Re: [PATCH ghak81 RFC V1 5/5] audit: collect audit task parameters

[Paul Moore]

On Fri, May 4, 2018 at 4:54 PM, Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
> The audit-related parameters in struct task_struct should ideally be
> collected together and accessed through a standard audit API.
>
> Collect the existing loginuid, sessionid and audit_context together in a
> new struct audit_task_info pointer called "audit" in struct task_struct.
>
> Use kmem_cache to manage this pool of memory.
> Un-inline audit_free() to be able to always recover that memory.
>
> See: https://github.com/linux-audit/audit-kernel/issues/81
>
> Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> ---
>  MAINTAINERS                |  2 +-
>  include/linux/audit.h      |  8 ++++----
>  include/linux/audit_task.h | 31 +++++++++++++++++++++++++++++++
>  include/linux/sched.h      |  6 ++----
>  init/init_task.c           |  8 ++++++--
>  kernel/auditsc.c           |  4 ++--
>  6 files changed, 46 insertions(+), 13 deletions(-)
>  create mode 100644 include/linux/audit_task.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 0a1410d..8c7992d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2510,7 +2510,7 @@ L:        linux-audit@xxxxxxxxxx (moderated for non-subscribers)
>  W:     https://github.com/linux-audit
>  T:     git git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit.git
>  S:     Supported
> -F:     include/linux/audit.h
> +F:     include/linux/audit*.h
>  F:     include/uapi/linux/audit.h
>  F:     kernel/audit*
>
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index dba0d45..1324969 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -237,11 +237,11 @@ extern void __audit_inode_child(struct inode *parent,
>
>  static inline void audit_set_context(struct task_struct *task, struct audit_context *ctx)
>  {
> -       task->audit_context = ctx;
> +       task->audit.ctx = ctx;
>  }
>  static inline struct audit_context *audit_context(struct task_struct *task)
>  {
> -       return task->audit_context;
> +       return task->audit.ctx;
>  }
>  static inline bool audit_dummy_context(void)
>  {
> @@ -330,12 +330,12 @@ extern int auditsc_get_stamp(struct audit_context *ctx,
>
>  static inline kuid_t audit_get_loginuid(struct task_struct *tsk)
>  {
> -       return tsk->loginuid;
> +       return tsk->audit.loginuid;
>  }
>
>  static inline unsigned int audit_get_sessionid(struct task_struct *tsk)
>  {
> -       return tsk->sessionid;
> +       return tsk->audit.sessionid;
>  }
>
>  extern void __audit_ipc_obj(struct kern_ipc_perm *ipcp);
> diff --git a/include/linux/audit_task.h b/include/linux/audit_task.h
> new file mode 100644
> index 0000000..d4b3a20
> --- /dev/null
> +++ b/include/linux/audit_task.h
> @@ -0,0 +1,31 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* audit_task.h -- definition of audit_task_info structure
> + *
> + * Copyright 2018 Red Hat Inc., Raleigh, North Carolina.
> + * All Rights Reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * Written by Richard Guy Briggs <rgb@xxxxxxxxxx>
> + *
> + */
> +
> +#ifndef _LINUX_AUDIT_TASK_H_
> +#define _LINUX_AUDIT_TASK_H_
> +
> +struct audit_context;
> +struct audit_task_info {
> +       kuid_t                  loginuid;
> +       unsigned int            sessionid;
> +       struct audit_context    *ctx;
> +};
> +
> +#endif
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index b3d697f..b58eca0 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -27,9 +27,9 @@
>  #include <linux/signal_types.h>
>  #include <linux/mm_types_task.h>
>  #include <linux/task_io_accounting.h>
> +#include <linux/audit_task.h>
>
>  /* task_struct member predeclarations (sorted alphabetically): */
> -struct audit_context;
>  struct backing_dev_info;
>  struct bio_list;
>  struct blk_plug;
> @@ -832,10 +832,8 @@ struct task_struct {
>
>         struct callback_head            *task_works;
>
> -       struct audit_context            *audit_context;
>  #ifdef CONFIG_AUDITSYSCALL
> -       kuid_t                          loginuid;
> -       unsigned int                    sessionid;
> +       struct audit_task_info          audit;
>  #endif

Considering that the audit_context pointer is now in the
audit_task_info struct, should the audit_task_info struct be placed
outside the CONFIG_AUDITSYSCALL protections?  Or rather, shouldn't the
CONFIG_AUDITSYSCALL protections be moved inside audit_task_info or
removed entirely?

> diff --git a/init/init_task.c b/init/init_task.c
> index c788f91..d33260d 100644
> --- a/init/init_task.c
> +++ b/init/init_task.c
> @@ -9,6 +9,7 @@
>  #include <linux/init.h>
>  #include <linux/fs.h>
>  #include <linux/mm.h>
> +#include <linux/audit.h>
>
>  #include <asm/pgtable.h>
>  #include <linux/uaccess.h>
> @@ -118,8 +119,11 @@ struct task_struct init_task
>         .thread_group   = LIST_HEAD_INIT(init_task.thread_group),
>         .thread_node    = LIST_HEAD_INIT(init_signals.thread_head),
>  #ifdef CONFIG_AUDITSYSCALL
> -       .loginuid       = INVALID_UID,
> -       .sessionid      = AUDIT_SID_UNSET,
> +       .audit          = {
> +               .loginuid       = INVALID_UID,
> +               .sessionid      = AUDIT_SID_UNSET,
> +               .ctx            = NULL,
> +       },
>  #endif
>  #ifdef CONFIG_PERF_EVENTS
>         .perf_event_mutex = __MUTEX_INITIALIZER(init_task.perf_event_mutex),
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index f294e4a..b5d8bff 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -2068,8 +2068,8 @@ int audit_set_loginuid(kuid_t loginuid)
>                         sessionid = (unsigned int)atomic_inc_return(&session_id);
>         }
>
> -       task->sessionid = sessionid;
> -       task->loginuid = loginuid;
> +       task->audit.sessionid = sessionid;
> +       task->audit.loginuid = loginuid;
>  out:
>         audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
>         return rc;
> --
> 1.8.3.1

-- 
paul moore
www.paul-moore.com