Re: [PATCH 2/2] trusted-key: added support for loading a key blobin the TPM
From: David Safford
Date: Wed Nov 02 2011 - 13:30:14 EST
On Wed, 2011-11-02 at 13:41 +0100, Roberto Sassu wrote:
> The new functions 'tpm_loadkey2', 'tpm_evictkey' and 'tpm_flushspecific'
> allow to load/unload a TPM key whose blob is provided from the userspace
> interface and to use it for sealing or unsealing the symmetric key.
This looks like a nice extension.
I'll test it out thoroughly, but for now here are a couple of
minor initial suggestions...
dave
>
> Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxx>
> ---
> Documentation/security/keys-trusted-encrypted.txt | 6 +-
> include/linux/tpm_command.h | 6 +
> security/keys/trusted.c | 203 ++++++++++++++++++++-
> security/keys/trusted.h | 27 +++-
> 4 files changed, 234 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/security/keys-trusted-encrypted.txt b/Documentation/security/keys-trusted-encrypted.txt
> index 5f50cca..afebb58 100644
> --- a/Documentation/security/keys-trusted-encrypted.txt
> +++ b/Documentation/security/keys-trusted-encrypted.txt
> @@ -27,8 +27,10 @@ Usage:
> keyctl print keyid
>
> options:
> - keyhandle= ascii hex value of sealing key default 0x40000000 (SRK)
> - keyauth= ascii hex auth for sealing key default 0x00...i
> + keyhandle= ascii hex value of sealing key handle default 0x40000000 (SRK)
> + keyblob= ascii hex value of sealing key blob (no default)
> + srkauth= ascii hex auth for SRK key default 0x00...
> + keyauth= ascii hex auth for sealing key (not SRK) default 0x00...
> (40 ascii zeros)
> blobauth= ascii hex auth for sealed data default 0x00...
> (40 ascii zeros)
> diff --git a/include/linux/tpm_command.h b/include/linux/tpm_command.h
> index 727512e..e3348b7 100644
> --- a/include/linux/tpm_command.h
> +++ b/include/linux/tpm_command.h
> @@ -15,7 +15,10 @@
> #define TPM_TAG_RSP_AUTH2_COMMAND 198
>
> /* Command Ordinals */
> +#define TPM_ORD_EVICTKEY 34
> +#define TPM_ORD_FLUSHSPECIFIC 186
> #define TPM_ORD_GETRANDOM 70
> +#define TPM_ORD_LOADKEY2 65
> #define TPM_ORD_OSAP 11
> #define TPM_ORD_OIAP 10
> #define TPM_ORD_SEAL 23
> @@ -24,5 +27,8 @@
> /* Other constants */
> #define SRKHANDLE 0x40000000
> #define TPM_NONCE_SIZE 20
> +#define TPM_RT_KEY 0x00000001
> +#define TPM_TAG_KEY12 0x0028
> +#define TPM_BAD_ORDINAL 10
>
> #endif
> diff --git a/security/keys/trusted.c b/security/keys/trusted.c
> index 8777015..c332e3b 100644
> --- a/security/keys/trusted.c
> +++ b/security/keys/trusted.c
> @@ -688,12 +688,118 @@ static int tpm_unseal(struct tpm_buf *tb,
> }
>
> /*
> + * Load a TPM key from the blob provided by userspace
> + */
> +static int tpm_loadkey2(struct tpm_buf *tb,
> + uint32_t keyhandle, unsigned char *keyauth,
> + const unsigned char *keyblob, int keybloblen,
> + uint32_t *newhandle)
> +{
> + unsigned char nonceodd[TPM_NONCE_SIZE];
> + unsigned char enonce[TPM_NONCE_SIZE];
> + unsigned char authdata[SHA1_DIGEST_SIZE];
> + uint32_t authhandle = 0;
> + unsigned char cont = 0;
> + uint32_t ordinal;
> + int ret;
> +
> + ordinal = htonl(TPM_ORD_LOADKEY2);
> +
> + /* session for loading the key */
> + ret = oiap(tb, &authhandle, enonce);
> + if (ret < 0) {
> + pr_info("trusted_key: oiap failed (%d)\n", ret);
> + return ret;
> + }
> +
> + /* generate odd nonce */
> + ret = tpm_get_random(tb, nonceodd, TPM_NONCE_SIZE);
> + if (ret < 0) {
> + pr_info("trusted_key: tpm_get_random failed (%d)\n", ret);
> + return ret;
> + }
> +
> + /* calculate authorization HMAC value */
> + ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
> + nonceodd, cont, sizeof(uint32_t), &ordinal,
> + keybloblen, keyblob, 0, 0);
> + if (ret < 0)
> + return ret;
> +
> + /* build the request buffer */
> + INIT_BUF(tb);
> + store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
> + store32(tb, TPM_LOADKEY2_SIZE + keybloblen);
> + store32(tb, TPM_ORD_LOADKEY2);
> + store32(tb, keyhandle);
> + storebytes(tb, keyblob, keybloblen);
> + store32(tb, authhandle);
> + storebytes(tb, nonceodd, TPM_NONCE_SIZE);
> + store8(tb, cont);
> + storebytes(tb, authdata, SHA1_DIGEST_SIZE);
> +
> + ret = trusted_tpm_send(TPM_ANY_NUM, tb->data, MAX_BUF_SIZE);
> + if (ret < 0) {
> + pr_info("trusted_key: authhmac failed (%d)\n", ret);
> + return ret;
> + }
> +
> + ret = TSS_checkhmac1(tb->data, ordinal, nonceodd, keyauth,
> + SHA1_DIGEST_SIZE, 0, 0);
> + if (ret < 0) {
> + pr_info("trusted_key: TSS_checkhmac1 failed (%d)\n", ret);
> + return ret;
> + }
> +
> + *newhandle = LOAD32(tb->data, TPM_DATA_OFFSET);
> + return 0;
> +}
> +
> +/*
> + * Execute the FlushSpecific TPM command
> + */
> +uint32_t tpm_flushspecific(struct tpm_buf *tb, uint32_t handle,
> + uint32_t resourcetype)
static?
> +{
> + INIT_BUF(tb);
> + store16(tb, TPM_TAG_RQU_COMMAND);
> + store32(tb, TPM_FLUSHSPECIFIC_SIZE);
> + store32(tb, TPM_ORD_FLUSHSPECIFIC);
> + store32(tb, handle);
> + store32(tb, resourcetype);
> +
> + return trusted_tpm_send(TPM_ANY_NUM, tb->data, MAX_BUF_SIZE);
> +}
> +
> +/*
> + * Evict a key from the TPM
> + */
> +uint32_t tpm_evictkey(struct tpm_buf *tb, uint32_t keyhandle)
static?
> +{
> + int ret;
> +
> + INIT_BUF(tb);
> + store16(tb, TPM_TAG_RQU_COMMAND);
> + store32(tb, TPM_EVICTKEY_SIZE);
> + store32(tb, TPM_ORD_EVICTKEY);
> + store32(tb, keyhandle);
> +
> + ret = trusted_tpm_send(TPM_ANY_NUM, tb->data, sizeof tb->data);
> + if (ret < 0)
> + ret = tpm_flushspecific(tb, keyhandle, TPM_RT_KEY);
> +
> + return ret;
> +}
> +
> +/*
> * Have the TPM seal(encrypt) the symmetric key
> */
> static int key_seal(struct trusted_key_payload *p,
> struct trusted_key_options *o)
> {
> struct tpm_buf *tb;
> + uint32_t keyhandle;
> + unsigned char *parentauth;
> int ret;
>
> tb = kzalloc(sizeof *tb, GFP_KERNEL);
> @@ -703,12 +809,40 @@ static int key_seal(struct trusted_key_payload *p,
> /* include migratable flag at end of sealed key */
> p->key[p->key_len] = p->migratable;
>
> - ret = tpm_seal(tb, o->keytype, o->keyhandle, o->keyauth,
> + /* set default values */
> + keyhandle = o->keyhandle;
> + parentauth = o->srkauth;
> +
> + if (o->keytype == SEAL_keytype) {
> + parentauth = o->keyauth;
> + if (o->keyblob_len > 0) {
> + ret = tpm_loadkey2(tb, SRKHANDLE, o->srkauth,
> + o->keyblob, o->keyblob_len,
> + &keyhandle);
> + if (ret < 0) {
> + pr_info("trusted_key: loadkey2 failed (%d)\n",
> + ret);
> + goto out;
> + }
> +
> + dump_tpm_key12_handle(keyhandle);
> + }
> + }
> +
> + ret = tpm_seal(tb, o->keytype, keyhandle, parentauth,
> p->key, p->key_len + 1, p->blob, &p->blob_len,
> o->blobauth, o->pcrinfo, o->pcrinfo_len);
> if (ret < 0)
> pr_info("trusted_key: srkseal failed (%d)\n", ret);
>
> + if (o->keyblob_len > 0) {
> + int evictret = tpm_evictkey(tb, keyhandle);
> +
> + if (evictret < 0)
> + pr_info("trusted_key: evictkey failed (%d)\n",
> + evictret);
> + }
> +out:
> kfree(tb);
> return ret;
> }
> @@ -720,13 +854,33 @@ static int key_unseal(struct trusted_key_payload *p,
> struct trusted_key_options *o)
> {
> struct tpm_buf *tb;
> + uint32_t keyhandle;
> + unsigned char *parentauth;
> int ret;
>
> tb = kzalloc(sizeof *tb, GFP_KERNEL);
> if (!tb)
> return -ENOMEM;
>
> - ret = tpm_unseal(tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
> + /* set default values */
> + keyhandle = o->keyhandle;
> + parentauth = o->srkauth;
> +
> + if (o->keytype == SEAL_keytype) {
> + parentauth = o->keyauth;
> + if (o->keyblob_len > 0) {
> + ret = tpm_loadkey2(tb, SRKHANDLE, o->srkauth,
> + o->keyblob, o->keyblob_len,
> + &keyhandle);
> + if (ret < 0) {
> + pr_info("trusted_key: loadkey2 failed (%d)\n",
> + ret);
> + goto out;
> + }
> + }
> + }
> +
> + ret = tpm_unseal(tb, keyhandle, parentauth, p->blob, p->blob_len,
> o->blobauth, p->key, &p->key_len);
> if (ret < 0)
> pr_info("trusted_key: srkunseal failed (%d)\n", ret);
> @@ -734,14 +888,22 @@ static int key_unseal(struct trusted_key_payload *p,
> /* pull migratable flag out of sealed key */
> p->migratable = p->key[--p->key_len];
>
> + if (o->keyblob_len > 0) {
> + int evictret = tpm_evictkey(tb, keyhandle);
> +
> + if (evictret < 0)
> + pr_info("trusted_key: evictkey failed (%d)\n",
> + evictret);
> + }
> +out:
> kfree(tb);
> return ret;
> }
>
> enum {
> Opt_err = -1,
> - Opt_new, Opt_load, Opt_update,
> - Opt_keyhandle, Opt_keyauth, Opt_blobauth,
> + Opt_new, Opt_load, Opt_update, Opt_srkauth,
> + Opt_keyhandle, Opt_keyblob, Opt_keyauth, Opt_blobauth,
> Opt_pcrinfo, Opt_pcrlock, Opt_migratable
> };
>
> @@ -749,7 +911,9 @@ static const match_table_t key_tokens = {
> {Opt_new, "new"},
> {Opt_load, "load"},
> {Opt_update, "update"},
> + {Opt_srkauth, "srkauth=%s"},
> {Opt_keyhandle, "keyhandle=%s"},
> + {Opt_keyblob, "keyblob=%s"},
> {Opt_keyauth, "keyauth=%s"},
> {Opt_blobauth, "blobauth=%s"},
> {Opt_pcrinfo, "pcrinfo=%s"},
> @@ -768,6 +932,8 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
> int res;
> unsigned long handle;
> unsigned long lock;
> + uint16_t tpm_key_tag;
> + uint32_t value;
>
> while ((p = strsep(&c, " \t"))) {
> if (*p == '\0' || *p == ' ' || *p == '\t')
> @@ -788,6 +954,35 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
> opt->keytype = SEAL_keytype;
> opt->keyhandle = handle;
> break;
> + case Opt_keyblob:
> + if (strlen(args[0].from) >= MAX_KEYBLOB_SIZE * 2)
> + return -EINVAL;
> + hex2bin(opt->keyblob, args[0].from, MAX_KEYBLOB_SIZE);
> + tpm_key_tag = LOAD16(opt->keyblob, 0);
> + if (tpm_key_tag != TPM_TAG_KEY12)
> + return -EINVAL;
> + opt->keytype = SEAL_keytype;
> + opt->keyblob_len = TPM_KEY12_EXPSIZE_OFFSET;
> + /* key exponent size */
> + value = LOAD32(opt->keyblob, opt->keyblob_len);
> + opt->keyblob_len += sizeof(uint32_t) + value;
> + /* PCRINFO size */
> + value = LOAD32(opt->keyblob, opt->keyblob_len);
> + opt->keyblob_len += sizeof(uint32_t) + value;
> + /* key length */
> + value = LOAD32(opt->keyblob, opt->keyblob_len);
> + opt->keyblob_len += sizeof(uint32_t) + value;
> + /* enc data size */
> + value = LOAD32(opt->keyblob, opt->keyblob_len);
> + opt->keyblob_len += sizeof(uint32_t) + value;
> + if (opt->keyblob_len >= MAX_KEYBLOB_SIZE)
> + return -EINVAL;
> + break;
> + case Opt_srkauth:
> + if (strlen(args[0].from) != 2 * SHA1_DIGEST_SIZE)
> + return -EINVAL;
> + hex2bin(opt->srkauth, args[0].from, SHA1_DIGEST_SIZE);
> + break;
> case Opt_keyauth:
> if (strlen(args[0].from) != 2 * SHA1_DIGEST_SIZE)
> return -EINVAL;
> diff --git a/security/keys/trusted.h b/security/keys/trusted.h
> index 3249fbd..6a9f373 100644
> --- a/security/keys/trusted.h
> +++ b/security/keys/trusted.h
> @@ -3,12 +3,16 @@
>
> /* implementation specific TPM constants */
> #define MAX_PCRINFO_SIZE 64
> -#define MAX_BUF_SIZE 512
> +#define MAX_BUF_SIZE 1024
> +#define MAX_KEYBLOB_SIZE 1024
> #define TPM_GETRANDOM_SIZE 14
> #define TPM_OSAP_SIZE 36
> #define TPM_OIAP_SIZE 10
> #define TPM_SEAL_SIZE 87
> #define TPM_UNSEAL_SIZE 104
> +#define TPM_LOADKEY2_SIZE 59
> +#define TPM_EVICTKEY_SIZE 14
> +#define TPM_FLUSHSPECIFIC_SIZE 18
> #define TPM_SIZE_OFFSET 2
> #define TPM_RETURN_OFFSET 6
> #define TPM_DATA_OFFSET 10
> @@ -17,6 +21,8 @@
> #define LOAD32N(buffer, offset) (*(uint32_t *)&buffer[offset])
> #define LOAD16(buffer, offset) (ntohs(*(uint16_t *)&buffer[offset]))
>
> +#define TPM_KEY12_EXPSIZE_OFFSET 31
> +
> struct tpm_buf {
> int len;
> unsigned char data[MAX_BUF_SIZE];
> @@ -39,6 +45,9 @@ enum {
> struct trusted_key_options {
> uint16_t keytype;
> uint32_t keyhandle;
> + uint32_t keyblob_len;
> + unsigned char keyblob[MAX_KEYBLOB_SIZE];
> + unsigned char srkauth[SHA1_DIGEST_SIZE];
> unsigned char keyauth[SHA1_DIGEST_SIZE];
> unsigned char blobauth[SHA1_DIGEST_SIZE];
> uint32_t pcrinfo_len;
> @@ -52,7 +61,12 @@ struct trusted_key_options {
> static inline void dump_options(struct trusted_key_options *o)
> {
> pr_info("trusted_key: sealing key type %d\n", o->keytype);
> - pr_info("trusted_key: sealing key handle %0X\n", o->keyhandle);
> + if (o->keyblob_len > 0) {
> + pr_info("trusted_key: sealing key blob %d\n", o->keyblob_len);
> + print_hex_dump(KERN_INFO, "keyblob ", DUMP_PREFIX_NONE,
> + 16, 1, o->keyblob, o->keyblob_len, 0);
> + } else
> + pr_info("trusted_key: sealing key handle %0X\n", o->keyhandle);
> pr_info("trusted_key: pcrlock %d\n", o->pcrlock);
> pr_info("trusted_key: pcrinfo %d\n", o->pcrinfo_len);
> print_hex_dump(KERN_INFO, "pcrinfo ", DUMP_PREFIX_NONE,
> @@ -90,6 +104,11 @@ static inline void dump_tpm_buf(unsigned char *buf)
> len = LOAD32(buf, TPM_SIZE_OFFSET);
> print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE, 16, 1, buf, len, 0);
> }
> +static inline void dump_tpm_key12_handle(uint32_t handle)
> +{
> + print_hex_dump(KERN_INFO, "trusted-key: key handle ", DUMP_PREFIX_NONE,
> + 16, 1, &handle, 4, 0);
> +}
> #else
> static inline void dump_options(struct trusted_key_options *o)
> {
> @@ -106,6 +125,10 @@ static inline void dump_sess(struct osapsess *s)
> static inline void dump_tpm_buf(unsigned char *buf)
> {
> }
> +
> +static inline void dump_tpm_key12_handle(uint32_t handle)
> +{
> +}
> #endif
>
> static inline void store8(struct tpm_buf *buf, const unsigned char value)
--
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