Re: [PATCH v5 3/3] fanotify,audit: Allow audit to use the full permission event response
From: Paul Moore <paul@paul-moore.com>
Date: 2022-12-20 23:32:07
Also in:
linux-fsdevel, lkml
On Mon, Dec 12, 2022 at 9:06 AM Richard Guy Briggs [off-list ref] 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 [off-list ref]. 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 <redacted> Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2 (local) Signed-off-by: Richard Guy Briggs <redacted> --- fs/notify/fanotify/fanotify.c | 3 ++- include/linux/audit.h | 9 +++++---- kernel/auditsc.c | 25 ++++++++++++++++++++++--- 3 files changed, 29 insertions(+), 8 deletions(-)
...
quoted hunk ↗ jump to hunk
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
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