Re: [PATCH v24 21/25] audit: add support for non-syscall auxiliary records

Richard Guy Briggs
2021-01-27T01:51:45Z

On 2021-01-26 08:41, Casey Schaufler 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>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> Cc: linux-audit@redhat.com
> To: Richard Guy Briggs <rgb@redhat.com>

This has been minorly bothering me for several revisions... Is there a
way for the development/authorship to be accurately reflected
if/when this patch is merged before the contid patch set?

> ---
> include/linux/audit.h | 8 ++++++++
> kernel/audit.h | 1 +
> kernel/auditsc.c | 33 ++++++++++++++++++++++++++++-----
> 3 files changed, 37 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index 418a485af114..97cd7471e572 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -289,6 +289,8 @@ static inline int audit_signal_info(int sig, struct task_struct *t)
> /* Public API */
> extern int audit_alloc(struct task_struct *task);
> extern void __audit_free(struct task_struct *task);
> +extern struct audit_context *audit_alloc_local(gfp_t gfpflags);
> +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);
> @@ -552,6 +554,12 @@ static inline void audit_log_nfcfg(const char *name, u8 af,
> extern int audit_n_rules;
> extern int audit_signals;
> #else /* CONFIG_AUDITSYSCALL */
> ++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 int audit_alloc(struct task_struct *task)
> {
> return 0;
> diff --git a/kernel/audit.h b/kernel/audit.h
> index ce41886807bb..3f2285e1c6e0 100644
> --- a/kernel/audit.h
> +++ b/kernel/audit.h
> @@ -99,6 +99,7 @@ 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 de2b2ecb3aea..479b3933d788 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -927,11 +927,13 @@ 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;
> @@ -967,7 +969,8 @@ int audit_alloc(struct task_struct *tsk)
> return 0;
> }
>
> - if (!(context = audit_alloc_context(state))) {
> + context = audit_alloc_context(state, GFP_KERNEL);
> + if (!context) {
> kfree(key);
> audit_log_lost("out of memory in audit_alloc");
> return -ENOMEM;
> @@ -979,8 +982,27 @@ int audit_alloc(struct task_struct *tsk)
> return 0;
> }
>
> -static inline void audit_free_context(struct audit_context *context)
> +struct audit_context *audit_alloc_local(gfp_t gfpflags)
> {
> + struct audit_context *context = NULL;
> +
> + context = audit_alloc_context(AUDIT_RECORD_CONTEXT, gfpflags);
> + if (!context) {
> + audit_log_lost("out of memory in audit_alloc_local");
> + goto out;
> + }
> + context->serial = audit_serial();
> + ktime_get_coarse_real_ts64(&context->ctime);
> + context->local = true;
> +out:
> + return context;
> +}
> +EXPORT_SYMBOL(audit_alloc_local);
> +
> +void audit_free_context(struct audit_context *context)
> +{
> + if (!context)
> + return;
> audit_free_module(context);
> audit_free_names(context);
> unroll_tree_refs(context, NULL, 0);
> @@ -991,6 +1013,7 @@ 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,
> @@ -2214,7 +2237,7 @@ EXPORT_SYMBOL_GPL(__audit_inode_child);
> 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();
> --
> 2.25.4
>

- 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