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ima: always measure and audit files in policy

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All files matching a "measure" rule must be included in the IMA
measurement list, even when the file hash cannot be calculated.
Similarly, all files matching an "audit" rule must be audited, even when
the file hash can not be calculated.

The file data hash field contained in the IMA measurement list template
data will contain 0's instead of the actual file hash digest.

Note:
In general, adding, deleting or in anyway changing which files are
included in the IMA measurement list is not a good idea, as it might
result in not being able to unseal trusted keys sealed to a specific
TPM PCR value.  This patch not only adds file measurements that were
not previously measured, but specifies that the file hash value for
these files will be 0's.

As the IMA measurement list ordering is not consistent from one boot
to the next, it is unlikely that anyone is sealing keys based on the
IMA measurement list.  Remote attestation servers should be able to
process these new measurement records, but might complain about
these unknown records.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Reviewed-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
This commit is contained in:
Mimi Zohar
2017-06-17 23:56:23 -04:00
parent 2068626d13
commit f3cc6b25dc
3 changed files with 55 additions and 29 deletions
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9
security/integrity/ima/ima_main.c
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@@ -235,11 +235,8 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
if (rc != 0) {
if (file->f_flags & O_DIRECT)
rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES;
if (rc != 0 && rc != -EBADF && rc != -EINVAL)
goto out_digsig;
}
if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
pathname = ima_d_path(&file->f_path, &pathbuf, filename);
@@ -247,12 +244,14 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
if (action & IMA_MEASURE)
ima_store_measurement(iint, file, pathname,
xattr_value, xattr_len, pcr);
if (action & IMA_APPRAISE_SUBMASK)
if (rc == 0 && (action & IMA_APPRAISE_SUBMASK))
rc = ima_appraise_measurement(func, iint, file, pathname,
xattr_value, xattr_len, opened);
if (action & IMA_AUDIT)
ima_audit_measurement(iint, pathname);
if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
rc = 0;
out_digsig:
if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG) &&
!(iint->flags & IMA_NEW_FILE))