[PATCH 1/3] mm: Create utility functions for accessing a tasks commandline value
Add two new functions to mm.h:
* copy_cmdline()
* get_cmdline_length()
Signed-off-by: William Roberts <wroberts(a)tresys.com>
---
include/linux/mm.h | 7 +++++++
mm/util.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 55 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1cedd00..b4d7c26 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1135,6 +1135,13 @@ int set_page_dirty(struct page *page);
int set_page_dirty_lock(struct page *page);
int clear_page_dirty_for_io(struct page *page);
+extern int copy_cmdline(struct task_struct *task, struct mm_struct *mm,
+ char *buf, unsigned int buflen);
+static inline unsigned int get_cmdline_length(struct mm_struct *mm)
+{
+ return mm->arg_end ? mm->arg_end - mm->arg_start : 0;
+}
+
/* 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..c8cad32 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -9,6 +9,7 @@
#include <linux/swapops.h>
#include <linux/mman.h>
#include <linux/hugetlb.h>
+#include <linux/mm.h>
#include <asm/uaccess.h>
@@ -410,6 +411,53 @@ unsigned long vm_commit_limit(void)
* sysctl_overcommit_ratio / 100) + total_swap_pages;
}
+/**
+ * copy_cmdline - Copy's the tasks commandline value to a buffer
+ * @task: The task whose command line to copy
+ * @mm: The mm struct refering to task with proper semaphores held
+ * @buf: The buffer to copy the value into
+ * @buflen: The length og the buffer. It trucates the value to
+ * buflen.
+ * @return: The number of chars copied.
+ */
+int copy_cmdline(struct task_struct *task, struct mm_struct *mm,
+ char *buf, unsigned int buflen)
+{
+ int res = 0;
+ unsigned int len;
+
+ if (!task || !mm || !buf)
+ return -1;
+
+ res = access_process_vm(task, mm->arg_start, buf, buflen, 0);
+ if (res <= 0)
+ return 0;
+
+ if (res > buflen)
+ res = buflen;
+ /*
+ * If the nul at the end of args had been overwritten, then
+ * assume application is using setproctitle(3).
+ */
+ if (buf[res-1] != '\0') {
+ /* Nul between start and end of vm space?
+ If so then truncate */
+ len = strnlen(buf, res);
+ if (len < res) {
+ res = len;
+ } else {
+ /* No nul, truncate buflen if to big */
+ len = mm->env_end - mm->env_start;
+ if (len > buflen - res)
+ len = buflen - res;
+ /* Copy any remaining data */
+ res += access_process_vm(task, mm->env_start, buf+res,
+ len, 0);
+ res = strnlen(buf, res);
+ }
+ }
+ return res;
+}
/* Tracepoints definitions. */
EXPORT_TRACEPOINT_SYMBOL(kmalloc);
--
1.7.9.5