Re: [PATCH v1 1/2] audit: record fanotify event regardless of presence of rules

On Tue, May 27, 2025 at 9:10 AM Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > On 2025-04-11 14:14, Paul Moore wrote: > > On Mar 5, 2025 Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > > > > > > When no audit rules are in place, fanotify event results are > > > unconditionally dropped due to an explicit check for the existence of > > > any audit rules. Given this is a report from another security > > > sub-system, allow it to be recorded regardless of the existence of any > > > audit rules. > > > > > > To test, install and run the fapolicyd daemon with default config. Then > > > as an unprivileged user, create and run a very simple binary that should > > > be denied. Then check for an event with > > > ausearch -m FANOTIFY -ts recent > > > > > > Link: https://issues.redhat.com/browse/RHEL-1367 > > > Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > > > Acked-by: Jan Kara <jack(a)suse.cz&gt; > > > --- > > > include/linux/audit.h | 8 +------- > > > kernel/auditsc.c | 2 +- > > > 2 files changed, 2 insertions(+), 8 deletions(-) > > > > > > diff --git a/include/linux/audit.h b/include/linux/audit.h > > > index 0050ef288ab3..d0c6f23503a1 100644 > > > --- a/include/linux/audit.h > > > +++ b/include/linux/audit.h > > > @@ -418,7 +418,7 @@ extern void __audit_log_capset(const struct cred *new, const struct cred *old); > > > extern void __audit_mmap_fd(int fd, int flags); > > > extern void __audit_openat2_how(struct open_how *how); > > > extern void __audit_log_kern_module(char *name); > > > -extern void __audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar); > > > +extern void audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar); > > > extern void __audit_tk_injoffset(struct timespec64 offset); > > > extern void __audit_ntp_log(const struct audit_ntp_data *ad); > > > extern void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries, > > > @@ -525,12 +525,6 @@ static inline void audit_log_kern_module(char *name) > > > __audit_log_kern_module(name); > > > } > > > > > > -static inline void audit_fanotify(u32 response, struct fanotify_response_info_audit_rule *friar) > > > -{ > > > - if (!audit_dummy_context()) > > > - __audit_fanotify(response, friar); > > > -} > > > > It seems like we should at least have an audit_enabled() check, yes? > > We've had people complain about audit events being generated when audit > > is disabled, any while we don't currently have such a check in place > > here, I believe the dummy context check is doing that for us. > > > > static inline void audit_fanotify(...) > > { > > if (!audit_enabled) > > return; > > __audit_fanotify(...); > > } > > That would be consistent with other security events messages. I was > going through the selinux code to see what it does and I am missing it > if selinux checks with audit_enabled(). Are selinux messages somehow > exempt from audit_enabled()? There are likely a number of callers in the kernel that don't have audit_enabled() checks, some are probably bugs, others probably intentional; I wouldn't worry too much about what one subsystem does when deciding what to do for another. In the case of fanotify, I suspect the right thing to do is add an audit_enabled() check since it is already doing an audit_dummy_context() check. To be clear, there may be some cases where we do an audit_dummy_context() check and doing an audit_enabled() check would be wrong, but I don't believe that is the case with fanotify.

paul-moore.com