Commit 20c59ce0 authored by Maurizio Drocco's avatar Maurizio Drocco Committed by Mimi Zohar
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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: default avatarMaurizio Drocco <maurizio.drocco@ibm.com>
Reviewed-by: default avatarBruno Meneguele <bmeneg@redhat.com>
Tested-by: Bruno Meneguele <bmeneg@redhat.com>  (TPM 1.2, TPM 2.0)
Signed-off-by: default avatarMimi Zohar <zohar@linux.ibm.com>
parent 48778464
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+1 −1
Original line number Diff line number Diff line
@@ -30,7 +30,7 @@

enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_BINARY_NO_FIELD_LEN,
		     IMA_SHOW_BINARY_OLD_STRING_FMT, IMA_SHOW_ASCII };
enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 };
enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8, TPM_PCR10 = 10 };

/* digest size for IMA, fits SHA1 or MD5 */
#define IMA_DIGEST_SIZE		SHA1_DIGEST_SIZE
+14 −1
Original line number Diff line number Diff line
@@ -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;