Hello.
I want to get argv[0] from "struct linux_binprm".
But it seems that elements of "struct linux_binprm" has changed at 2.6.23-rc1 .
And I want to know how to follow this change.
The following is the code,
but I'm not sure whether get_user_pages()/put_page() usage is correct.
This code is called from security_bprm_check().
Could somebody please review this code?
Regards.
static char *get_argv0(struct linux_binprm *bprm)
{
char *arg_ptr = kmalloc(PAGE_SIZE, GFP_KERNEL); /* Initial buffer. */
int arg_len = 0;
unsigned long pos = bprm->p;
int i = pos / PAGE_SIZE, offset = pos % PAGE_SIZE;
if (!bprm->argc || !arg_ptr) goto out;
while (1) {
struct page *page;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,23) && defined(CONFIG_MMU)
if (get_user_pages(current, bprm->mm, pos, 1, 0, 1, &page,
NULL) <= 0) goto out;
#else
page = bprm->page[i];
#endif
{ /* Map and copy to kernel buffer and unmap. */
const char *kaddr = kmap(page);
if (!kaddr) { /* Mapping failed. */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,23) && defined(CONFIG_MMU)
put_page(page);
#endif
goto out;
}
memmove(arg_ptr + arg_len, kaddr + offset, PAGE_SIZE -
offset);
kunmap(page);
}
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,23) && defined(CONFIG_MMU)
put_page(page);
pos += PAGE_SIZE - offset;
#endif
arg_len += PAGE_SIZE - offset;
if (memchr(arg_ptr, '\0', arg_len)) break;
{ /* Initial buffer was too small for argv[0]. Retry after
expanding buffer. */
char *tmp_arg_ptr = kmalloc(arg_len + PAGE_SIZE,
GFP_KERNEL);
if (!tmp_arg_ptr) goto out;
memmove(tmp_arg_ptr, arg_ptr, arg_len);
kfree(arg_ptr);
arg_ptr = tmp_arg_ptr;
}
i++;
offset = 0;
}
return arg_ptr;
out: /* Release initial buffer. */
kfree(arg_ptr);
return NULL;
}
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