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ima: change integrity cache to store measured pcr

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IMA avoids re-measuring files by storing the current state as a flag in
the integrity cache. It will then skip adding a new measurement log entry
if the cache reports the file as already measured.

If a policy measures an already measured file to a new PCR, the measurement
will not be added to the list. This patch implements a new bitfield for
specifying which PCR the file was measured into, rather than if it was
measured.

Signed-off-by: Eric Richter <erichte@linux.vnet.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
This commit is contained in:
Eric Richter 2016-06-01 13:14:06 -05:00 committed by Mimi Zohar
parent 67696f6d79
commit a422638d49
3 changed files with 11 additions and 3 deletions
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6
security/integrity/ima/ima_api.c
View File

@ -266,7 +266,7 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
xattr_len, NULL};
int violation = 0;
if (iint->flags & IMA_MEASURED)
if (iint->measured_pcrs & (0x1 << pcr))
return;
result = ima_alloc_init_template(&event_data, &entry);
@ -277,8 +277,10 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
}
result = ima_store_template(entry, violation, inode, filename, pcr);
if (!result || result == -EEXIST)
if (!result || result == -EEXIST) {
iint->flags |= IMA_MEASURED;
iint->measured_pcrs |= (0x1 << pcr);
}
if (result < 0)
ima_free_template_entry(entry);
}

1
security/integrity/ima/ima_appraise.c
View File

@ -370,6 +370,7 @@ static void ima_reset_appraise_flags(struct inode *inode, int digsig)
return;
iint->flags &= ~IMA_DONE_MASK;
iint->measured_pcrs = 0;
if (digsig)
iint->flags |= IMA_DIGSIG;
return;

7
security/integrity/ima/ima_main.c
View File

@ -125,6 +125,7 @@ static void ima_check_last_writer(struct integrity_iint_cache *iint,
if ((iint->version != inode->i_version) ||
(iint->flags & IMA_NEW_FILE)) {
iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
iint->measured_pcrs = 0;
if (iint->flags & IMA_APPRAISE)
ima_update_xattr(iint, file);
}
@ -210,7 +211,11 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
*/
iint->flags |= action;
action &= IMA_DO_MASK;
action &= ~((iint->flags & IMA_DONE_MASK) >> 1);
action &= ~((iint->flags & (IMA_DONE_MASK ^ IMA_MEASURED)) >> 1);
/* If target pcr is already measured, unset IMA_MEASURE action */
if ((action & IMA_MEASURE) && (iint->measured_pcrs & (0x1 << pcr)))
action ^= IMA_MEASURE;
/* Nothing to do, just return existing appraised status */
if (!action) {