[PATCH v1 07/41] SUNRPC: Obscure Kerberos encryption keys
From: Chuck Lever <cel@kernel.org>
Date: 2023-01-13 15:29:40
Subsystem:
kernel nfsd, sunrpc, and lockd servers, networking [general], nfs, sunrpc, and lockd clients, the rest · Maintainers:
Chuck Lever, Jeff Layton, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Trond Myklebust, Anna Schumaker, Linus Torvalds
From: Chuck Lever <redacted> The encryption subkeys are not used after the cipher transforms have been allocated and keyed. There is no need to retain them in struct krb5_ctx. Tested-by: Scott Mayhew <redacted> Signed-off-by: Chuck Lever <redacted> --- include/linux/sunrpc/gss_krb5.h | 2 -- net/sunrpc/auth_gss/gss_krb5_mech.c | 43 +++++++++++++++++++++-------------- 2 files changed, 26 insertions(+), 19 deletions(-)
diff --git a/include/linux/sunrpc/gss_krb5.h b/include/linux/sunrpc/gss_krb5.h
index 77f6adf20f7f..806df140feae 100644
--- a/include/linux/sunrpc/gss_krb5.h
+++ b/include/linux/sunrpc/gss_krb5.h@@ -114,8 +114,6 @@ struct krb5_ctx { struct xdr_netobj mech_used; u8 initiator_sign[GSS_KRB5_MAX_KEYLEN]; u8 acceptor_sign[GSS_KRB5_MAX_KEYLEN]; - u8 initiator_seal[GSS_KRB5_MAX_KEYLEN]; - u8 acceptor_seal[GSS_KRB5_MAX_KEYLEN]; u8 initiator_integ[GSS_KRB5_MAX_KEYLEN]; u8 acceptor_integ[GSS_KRB5_MAX_KEYLEN]; };
diff --git a/net/sunrpc/auth_gss/gss_krb5_mech.c b/net/sunrpc/auth_gss/gss_krb5_mech.c
index 3a464cb3f6e9..ba3cfcb2c7c5 100644
--- a/net/sunrpc/auth_gss/gss_krb5_mech.c
+++ b/net/sunrpc/auth_gss/gss_krb5_mech.c@@ -350,42 +350,49 @@ context_derive_keys_des3(struct krb5_ctx *ctx, gfp_t gfp_mask) static int context_derive_keys_new(struct krb5_ctx *ctx, gfp_t gfp_mask) { - struct xdr_netobj c, keyin, keyout; u8 cdata[GSS_KRB5_K5CLENGTH]; + struct xdr_netobj c = { + .len = sizeof(cdata), + .data = cdata, + }; + struct xdr_netobj keyin = { + .len = ctx->gk5e->keylength, + .data = ctx->Ksess, + }; + struct xdr_netobj keyout; + int ret = -EINVAL; + void *subkey; u32 err; - c.len = GSS_KRB5_K5CLENGTH; - c.data = cdata; - - keyin.data = ctx->Ksess; - keyin.len = ctx->gk5e->keylength; + subkey = kmalloc(ctx->gk5e->keylength, gfp_mask); + if (!subkey) + return -ENOMEM; keyout.len = ctx->gk5e->keylength; + keyout.data = subkey; /* initiator seal encryption */ set_cdata(cdata, KG_USAGE_INITIATOR_SEAL, KEY_USAGE_SEED_ENCRYPTION); - keyout.data = ctx->initiator_seal; err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask); if (err) { dprintk("%s: Error %d deriving initiator_seal key\n", __func__, err); - goto out_err; + goto out; } ctx->initiator_enc = context_v2_alloc_cipher(ctx, ctx->gk5e->encrypt_name, - ctx->initiator_seal); + subkey); if (ctx->initiator_enc == NULL) - goto out_err; + goto out; if (ctx->gk5e->aux_cipher) { ctx->initiator_enc_aux = context_v2_alloc_cipher(ctx, ctx->gk5e->aux_cipher, - ctx->initiator_seal); + subkey); if (ctx->initiator_enc_aux == NULL) goto out_free; } /* acceptor seal encryption */ set_cdata(cdata, KG_USAGE_ACCEPTOR_SEAL, KEY_USAGE_SEED_ENCRYPTION); - keyout.data = ctx->acceptor_seal; err = krb5_derive_key(ctx->gk5e, &keyin, &keyout, &c, gfp_mask); if (err) { dprintk("%s: Error %d deriving acceptor_seal key\n",
@@ -394,13 +401,13 @@ context_derive_keys_new(struct krb5_ctx *ctx, gfp_t gfp_mask) } ctx->acceptor_enc = context_v2_alloc_cipher(ctx, ctx->gk5e->encrypt_name, - ctx->acceptor_seal); + subkey); if (ctx->acceptor_enc == NULL) goto out_free; if (ctx->gk5e->aux_cipher) { ctx->acceptor_enc_aux = context_v2_alloc_cipher(ctx, ctx->gk5e->aux_cipher, - ctx->acceptor_seal); + subkey); if (ctx->acceptor_enc_aux == NULL) goto out_free; }
@@ -445,15 +452,17 @@ context_derive_keys_new(struct krb5_ctx *ctx, gfp_t gfp_mask) goto out_free; } - return 0; + ret = 0; +out: + kfree_sensitive(subkey); + return ret; out_free: crypto_free_sync_skcipher(ctx->acceptor_enc_aux); crypto_free_sync_skcipher(ctx->acceptor_enc); crypto_free_sync_skcipher(ctx->initiator_enc_aux); crypto_free_sync_skcipher(ctx->initiator_enc); -out_err: - return -EINVAL; + goto out; } static int