diff options
Diffstat (limited to 'rust/kernel')
| -rw-r--r-- | rust/kernel/prelude.rs | 2 | ||||
| -rw-r--r-- | rust/kernel/uaccess.rs | 71 |
2 files changed, 61 insertions, 12 deletions
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs index 2f30a398dddd..9a1a830f605c 100644 --- a/rust/kernel/prelude.rs +++ b/rust/kernel/prelude.rs @@ -46,3 +46,5 @@ pub use super::{str::CStr, ThisModule}; pub use super::init::InPlaceInit; pub use super::current; + +pub use super::uaccess::UserPtr; diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs index 85097eee81d9..a8fb4764185a 100644 --- a/rust/kernel/uaccess.rs +++ b/rust/kernel/uaccess.rs @@ -14,8 +14,51 @@ use crate::{ }; use core::mem::{size_of, MaybeUninit}; -/// The type used for userspace addresses. -pub type UserPtr = usize; +/// A pointer into userspace. +/// +/// This is the Rust equivalent to C pointers tagged with `__user`. +#[repr(transparent)] +#[derive(Copy, Clone)] +pub struct UserPtr(*mut c_void); + +impl UserPtr { + /// Create a `UserPtr` from an integer representing the userspace address. + #[inline] + pub fn from_addr(addr: usize) -> Self { + Self(addr as *mut c_void) + } + + /// Create a `UserPtr` from a pointer representing the userspace address. + #[inline] + pub fn from_ptr(addr: *mut c_void) -> Self { + Self(addr) + } + + /// Cast this userspace pointer to a raw const void pointer. + /// + /// It is up to the caller to use the returned pointer correctly. + #[inline] + pub fn as_const_ptr(self) -> *const c_void { + self.0 + } + + /// Cast this userspace pointer to a raw mutable void pointer. + /// + /// It is up to the caller to use the returned pointer correctly. + #[inline] + pub fn as_mut_ptr(self) -> *mut c_void { + self.0 + } + + /// Increment this user pointer by `add` bytes. + /// + /// This addition is wrapping, so wrapping around the address space does not result in a panic + /// even if `CONFIG_RUST_OVERFLOW_CHECKS` is enabled. + #[inline] + pub fn wrapping_byte_add(self, add: usize) -> UserPtr { + UserPtr(self.0.wrapping_byte_add(add)) + } +} /// A pointer to an area in userspace memory, which can be either read-only or read-write. /// @@ -177,7 +220,7 @@ impl UserSliceReader { pub fn skip(&mut self, num_skip: usize) -> Result { // Update `self.length` first since that's the fallible part of this operation. self.length = self.length.checked_sub(num_skip).ok_or(EFAULT)?; - self.ptr = self.ptr.wrapping_add(num_skip); + self.ptr = self.ptr.wrapping_byte_add(num_skip); Ok(()) } @@ -224,11 +267,11 @@ impl UserSliceReader { } // SAFETY: `out_ptr` points into a mutable slice of length `len`, so we may write // that many bytes to it. - let res = unsafe { bindings::copy_from_user(out_ptr, self.ptr as *const c_void, len) }; + let res = unsafe { bindings::copy_from_user(out_ptr, self.ptr.as_const_ptr(), len) }; if res != 0 { return Err(EFAULT); } - self.ptr = self.ptr.wrapping_add(len); + self.ptr = self.ptr.wrapping_byte_add(len); self.length -= len; Ok(()) } @@ -262,14 +305,14 @@ impl UserSliceReader { let res = unsafe { bindings::_copy_from_user( out.as_mut_ptr().cast::<c_void>(), - self.ptr as *const c_void, + self.ptr.as_const_ptr(), len, ) }; if res != 0 { return Err(EFAULT); } - self.ptr = self.ptr.wrapping_add(len); + self.ptr = self.ptr.wrapping_byte_add(len); self.length -= len; // SAFETY: The read above has initialized all bytes in `out`, and since `T` implements // `FromBytes`, any bit-pattern is a valid value for this type. @@ -386,11 +429,11 @@ impl UserSliceWriter { } // SAFETY: `data_ptr` points into an immutable slice of length `len`, so we may read // that many bytes from it. - let res = unsafe { bindings::copy_to_user(self.ptr as *mut c_void, data_ptr, len) }; + let res = unsafe { bindings::copy_to_user(self.ptr.as_mut_ptr(), data_ptr, len) }; if res != 0 { return Err(EFAULT); } - self.ptr = self.ptr.wrapping_add(len); + self.ptr = self.ptr.wrapping_byte_add(len); self.length -= len; Ok(()) } @@ -413,7 +456,7 @@ impl UserSliceWriter { // is a compile-time constant. let res = unsafe { bindings::_copy_to_user( - self.ptr as *mut c_void, + self.ptr.as_mut_ptr(), core::ptr::from_ref(value).cast::<c_void>(), len, ) @@ -421,7 +464,7 @@ impl UserSliceWriter { if res != 0 { return Err(EFAULT); } - self.ptr = self.ptr.wrapping_add(len); + self.ptr = self.ptr.wrapping_byte_add(len); self.length -= len; Ok(()) } @@ -445,7 +488,11 @@ fn raw_strncpy_from_user(dst: &mut [MaybeUninit<u8>], src: UserPtr) -> Result<us // SAFETY: `dst` is valid for writing `dst.len()` bytes. let res = unsafe { - bindings::strncpy_from_user(dst.as_mut_ptr().cast::<c_char>(), src as *const c_char, len) + bindings::strncpy_from_user( + dst.as_mut_ptr().cast::<c_char>(), + src.as_const_ptr().cast::<c_char>(), + len, + ) }; if res < 0 { |