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Fix buffer size in pk_write_*_pem()

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This commit is contained in:
Manuel Pégourié-Gonnard
2014-07-21 16:37:15 +02:00
parent 868c0eea08
commit 192253aaa9
5 changed files with 178 additions and 4 deletions
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87
library/pkwrite.c
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@ -294,10 +294,93 @@ int pk_write_key_der( pk_context *key, unsigned char *buf, size_t size )
#define PEM_BEGIN_PRIVATE_KEY_EC "-----BEGIN EC PRIVATE KEY-----\n"
#define PEM_END_PRIVATE_KEY_EC "-----END EC PRIVATE KEY-----\n"
/*
* Max sizes of key per types. Shown as tag + len (+ content).
*/
#if defined(POLARSSL_RSA_C)
/*
* RSA public keys:
* SubjectPublicKeyInfo ::= SEQUENCE { 1 + 3
* algorithm AlgorithmIdentifier, 1 + 1 (sequence)
* + 1 + 1 + 9 (rsa oid)
* + 1 + 1 (params null)
* subjectPublicKey BIT STRING } 1 + 3 + (1 + below)
* RSAPublicKey ::= SEQUENCE { 1 + 3
* modulus INTEGER, -- n 1 + 3 + MPI_MAX + 1
* publicExponent INTEGER -- e 1 + 3 + MPI_MAX + 1
* }
*/
#define RSA_PUB_DER_MAX_BYTES 38 + 2 * POLARSSL_MPI_MAX_SIZE
/*
* RSA private keys:
* RSAPrivateKey ::= SEQUENCE { 1 + 3
* version Version, 1 + 1 + 1
* modulus INTEGER, 1 + 3 + MPI_MAX + 1
* publicExponent INTEGER, 1 + 3 + MPI_MAX + 1
* privateExponent INTEGER, 1 + 3 + MPI_MAX + 1
* prime1 INTEGER, 1 + 3 + MPI_MAX / 2 + 1
* prime2 INTEGER, 1 + 3 + MPI_MAX / 2 + 1
* exponent1 INTEGER, 1 + 3 + MPI_MAX / 2 + 1
* exponent2 INTEGER, 1 + 3 + MPI_MAX / 2 + 1
* coefficient INTEGER, 1 + 3 + MPI_MAX / 2 + 1
* otherPrimeInfos OtherPrimeInfos OPTIONAL 0 (not supported)
* }
*/
#define MPI_MAX_SIZE_2 POLARSSL_MPI_MAX_SIZE / 2 + \
POLARSSL_MPI_MAX_SIZE % 2
#define RSA_PRV_DER_MAX_BYTES 47 + 3 * POLARSSL_MPI_MAX_SIZE \
+ 5 * MPI_MAX_SIZE_2
#else /* POLARSSL_RSA_C */
#define RSA_PUB_DER_MAX_BYTES 0
#define RSA_PRV_DER_MAX_BYTES 0
#endif /* POLARSSL_RSA_C */
#if defined(POLARSSL_ECP_C)
/*
* EC public keys:
* SubjectPublicKeyInfo ::= SEQUENCE { 1 + 2
* algorithm AlgorithmIdentifier, 1 + 1 (sequence)
* + 1 + 1 + 7 (ec oid)
* + 1 + 1 + 9 (namedCurve oid)
* subjectPublicKey BIT STRING 1 + 2 + 1 [1]
* + 1 (point format) [1]
* + 2 * ECP_MAX (coords) [1]
* }
*/
#define ECP_PUB_DER_MAX_BYTES 30 + 2 * POLARSSL_ECP_MAX_BYTES
/*
* EC private keys:
* ECPrivateKey ::= SEQUENCE { 1 + 2
* version INTEGER , 1 + 1 + 1
* privateKey OCTET STRING, 1 + 1 + ECP_MAX
* parameters [0] ECParameters OPTIONAL, 1 + 1 + (1 + 1 + 9)
* publicKey [1] BIT STRING OPTIONAL 1 + 2 + [1] above
* }
*/
#define ECP_PRV_DER_MAX_BYTES 29 + 3 * POLARSSL_ECP_MAX_BYTES
#else /* POLARSSL_ECP_C */
#define ECP_PUB_DER_MAX_BYTES 0
#define ECP_PRV_DER_MAX_BYTES 0
#endif /* POLARSSL_ECP_C */
#define PUB_DER_MAX_BYTES RSA_PUB_DER_MAX_BYTES > ECP_PUB_DER_MAX_BYTES ? \
RSA_PUB_DER_MAX_BYTES : ECP_PUB_DER_MAX_BYTES
#define PRV_DER_MAX_BYTES RSA_PRV_DER_MAX_BYTES > ECP_PRV_DER_MAX_BYTES ? \
RSA_PRV_DER_MAX_BYTES : ECP_PRV_DER_MAX_BYTES
int pk_write_pubkey_pem( pk_context *key, unsigned char *buf, size_t size )
{
int ret;
unsigned char output_buf[4096];
unsigned char output_buf[PUB_DER_MAX_BYTES];
size_t olen = 0;
if( ( ret = pk_write_pubkey_der( key, output_buf,
@ -319,7 +402,7 @@ int pk_write_pubkey_pem( pk_context *key, unsigned char *buf, size_t size )
int pk_write_key_pem( pk_context *key, unsigned char *buf, size_t size )
{
int ret;
unsigned char output_buf[4096];
unsigned char output_buf[PRV_DER_MAX_BYTES];
const char *begin, *end;
size_t olen = 0;