exec: introduce struct user_arg_ptr
No functional changes, preparation.
Introduce struct user_arg_ptr, change do_execve() paths to use it
instead of "char __user * const __user *argv".
This makes the argv/envp arguments opaque, we are ready to handle the
compat case which needs argv pointing to compat_uptr_t.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
diff --git a/fs/exec.c b/fs/exec.c
index b12e24f..526a039 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -398,12 +398,15 @@
return err;
}
-static const char __user *
-get_user_arg_ptr(const char __user * const __user *argv, int nr)
+struct user_arg_ptr {
+ const char __user *const __user *native;
+};
+
+static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
{
const char __user *ptr;
- if (get_user(ptr, argv + nr))
+ if (get_user(ptr, argv.native + nr))
return ERR_PTR(-EFAULT);
return ptr;
@@ -412,11 +415,11 @@
/*
* count() counts the number of strings in array ARGV.
*/
-static int count(const char __user * const __user * argv, int max)
+static int count(struct user_arg_ptr argv, int max)
{
int i = 0;
- if (argv != NULL) {
+ if (argv.native != NULL) {
for (;;) {
const char __user *p = get_user_arg_ptr(argv, i);
@@ -442,7 +445,7 @@
* processes's memory to the new process's stack. The call to get_user_pages()
* ensures the destination page is created and not swapped out.
*/
-static int copy_strings(int argc, const char __user *const __user *argv,
+static int copy_strings(int argc, struct user_arg_ptr argv,
struct linux_binprm *bprm)
{
struct page *kmapped_page = NULL;
@@ -533,14 +536,19 @@
/*
* Like copy_strings, but get argv and its values from kernel memory.
*/
-int copy_strings_kernel(int argc, const char *const *argv,
+int copy_strings_kernel(int argc, const char *const *__argv,
struct linux_binprm *bprm)
{
int r;
mm_segment_t oldfs = get_fs();
+ struct user_arg_ptr argv = {
+ .native = (const char __user *const __user *)__argv,
+ };
+
set_fs(KERNEL_DS);
- r = copy_strings(argc, (const char __user *const __user *)argv, bprm);
+ r = copy_strings(argc, argv, bprm);
set_fs(oldfs);
+
return r;
}
EXPORT_SYMBOL(copy_strings_kernel);
@@ -1393,10 +1401,10 @@
/*
* sys_execve() executes a new program.
*/
-int do_execve(const char * filename,
- const char __user *const __user *argv,
- const char __user *const __user *envp,
- struct pt_regs * regs)
+static int do_execve_common(const char *filename,
+ struct user_arg_ptr argv,
+ struct user_arg_ptr envp,
+ struct pt_regs *regs)
{
struct linux_binprm *bprm;
struct file *file;
@@ -1503,6 +1511,16 @@
return retval;
}
+int do_execve(const char *filename,
+ const char __user *const __user *__argv,
+ const char __user *const __user *__envp,
+ struct pt_regs *regs)
+{
+ struct user_arg_ptr argv = { .native = __argv };
+ struct user_arg_ptr envp = { .native = __envp };
+ return do_execve_common(filename, argv, envp, regs);
+}
+
void set_binfmt(struct linux_binfmt *new)
{
struct mm_struct *mm = current->mm;