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Merge pull request #4094 from d-otte/development

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wrong RSA_PRV_DER_MAX_BYTES for odd MBEDTLS_MPI_MAX_SIZE
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Janos Follath 2021-02-02 16:15:07 +00:00 committed by GitHub
commit 6a32ad83e3
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2 changed files with 17 additions and 11 deletions
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6
ChangeLog.d/issue4093.txt Normal file
View file

@ -0,0 +1,6 @@
Security
* Fix an errorneous estimation for an internal buffer in
mbedtls_pk_write_key_pem(). If MBEDTLS_MPI_MAX_SIZE is set to an odd
value the function might fail to write a private RSA keys of the largest
supported size.
Found by Daniel Otte, reported in #4093 and fixed in #4094.

22
library/pkwrite.c
View file

@ -487,7 +487,7 @@ int mbedtls_pk_write_key_der( mbedtls_pk_context *key, unsigned char *buf, size_
* publicExponent INTEGER -- e 1 + 3 + MPI_MAX + 1
* }
*/
#define RSA_PUB_DER_MAX_BYTES 38 + 2 * MBEDTLS_MPI_MAX_SIZE
#define RSA_PUB_DER_MAX_BYTES ( 38 + 2 * MBEDTLS_MPI_MAX_SIZE )
/*
* RSA private keys:
@ -504,10 +504,10 @@ int mbedtls_pk_write_key_der( mbedtls_pk_context *key, unsigned char *buf, size_
* otherPrimeInfos OtherPrimeInfos OPTIONAL 0 (not supported)
* }
*/
#define MPI_MAX_SIZE_2 MBEDTLS_MPI_MAX_SIZE / 2 + \
MBEDTLS_MPI_MAX_SIZE % 2
#define RSA_PRV_DER_MAX_BYTES 47 + 3 * MBEDTLS_MPI_MAX_SIZE \
+ 5 * MPI_MAX_SIZE_2
#define MPI_MAX_SIZE_2 ( MBEDTLS_MPI_MAX_SIZE / 2 + \
MBEDTLS_MPI_MAX_SIZE % 2 )
#define RSA_PRV_DER_MAX_BYTES ( 47 + 3 * MBEDTLS_MPI_MAX_SIZE \
+ 5 * MPI_MAX_SIZE_2 )
#else /* MBEDTLS_RSA_C */
@ -528,7 +528,7 @@ int mbedtls_pk_write_key_der( mbedtls_pk_context *key, unsigned char *buf, size_
* + 2 * ECP_MAX (coords) [1]
* }
*/
#define ECP_PUB_DER_MAX_BYTES 30 + 2 * MBEDTLS_ECP_MAX_BYTES
#define ECP_PUB_DER_MAX_BYTES ( 30 + 2 * MBEDTLS_ECP_MAX_BYTES )
/*
* EC private keys:
@ -539,7 +539,7 @@ int mbedtls_pk_write_key_der( mbedtls_pk_context *key, unsigned char *buf, size_
* publicKey [1] BIT STRING OPTIONAL 1 + 2 + [1] above
* }
*/
#define ECP_PRV_DER_MAX_BYTES 29 + 3 * MBEDTLS_ECP_MAX_BYTES
#define ECP_PRV_DER_MAX_BYTES ( 29 + 3 * MBEDTLS_ECP_MAX_BYTES )
#else /* MBEDTLS_ECP_C */
@ -548,10 +548,10 @@ int mbedtls_pk_write_key_der( mbedtls_pk_context *key, unsigned char *buf, size_
#endif /* MBEDTLS_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
#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 mbedtls_pk_write_pubkey_pem( mbedtls_pk_context *key, unsigned char *buf, size_t size )
{