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mm: Create utility function for accessing a tasks commandline value 

introduce get_cmdline() for retreiving the value of a processes
proc/self/cmdline value.

Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Richard Guy Briggs <rgb@redhat.com>

Signed-off-by: William Roberts <wroberts@tresys.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
This commit is contained in:
William Roberts 2014-02-11 10:11:59 -08:00 committed by Eric Paris
parent 147d2601d8
commit a90902531a
2 changed files with 49 additions and 0 deletions
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1
include/linux/mm.h
View File

@ -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)

48
mm/util.c
View File

@ -413,6 +413,54 @@ 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);