Re: [PATCH 1/2] audit: Allow auditing of proc/self/cmdline value

[Richard Guy Briggs <rgb@redhat.com>]

On Mon, Nov 18, 2013 at 04:41:19PM -0800, William Roberts wrote:
> Audit records will now contain a new field, cmdline.
> This is the value that is stored in proc/self/cmdline,
> and is useful for debugging when processes are being run
> via VM's. A primary example of this is Android, in which
> package names are set in this location, and thread names
> are set via PR_SET_NAME. The other benefit is this
> is not limited to 16 bytes as COMM historically has.

This patch looks good to me.

> Change-Id: I9bf0928a8aa249d22ecd55fa9cd27325dd394eb1
> Signed-off-by: William Roberts <wroberts@tresys.com>
> ---
>  fs/proc/base.c          |    2 +-
>  include/linux/proc_fs.h |    1 +
>  kernel/auditsc.c        |   33 +++++++++++++++++++++++++++++++++
>  3 files changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 2f198da..25b73d3 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -209,7 +209,7 @@ struct mm_struct *mm_for_maps(struct task_struct *task)
>  	return mm_access(task, PTRACE_MODE_READ);
>  }
>  
> -static int proc_pid_cmdline(struct task_struct *task, char * buffer)
> +int proc_pid_cmdline(struct task_struct *task, char *buffer)
>  {
>  	int res = 0;
>  	unsigned int len;
> diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
> index 85c5073..d85ac14 100644
> --- a/include/linux/proc_fs.h
> +++ b/include/linux/proc_fs.h
> @@ -118,6 +118,7 @@ struct pid_namespace;
>  
>  extern int pid_ns_prepare_proc(struct pid_namespace *ns);
>  extern void pid_ns_release_proc(struct pid_namespace *ns);
> +extern int proc_pid_cmdline(struct task_struct *task, char *buffer);
>  
>  /*
>   * proc_tty.c
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 27ad9dd..45fd3d0 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -67,6 +67,7 @@
>  #include <linux/syscalls.h>
>  #include <linux/capability.h>
>  #include <linux/fs_struct.h>
> +#include <linux/proc_fs.h>
>  
>  #include "audit.h"
>  
> @@ -1153,6 +1154,37 @@ error_path:
>  
>  EXPORT_SYMBOL(audit_log_task_context);
>  
> +static void audit_log_add_cmdline(struct audit_buffer *ab,
> +				  struct task_struct *tsk)
> +{
> +	int len;
> +	unsigned long page;
> +	char *msg = "(null)";
> +
> +	audit_log_format(ab, " cmdline=");
> +
> +	/* Get the process cmdline */
> +	page = __get_free_page(GFP_TEMPORARY);
> +	if (!page) {
> +		audit_log_untrustedstring(ab, msg);
> +		return;
> +	}
> +	len = proc_pid_cmdline(tsk, (char *)page);
> +	if (len <= 0) {
> +		free_page(page);
> +		audit_log_untrustedstring(ab, msg);
> +		return;
> +	}
> +	/*
> +	 * Ensure NULL terminated! Application could
> +	 * could be using setproctitle(3).
> +	 */
> +	((char *)page)[len-1] = '\0';
> +	msg = (char *)page;
> +	audit_log_untrustedstring(ab, msg);
> +	free_page(page);
> +}
> +
>  static void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
>  {
>  	char name[sizeof(tsk->comm)];
> @@ -1179,6 +1211,7 @@ static void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk
>  		}
>  		up_read(&mm->mmap_sem);
>  	}
> +	audit_log_add_cmdline(ab, tsk);
>  	audit_log_task_context(ab);
>  }
>  
> -- 
> 1.7.9.5
> 

- RGB

--
Richard Guy Briggs <rbriggs@redhat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545