bpf: Update XDP maps implementation

The implementation changed since the original commit was written, and
some mistakes went in:
- missing bpf_redirect_map wrapper
- extra bpf_map_lookup_elem on maps for which it is forbidden

bpf/aya-bpf/src/maps/xdp/cpu_map.rs

@@ -1,22 +1,22 @@
-use core::{mem, ptr::NonNull};
-
-use aya_bpf_cty::c_void;
+use core::{cell::UnsafeCell, mem};
 
 use crate::{
     bindings::{bpf_map_def, bpf_map_type::BPF_MAP_TYPE_CPUMAP},
-    helpers::bpf_map_lookup_elem,
+    helpers::bpf_redirect_map,
     maps::PinningType,
 };
 
 #[repr(transparent)]
 pub struct CpuMap {
-    def: bpf_map_def,
+    def: UnsafeCell<bpf_map_def>,
 }
 
+unsafe impl Sync for CpuMap {}
+
 impl CpuMap {
     pub const fn with_max_entries(max_entries: u32, flags: u32) -> CpuMap {
         CpuMap {
-            def: bpf_map_def {
+            def: UnsafeCell::new(bpf_map_def {
                 type_: BPF_MAP_TYPE_CPUMAP,
                 key_size: mem::size_of::<u32>() as u32,
                 value_size: mem::size_of::<u32>() as u32,
@@ -24,32 +24,31 @@ impl CpuMap {
                 map_flags: flags,
                 id: 0,
                 pinning: PinningType::None as u32,
-            },
+            }),
         }
     }
 
     pub const fn pinned(max_entries: u32, flags: u32) -> CpuMap {
         CpuMap {
-            def: bpf_map_def {
+            def: UnsafeCell::new(bpf_map_def {
                 type_: BPF_MAP_TYPE_CPUMAP,
                 key_size: mem::size_of::<u32>() as u32,
                 value_size: mem::size_of::<u32>() as u32,
                 max_entries,
                 map_flags: flags,
                 id: 0,
-                pinning: PinningType::None as u32,
-            },
+                pinning: PinningType::ByName as u32,
+            }),
         }
     }
 
-    pub fn get(&mut self, index: u32) -> Option<&u32> {
+    #[inline(always)]
+    pub fn redirect(&self, index: u32, flags: u64) -> u32 {
         unsafe {
-            let value = bpf_map_lookup_elem(
-                &mut self.def as *mut _ as *mut _,
-                &index as *const _ as *const c_void,
-            );
-            // FIXME: alignment
-            NonNull::new(value as *mut u32).map(|p| p.as_ref())
+            // Return XDP_REDIRECT on success, or the value of the two lower bits of the flags
+            // argument on error. Thus I have no idea why it returns a long (i64) instead of
+            // something saner, hence the unsigned_abs.
+            bpf_redirect_map(self.def.get() as *mut _, index.into(), flags).unsigned_abs() as u32
         }
     }
 }

bpf/aya-bpf/src/maps/xdp/dev_map.rs

@@ -1,22 +1,24 @@
-use core::{mem, ptr::NonNull};
+use core::{cell::UnsafeCell, mem, ptr::NonNull};
 
 use aya_bpf_cty::c_void;
 
 use crate::{
     bindings::{bpf_map_def, bpf_map_type::BPF_MAP_TYPE_DEVMAP},
-    helpers::bpf_map_lookup_elem,
+    helpers::{bpf_map_lookup_elem, bpf_redirect_map},
     maps::PinningType,
 };
 
 #[repr(transparent)]
 pub struct DevMap {
-    def: bpf_map_def,
+    def: UnsafeCell<bpf_map_def>,
 }
 
+unsafe impl Sync for DevMap {}
+
 impl DevMap {
     pub const fn with_max_entries(max_entries: u32, flags: u32) -> DevMap {
         DevMap {
-            def: bpf_map_def {
+            def: UnsafeCell::new(bpf_map_def {
                 type_: BPF_MAP_TYPE_DEVMAP,
                 key_size: mem::size_of::<u32>() as u32,
                 value_size: mem::size_of::<u32>() as u32,
@@ -24,32 +26,42 @@ impl DevMap {
                 map_flags: flags,
                 id: 0,
                 pinning: PinningType::None as u32,
-            },
+            }),
         }
     }
 
     pub const fn pinned(max_entries: u32, flags: u32) -> DevMap {
         DevMap {
-            def: bpf_map_def {
+            def: UnsafeCell::new(bpf_map_def {
                 type_: BPF_MAP_TYPE_DEVMAP,
                 key_size: mem::size_of::<u32>() as u32,
                 value_size: mem::size_of::<u32>() as u32,
                 max_entries,
                 map_flags: flags,
                 id: 0,
-                pinning: PinningType::None as u32,
-            },
+                pinning: PinningType::ByName as u32,
+            }),
         }
     }
 
-    pub fn get(&mut self, index: u32) -> Option<&u32> {
+    #[inline(always)]
+    pub fn get(&self, index: u32) -> Option<u32> {
         unsafe {
             let value = bpf_map_lookup_elem(
-                &mut self.def as *mut _ as *mut _,
+                self.def.get() as *mut _,
                 &index as *const _ as *const c_void,
             );
-            // FIXME: alignment
-            NonNull::new(value as *mut u32).map(|p| p.as_ref())
+            NonNull::new(value as *mut u32).map(|p| *p.as_ref())
+        }
+    }
+
+    #[inline(always)]
+    pub fn redirect(&self, index: u32, flags: u64) -> u32 {
+        // Return XDP_REDIRECT on success, or the value of the two lower bits of the flags
+        // argument on error. Thus I have no idea why it returns a long (i64) instead of
+        // something saner, hence the unsigned_abs.
+        unsafe {
+            bpf_redirect_map(self.def.get() as *mut _, index.into(), flags).unsigned_abs() as u32
         }
     }
 }

bpf/aya-bpf/src/maps/xdp/dev_map_hash.rs

@@ -1,22 +1,25 @@
-use core::{mem, ptr::NonNull};
+use core::{cell::UnsafeCell, mem, ptr::NonNull};
 
+use aya_bpf_bindings::bindings::bpf_devmap_val;
 use aya_bpf_cty::c_void;
 
 use crate::{
     bindings::{bpf_map_def, bpf_map_type::BPF_MAP_TYPE_DEVMAP_HASH},
-    helpers::bpf_map_lookup_elem,
+    helpers::{bpf_map_lookup_elem, bpf_redirect_map},
     maps::PinningType,
 };
 
 #[repr(transparent)]
 pub struct DevMapHash {
-    def: bpf_map_def,
+    def: UnsafeCell<bpf_map_def>,
 }
 
+unsafe impl Sync for DevMapHash {}
+
 impl DevMapHash {
     pub const fn with_max_entries(max_entries: u32, flags: u32) -> DevMapHash {
         DevMapHash {
-            def: bpf_map_def {
+            def: UnsafeCell::new(bpf_map_def {
                 type_: BPF_MAP_TYPE_DEVMAP_HASH,
                 key_size: mem::size_of::<u32>() as u32,
                 value_size: mem::size_of::<u32>() as u32,
@@ -24,32 +27,40 @@ impl DevMapHash {
                 map_flags: flags,
                 id: 0,
                 pinning: PinningType::None as u32,
-            },
+            }),
         }
     }
 
     pub const fn pinned(max_entries: u32, flags: u32) -> DevMapHash {
         DevMapHash {
-            def: bpf_map_def {
+            def: UnsafeCell::new(bpf_map_def {
                 type_: BPF_MAP_TYPE_DEVMAP_HASH,
                 key_size: mem::size_of::<u32>() as u32,
                 value_size: mem::size_of::<u32>() as u32,
                 max_entries,
                 map_flags: flags,
                 id: 0,
-                pinning: PinningType::None as u32,
-            },
+                pinning: PinningType::ByName as u32,
+            }),
         }
     }
 
-    pub fn get(&mut self, index: u32) -> Option<&u32> {
+    #[inline(always)]
+    pub unsafe fn get(&self, index: u32) -> Option<&bpf_devmap_val> {
+        let value = bpf_map_lookup_elem(
+            self.def.get() as *mut _,
+            &index as *const _ as *const c_void,
+        );
+        NonNull::new(value as *mut bpf_devmap_val).map(|p| p.as_ref())
+    }
+
+    #[inline(always)]
+    pub fn redirect(&self, index: u32, flags: u64) -> u32 {
         unsafe {
-            let value = bpf_map_lookup_elem(
-                &mut self.def as *mut _ as *mut _,
-                &index as *const _ as *const c_void,
-            );
-            // FIXME: alignment
-            NonNull::new(value as *mut u32).map(|p| p.as_ref())
+            // Return XDP_REDIRECT on success, or the value of the two lower bits of the flags
+            // argument on error. Thus I have no idea why it returns a long (i64) instead of
+            // something saner, hence the unsigned_abs.
+            bpf_redirect_map(self.def.get() as *mut _, index.into(), flags).unsigned_abs() as u32
         }
     }
 }

bpf/aya-bpf/src/maps/xdp/xsk_map.rs

@@ -1,22 +1,25 @@
-use core::{mem, ptr::NonNull};
+use core::{cell::UnsafeCell, mem, ptr::NonNull};
 
+use aya_bpf_bindings::bindings::bpf_xdp_sock;
 use aya_bpf_cty::c_void;
 
 use crate::{
     bindings::{bpf_map_def, bpf_map_type::BPF_MAP_TYPE_XSKMAP},
-    helpers::bpf_map_lookup_elem,
+    helpers::{bpf_map_lookup_elem, bpf_redirect_map},
     maps::PinningType,
 };
 
 #[repr(transparent)]
 pub struct XskMap {
-    def: bpf_map_def,
+    def: UnsafeCell<bpf_map_def>,
 }
 
+unsafe impl Sync for XskMap {}
+
 impl XskMap {
     pub const fn with_max_entries(max_entries: u32, flags: u32) -> XskMap {
         XskMap {
-            def: bpf_map_def {
+            def: UnsafeCell::new(bpf_map_def {
                 type_: BPF_MAP_TYPE_XSKMAP,
                 key_size: mem::size_of::<u32>() as u32,
                 value_size: mem::size_of::<u32>() as u32,
@@ -24,32 +27,41 @@ impl XskMap {
                 map_flags: flags,
                 id: 0,
                 pinning: PinningType::None as u32,
-            },
+            }),
         }
     }
 
     pub const fn pinned(max_entries: u32, flags: u32) -> XskMap {
         XskMap {
-            def: bpf_map_def {
+            def: UnsafeCell::new(bpf_map_def {
                 type_: BPF_MAP_TYPE_XSKMAP,
                 key_size: mem::size_of::<u32>() as u32,
                 value_size: mem::size_of::<u32>() as u32,
                 max_entries,
                 map_flags: flags,
                 id: 0,
-                pinning: PinningType::None as u32,
-            },
+                pinning: PinningType::ByName as u32,
+            }),
         }
     }
 
-    pub fn get(&mut self, index: u32) -> Option<&u32> {
+    #[inline(always)]
+    pub unsafe fn get(&self, index: u32) -> Option<&bpf_xdp_sock> {
+        let value = bpf_map_lookup_elem(
+            self.def.get() as *mut _,
+            &index as *const _ as *const c_void,
+        );
+        // FIXME: alignment
+        NonNull::new(value as *mut bpf_xdp_sock).map(|p| p.as_ref())
+    }
+
+    #[inline(always)]
+    pub fn redirect(&self, index: u32, flags: u64) -> u32 {
         unsafe {
-            let value = bpf_map_lookup_elem(
-                &mut self.def as *mut _ as *mut _,
-                &index as *const _ as *const c_void,
-            );
-            // FIXME: alignment
-            NonNull::new(value as *mut u32).map(|p| p.as_ref())
+            // Return XDP_REDIRECT on success, or the value of the two lower bits of the flags
+            // argument on error. Thus I have no idea why it returns a long (i64) instead of
+            // something saner, hence the unsigned_abs.
+            bpf_redirect_map(self.def.get() as *mut _, index.into(), flags).unsigned_abs() as u32
         }
     }
 }