On Fri May 31, 2024 at 3:35 AM EEST, Stefan Berger wrote: > > > On 5/28/24 17:08, Jarkko Sakkinen wrote: > > TPM2 ASN.1 format is required for trusted keys and asymmetric keys. Move it > > to crypto in order to make it available for both. Implement validation with > > coverage of all TPMT_PUBLIC shared fields. Key type specific fields must be > > covered by the different subsystems using this. > > > > A Kconfig option CRYPTO_TPM2_KEY can be used to select the feature, which > > depends only crypto subsystem itself and ASN.1 parser. > > > > Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > > --- > > v6: > > * Relocate to crypto. Validate the shared part and provide > > accessor functions. Use a fixed buffer size. > > v2: > > * Do not allocate blob twice. Use the one inside struct tpm2_key. > > --- > > crypto/Kconfig | 7 ++ > > crypto/Makefile | 6 + > > crypto/tpm2_key.asn1 | 11 ++ > > crypto/tpm2_key.c | 134 ++++++++++++++++++++ > > include/crypto/tpm2_key.h | 46 +++++++ > > security/keys/trusted-keys/Kconfig | 2 +- > > security/keys/trusted-keys/Makefile | 2 - > > security/keys/trusted-keys/tpm2key.asn1 | 11 -- > > security/keys/trusted-keys/trusted_tpm2.c | 141 +++++----------------- > > 9 files changed, 235 insertions(+), 125 deletions(-) > > create mode 100644 crypto/tpm2_key.asn1 > > create mode 100644 crypto/tpm2_key.c > > create mode 100644 include/crypto/tpm2_key.h > > delete mode 100644 security/keys/trusted-keys/tpm2key.asn1 > > > > diff --git a/crypto/Kconfig b/crypto/Kconfig > > index 5688d42a59c2..c8989bc71f57 100644 > > --- a/crypto/Kconfig > > +++ b/crypto/Kconfig > > @@ -5,6 +5,13 @@ > > config XOR_BLOCKS > > tristate > > > > +config CRYPTO_TPM2_KEY > > + bool > > + depends on CRYPTO > > + select ASN1 > > + select OID_REGISTRY > > + default n > > + > > # > > # async_tx api: hardware offloaded memory transfer/transform support > > # > > diff --git a/crypto/Makefile b/crypto/Makefile > > index edbbaa3ffef5..d932fdb72319 100644 > > --- a/crypto/Makefile > > +++ b/crypto/Makefile > > @@ -216,3 +216,9 @@ obj-$(CONFIG_CRYPTO_SIMD) += crypto_simd.o > > # Key derivation function > > # > > obj-$(CONFIG_CRYPTO_KDF800108_CTR) += kdf_sp800108.o > > + > > +ifdef CONFIG_CRYPTO_TPM2_KEY > > +$(obj)/tpm2_key.asn1.o: $(obj)/tpm2_key.asn1.h $(obj)/tpm2_key.asn1.c > > +$(obj)/tpm2_key.o: $(obj)/tpm2_key.asn1.h > > +obj-y += tpm2_key.o tpm2_key.asn1.o > > +endif > > diff --git a/crypto/tpm2_key.asn1 b/crypto/tpm2_key.asn1 > > new file mode 100644 > > index 000000000000..b235d02ab78e > > --- /dev/null > > +++ b/crypto/tpm2_key.asn1 > > @@ -0,0 +1,11 @@ > > +--- > > +--- ASN.1 for TPM 2.0 keys > > +--- > > + > > +TPMKey ::= SEQUENCE { > > + type OBJECT IDENTIFIER ({tpm2_key_get_type}), > > + emptyAuth [0] EXPLICIT BOOLEAN OPTIONAL, > > + parent INTEGER ({tpm2_key_get_parent}), > > + pubkey OCTET STRING ({tpm2_get_public}), > > + privkey OCTET STRING ({tpm2_get_private}) > > + } > > diff --git a/crypto/tpm2_key.c b/crypto/tpm2_key.c > > new file mode 100644 > > index 000000000000..78f55478d046 > > --- /dev/null > > +++ b/crypto/tpm2_key.c > > @@ -0,0 +1,134 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > + > > +#include <crypto/tpm2_key.h> > > +#include <linux/oid_registry.h> > > +#include <linux/slab.h> > > +#include <linux/types.h> > > +#include <asm/unaligned.h> > > +#include "tpm2_key.asn1.h" > > + > > +#undef pr_fmt > > +#define pr_fmt(fmt) "tpm2_key: "fmt > > + > > +struct tpm2_key_decoder_context { > > + u32 parent; > > + const u8 *pub; > > + u32 pub_len; > > + const u8 *priv; > > + u32 priv_len; > > + enum OID oid; > > +}; > > + > > +int tpm2_key_get_parent(void *context, size_t hdrlen, > > + unsigned char tag, > > + const void *value, size_t vlen) > > +{ > > + struct tpm2_key_decoder_context *decoder = context; > > + const u8 *v = value; > > + int i; > > + > > + decoder->parent = 0; > > + for (i = 0; i < vlen; i++) { > > + decoder->parent <<= 8; > > + decoder->parent |= v[i]; > > + } > > + > > + return 0; > > +} > > + > > +int tpm2_key_get_type(void *context, size_t hdrlen, > > + unsigned char tag, > > + const void *value, size_t vlen) > > +{ > > + struct tpm2_key_decoder_context *decoder = context; > > + > > + decoder->oid = look_up_OID(value, vlen); > > + return 0; > > +} > > + > > +static inline bool tpm2_key_is_valid(const void *value, size_t vlen) > > +{ > > + if (vlen < 2 || vlen > TPM2_KEY_BYTES_MAX) > > + return false; > > + > > + if (get_unaligned_be16(value) != vlen - 2) > > + return false; > > + > > + return true; > > +} > > + > > +int tpm2_get_public(void *context, size_t hdrlen, unsigned char tag, > > + const void *value, size_t vlen) > > +{ > > + struct tpm2_key_decoder_context *decoder = context; > > + > > + if (!tpm2_key_is_valid(value, vlen)) > > + return -EBADMSG; > > + > > + if (sizeof(struct tpm2_key_desc) > vlen - 2) > > + return -EBADMSG; > > + > > + decoder->pub = value; > > + decoder->pub_len = vlen; > > + return 0; > > +} > > + > > +int tpm2_get_private(void *context, size_t hdrlen, unsigned char tag, > > + const void *value, size_t vlen) > > +{ > > + struct tpm2_key_decoder_context *decoder = context; > > + > > + if (!tpm2_key_is_valid(value, vlen)) > > + return -EBADMSG; > > + > > + decoder->priv = value; > > + decoder->priv_len = vlen; > > + return 0; > > +} > > + > > +/** > > + * tpm_key_decode() - Decode TPM2 ASN.1 key > > + * @src: ASN.1 source. > > + * @src_len: ASN.1 source length. > > + * > > + * Decodes the TPM2 ASN.1 key and validates that the public key data has all > > + * the shared fields of TPMT_PUBLIC. This is full coverage of the memory that > > + * can be validated before doing any key type specific validation. > > I am not sure what the last sentence means. I think the whole paragraph should be rewritten. So what it does is that it takes the private and public parts and concanates them together so maybe just write: "Load TPMT_PUBLIC and TPMT_PRIVATE from ASN.1 file, and concatenate the blobs together as a single blob, as this is expected format for the TPM2 commands. In addition, validate TPMT_PUBLIC fields so that they make sense for trusted and asymmetric keys." What you think of this? > > > + * > > + * Return: > > + * - TPM2 ASN.1 key on success. > > + * - -EBADMSG when decoding fails. > > + * - -ENOMEM when OOM while allocating struct tpm2_key. > > + */ > > +struct tpm2_key *tpm2_key_decode(const u8 *src, u32 src_len) > > +{ > > + struct tpm2_key_decoder_context decoder; > > + struct tpm2_key *key; > > + u8 *data; > > + int ret; > > + > > + memset(&decoder, 0, sizeof(decoder)); > > + ret = asn1_ber_decoder(&tpm2_key_decoder, &decoder, src, src_len); > > + if (ret < 0) { > > + if (ret != -EBADMSG) > > + pr_info("Decoder error %d\n", ret); > > + > > + return ERR_PTR(-EBADMSG); > > + } > > + > > + key = kzalloc(sizeof(*key), GFP_KERNEL); > > + if (!key) > > + return ERR_PTR(-ENOMEM); > > + > > + data = &key->data[0]; > > + memcpy(&data[0], decoder.priv, decoder.priv_len); > > + memcpy(&data[decoder.priv_len], decoder.pub, decoder.pub_len); > > + > > + key->oid = decoder.oid; > > + key->priv_len = decoder.priv_len; > > + key->pub_len = decoder.pub_len; > > + key->parent = decoder.parent; > > + key->desc = (struct tpm2_key_desc *)&data[decoder.priv_len + 2]; > > + return key; > > +} > > +EXPORT_SYMBOL_GPL(tpm2_key_decode); > > diff --git a/include/crypto/tpm2_key.h b/include/crypto/tpm2_key.h > > new file mode 100644 > > index 000000000000..74debaf707bf > > --- /dev/null > > +++ b/include/crypto/tpm2_key.h > > @@ -0,0 +1,46 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > +#ifndef __LINUX_TPM2_KEY_H__ > > +#define __LINUX_TPM2_KEY_H__ > > + > > +#include <linux/oid_registry.h> > > +#include <linux/slab.h> > > + > > +#define TPM2_KEY_BYTES_MAX 1024 > > + > > +/* TPM2 Structures 12.2.4: TPMT_PUBLIC */ > > +struct tpm2_key_desc { > > + __be16 type; > > + __be16 name_alg; > > + __be32 object_attributes; > > + __be16 policy_size; > > +} __packed; > > + > > +/* Decoded TPM2 ASN.1 key. */ > > +struct tpm2_key { > > + u8 data[2 * TPM2_KEY_BYTES_MAX]; > > + struct tpm2_key_desc *desc; > > + u16 priv_len; > > + u16 pub_len; > > + u32 parent; > > + enum OID oid; > > + char oid_str[64]; > > +}; > > + > > +struct tpm2_key *tpm2_key_decode(const u8 *src, u32 src_len); > > + > > +static inline const void *tpm2_key_data(const struct tpm2_key *key) > > +{ > > + return &key->data[0]; > > +} > > + > > +static inline u16 tpm2_key_type(const struct tpm2_key *key) > > +{ > > + return be16_to_cpu(key->desc->type); > > +} > > + > > +static inline int tpm2_key_policy_size(const struct tpm2_key *key) > > +{ > > + return be16_to_cpu(key->desc->policy_size); > > +} > > + > > +#endif /* __LINUX_TPM2_KEY_H__ */ > > diff --git a/security/keys/trusted-keys/Kconfig b/security/keys/trusted-keys/Kconfig > > index 1fb8aa001995..00d9489384ac 100644 > > --- a/security/keys/trusted-keys/Kconfig > > +++ b/security/keys/trusted-keys/Kconfig > > @@ -9,9 +9,9 @@ config TRUSTED_KEYS_TPM > > select CRYPTO_HMAC > > select CRYPTO_SHA1 > > select CRYPTO_HASH_INFO > > + select CRYPTO_TPM2_KEY > > select ASN1_ENCODER > > select OID_REGISTRY > > - select ASN1 > > select HAVE_TRUSTED_KEYS > > help > > Enable use of the Trusted Platform Module (TPM) as trusted key > > diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile > > index f0f3b27f688b..2674d5c10fc9 100644 > > --- a/security/keys/trusted-keys/Makefile > > +++ b/security/keys/trusted-keys/Makefile > > @@ -7,9 +7,7 @@ obj-$(CONFIG_TRUSTED_KEYS) += trusted.o > > trusted-y += trusted_core.o > > trusted-$(CONFIG_TRUSTED_KEYS_TPM) += trusted_tpm1.o > > > > -$(obj)/trusted_tpm2.o: $(obj)/tpm2key.asn1.h > > trusted-$(CONFIG_TRUSTED_KEYS_TPM) += trusted_tpm2.o > > -trusted-$(CONFIG_TRUSTED_KEYS_TPM) += tpm2key.asn1.o > > > > trusted-$(CONFIG_TRUSTED_KEYS_TEE) += trusted_tee.o > > > > diff --git a/security/keys/trusted-keys/tpm2key.asn1 b/security/keys/trusted-keys/tpm2key.asn1 > > deleted file mode 100644 > > index f57f869ad600..000000000000 > > --- a/security/keys/trusted-keys/tpm2key.asn1 > > +++ /dev/null > > @@ -1,11 +0,0 @@ > > ---- > > ---- ASN.1 for TPM 2.0 keys > > ---- > > - > > -TPMKey ::= SEQUENCE { > > - type OBJECT IDENTIFIER ({tpm2_key_type}), > > - emptyAuth [0] EXPLICIT BOOLEAN OPTIONAL, > > - parent INTEGER ({tpm2_key_parent}), > > - pubkey OCTET STRING ({tpm2_key_pub}), > > - privkey OCTET STRING ({tpm2_key_priv}) > > - } > > diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c > > index 06c8fa7b21ae..b9e505e99e8c 100644 > > --- a/security/keys/trusted-keys/trusted_tpm2.c > > +++ b/security/keys/trusted-keys/trusted_tpm2.c > > @@ -13,11 +13,10 @@ > > > > #include <keys/trusted-type.h> > > #include <keys/trusted_tpm.h> > > +#include <crypto/tpm2_key.h> > > > > #include <asm/unaligned.h> > > > > -#include "tpm2key.asn1.h" > > - > > static struct tpm2_hash tpm2_hash_map[] = { > > {HASH_ALGO_SHA1, TPM_ALG_SHA1}, > > {HASH_ALGO_SHA256, TPM_ALG_SHA256}, > > @@ -98,106 +97,6 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, > > return ret; > > } > > > > -struct tpm2_key_context { > > - u32 parent; > > - const u8 *pub; > > - u32 pub_len; > > - const u8 *priv; > > - u32 priv_len; > > -}; > > - > > -static int tpm2_key_decode(struct trusted_key_payload *payload, > > - struct trusted_key_options *options, > > - u8 **buf) > > -{ > > - int ret; > > - struct tpm2_key_context ctx; > > - u8 *blob; > > - > > - memset(&ctx, 0, sizeof(ctx)); > > - > > - ret = asn1_ber_decoder(&tpm2key_decoder, &ctx, payload->blob, > > - payload->blob_len); > > - if (ret < 0) > > - return ret; > > - > > - if (ctx.priv_len + ctx.pub_len > MAX_BLOB_SIZE) > > - return -E2BIG; > > - > > - blob = kmalloc(ctx.priv_len + ctx.pub_len + 4, GFP_KERNEL); > > - if (!blob) > > - return -ENOMEM; > > - > > - *buf = blob; > > - options->keyhandle = ctx.parent; > > - > > - memcpy(blob, ctx.priv, ctx.priv_len); > > - blob += ctx.priv_len; > > - > > - memcpy(blob, ctx.pub, ctx.pub_len); > > - > > - return 0; > > -} > > - > > -int tpm2_key_parent(void *context, size_t hdrlen, > > - unsigned char tag, > > - const void *value, size_t vlen) > > -{ > > - struct tpm2_key_context *ctx = context; > > - const u8 *v = value; > > - int i; > > - > > - ctx->parent = 0; > > - for (i = 0; i < vlen; i++) { > > - ctx->parent <<= 8; > > - ctx->parent |= v[i]; > > - } > > - > > - return 0; > > -} > > - > > -int tpm2_key_type(void *context, size_t hdrlen, > > - unsigned char tag, > > - const void *value, size_t vlen) > > -{ > > - enum OID oid = look_up_OID(value, vlen); > > - > > - if (oid != OID_TPMSealedData) { > > - char buffer[50]; > > - > > - sprint_oid(value, vlen, buffer, sizeof(buffer)); > > - pr_debug("OID is \"%s\" which is not TPMSealedData\n", > > - buffer); > > - return -EINVAL; > > - } > > - > > - return 0; > > -} > > - > > -int tpm2_key_pub(void *context, size_t hdrlen, > > - unsigned char tag, > > - const void *value, size_t vlen) > > -{ > > - struct tpm2_key_context *ctx = context; > > - > > - ctx->pub = value; > > - ctx->pub_len = vlen; > > - > > - return 0; > > -} > > - > > -int tpm2_key_priv(void *context, size_t hdrlen, > > - unsigned char tag, > > - const void *value, size_t vlen) > > -{ > > - struct tpm2_key_context *ctx = context; > > - > > - ctx->priv = value; > > - ctx->priv_len = vlen; > > - > > - return 0; > > -} > > - > > /** > > * tpm2_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer. > > * > > @@ -387,22 +286,43 @@ static int tpm2_load_cmd(struct tpm_chip *chip, > > struct trusted_key_options *options, > > u32 *blob_handle) > > { > > - struct tpm_buf buf; > > unsigned int private_len; > > unsigned int public_len; > > unsigned int blob_len; > > - u8 *blob, *pub; > > - int rc; > > + struct tpm2_key *key; > > + const u8 *blob, *pub; > > + struct tpm_buf buf; > > u32 attrs; > > + int rc; > > > > - rc = tpm2_key_decode(payload, options, &blob); > > - if (rc) { > > - /* old form */ > > + key = tpm2_key_decode(payload->blob, payload->blob_len); > > + if (IS_ERR(key)) { > > + /* Get the error code and reset the pointer to the key: */ > > + rc = PTR_ERR(key); > > + key = NULL; > > + > > + if (rc == -ENOMEM) > > + return -ENOMEM; > > + > > + /* A sanity check, as only -EBADMSG or -ENOMEM are expected: */ > > + if (rc != -EBADMSG) > > + pr_err("tpm2_key_decode(): spurious error code %d\n", rc); > > tpm2_key_decode seems simple enough that it only returns key, -ENOMEM or > EBADMSG. So what is your suggestion here? The reasoning here is that asymmetric keys use -EBADMSG not only as error but also iterator, when probing which can load a specific key. > > > + > > + /* Fallback to the legacy format: */ > > blob = payload->blob; > > payload->old_format = 1; > > + } else { > > + blob = tpm2_key_data(key); > > + if (key->oid != OID_TPMSealedData) { > > + kfree(key); > > + return -EBADMSG; > > + } > > } > > > > - /* new format carries keyhandle but old format doesn't */ > > + /* > > + * Must be non-zero here, either extracted from the ASN.1 for the new > > + * format or specified on the command line for the old. > > sentence seems incomplete: ... for the old one. OR ... for the old format. Yep, I think it is a plain mistake. > > > + */ > > if (!options->keyhandle) > > return -EINVAL; > > > > @@ -464,8 +384,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip, > > (__be32 *) &buf.data[TPM_HEADER_SIZE]); > > > > out: > > - if (blob != payload->blob) > > - kfree(blob); > > + kfree(key); > > tpm_buf_destroy(&buf); > > > > if (rc > 0) Thanks for the feedback. BR, Jarkko