[PATCH v5 10/18] ima: Store measurement after appraisal

Thiago Jung Bauermann
2017-10-18T00:54:55Z

When module-style signatures appended at the end of files are supported for
IMA appraisal, the code will fallback to the xattr signature if the
appended one fails to verify.

The problem is that we don't know whether we need to fallback to the xattr
signature until the appraise step, and by then the measure step was already
completed and would need to be done again in case the template includes the
signature.

To avoid this problem, do the appraisal first so that the correct signature
is stored by the template in the measure step.

Suggested-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
---
security/integrity/ima/ima_main.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 747a4fd9e2de..8e96450e27f5 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -242,12 +242,12 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
if (!pathbuf) /* ima_rdwr_violation possibly pre-fetched */
pathname = ima_d_path(&file->f_path, &pathbuf, filename);

- if (action & IMA_MEASURE)
- ima_store_measurement(iint, file, pathname,
- xattr_value, xattr_len, pcr);
if (rc == 0 && (action & IMA_APPRAISE_SUBMASK))
rc = ima_appraise_measurement(func, iint, file, pathname,
xattr_value, xattr_len, opened);
+ if (action & IMA_MEASURE)
+ ima_store_measurement(iint, file, pathname,
+ xattr_value, xattr_len, pcr);
if (action & IMA_AUDIT)
ima_audit_measurement(iint, pathname);