On Wed, Jul 29, 2026 at 7:03 PM Paul Moore <[email protected]> wrote:
>
> On Fri, Jul 24, 2026 at 11:03 AM Ricardo Robaina <[email protected]> wrote:
> >
> > The clone3(2) syscall moves most parameters to struct clone_args.
> > For this reason, the generic SYSCALL audit record does not capture
> > the structured arguments.
> >
> > Add a CLONE3 auxiliary record that logs: flags, exit_signal, cgroup,
> > and pidfd fields from struct clone_args. When CLONE_PIDFD is set and
> > the syscall succeeds, the resolved pidfd is logged; otherwise
> > pidfd=(null).
> >
> > ----
> > type=SYSCALL : syscall=clone3 a0=0x7ffe7f1ec640 a1=0x58 a2=0x0 ...
> > type=CLONE3 : cl3_flags=0x1000 exit_signal=17 cgroup=0 pidfd=3
> >
> > Link: https://github.com/linux-audit/audit-kernel/issues/151
> > Signed-off-by: Ricardo Robaina <[email protected]>
> > ---
> > include/linux/audit.h | 10 ++++++++++
> > include/uapi/linux/audit.h | 1 +
> > kernel/auditsc.c | 20 ++++++++++++++++++++
> > kernel/fork.c | 4 +++-
> > 4 files changed, 34 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/linux/audit.h b/include/linux/audit.h
> > index 45abb3722d30..833f349bf415 100644
> > --- a/include/linux/audit.h
> > +++ b/include/linux/audit.h
> > @@ -449,6 +449,7 @@ 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,
> > enum audit_nfcfgop op, gfp_t gfp);
> > +extern void __audit_log_clone3(struct kernel_clone_args *kargs, int ret);
> >
> > static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
> > {
> > @@ -598,6 +599,12 @@ static inline void audit_log_nfcfg(const char *name,
> > u8 af,
> > __audit_log_nfcfg(name, af, nentries, op, gfp);
> > }
> >
> > +static inline void audit_log_clone3(struct kernel_clone_args *kargs, int
> > ret)
> > +{
> > + if (!audit_dummy_context())
> > + __audit_log_clone3(kargs, ret);
> > +}
> > +
> > extern int audit_n_rules;
> > extern int audit_signals;
> > #else /* CONFIG_AUDITSYSCALL */
> > @@ -730,6 +737,9 @@ static inline void audit_log_nfcfg(const char *name, u8
> > af,
> > enum audit_nfcfgop op, gfp_t gfp)
> > { }
> >
> > +static inline void audit_log_clone3(struct kernel_clone_args *kargs, int
> > ret)
> > +{ }
> > +
> > #define audit_n_rules 0
> > #define audit_signals 0
> > #endif /* CONFIG_AUDITSYSCALL */
> > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> > index e8f5ce677df7..37357e17adbf 100644
> > --- a/include/uapi/linux/audit.h
> > +++ b/include/uapi/linux/audit.h
> > @@ -122,6 +122,7 @@
> > #define AUDIT_OPENAT2 1337 /* Record showing openat2 how args
> > */
> > #define AUDIT_DM_CTRL 1338 /* Device Mapper target control */
> > #define AUDIT_DM_EVENT 1339 /* Device Mapper events */
> > +#define AUDIT_CLONE3 1343 /* Record showing clone3 args */
> >
> > #define AUDIT_AVC 1400 /* SE Linux avc denial or grant */
> > #define AUDIT_SELINUX_ERR 1401 /* Internal SE Linux Errors */
> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index 6610e667c728..c0106bb71c19 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -2882,6 +2882,26 @@ void __audit_log_nfcfg(const char *name, u8 af,
> > unsigned int nentries,
> > }
> > EXPORT_SYMBOL_GPL(__audit_log_nfcfg);
> >
> > +void __audit_log_clone3(struct kernel_clone_args *kargs, int ret)
> > +{
> > + struct audit_buffer *ab;
> > + int pidfd;
> > +
> > + ab = audit_log_start(audit_context(), GFP_KERNEL,
> > + AUDIT_CLONE3);
> > + if (!ab)
> > + return;
> > +
> > + audit_log_format(ab, "cl3_flags=0x%llx exit_signal=%d cgroup=%d",
> > + kargs->flags, kargs->exit_signal, kargs->cgroup);
> > + if ((kargs->flags & CLONE_PIDFD) && ret >= 0 &&
> > + !get_user(pidfd, kargs->pidfd))
> > + audit_log_format(ab, " pidfd=%d", pidfd);
>
> Do we care about distinguishing between the combination of CLONE_PIDFD
> and CLONE_THREAD vs CLONE_PIDFD alone? In other words, do we care if
> the "pidfd" field sometimes represents a pidfd of the child process vs
> a thread in the current process?
>
Hi Paul,
Thanks for reviewing this patch.
The flags field can be use to check if CLONE_THREAD is set, so it's
possible to determine whether the pidfd refers to a child process or a
thread by inspecting the flags. Do you think we should include a
dedicated field for that?
> > + else
> > + audit_log_format(ab, " pidfd=(null)");
> > + audit_log_end(ab);
> > +}
> > +
> > static void audit_log_task(struct audit_buffer *ab)
> > {
> > kuid_t auid, uid;
> > diff --git a/kernel/fork.c b/kernel/fork.c
> > index f0e2e131a9a5..0f52e8c0e900 100644
> > --- a/kernel/fork.c
> > +++ b/kernel/fork.c
> > @@ -3047,7 +3047,9 @@ SYSCALL_DEFINE2(clone3, struct clone_args __user *,
> > uargs, size_t, size)
> > if (!clone3_args_valid(&kargs))
> > return -EINVAL;
> >
> > - return kernel_clone(&kargs);
> > + err = kernel_clone(&kargs);
> > + audit_log_clone3(&kargs, err);
> > + return err;
> > }
> >
> > void walk_process_tree(struct task_struct *top, proc_visitor visitor, void
> > *data)
> > --
> > 2.53.0
>
> --
> paul-moore.com
>
-Ricardo
