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PK: document context validity requirements

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Document when a context must be initialized or not, when it must be
set up or not, and whether it needs a private key or a public key will
do.

The implementation is sometimes more liberal than the documentation,
accepting a non-set-up context as a context that can't perform the
requested information. This preserves backward compatibility.
This commit is contained in:
Gilles Peskine 2018-12-19 17:52:05 +01:00
parent 8c71b3ecb3
commit 6af45ec53e
3 changed files with 55 additions and 33 deletions
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77
include/mbedtls/pk.h
View File

@ -207,7 +207,7 @@ void mbedtls_pk_init( mbedtls_pk_context *ctx );
/**
* \brief Free the components of a #mbedtls_pk_context.
*
* \param ctx The context to clear.
* \param ctx The context to clear. It must have been initialized.
* If this is \c NULL, this function does nothing.
*/
void mbedtls_pk_free( mbedtls_pk_context *ctx );
@ -224,7 +224,7 @@ void mbedtls_pk_restart_init( mbedtls_pk_restart_ctx *ctx );
/**
* \brief Free the components of a restart context
*
* \param ctx The context to clear.
* \param ctx The context to clear. It must have been initialized.
* If this is \c NULL, this function does nothing.
*/
void mbedtls_pk_restart_free( mbedtls_pk_restart_ctx *ctx );
@ -234,7 +234,8 @@ void mbedtls_pk_restart_free( mbedtls_pk_restart_ctx *ctx );
* \brief Initialize a PK context with the information given
* and allocates the type-specific PK subcontext.
*
* \param ctx Context to initialize. Must be empty (type NONE).
* \param ctx Context to initialize. It must not have been set
* up yet (type #MBEDTLS_PK_NONE).
* \param info Information to use
*
* \return 0 on success,
@ -250,7 +251,8 @@ int mbedtls_pk_setup( mbedtls_pk_context *ctx, const mbedtls_pk_info_t *info );
/**
* \brief Initialize an RSA-alt context
*
* \param ctx Context to initialize. Must be empty (type NONE).
* \param ctx Context to initialize. It must not have been set
* up yet (type #MBEDTLS_PK_NONE).
* \param key RSA key pointer
* \param decrypt_func Decryption function
* \param sign_func Signing function
@ -270,7 +272,7 @@ int mbedtls_pk_setup_rsa_alt( mbedtls_pk_context *ctx, void * key,
/**
* \brief Get the size in bits of the underlying key
*
* \param ctx Context to use
* \param ctx The context to query. It must have been initialized.
*
* \return Key size in bits, or 0 on error
*/
@ -278,7 +280,8 @@ size_t mbedtls_pk_get_bitlen( const mbedtls_pk_context *ctx );
/**
* \brief Get the length in bytes of the underlying key
* \param ctx Context to use
*
* \param ctx The context to query. It must have been initialized.
*
* \return Key length in bytes, or 0 on error
*/
@ -290,18 +293,21 @@ static inline size_t mbedtls_pk_get_len( const mbedtls_pk_context *ctx )
/**
* \brief Tell if a context can do the operation given by type
*
* \param ctx Context to test
* \param type Target type
* \param ctx The context to query. It must have been initialized.
* \param type The desired type.
*
* \return 0 if context can't do the operations,
* 1 otherwise.
* \return 1 if the context can do operations on the given type.
* \return 0 if the context cannot do the operations on the given
* type. This is always the case for a context that has
* been initialized but not set up, or that has been
* cleared with mbedtls_pk_free().
*/
int mbedtls_pk_can_do( const mbedtls_pk_context *ctx, mbedtls_pk_type_t type );
/**
* \brief Verify signature (including padding if relevant).
*
* \param ctx PK context to use
* \param ctx The PK context to use. It must have been set up.
* \param md_alg Hash algorithm used (see notes)
* \param hash Hash of the message to sign
* \param hash_len Hash length or 0 (see notes)
@ -334,7 +340,7 @@ int mbedtls_pk_verify( mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
* \c mbedtls_ecp_set_max_ops() to reduce blocking for ECC
* operations. For RSA, same as \c mbedtls_pk_verify().
*
* \param ctx PK context to use
* \param ctx The PK context to use. It must have been set up.
* \param md_alg Hash algorithm used (see notes)
* \param hash Hash of the message to sign
* \param hash_len Hash length or 0 (see notes)
@ -358,7 +364,7 @@ int mbedtls_pk_verify_restartable( mbedtls_pk_context *ctx,
*
* \param type Signature type (inc. possible padding type) to verify
* \param options Pointer to type-specific options, or NULL
* \param ctx PK context to use
* \param ctx The PK context to use. It must have been set up.
* \param md_alg Hash algorithm used (see notes)
* \param hash Hash of the message to sign
* \param hash_len Hash length or 0 (see notes)
@ -389,7 +395,8 @@ int mbedtls_pk_verify_ext( mbedtls_pk_type_t type, const void *options,
/**
* \brief Make signature, including padding if relevant.
*
* \param ctx PK context to use - must hold a private key
* \param ctx The PK context to use. It must have been set up
* with a private key.
* \param md_alg Hash algorithm used (see notes)
* \param hash Hash of the message to sign
* \param hash_len Hash length or 0 (see notes)
@ -423,7 +430,8 @@ int mbedtls_pk_sign( mbedtls_pk_context *ctx, mbedtls_md_type_t md_alg,
* \c mbedtls_ecp_set_max_ops() to reduce blocking for ECC
* operations. For RSA, same as \c mbedtls_pk_sign().
*
* \param ctx PK context to use - must hold a private key
* \param ctx The PK context to use. It must have been set up
* with a private key.
* \param md_alg Hash algorithm used (see notes)
* \param hash Hash of the message to sign
* \param hash_len Hash length or 0 (see notes)
@ -447,7 +455,8 @@ int mbedtls_pk_sign_restartable( mbedtls_pk_context *ctx,
/**
* \brief Decrypt message (including padding if relevant).
*
* \param ctx PK context to use - must hold a private key
* \param ctx The PK context to use. It must have been set up
* with a private key.
* \param input Input to decrypt
* \param ilen Input size
* \param output Decrypted output
@ -468,7 +477,7 @@ int mbedtls_pk_decrypt( mbedtls_pk_context *ctx,
/**
* \brief Encrypt message (including padding if relevant).
*
* \param ctx PK context to use
* \param ctx The PK context to use. It must have been set up.
* \param input Message to encrypt
* \param ilen Message size
* \param output Encrypted output
@ -499,7 +508,7 @@ int mbedtls_pk_check_pair( const mbedtls_pk_context *pub, const mbedtls_pk_conte
/**
* \brief Export debug information
*
* \param ctx Context to use
* \param ctx The PK context to use. It must have been initialized.
* \param items Place to write debug items
*
* \return 0 on success or MBEDTLS_ERR_PK_BAD_INPUT_DATA
@ -509,7 +518,7 @@ int mbedtls_pk_debug( const mbedtls_pk_context *ctx, mbedtls_pk_debug_item *item
/**
* \brief Access the type name
*
* \param ctx Context to use
* \param ctx The PK context to use. It must have been initialized.
*
* \return Type name on success, or "invalid PK"
*/
@ -518,9 +527,10 @@ const char * mbedtls_pk_get_name( const mbedtls_pk_context *ctx );
/**
* \brief Get the key type
*
* \param ctx Context to use
* \param ctx The PK context to use. It must have been initialized.
*
* \return Type on success, or MBEDTLS_PK_NONE
* \return Type on success.
* \return #MBEDTLS_PK_NONE for a context that has not been set up.
*/
mbedtls_pk_type_t mbedtls_pk_get_type( const mbedtls_pk_context *ctx );
@ -529,7 +539,8 @@ mbedtls_pk_type_t mbedtls_pk_get_type( const mbedtls_pk_context *ctx );
/**
* \brief Parse a private key in PEM or DER format
*
* \param ctx key to be initialized
* \param ctx The PK context to fill. It must have been initialized
* but not set up.
* \param key Input buffer to parse.
* The buffer must contain the input exactly, with no
* extra trailing material. For PEM, the buffer must
@ -561,7 +572,8 @@ int mbedtls_pk_parse_key( mbedtls_pk_context *ctx,
/**
* \brief Parse a public key in PEM or DER format
*
* \param ctx key to be initialized
* \param ctx The PK context to fill. It must have been initialized
* but not set up.
* \param key Input buffer to parse.
* The buffer must contain the input exactly, with no
* extra trailing material. For PEM, the buffer must
@ -586,7 +598,8 @@ int mbedtls_pk_parse_public_key( mbedtls_pk_context *ctx,
/**
* \brief Load and parse a private key
*
* \param ctx key to be initialized
* \param ctx The PK context to fill. It must have been initialized
* but not set up.
* \param path filename to read the private key from
* \param password Optional password to decrypt the file.
* Pass \c NULL if expecting a non-encrypted key.
@ -609,7 +622,8 @@ int mbedtls_pk_parse_keyfile( mbedtls_pk_context *ctx,
/**
* \brief Load and parse a public key
*
* \param ctx key to be initialized
* \param ctx The PK context to fill. It must have been initialized
* but not set up.
* \param path filename to read the public key from
*
* \note On entry, ctx must be empty, either freshly initialised
@ -632,7 +646,7 @@ int mbedtls_pk_parse_public_keyfile( mbedtls_pk_context *ctx, const char *path )
* return value to determine where you should start
* using the buffer
*
* \param ctx private to write away
* \param ctx PK context which must contain a valid private key.
* \param buf buffer to write to
* \param size size of the buffer
*
@ -647,7 +661,7 @@ int mbedtls_pk_write_key_der( mbedtls_pk_context *ctx, unsigned char *buf, size_
* return value to determine where you should start
* using the buffer
*
* \param ctx public key to write away
* \param ctx PK context which must contain a valid public or private key.
* \param buf buffer to write to
* \param size size of the buffer
*
@ -660,7 +674,7 @@ int mbedtls_pk_write_pubkey_der( mbedtls_pk_context *ctx, unsigned char *buf, si
/**
* \brief Write a public key to a PEM string
*
* \param ctx Context containing the public key to write.
* \param ctx PK context which must contain a valid public or private key.
* \param buf Buffer to write to. The output includes a
* terminating null byte.
* \param size Size of the buffer in bytes.
@ -672,7 +686,7 @@ int mbedtls_pk_write_pubkey_pem( mbedtls_pk_context *ctx, unsigned char *buf, si
/**
* \brief Write a private key to a PKCS#1 or SEC1 PEM string
*
* \param ctx Context containing the private key to write.
* \param ctx PK context which must contain a valid private key.
* \param buf Buffer to write to. The output includes a
* terminating null byte.
* \param size Size of the buffer in bytes.
@ -694,7 +708,8 @@ int mbedtls_pk_write_key_pem( mbedtls_pk_context *ctx, unsigned char *buf, size_
*
* \param p the position in the ASN.1 data
* \param end end of the buffer
* \param pk the key to fill
* \param pk The PK context to fill. It must have been initialized
* but not set up.
*
* \return 0 if successful, or a specific PK error code
*/
@ -709,7 +724,7 @@ int mbedtls_pk_parse_subpubkey( unsigned char **p, const unsigned char *end,
*
* \param p reference to current position pointer
* \param start start of the buffer (for bounds-checking)
* \param key public key to write away
* \param key PK context which must contain a valid public or private key.
*
* \return the length written or a negative error code
*/

5
library/pk.c
View File

@ -183,6 +183,9 @@ int mbedtls_pk_setup_rsa_alt( mbedtls_pk_context *ctx, void * key,
*/
int mbedtls_pk_can_do( const mbedtls_pk_context *ctx, mbedtls_pk_type_t type )
{
/* A context with null pk_info is not set up yet and can't do anything.
* For backward compatibility, also accept NULL instead of a context
* pointer. */
if( ctx == NULL || ctx->pk_info == NULL )
return( 0 );
@ -493,6 +496,8 @@ int mbedtls_pk_check_pair( const mbedtls_pk_context *pub, const mbedtls_pk_conte
*/
size_t mbedtls_pk_get_bitlen( const mbedtls_pk_context *ctx )
{
/* For backward compatibility, accept NULL or a context that
* isn't set up yet, and return a fake value that should be safe. */
if( ctx == NULL || ctx->pk_info == NULL )
return( 0 );

6
tests/suites/test_suite_pk.function
View File

@ -90,10 +90,12 @@ void valid_parameters( )
TEST_ASSERT( mbedtls_pk_setup( &pk, NULL ) ==
MBEDTLS_ERR_PK_BAD_INPUT_DATA );
/* In informational functions, we accept NULL where a context pointer
* is expected because that's what the library has done forever.
* We do not document that NULL is accepted, so we may wish to change
* the behavior in a future version. */
TEST_ASSERT( mbedtls_pk_get_bitlen( NULL ) == 0 );
TEST_ASSERT( mbedtls_pk_get_len( NULL ) == 0 );
TEST_ASSERT( mbedtls_pk_can_do( NULL, MBEDTLS_PK_NONE ) == 0 );
TEST_ASSERT( mbedtls_pk_sign_restartable( &pk,