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&gt; 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&gt;. > > 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&gt; > Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2 > Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > --- > 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 -- Linux-audit mailing list Linux-audit(a)redhat.com https://listman.redhat.com/mailman/listinfo/linux-audit