On 01/13/2014 12:02 PM, William Roberts wrote:
> introduce get_cmdline() for retreiving the value of a processes
> proc/self/cmdline value.
>
> Signed-off-by: William Roberts <wroberts@xxxxxxxxxx>
Acked-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
> ---
> include/linux/mm.h | 1 +
> mm/util.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 49 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 3552717..01e7970 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1134,6 +1134,7 @@ void account_page_writeback(struct page *page);
> int set_page_dirty(struct page *page);
> int set_page_dirty_lock(struct page *page);
> int clear_page_dirty_for_io(struct page *page);
> +int get_cmdline(struct task_struct *task, char *buffer, int buflen);
>
> /* Is the vma a continuation of the stack vma above it? */
> static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
> diff --git a/mm/util.c b/mm/util.c
> index f7bc209..5285ff0 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -410,6 +410,54 @@ unsigned long vm_commit_limit(void)
> * sysctl_overcommit_ratio / 100) + total_swap_pages;
> }
>
> +/**
> + * get_cmdline() - copy the cmdline value to a buffer.
> + * @task: the task whose cmdline value to copy.
> + * @buffer: the buffer to copy to.
> + * @buflen: the length of the buffer. Larger cmdline values are truncated
> + * to this length.
> + * Returns the size of the cmdline field copied. Note that the copy does
> + * not guarantee an ending NULL byte.
> + */
> +int get_cmdline(struct task_struct *task, char *buffer, int buflen)
> +{
> + int res = 0;
> + unsigned int len;
> + struct mm_struct *mm = get_task_mm(task);
> + if (!mm)
> + goto out;
> + if (!mm->arg_end)
> + goto out_mm; /* Shh! No looking before we're done */
> +
> + len = mm->arg_end - mm->arg_start;
> +
> + if (len > buflen)
> + len = buflen;
> +
> + res = access_process_vm(task, mm->arg_start, buffer, len, 0);
> +
> + /*
> + * If the nul at the end of args has been overwritten, then
> + * assume application is using setproctitle(3).
> + */
> + if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
> + len = strnlen(buffer, res);
> + if (len < res) {
> + res = len;
> + } else {
> + len = mm->env_end - mm->env_start;
> + if (len > buflen - res)
> + len = buflen - res;
> + res += access_process_vm(task, mm->env_start,
> + buffer+res, len, 0);
> + res = strnlen(buffer, res);
> + }
> + }
> +out_mm:
> + mmput(mm);
> +out:
> + return res;
> +}
>
> /* Tracepoints definitions. */
> EXPORT_TRACEPOINT_SYMBOL(kmalloc);
>
--
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