On 2026-07-24 12:02, Ricardo Robaina 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);
Would there be any confusion if this were simply "flags=..." since it is
already a record type AUDIT_CLONE3?
> + if ((kargs->flags & CLONE_PIDFD) && ret >= 0 &&
> + !get_user(pidfd, kargs->pidfd))
> + audit_log_format(ab, " pidfd=%d", pidfd);
> + else
> + audit_log_format(ab, " pidfd=(null)");
Is there any interest in:
child_tid (was captured by generic audit syscall arg 4)
parent_tid (was captured by generic audit syscall arg 3 or 4)
tls (was captured by generic audit syscall arg 4)
set_tid
Is there a situation where a valid pid is returned without CLONE_PIDFD set?
Otherwise, looks reasonable to me.
> + 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
- RGB
--
Richard Guy Briggs <[email protected]>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
Upstream IRC: SunRaycer
Voice: +1.613.860 2354 SMS: +1.613.518.6570
