audit: add record for multiple task security contexts

Replace the single skb pointer in an audit_buffer with a list of
skb pointers. Add the audit_stamp information to the audit_buffer as
there's no guarantee that there will be an audit_context containing
the stamp associated with the event. At audit_log_end() time create
auxiliary records as have been added to the list. Functions are
created to manage the skb list in the audit_buffer.

Create a new audit record AUDIT_MAC_TASK_CONTEXTS.
An example of the MAC_TASK_CONTEXTS record is:

    type=MAC_TASK_CONTEXTS
      msg=audit(1600880931.832:113)
      subj_apparmor=unconfined
      subj_smack=_

When an audit event includes a AUDIT_MAC_TASK_CONTEXTS record the
"subj=" field in other records in the event will be "subj=?".
An AUDIT_MAC_TASK_CONTEXTS record is supplied when the system has
multiple security modules that may make access decisions based on a
subject security context.

Refactor audit_log_task_context(), creating a new audit_log_subj_ctx().
This is used in netlabel auditing to provide multiple subject security
contexts as necessary.

Suggested-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subj tweak, audit example readability indents]
Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Casey Schaufler
2025-08-16 10:28:58 -07:00
committed by Paul Moore
parent a59076f266
commit eb59d494ee
7 changed files with 203 additions and 42 deletions

View File

@@ -84,7 +84,6 @@ struct audit_buffer *netlbl_audit_start_common(int type,
struct netlbl_audit *audit_info)
{
struct audit_buffer *audit_buf;
struct lsm_context ctx;
if (audit_enabled == AUDIT_OFF)
return NULL;
@@ -96,13 +95,7 @@ struct audit_buffer *netlbl_audit_start_common(int type,
audit_log_format(audit_buf, "netlabel: auid=%u ses=%u",
from_kuid(&init_user_ns, audit_info->loginuid),
audit_info->sessionid);
if (lsmprop_is_set(&audit_info->prop) &&
security_lsmprop_to_secctx(&audit_info->prop, &ctx,
LSM_ID_UNDEF) > 0) {
audit_log_format(audit_buf, " subj=%s", ctx.context);
security_release_secctx(&ctx);
}
audit_log_subj_ctx(audit_buf, &audit_info->prop);
return audit_buf;
}