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net: add copy_safe_from_sockptr() helper

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copy_from_sockptr() helper is unsafe, unless callers
did the prior check against user provided optlen.

Too many callers get this wrong, lets add a helper to
fix them and avoid future copy/paste bugs.

Instead of :

   if (optlen < sizeof(opt)) {
       err = -EINVAL;
       break;
   }
   if (copy_from_sockptr(&opt, optval, sizeof(opt)) {
       err = -EFAULT;
       break;
   }

Use :

   err = copy_safe_from_sockptr(&opt, sizeof(opt),
                                optval, optlen);
   if (err)
       break;

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240408082845.3957374-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-04-08 08:28:43 +00:00 committed by Jakub Kicinski
parent cf1b7201df
commit 6309863b31
1 changed files with 25 additions and 0 deletions
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25
include/linux/sockptr.h
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@ -50,11 +50,36 @@ static inline int copy_from_sockptr_offset(void *dst, sockptr_t src,
return 0; return 0;
} }
/* Deprecated.
* This is unsafe, unless caller checked user provided optlen.
* Prefer copy_safe_from_sockptr() instead.
*/
static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size) static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size)
{ {
return copy_from_sockptr_offset(dst, src, 0, size); return copy_from_sockptr_offset(dst, src, 0, size);
} }
/**
* copy_safe_from_sockptr: copy a struct from sockptr
* @dst: Destination address, in kernel space. This buffer must be @ksize
* bytes long.
* @ksize: Size of @dst struct.
* @optval: Source address. (in user or kernel space)
* @optlen: Size of @optval data.
*
* Returns:
* * -EINVAL: @optlen < @ksize
* * -EFAULT: access to userspace failed.
* * 0 : @ksize bytes were copied
*/
static inline int copy_safe_from_sockptr(void *dst, size_t ksize,
sockptr_t optval, unsigned int optlen)
{
if (optlen < ksize)
return -EINVAL;
return copy_from_sockptr(dst, optval, ksize);
}
static inline int copy_struct_from_sockptr(void *dst, size_t ksize, static inline int copy_struct_from_sockptr(void *dst, size_t ksize,
sockptr_t src, size_t usize) sockptr_t src, size_t usize)
{ {