Re: [PATCH v5 3/3] fanotify,audit: Allow audit to use the full permission event response
On Mon, Dec 12, 2022 at 9:06 AM Richard Guy Briggs <rgb(a)redhat.com> wrote:
This patch passes the full response so that the audit function can use all
of it. The audit function was updated to log the additional information in
the AUDIT_FANOTIFY record.
Currently the only type of fanotify info that is defined is an audit
rule number, but convert it to hex encoding to future-proof the field.
Hex encoding suggested by Paul Moore <paul(a)paul-moore.com>.
Sample records:
type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1 fan_info=3137
subj_trust=3 obj_trust=5
type=FANOTIFY msg=audit(1659730979.839:284): resp=1 fan_type=0 fan_info=3F subj_trust=2
obj_trust=2
Suggested-by: Steve Grubb <sgrubb(a)redhat.com>
Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com>
---
fs/notify/fanotify/fanotify.c | 3 ++-
include/linux/audit.h | 9 +++++----
kernel/auditsc.c | 25 ++++++++++++++++++++++---
3 files changed, 29 insertions(+), 8 deletions(-)
...
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index d1fb821de104..8d523066d81f 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -64,6 +64,7 @@
#include <uapi/linux/limits.h>
#include <uapi/linux/netfilter/nf_tables.h>
#include <uapi/linux/openat2.h> // struct open_how
+#include <uapi/linux/fanotify.h>
#include "audit.h"
@@ -2877,10 +2878,28 @@ void __audit_log_kern_module(char *name)
context->type = AUDIT_KERN_MODULE;
}
-void __audit_fanotify(u32 response)
+void __audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar)
{
- audit_log(audit_context(), GFP_KERNEL,
- AUDIT_FANOTIFY, "resp=%u", response);
+ struct audit_context *ctx = audit_context();
+ struct audit_buffer *ab;
+ char numbuf[12];
+
+ if (friar->hdr.type == FAN_RESPONSE_INFO_NONE) {
+ audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
+ "resp=%u fan_type=%u fan_info=3F subj_trust=2
obj_trust=2",
+ response, FAN_RESPONSE_INFO_NONE);
The fan_info, subj_trust, and obj_trust constant values used here are
awfully magic-numbery and not the usual sentinel values one might
expect for a "none" operation, e.g. zeros/INT_MAX/etc. I believe a
comment here explaining the values would be a good idea.
+ return;
+ }
+ ab = audit_log_start(ctx, GFP_KERNEL, AUDIT_FANOTIFY);
+ if (ab) {
+ audit_log_format(ab, "resp=%u fan_type=%u fan_info=",
+ response, friar->hdr.type);
+ snprintf(numbuf, sizeof(numbuf), "%u", friar->rule_number);
+ audit_log_n_hex(ab, numbuf, sizeof(numbuf));
It looks like the kernel's printf format string parsing supports %X so
why not just use that for now, we can always complicate it later if
needed. It would probably also remove the need for the @ab, @numbuf,
and @ctx variables. For example:
audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
"resp=%u fan_type=%u fan_info=%X subj_trust=%u obj_trust=%u",
response, friar->hdr.type, friar->rule_number,
friar->subj_trust, friar->obj_trust);
Am I missing something?
+ audit_log_format(ab, " subj_trust=%u
obj_trust=%u",
+ friar->subj_trust, friar->obj_trust);
+ audit_log_end(ab);
+ }
}
void __audit_tk_injoffset(struct timespec64 offset)
--
2.27.0
--
paul-moore.com