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Message-ID: <4EB18138.6050400@polito.it>
Date: Wed, 02 Nov 2011 18:43:20 +0100
From: Roberto Sassu <roberto.sassu@...ito.it>
To: David Safford <safford@...son.ibm.com>
CC: keyrings@...ux-nfs.org, linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org, zohar@...ibm.com,
dhowells@...hat.com, jmorris@...ei.org
Subject: Re: [PATCH 2/2] trusted-key: added support for loading a key blob
in the TPM
On 11/02/2011 06:26 PM, David Safford wrote:
> 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...
>
Thanks, i will fix them and submit a new version of
the patches after receiving other comments.
Roberto Sassu
> dave
>
>>
>> Signed-off-by: Roberto Sassu<roberto.sassu@...ito.it>
>> ---
>> 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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