From 20c59ce010f84300f6c655d32db2610d3433f85c Mon Sep 17 00:00:00 2001 From: Maurizio Drocco Date: Tue, 23 Jun 2020 11:57:32 -0400 Subject: ima: extend boot_aggregate with kernel measurements Registers 8-9 are used to store measurements of the kernel and its command line (e.g., grub2 bootloader with tpm module enabled). IMA should include them in the boot aggregate. Registers 8-9 should be only included in non-SHA1 digests to avoid ambiguity. Signed-off-by: Maurizio Drocco Reviewed-by: Bruno Meneguele Tested-by: Bruno Meneguele (TPM 1.2, TPM 2.0) Signed-off-by: Mimi Zohar --- security/integrity/ima/ima_crypto.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'security/integrity/ima/ima_crypto.c') diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c index 220b14920c37..011c3c76af86 100644 --- a/security/integrity/ima/ima_crypto.c +++ b/security/integrity/ima/ima_crypto.c @@ -823,13 +823,26 @@ static int ima_calc_boot_aggregate_tfm(char *digest, u16 alg_id, if (rc != 0) return rc; - /* cumulative sha1 over tpm registers 0-7 */ + /* cumulative digest over TPM registers 0-7 */ for (i = TPM_PCR0; i < TPM_PCR8; i++) { ima_pcrread(i, &d); /* now accumulate with current aggregate */ rc = crypto_shash_update(shash, d.digest, crypto_shash_digestsize(tfm)); } + /* + * Extend cumulative digest over TPM registers 8-9, which contain + * measurement for the kernel command line (reg. 8) and image (reg. 9) + * in a typical PCR allocation. Registers 8-9 are only included in + * non-SHA1 boot_aggregate digests to avoid ambiguity. + */ + if (alg_id != TPM_ALG_SHA1) { + for (i = TPM_PCR8; i < TPM_PCR10; i++) { + ima_pcrread(i, &d); + rc = crypto_shash_update(shash, d.digest, + crypto_shash_digestsize(tfm)); + } + } if (!rc) crypto_shash_final(shash, digest); return rc; -- cgit v1.2.3