diff options
Diffstat (limited to 'stubdom')
| -rw-r--r-- | stubdom/vtpm/vtpmblk.c | 74 |
1 files changed, 60 insertions, 14 deletions
diff --git a/stubdom/vtpm/vtpmblk.c b/stubdom/vtpm/vtpmblk.c index b343bd84b2..fe529ab5ac 100644 --- a/stubdom/vtpm/vtpmblk.c +++ b/stubdom/vtpm/vtpmblk.c @@ -26,6 +26,7 @@ static struct blkfront_dev* blkdev = NULL; static int blkfront_fd = -1; +static uint64_t slot_size = 0; int init_vtpmblk(struct tpmfront_dev* tpmfront_dev) { @@ -45,6 +46,8 @@ int init_vtpmblk(struct tpmfront_dev* tpmfront_dev) goto error; } + slot_size = blkinfo.sectors * blkinfo.sector_size / 2; + return 0; error: shutdown_blkfront(blkdev); @@ -59,15 +62,20 @@ void shutdown_vtpmblk(void) blkdev = NULL; } -int write_vtpmblk_raw(uint8_t *data, size_t data_length) +static int write_vtpmblk_raw(uint8_t *data, size_t data_length, int slot) { int rc; uint32_t lenbuf; - debug("Begin Write data=%p len=%u", data, data_length); + debug("Begin Write data=%p len=%u slot=%u ssize=%u", data, data_length, slot, slot_size); + + if (data_length > slot_size - 4) { + error("vtpm data cannot fit in data slot (%d/%d).", data_length, slot_size - 4); + return -1; + } lenbuf = cpu_to_be32((uint32_t)data_length); - lseek(blkfront_fd, 0, SEEK_SET); + lseek(blkfront_fd, slot * slot_size, SEEK_SET); if((rc = write(blkfront_fd, (uint8_t*)&lenbuf, 4)) != 4) { error("write(length) failed! error was %s", strerror(errno)); return -1; @@ -82,12 +90,12 @@ int write_vtpmblk_raw(uint8_t *data, size_t data_length) return 0; } -int read_vtpmblk_raw(uint8_t **data, size_t *data_length) +static int read_vtpmblk_raw(uint8_t **data, size_t *data_length, int slot) { int rc; uint32_t lenbuf; - lseek(blkfront_fd, 0, SEEK_SET); + lseek(blkfront_fd, slot * slot_size, SEEK_SET); if(( rc = read(blkfront_fd, (uint8_t*)&lenbuf, 4)) != 4) { error("read(length) failed! error was %s", strerror(errno)); return -1; @@ -97,6 +105,10 @@ int read_vtpmblk_raw(uint8_t **data, size_t *data_length) error("read 0 data_length for NVM"); return -1; } + if(*data_length > slot_size - 4) { + error("read invalid data_length for NVM"); + return -1; + } *data = tpm_malloc(*data_length); if((rc = read(blkfront_fd, *data, *data_length)) != *data_length) { @@ -104,7 +116,7 @@ int read_vtpmblk_raw(uint8_t **data, size_t *data_length) return -1; } - info("Read %u bytes from NVM persistent storage", *data_length); + info("Read %u bytes from NVM persistent storage (slot %d)", *data_length, slot); return 0; } @@ -221,6 +233,9 @@ egress: return rc; } +/* Current active state slot, or -1 if no valid saved state exists */ +static int active_slot = -1; + int write_vtpmblk(struct tpmfront_dev* tpmfront_dev, uint8_t* data, size_t data_length) { int rc; uint8_t* cipher = NULL; @@ -228,12 +243,17 @@ int write_vtpmblk(struct tpmfront_dev* tpmfront_dev, uint8_t* data, size_t data_ uint8_t hashkey[HASHKEYSZ]; uint8_t* symkey = hashkey + HASHSZ; + /* Switch to the other slot. Note that in a new vTPM, the read will not + * succeed, so active_slot will be -1 and we will write to slot 0. + */ + active_slot = !active_slot; + /* Encrypt the data */ if((rc = encrypt_vtpmblk(data, data_length, &cipher, &cipher_len, symkey))) { goto abort_egress; } /* Write to disk */ - if((rc = write_vtpmblk_raw(cipher, cipher_len))) { + if((rc = write_vtpmblk_raw(cipher, cipher_len, active_slot))) { goto abort_egress; } /* Get sha1 hash of data */ @@ -256,7 +276,8 @@ int read_vtpmblk(struct tpmfront_dev* tpmfront_dev, uint8_t** data, size_t *data size_t cipher_len = 0; size_t keysize; uint8_t* hashkey = NULL; - uint8_t hash[HASHSZ]; + uint8_t hash0[HASHSZ]; + uint8_t hash1[HASHSZ]; uint8_t* symkey; /* Retreive the hash and the key from the manager */ @@ -270,14 +291,32 @@ int read_vtpmblk(struct tpmfront_dev* tpmfront_dev, uint8_t** data, size_t *data } symkey = hashkey + HASHSZ; - /* Read from disk now */ - if((rc = read_vtpmblk_raw(&cipher, &cipher_len))) { + active_slot = 0; + debug("Reading slot 0 from disk\n"); + if((rc = read_vtpmblk_raw(&cipher, &cipher_len, 0))) { goto abort_egress; } /* Compute the hash of the cipher text and compare */ - sha1(cipher, cipher_len, hash); - if(memcmp(hash, hashkey, HASHSZ)) { + sha1(cipher, cipher_len, hash0); + if(!memcmp(hash0, hashkey, HASHSZ)) + goto valid; + + free(cipher); + cipher = NULL; + + active_slot = 1; + debug("Reading slot 1 from disk (offset=%u)\n", slot_size); + if((rc = read_vtpmblk_raw(&cipher, &cipher_len, 1))) { + goto abort_egress; + } + + /* Compute the hash of the cipher text and compare */ + sha1(cipher, cipher_len, hash1); + if(!memcmp(hash1, hashkey, HASHSZ)) + goto valid; + + { int i; error("NVM Storage Checksum failed!"); printf("Expected: "); @@ -285,14 +324,20 @@ int read_vtpmblk(struct tpmfront_dev* tpmfront_dev, uint8_t** data, size_t *data printf("%02hhX ", hashkey[i]); } printf("\n"); - printf("Actual: "); + printf("Slot 0: "); + for(i = 0; i < HASHSZ; ++i) { + printf("%02hhX ", hash0[i]); + } + printf("\n"); + printf("Slot 1: "); for(i = 0; i < HASHSZ; ++i) { - printf("%02hhX ", hash[i]); + printf("%02hhX ", hash1[i]); } printf("\n"); rc = -1; goto abort_egress; } +valid: /* Decrypt the blob */ if((rc = decrypt_vtpmblk(cipher, cipher_len, data, data_length, symkey))) { @@ -300,6 +345,7 @@ int read_vtpmblk(struct tpmfront_dev* tpmfront_dev, uint8_t** data, size_t *data } goto egress; abort_egress: + active_slot = -1; egress: free(cipher); free(hashkey); |