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exec: introduce struct user_arg_ptr

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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>
This commit is contained in:
Oleg Nesterov 2011-03-06 18:02:37 +01:00
parent 1d1dbf8135
commit ba2d01629d
1 changed files with 30 additions and 12 deletions
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42
fs/exec.c
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@ -398,12 +398,15 @@ err:
return err; return err;
} }
static const char __user * struct user_arg_ptr {
get_user_arg_ptr(const char __user * const __user *argv, int nr) 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; const char __user *ptr;
if (get_user(ptr, argv + nr)) if (get_user(ptr, argv.native + nr))
return ERR_PTR(-EFAULT); return ERR_PTR(-EFAULT);
return ptr; return ptr;
@ -412,11 +415,11 @@ get_user_arg_ptr(const char __user * const __user *argv, int nr)
/* /*
* count() counts the number of strings in array ARGV. * 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; int i = 0;
if (argv != NULL) { if (argv.native != NULL) {
for (;;) { for (;;) {
const char __user *p = get_user_arg_ptr(argv, i); const char __user *p = get_user_arg_ptr(argv, i);
@ -442,7 +445,7 @@ static int count(const char __user * const __user * argv, int max)
* processes's memory to the new process's stack. The call to get_user_pages() * 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. * 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 linux_binprm *bprm)
{ {
struct page *kmapped_page = NULL; struct page *kmapped_page = NULL;
@ -533,14 +536,19 @@ out:
/* /*
* Like copy_strings, but get argv and its values from kernel memory. * 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) struct linux_binprm *bprm)
{ {
int r; int r;
mm_segment_t oldfs = get_fs(); mm_segment_t oldfs = get_fs();
struct user_arg_ptr argv = {
.native = (const char __user *const __user *)__argv,
};
set_fs(KERNEL_DS); set_fs(KERNEL_DS);
r = copy_strings(argc, (const char __user *const __user *)argv, bprm); r = copy_strings(argc, argv, bprm);
set_fs(oldfs); set_fs(oldfs);
return r; return r;
} }
EXPORT_SYMBOL(copy_strings_kernel); EXPORT_SYMBOL(copy_strings_kernel);
@ -1393,10 +1401,10 @@ EXPORT_SYMBOL(search_binary_handler);
/* /*
* sys_execve() executes a new program. * sys_execve() executes a new program.
*/ */
int do_execve(const char * filename, static int do_execve_common(const char *filename,
const char __user *const __user *argv, struct user_arg_ptr argv,
const char __user *const __user *envp, struct user_arg_ptr envp,
struct pt_regs * regs) struct pt_regs *regs)
{ {
struct linux_binprm *bprm; struct linux_binprm *bprm;
struct file *file; struct file *file;
@ -1503,6 +1511,16 @@ out_ret:
return retval; 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) void set_binfmt(struct linux_binfmt *new)
{ {
struct mm_struct *mm = current->mm; struct mm_struct *mm = current->mm;