Re: [PATCH ghak90 V5 03/10] audit: read container ID of a process

[Ondrej Mosnacek <omosnace@redhat.com>]

On Fri, Mar 15, 2019 at 7:33 PM Richard Guy Briggs <rgb@redhat.com> wrote:
> Add support for reading the audit container identifier from the proc
> filesystem.
>
> This is a read from the proc entry of the form
> /proc/PID/audit_containerid where PID is the process ID of the task
> whose audit container identifier is sought.
>
> The read expects up to a u64 value (unset: 18446744073709551615).
>
> This read requires CAP_AUDIT_CONTROL.
>
> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> Acked-by: Serge Hallyn <serge@hallyn.com>

Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>

> ---
>  fs/proc/base.c | 23 +++++++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 2505c46c8701..0b833cbdf5b6 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -1295,6 +1295,24 @@ static ssize_t proc_sessionid_read(struct file * file, char __user * buf,
>         .llseek         = generic_file_llseek,
>  };
>
> +static ssize_t proc_contid_read(struct file *file, char __user *buf,
> +                                 size_t count, loff_t *ppos)
> +{
> +       struct inode *inode = file_inode(file);
> +       struct task_struct *task = get_proc_task(inode);
> +       ssize_t length;
> +       char tmpbuf[TMPBUFLEN*2];
> +
> +       if (!task)
> +               return -ESRCH;
> +       /* if we don't have caps, reject */
> +       if (!capable(CAP_AUDIT_CONTROL))
> +               return -EPERM;
> +       length = scnprintf(tmpbuf, TMPBUFLEN*2, "%llu", audit_get_contid(task));
> +       put_task_struct(task);
> +       return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
> +}
> +
>  static ssize_t proc_contid_write(struct file *file, const char __user *buf,
>                                    size_t count, loff_t *ppos)
>  {
> @@ -1325,6 +1343,7 @@ static ssize_t proc_contid_write(struct file *file, const char __user *buf,
>  }
>
>  static const struct file_operations proc_contid_operations = {
> +       .read           = proc_contid_read,
>         .write          = proc_contid_write,
>         .llseek         = generic_file_llseek,
>  };
> @@ -3039,7 +3058,7 @@ static int proc_stack_depth(struct seq_file *m, struct pid_namespace *ns,
>  #ifdef CONFIG_AUDIT
>         REG("loginuid",   S_IWUSR|S_IRUGO, proc_loginuid_operations),
>         REG("sessionid",  S_IRUGO, proc_sessionid_operations),
> -       REG("audit_containerid", S_IWUSR, proc_contid_operations),
> +       REG("audit_containerid", S_IWUSR|S_IRUSR, proc_contid_operations),
>  #endif
>  #ifdef CONFIG_FAULT_INJECTION
>         REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
> @@ -3428,7 +3447,7 @@ static int proc_tid_comm_permission(struct inode *inode, int mask)
>  #ifdef CONFIG_AUDIT
>         REG("loginuid",  S_IWUSR|S_IRUGO, proc_loginuid_operations),
>         REG("sessionid",  S_IRUGO, proc_sessionid_operations),
> -       REG("audit_containerid", S_IWUSR, proc_contid_operations),
> +       REG("audit_containerid", S_IWUSR|S_IRUSR, proc_contid_operations),
>  #endif
>  #ifdef CONFIG_FAULT_INJECTION
>         REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
> --
> 1.8.3.1
>

-- 
Ondrej Mosnacek <omosnace at redhat dot com>
Software Engineer, Security Technologies
Red Hat, Inc.