diff options
Diffstat (limited to 'crypto/dh.c')
| -rw-r--r-- | crypto/dh.c | 66 |
1 files changed, 63 insertions, 3 deletions
diff --git a/crypto/dh.c b/crypto/dh.c index 5659fe7f446d..09a44de4209d 100644 --- a/crypto/dh.c +++ b/crypto/dh.c @@ -16,14 +16,16 @@ #include <linux/mpi.h> struct dh_ctx { - MPI p; - MPI g; - MPI xa; + MPI p; /* Value is guaranteed to be set. */ + MPI q; /* Value is optional. */ + MPI g; /* Value is guaranteed to be set. */ + MPI xa; /* Value is guaranteed to be set. */ }; static void dh_clear_ctx(struct dh_ctx *ctx) { mpi_free(ctx->p); + mpi_free(ctx->q); mpi_free(ctx->g); mpi_free(ctx->xa); memset(ctx, 0, sizeof(*ctx)); @@ -60,6 +62,12 @@ static int dh_set_params(struct dh_ctx *ctx, struct dh *params) if (!ctx->p) return -EINVAL; + if (params->q && params->q_size) { + ctx->q = mpi_read_raw_data(params->q, params->q_size); + if (!ctx->q) + return -EINVAL; + } + ctx->g = mpi_read_raw_data(params->g, params->g_size); if (!ctx->g) return -EINVAL; @@ -93,6 +101,55 @@ err_clear_ctx: return -EINVAL; } +/* + * SP800-56A public key verification: + * + * * If Q is provided as part of the domain paramenters, a full validation + * according to SP800-56A section 5.6.2.3.1 is performed. + * + * * If Q is not provided, a partial validation according to SP800-56A section + * 5.6.2.3.2 is performed. + */ +static int dh_is_pubkey_valid(struct dh_ctx *ctx, MPI y) +{ + if (unlikely(!ctx->p)) + return -EINVAL; + + /* + * Step 1: Verify that 2 <= y <= p - 2. + * + * The upper limit check is actually y < p instead of y < p - 1 + * as the mpi_sub_ui function is yet missing. + */ + if (mpi_cmp_ui(y, 1) < 1 || mpi_cmp(y, ctx->p) >= 0) + return -EINVAL; + + /* Step 2: Verify that 1 = y^q mod p */ + if (ctx->q) { + MPI val = mpi_alloc(0); + int ret; + + if (!val) + return -ENOMEM; + + ret = mpi_powm(val, y, ctx->q, ctx->p); + + if (ret) { + mpi_free(val); + return ret; + } + + ret = mpi_cmp_ui(val, 1); + + mpi_free(val); + + if (ret != 0) + return -EINVAL; + } + + return 0; +} + static int dh_compute_value(struct kpp_request *req) { struct crypto_kpp *tfm = crypto_kpp_reqtfm(req); @@ -115,6 +172,9 @@ static int dh_compute_value(struct kpp_request *req) ret = -EINVAL; goto err_free_val; } + ret = dh_is_pubkey_valid(ctx, base); + if (ret) + goto err_free_base; } else { base = ctx->g; } |