From 452770a4fafcdb2d80bb793a91aec9ff84769fdc Mon Sep 17 00:00:00 2001 From: Harald Freudenberger Date: Thu, 15 Jan 2026 13:00:25 +0100 Subject: [PATCH] crypto: s390/phmac - Refuse clear key material by default This patch exploits the new xflag PKEY_XFLAG_NOCLEARKEY from the pkey layer. So now by default the phmac refuses the use of clear key material ("clear key tokens") in the setkey function with -EINVAL. With a new kernel module parameter "clrkey" this behavior can be controlled. By default clrkey is 'N' but for testing purpose on module load a true value (1, 'Y') may be given to accept clear key tokens. Note that during selftest clear keys are always used and thus the xflag PKEY_XFLAG_NOCLEARKEY is NOT set as long as the algorithm is in a larval state indicated by crypto_ahash_tested() returning false. Signed-off-by: Harald Freudenberger Reviewed-by: Holger Dengler Reviewed-by: Ingo Franzki Signed-off-by: Herbert Xu --- arch/s390/crypto/phmac_s390.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) diff --git a/arch/s390/crypto/phmac_s390.c b/arch/s390/crypto/phmac_s390.c index 88342bd4c37a7..03ca33ffe6ccf 100644 --- a/arch/s390/crypto/phmac_s390.c +++ b/arch/s390/crypto/phmac_s390.c @@ -23,6 +23,10 @@ static struct crypto_engine *phmac_crypto_engine; #define MAX_QLEN 10 +static bool pkey_clrkey_allowed; +module_param_named(clrkey, pkey_clrkey_allowed, bool, 0444); +MODULE_PARM_DESC(clrkey, "Allow clear key material (default N)"); + /* * A simple hash walk helper */ @@ -311,10 +315,14 @@ static inline int phmac_tfm_ctx_setkey(struct phmac_tfm_ctx *tfm_ctx, * This function may sleep - don't call in non-sleeping context. */ static inline int convert_key(const u8 *key, unsigned int keylen, - struct phmac_protkey *pk) + struct phmac_protkey *pk, bool tested) { + u32 xflags = PKEY_XFLAG_NOMEMALLOC; int rc, i; + if (tested && !pkey_clrkey_allowed) + xflags |= PKEY_XFLAG_NOCLEARKEY; + pk->len = sizeof(pk->protkey); /* @@ -328,7 +336,7 @@ static inline int convert_key(const u8 *key, unsigned int keylen, } rc = pkey_key2protkey(key, keylen, pk->protkey, &pk->len, &pk->type, - PKEY_XFLAG_NOMEMALLOC); + xflags); } out: @@ -350,7 +358,7 @@ out: * unnecessary additional conversion but never to invalid data on the * hash operation. */ -static int phmac_convert_key(struct phmac_tfm_ctx *tfm_ctx) +static int phmac_convert_key(struct phmac_tfm_ctx *tfm_ctx, bool tested) { struct phmac_protkey pk; int rc; @@ -359,7 +367,7 @@ static int phmac_convert_key(struct phmac_tfm_ctx *tfm_ctx) tfm_ctx->pk_state = PK_STATE_CONVERT_IN_PROGRESS; spin_unlock_bh(&tfm_ctx->pk_lock); - rc = convert_key(tfm_ctx->keybuf, tfm_ctx->keylen, &pk); + rc = convert_key(tfm_ctx->keybuf, tfm_ctx->keylen, &pk, tested); /* update context */ spin_lock_bh(&tfm_ctx->pk_lock); @@ -404,6 +412,7 @@ static int phmac_kmac_update(struct ahash_request *req, bool maysleep) struct kmac_sha2_ctx *ctx = &req_ctx->kmac_ctx; struct hash_walk_helper *hwh = &req_ctx->hwh; unsigned int bs = crypto_ahash_blocksize(tfm); + bool tested = crypto_ahash_tested(tfm); unsigned int offset, k, n; int rc = 0; @@ -444,7 +453,7 @@ static int phmac_kmac_update(struct ahash_request *req, bool maysleep) rc = -EKEYEXPIRED; goto out; } - rc = phmac_convert_key(tfm_ctx); + rc = phmac_convert_key(tfm_ctx, tested); if (rc) goto out; spin_lock_bh(&tfm_ctx->pk_lock); @@ -480,7 +489,7 @@ static int phmac_kmac_update(struct ahash_request *req, bool maysleep) rc = -EKEYEXPIRED; goto out; } - rc = phmac_convert_key(tfm_ctx); + rc = phmac_convert_key(tfm_ctx, tested); if (rc) goto out; spin_lock_bh(&tfm_ctx->pk_lock); @@ -517,6 +526,7 @@ static int phmac_kmac_final(struct ahash_request *req, bool maysleep) struct kmac_sha2_ctx *ctx = &req_ctx->kmac_ctx; unsigned int ds = crypto_ahash_digestsize(tfm); unsigned int bs = crypto_ahash_blocksize(tfm); + bool tested = crypto_ahash_tested(tfm); unsigned int k, n; int rc = 0; @@ -537,7 +547,7 @@ static int phmac_kmac_final(struct ahash_request *req, bool maysleep) rc = -EKEYEXPIRED; goto out; } - rc = phmac_convert_key(tfm_ctx); + rc = phmac_convert_key(tfm_ctx, tested); if (rc) goto out; spin_lock_bh(&tfm_ctx->pk_lock); @@ -741,11 +751,12 @@ static int phmac_setkey(struct crypto_ahash *tfm, struct phmac_tfm_ctx *tfm_ctx = crypto_ahash_ctx(tfm); unsigned int ds = crypto_ahash_digestsize(tfm); unsigned int bs = crypto_ahash_blocksize(tfm); + bool tested = crypto_ahash_tested(tfm); unsigned int tmpkeylen; u8 *tmpkey = NULL; int rc = 0; - if (!crypto_ahash_tested(tfm)) { + if (!tested) { /* * selftest running: key is a raw hmac clear key and needs * to get embedded into a 'clear key token' in order to have @@ -770,7 +781,7 @@ static int phmac_setkey(struct crypto_ahash *tfm, goto out; /* convert raw key into protected key */ - rc = phmac_convert_key(tfm_ctx); + rc = phmac_convert_key(tfm_ctx, tested); if (rc) goto out; -- 2.47.3