Re: [PATCH ghak90 (was ghak32) V4 05/10] audit: add support for non-syscall auxiliary records

Richard Guy Briggs
2018-11-01T18:48:53Z

On 2018-10-19 19:17, Paul Moore wrote:
> On Sun, Aug 5, 2018 at 4:33 AM Richard Guy Briggs <rgb@redhat.com> wrote:
> > Standalone audit records have the timestamp and serial number generated
> > on the fly and as such are unique, making them standalone. This new
> > function audit_alloc_local() generates a local audit context that will
> > be used only for a standalone record and its auxiliary record(s). The
> > context is discarded immediately after the local associated records are
> > produced.
> >
> > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > Acked-by: Serge Hallyn <serge@hallyn.com>
> > ---
> > include/linux/audit.h | 8 ++++++++
> > kernel/audit.h | 1 +
> > kernel/auditsc.c | 33 ++++++++++++++++++++++++++++-----
> > 3 files changed, 37 insertions(+), 5 deletions(-)
>
> I'm not in love with the local flag, and the whole local context in
> general, but that's a larger discussion and not something I want to
> force on this patchset; we can fix it later.

I understand your reasoning to combine it so that if one patch gets
backported then both do, or if one gets reverted both do, but I really
prefer them seperate for similar reasons if there is more than one user.

> I think this patch looks fine, but it seems a bit odd standalone; it's
> almost always better to include new capabilities/functions in the same
> patch as the user. Since the only user is the networking bits, it
> might make more sense to fold this patch into that one.

It was kept seperate due to tty_audit usage. See my reasoning for patch
6, but I'm willing to negotiate if that merits an exception like the
USER records do.

> > diff --git a/include/linux/audit.h b/include/linux/audit.h
> > index 4f514ed..1f340ad 100644
> > --- a/include/linux/audit.h
> > +++ b/include/linux/audit.h
> > @@ -234,7 +234,9 @@ struct audit_task_info {
> > extern struct audit_task_info init_struct_audit;
> > extern void __init audit_task_init(void);
> > extern int audit_alloc(struct task_struct *task);
> > +extern struct audit_context *audit_alloc_local(gfp_t gfpflags);
> > extern void audit_free(struct task_struct *task);
> > +extern void audit_free_context(struct audit_context *context);
> > extern void __audit_syscall_entry(int major, unsigned long a0, unsigned long a1,
> > unsigned long a2, unsigned long a3);
> > extern void __audit_syscall_exit(int ret_success, long ret_value);
> > @@ -495,6 +497,12 @@ static inline int audit_alloc(struct task_struct *task)
> > {
> > return 0;
> > }
> > +static inline struct audit_context *audit_alloc_local(gfp_t gfpflags)
> > +{
> > + return NULL;
> > +}
> > +static inline void audit_free_context(struct audit_context *context)
> > +{ }
> > static inline void audit_free(struct task_struct *task)
> > { }
> > static inline void audit_syscall_entry(int major, unsigned long a0,
> > diff --git a/kernel/audit.h b/kernel/audit.h
> > index 1cf1c35..a6d00a5 100644
> > --- a/kernel/audit.h
> > +++ b/kernel/audit.h
> > @@ -110,6 +110,7 @@ struct audit_proctitle {
> > struct audit_context {
> > int dummy; /* must be the first element */
> > int in_syscall; /* 1 if task is in a syscall */
> > + bool local; /* local context needed */
> > enum audit_state state, current_state;
> > unsigned int serial; /* serial number for record */
> > int major; /* syscall number */
> > diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> > index cdb24cf..7627f21 100644
> > --- a/kernel/auditsc.c
> > +++ b/kernel/auditsc.c
> > @@ -913,11 +913,13 @@ static inline void audit_free_aux(struct audit_context *context)
> > }
> > }
> >
> > -static inline struct audit_context *audit_alloc_context(enum audit_state state)
> > +static inline struct audit_context *audit_alloc_context(enum audit_state state,
> > + gfp_t gfpflags)
> > {
> > struct audit_context *context;
> >
> > - context = kzalloc(sizeof(*context), GFP_KERNEL);
> > + /* We can be called in atomic context via audit_tg() */
> > + context = kzalloc(sizeof(*context), gfpflags);
> > if (!context)
> > return NULL;
> > context->state = state;
> > @@ -970,7 +972,8 @@ int audit_alloc(struct task_struct *tsk)
> > return 0;
> > }
> >
> > - if (!(context = audit_alloc_context(state))) {
> > + context = audit_alloc_context(state, GFP_KERNEL);
> > + if (!(context)) {
> > tsk->audit = NULL;
> > kmem_cache_free(audit_task_cache, info);
> > kfree(key);
> > @@ -991,8 +994,27 @@ struct audit_task_info init_struct_audit = {
> > .ctx = NULL,
> > };
> >
> > -static inline void audit_free_context(struct audit_context *context)
> > +struct audit_context *audit_alloc_local(gfp_t gfpflags)
> > {
> > + struct audit_context *context;
> > +
> > + if (!audit_ever_enabled)
> > + return NULL; /* Return if not auditing. */
> > +
> > + context = audit_alloc_context(AUDIT_RECORD_CONTEXT, gfpflags);
> > + if (!context)
> > + return NULL;
> > + context->serial = audit_serial();
> > + context->ctime = current_kernel_time64();
> > + context->local = true;
> > + return context;
> > +}
> > +EXPORT_SYMBOL(audit_alloc_local);
> > +
> > +void audit_free_context(struct audit_context *context)
> > +{
> > + if (!context)
> > + return;
> > audit_free_names(context);
> > unroll_tree_refs(context, NULL, 0);
> > free_tree_refs(context);
> > @@ -1002,6 +1024,7 @@ static inline void audit_free_context(struct audit_context *context)
> > audit_proctitle_free(context);
> > kfree(context);
> > }
> > +EXPORT_SYMBOL(audit_free_context);
> >
> > static int audit_log_pid_context(struct audit_context *context, pid_t pid,
> > kuid_t auid, kuid_t uid, unsigned int sessionid,
> > @@ -2024,7 +2047,7 @@ void __audit_inode_child(struct inode *parent,
> > int auditsc_get_stamp(struct audit_context *ctx,
> > struct timespec64 *t, unsigned int *serial)
> > {
> > - if (!ctx->in_syscall)
> > + if (!ctx->in_syscall && !ctx->local)
> > return 0;
> > if (!ctx->serial)
> > ctx->serial = audit_serial();
>
> --
> paul moore
> www.paul-moore.com

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635