[RFC 10/20] ima: Implement hierarchical processing of file accesses

Stefan Berger
2021-11-30T16:08:05Z

Implement hierarchical processing of file accesses in IMA namespaces by
walking the list of IMA namespaces towards the init_ima_ns. This way
file accesses can be audited in an IMA namespace and also be evaluated
against the IMA policies of parent IMA namespaces.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
security/integrity/ima/ima_main.c | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index d692c9d53a98..42cbcaf2dc1e 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -199,10 +199,10 @@ void ima_file_free(struct file *file)
ima_check_last_writer(iint, inode, file);
}

-static int process_measurement(struct ima_namespace *ns,
- struct file *file, const struct cred *cred,
- u32 secid, char *buf, loff_t size, int mask,
- enum ima_hooks func)
+static int _process_measurement(struct ima_namespace *ns,
+ struct file *file, const struct cred *cred,
+ u32 secid, char *buf, loff_t size, int mask,
+ enum ima_hooks func)
{
struct inode *inode = file_inode(file);
struct integrity_iint_cache *iint = NULL;
@@ -404,6 +404,27 @@ static int process_measurement(struct ima_namespace *ns,
return 0;
}

+static int process_measurement(struct ima_namespace *ns,
+ struct file *file, const struct cred *cred,
+ u32 secid, char *buf, loff_t size, int mask,
+ enum ima_hooks func)
+{
+ int ret = 0;
+ struct user_namespace *user_ns;
+
+ do {
+ ret = _process_measurement(ns, file, cred, secid, buf, size, mask, func);
+ if (ret)
+ break;
+ user_ns = ns->user_ns->parent;
+ if (!user_ns)
+ break;
+ ns = user_ns->ima_ns;
+ } while (1);
+
+ return ret;
+}
+
/**
* ima_file_mmap - based on policy, collect/store measurement.
* @file: pointer to the file to be measured (May be NULL)
--
2.31.1