an ASN1 data structure. */ #define MBEDTLS_ERR_ASN1_OUT_OF_DATA … /** ASN1 tag was of an unexpected value. */ #define MBEDTLS_ERR_ASN1_UNEXPECTED_TAG … /** Error when trying to determine the length or invalid length. */ #define MBEDTLS_ERR_ASN1_INVALID_LENGTH … /** Actual length differs from expected length. */ #define MBEDTLS_ERR_ASN1_LENGTH_MISMATCH … /** Data is invalid. */ #define MBEDTLS_ERR_ASN1_INVALID_DATA … /** Memory allocation failed */ #define MBEDTLS_ERR_ASN1_ALLOC_FAILED … /** Buffer too small when writing ASN.1 data structure. */ #define MBEDTLS_ERR_ASN1_BUF_TOO_SMALL … /** \} name ASN1 Error codes */ /** * \name DER constants * These constants comply with the DER encoded ASN.1 type tags. * DER encoding uses hexadecimal representation. * An example DER sequence is:\n * - 0x02 -- tag indicating INTEGER * - 0x01 -- length in octets * - 0x05 -- value * Such sequences are typically read into \c ::mbedtls_x509_buf. * \{ */ #define MBEDTLS_ASN1_BOOLEAN … #define MBEDTLS_ASN1_INTEGER … #define MBEDTLS_ASN1_BIT_STRING … #define MBEDTLS_ASN1_OCTET_STRING … #define MBEDTLS_ASN1_NULL … #define MBEDTLS_ASN1_OID … #define MBEDTLS_ASN1_ENUMERATED … #define MBEDTLS_ASN1_UTF8_STRING … #define MBEDTLS_ASN1_SEQUENCE … #define MBEDTLS_ASN1_SET … #define MBEDTLS_ASN1_PRINTABLE_STRING … #define MBEDTLS_ASN1_T61_STRING … #define MBEDTLS_ASN1_IA5_STRING … #define MBEDTLS_ASN1_UTC_TIME … #define MBEDTLS_ASN1_GENERALIZED_TIME … #define MBEDTLS_ASN1_UNIVERSAL_STRING … #define MBEDTLS_ASN1_BMP_STRING … #define MBEDTLS_ASN1_PRIMITIVE … #define MBEDTLS_ASN1_CONSTRUCTED … #define MBEDTLS_ASN1_CONTEXT_SPECIFIC … /* Slightly smaller way to check if tag is a string tag * compared to canonical implementation. */ #define MBEDTLS_ASN1_IS_STRING_TAG(tag) … /* * Bit masks for each of the components of an ASN.1 tag as specified in * ITU X.690 (08/2015), section 8.1 "General rules for encoding", * paragraph 8.1.2.2: * * Bit 8 7 6 5 1 * +-------+-----+------------+ * | Class | P/C | Tag number | * +-------+-----+------------+ */ #define MBEDTLS_ASN1_TAG_CLASS_MASK … #define MBEDTLS_ASN1_TAG_PC_MASK … #define MBEDTLS_ASN1_TAG_VALUE_MASK … /** \} name DER constants */ /** Returns the size of the binary string, without the trailing \\0 */ #define MBEDTLS_OID_SIZE(x) … /** * Compares an mbedtls_asn1_buf structure to a reference OID. * * Only works for 'defined' oid_str values (MBEDTLS_OID_HMAC_SHA1), you cannot use a * 'unsigned char *oid' here! */ #define MBEDTLS_OID_CMP(oid_str, oid_buf) … #define MBEDTLS_OID_CMP_RAW(oid_str, oid_buf, oid_buf_len) … #ifdef __cplusplus extern "C" { #endif /** * \name Functions to parse ASN.1 data structures * \{ */ /** * Type-length-value structure that allows for ASN1 using DER. */ mbedtls_asn1_buf; /** * Container for ASN1 bit strings. */ mbedtls_asn1_bitstring; /** * Container for a sequence of ASN.1 items */ mbedtls_asn1_sequence; /** * Container for a sequence or list of 'named' ASN.1 data items */ mbedtls_asn1_named_data; #if defined(MBEDTLS_ASN1_PARSE_C) || defined(MBEDTLS_X509_CREATE_C) || \ defined(MBEDTLS_PSA_UTIL_HAVE_ECDSA) /** * \brief Get the length of an ASN.1 element. * Updates the pointer to immediately behind the length. * * \param p On entry, \c *p points to the first byte of the length, * i.e. immediately after the tag. * On successful completion, \c *p points to the first byte * after the length, i.e. the first byte of the content. * On error, the value of \c *p is undefined. * \param end End of data. * \param len On successful completion, \c *len contains the length * read from the ASN.1 input. * * \return 0 if successful. * \return #MBEDTLS_ERR_ASN1_OUT_OF_DATA if the ASN.1 element * would end beyond \p end. * \return #MBEDTLS_ERR_ASN1_INVALID_LENGTH if the length is unparsable. */ int mbedtls_asn1_get_len(unsigned char **p, const unsigned char *end, size_t *len); /** * \brief Get the tag and length of the element. * Check for the requested tag. * Updates the pointer to immediately behind the tag and length. * * \param p On entry, \c *p points to the start of the ASN.1 element. * On successful completion, \c *p points to the first byte * after the length, i.e. the first byte of the content. * On error, the value of \c *p is undefined. * \param end End of data. * \param len On successful completion, \c *len contains the length * read from the ASN.1 input. * \param tag The expected tag. * * \return 0 if successful. * \return #MBEDTLS_ERR_ASN1_UNEXPECTED_TAG if the data does not start * with the requested tag. * \return #MBEDTLS_ERR_ASN1_OUT_OF_DATA if the ASN.1 element * would end beyond \p end. * \return #MBEDTLS_ERR_ASN1_INVALID_LENGTH if the length is unparsable. */ int mbedtls_asn1_get_tag(unsigned char **p, const unsigned char *end, size_t *len, int tag); #endif /* MBEDTLS_ASN1_PARSE_C || MBEDTLS_X509_CREATE_C || MBEDTLS_PSA_UTIL_HAVE_ECDSA */ #if defined(MBEDTLS_ASN1_PARSE_C) /** * \brief Retrieve a boolean ASN.1 tag and its value. * Updates the pointer to immediately behind the full tag. * * \param p On entry, \c *p points to the start of the ASN.1 element. * On successful completion, \c *p points to the first byte * beyond the ASN.1 element. * On error, the value of \c *p is undefined. * \param end End of data. * \param val On success, the parsed value (\c 0 or \c 1). * * \return 0 if successful. * \return An ASN.1 error code if the input does not start with * a valid ASN.1 BOOLEAN. */ int mbedtls_asn1_get_bool(unsigned char **p, const unsigned char *end, int *val); /** * \brief Retrieve an integer ASN.1 tag and its value. * Updates the pointer to immediately behind the full tag. * * \param p On entry, \c *p points to the start of the ASN.1 element. * On successful completion, \c *p points to the first byte * beyond the ASN.1 element. * On error, the value of \c *p is undefined. * \param end End of data. * \param val On success, the parsed value. * * \return 0 if successful. * \return An ASN.1 error code if the input does not start with * a valid ASN.1 INTEGER. * \return #MBEDTLS_ERR_ASN1_INVALID_LENGTH if the parsed value does * not fit in an \c int. */ int mbedtls_asn1_get_int(unsigned char **p, const unsigned char *end, int *val); /** * \brief Retrieve an enumerated ASN.1 tag and its value. * Updates the pointer to immediately behind the full tag. * * \param p On entry, \c *p points to the start of the ASN.1 element. * On successful completion, \c *p points to the first byte * beyond the ASN.1 element. * On error, the value of \c *p is undefined. * \param end End of data. * \param val On success, the parsed value. * * \return 0 if successful. * \return An ASN.1 error code if the input does not start with * a valid ASN.1 ENUMERATED. * \return #MBEDTLS_ERR_ASN1_INVALID_LENGTH if the parsed value does * not fit in an \c int. */ int mbedtls_asn1_get_enum(unsigned char **p, const unsigned char *end, int *val); /** * \brief Retrieve a bitstring ASN.1 tag and its value. * Updates the pointer to immediately behind the full tag. * * \param p On entry, \c *p points to the start of the ASN.1 element. * On successful completion, \c *p is equal to \p end. * On error, the value of \c *p is undefined. * \param end End of data. * \param bs On success, ::mbedtls_asn1_bitstring information about * the parsed value. * * \return 0 if successful. * \return #MBEDTLS_ERR_ASN1_LENGTH_MISMATCH if the input contains * extra data after a valid BIT STRING. * \return An ASN.1 error code if the input does not start with * a valid ASN.1 BIT STRING. */ int mbedtls_asn1_get_bitstring(unsigned char **p, const unsigned char *end, mbedtls_asn1_bitstring *bs); /** * \brief Retrieve a bitstring ASN.1 tag without unused bits and its * value. * Updates the pointer to the beginning of the bit/octet string. * * \param p On entry, \c *p points to the start of the ASN.1 element. * On successful completion, \c *p points to the first byte * of the content of the BIT STRING. * On error, the value of \c *p is undefined. * \param end End of data. * \param len On success, \c *len is the length of the content in bytes. * * \return 0 if successful. * \return #MBEDTLS_ERR_ASN1_INVALID_DATA if the input starts with * a valid BIT STRING with a nonzero number of unused bits. * \return An ASN.1 error code if the input does not start with * a valid ASN.1 BIT STRING. */ int mbedtls_asn1_get_bitstring_null(unsigned char **p, const unsigned char *end, size_t *len); /** * \brief Parses and splits an ASN.1 "SEQUENCE OF <tag>". * Updates the pointer to immediately behind the full sequence tag. * * This function allocates memory for the sequence elements. You can free * the allocated memory with mbedtls_asn1_sequence_free(). * * \note On error, this function may return a partial list in \p cur. * You must set `cur->next = NULL` before calling this function! * Otherwise it is impossible to distinguish a previously non-null * pointer from a pointer to an object allocated by this function. * * \note If the sequence is empty, this function does not modify * \c *cur. If the sequence is valid and non-empty, this * function sets `cur->buf.tag` to \p tag. This allows * callers to distinguish between an empty sequence and * a one-element sequence. * * \param p On entry, \c *p points to the start of the ASN.1 element. * On successful completion, \c *p is equal to \p end. * On error, the value of \c *p is undefined. * \param end End of data. * \param cur A ::mbedtls_asn1_sequence which this function fills. * When this function returns, \c *cur is the head of a linked * list. Each node in this list is allocated with * mbedtls_calloc() apart from \p cur itself, and should * therefore be freed with mbedtls_free(). * The list describes the content of the sequence. * The head of the list (i.e. \c *cur itself) describes the * first element, `*cur->next` describes the second element, etc. * For each element, `buf.tag == tag`, `buf.len` is the length * of the content of the content of the element, and `buf.p` * points to the first byte of the content (i.e. immediately * past the length of the element). * Note that list elements may be allocated even on error. * \param tag Each element of the sequence must have this tag. * * \return 0 if successful. * \return #MBEDTLS_ERR_ASN1_LENGTH_MISMATCH if the input contains * extra data after a valid SEQUENCE OF \p tag. * \return #MBEDTLS_ERR_ASN1_UNEXPECTED_TAG if the input starts with * an ASN.1 SEQUENCE in which an element has a tag that * is different from \p tag. * \return #MBEDTLS_ERR_ASN1_ALLOC_FAILED if a memory allocation failed. * \return An ASN.1 error code if the input does not start with * a valid ASN.1 SEQUENCE. */ int mbedtls_asn1_get_sequence_of(unsigned char **p, const unsigned char *end, mbedtls_asn1_sequence *cur, int tag); /** * \brief Free a heap-allocated linked list presentation of * an ASN.1 sequence, including the first element. * * There are two common ways to manage the memory used for the representation * of a parsed ASN.1 sequence: * - Allocate a head node `mbedtls_asn1_sequence *head` with mbedtls_calloc(). * Pass this node as the `cur` argument to mbedtls_asn1_get_sequence_of(). * When you have finished processing the sequence, * call mbedtls_asn1_sequence_free() on `head`. * - Allocate a head node `mbedtls_asn1_sequence *head` in any manner, * for example on the stack. Make sure that `head->next == NULL`. * Pass `head` as the `cur` argument to mbedtls_asn1_get_sequence_of(). * When you have finished processing the sequence, * call mbedtls_asn1_sequence_free() on `head->cur`, * then free `head` itself in the appropriate manner. * * \param seq The address of the first sequence component. This may * be \c NULL, in which case this functions returns * immediately. */ void mbedtls_asn1_sequence_free(mbedtls_asn1_sequence *seq); /** * \brief Traverse an ASN.1 SEQUENCE container and * call a callback for each entry. * * This function checks that the input is a SEQUENCE of elements that * each have a "must" tag, and calls a callback function on the elements * that have a "may" tag. * * For example, to validate that the input is a SEQUENCE of `tag1` and call * `cb` on each element, use * ``` * mbedtls_asn1_traverse_sequence_of(&p, end, 0xff, tag1, 0, 0, cb, ctx); * ``` * * To validate that the input is a SEQUENCE of ANY and call `cb` on * each element, use * ``` * mbedtls_asn1_traverse_sequence_of(&p, end, 0, 0, 0, 0, cb, ctx); * ``` * * To validate that the input is a SEQUENCE of CHOICE {NULL, OCTET STRING} * and call `cb` on each element that is an OCTET STRING, use * ``` * mbedtls_asn1_traverse_sequence_of(&p, end, 0xfe, 0x04, 0xff, 0x04, cb, ctx); * ``` * * The callback is called on the elements with a "may" tag from left to * right. If the input is not a valid SEQUENCE of elements with a "must" tag, * the callback is called on the elements up to the leftmost point where * the input is invalid. * * \warning This function is still experimental and may change * at any time. * * \param p The address of the pointer to the beginning of * the ASN.1 SEQUENCE header. This is updated to * point to the end of the ASN.1 SEQUENCE container * on a successful invocation. * \param end The end of the ASN.1 SEQUENCE container. * \param tag_must_mask A mask to be applied to the ASN.1 tags found within * the SEQUENCE before comparing to \p tag_must_val. * \param tag_must_val The required value of each ASN.1 tag found in the * SEQUENCE, after masking with \p tag_must_mask. * Mismatching tags lead to an error. * For example, a value of \c 0 for both \p tag_must_mask * and \p tag_must_val means that every tag is allowed, * while a value of \c 0xFF for \p tag_must_mask means * that \p tag_must_val is the only allowed tag. * \param tag_may_mask A mask to be applied to the ASN.1 tags found within * the SEQUENCE before comparing to \p tag_may_val. * \param tag_may_val The desired value of each ASN.1 tag found in the * SEQUENCE, after masking with \p tag_may_mask. * Mismatching tags will be silently ignored. * For example, a value of \c 0 for \p tag_may_mask and * \p tag_may_val means that any tag will be considered, * while a value of \c 0xFF for \p tag_may_mask means * that all tags with value different from \p tag_may_val * will be ignored. * \param cb The callback to trigger for each component * in the ASN.1 SEQUENCE that matches \p tag_may_val. * The callback function is called with the following * parameters: * - \p ctx. * - The tag of the current element. * - A pointer to the start of the current element's * content inside the input. * - The length of the content of the current element. * If the callback returns a non-zero value, * the function stops immediately, * forwarding the callback's return value. * \param ctx The context to be passed to the callback \p cb. * * \return \c 0 if successful the entire ASN.1 SEQUENCE * was traversed without parsing or callback errors. * \return #MBEDTLS_ERR_ASN1_LENGTH_MISMATCH if the input * contains extra data after a valid SEQUENCE * of elements with an accepted tag. * \return #MBEDTLS_ERR_ASN1_UNEXPECTED_TAG if the input starts * with an ASN.1 SEQUENCE in which an element has a tag * that is not accepted. * \return An ASN.1 error code if the input does not start with * a valid ASN.1 SEQUENCE. * \return A non-zero error code forwarded from the callback * \p cb in case the latter returns a non-zero value. */ int mbedtls_asn1_traverse_sequence_of( unsigned char **p, const unsigned char *end, unsigned char tag_must_mask, unsigned char tag_must_val, unsigned char tag_may_mask, unsigned char tag_may_val, int (*cb)(void *ctx, int tag, unsigned char *start, size_t len), void *ctx); #if defined(MBEDTLS_BIGNUM_C) /** * \brief Retrieve an integer ASN.1 tag and its value. * Updates the pointer to immediately behind the full tag. * * \param p On entry, \c *p points to the start of the ASN.1 element. * On successful completion, \c *p points to the first byte * beyond the ASN.1 element. * On error, the value of \c *p is undefined. * \param end End of data. * \param X On success, the parsed value. * * \return 0 if successful. * \return An ASN.1 error code if the input does not start with * a valid ASN.1 INTEGER. * \return #MBEDTLS_ERR_ASN1_INVALID_LENGTH if the parsed value does * not fit in an \c int. * \return An MPI error code if the parsed value is too large. */ int mbedtls_asn1_get_mpi(unsigned char **p, const unsigned char *end, mbedtls_mpi *X); #endif /* MBEDTLS_BIGNUM_C */ /** * \brief Retrieve an AlgorithmIdentifier ASN.1 sequence. * Updates the pointer to immediately behind the full * AlgorithmIdentifier. * * \param p On entry, \c *p points to the start of the ASN.1 element. * On successful completion, \c *p points to the first byte * beyond the AlgorithmIdentifier element. * On error, the value of \c *p is undefined. * \param end End of data. * \param alg The buffer to receive the OID. * \param params The buffer to receive the parameters. * This is zeroized if there are no parameters. * * \return 0 if successful or a specific ASN.1 or MPI error code. */ int mbedtls_asn1_get_alg(unsigned char **p, const unsigned char *end, mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params); /** * \brief Retrieve an AlgorithmIdentifier ASN.1 sequence with NULL or no * params. * Updates the pointer to immediately behind the full * AlgorithmIdentifier. * * \param p On entry, \c *p points to the start of the ASN.1 element. * On successful completion, \c *p points to the first byte * beyond the AlgorithmIdentifier element. * On error, the value of \c *p is undefined. * \param end End of data. * \param alg The buffer to receive the OID. * * \return 0 if successful or a specific ASN.1 or MPI error code. */ int mbedtls_asn1_get_alg_null(unsigned char **p, const unsigned char *end, mbedtls_asn1_buf *alg); /** * \brief Find a specific named_data entry in a sequence or list based on * the OID. * * \param list The list to seek through * \param oid The OID to look for * \param len Size of the OID * * \return NULL if not found, or a pointer to the existing entry. */ const mbedtls_asn1_named_data *mbedtls_asn1_find_named_data(const mbedtls_asn1_named_data *list, const char *oid, size_t len); #if !defined(MBEDTLS_DEPRECATED_REMOVED) /** * \brief Free a mbedtls_asn1_named_data entry * * \deprecated This function is deprecated and will be removed in a * future version of the library. * Please use mbedtls_asn1_free_named_data_list() * or mbedtls_asn1_free_named_data_list_shallow(). * * \param entry The named data entry to free. * This function calls mbedtls_free() on * `entry->oid.p` and `entry->val.p`. */ void MBEDTLS_DEPRECATED mbedtls_asn1_free_named_data(mbedtls_asn1_named_data *entry); #endif /* MBEDTLS_DEPRECATED_REMOVED */ /** * \brief Free all entries in a mbedtls_asn1_named_data list. * * \param head Pointer to the head of the list of named data entries to free. * This function calls mbedtls_free() on * `entry->oid.p` and `entry->val.p` and then on `entry` * for each list entry, and sets \c *head to \c NULL. */ void mbedtls_asn1_free_named_data_list(mbedtls_asn1_named_data **head); /** * \brief Free all shallow entries in a mbedtls_asn1_named_data list, * but do not free internal pointer targets. * * \param name Head of the list of named data entries to free. * This function calls mbedtls_free() on each list element. */ void mbedtls_asn1_free_named_data_list_shallow(mbedtls_asn1_named_data *name); /** \} name Functions to parse ASN.1 data structures */ /** \} addtogroup asn1_module */ #endif /* MBEDTLS_ASN1_PARSE_C */ #ifdef __cplusplus } #endif #endif /* asn1.h */
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