ima: change integrity cache to store measured pcr

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>

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 8363ba3..9df26a2 100644 (file)
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -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);
 }

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index fe8e923..4b9b4a4 100644 (file)
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -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;

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 3627afd..596ef61 100644 (file)
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -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) {