Add crud support for BPF_MAP_TYPE_BLOOM_FILTER

Update map_key documentation to include bloom filter

Add bloom filter test

Add specific lookup for bloom filter

Finalize PR

Improve error message

Author: barthr

libbpf-rs/src/map.rs

@@ -556,10 +556,11 @@ impl MapHandle {
         Ok(ncpu * aligned_val_size)
     }
 
-    /// Apply a key check and return a null pointer in case of dealing with queue/stack map,
-    /// before passing the key to the bpf functions that support the map of type queue/stack.
+    /// Apply a key check and return a null pointer in case of dealing with queue/stack/bloom-filter map,
+    /// before passing the key to the bpf functions that support the map of type queue/stack/bloom-filter.
     fn map_key(&self, key: &[u8]) -> *const c_void {
-        if self.key_size() == 0 && matches!(self.map_type(), MapType::Queue | MapType::Stack) {
+        // For all they keyless maps we null out the key per documentation of libbpf
+        if self.key_size() == 0 && self.map_type().is_keyless() {
             return ptr::null();
         }
 
@@ -631,7 +632,13 @@ impl MapHandle {
     ///
     /// If the map is one of the per-cpu data structures, the function [`MapHandle::lookup_percpu()`]
     /// must be used.
+    /// If the map is of type bloom_filter the function [`MapHandle::lookup_bloom_filter()`] must be used
     pub fn lookup(&self, key: &[u8], flags: MapFlags) -> Result<Option<Vec<u8>>> {
+        if self.map_type().is_bloom_filter() {
+            return Err(Error::with_invalid_data(
+                "lookup_bloom_filter() must be used for bloom filter maps",
+            ));
+        }
         if self.map_type().is_percpu() {
             return Err(Error::with_invalid_data(format!(
                 "lookup_percpu() must be used for per-cpu maps (type of the map is {})",
@@ -643,6 +650,30 @@ impl MapHandle {
         self.lookup_raw(key, flags, out_size)
     }
 
+    /// Returns if the given value is likely present in bloom_filter as `bool`.
+    ///
+    /// `value` must have exactly [`MapHandle::value_size()`] elements.
+    pub fn lookup_bloom_filter(&self, value: &[u8]) -> Result<bool> {
+        let ret = unsafe {
+            libbpf_sys::bpf_map_lookup_elem(
+                self.fd.as_raw_fd(),
+                ptr::null(),
+                value.to_vec().as_mut_ptr() as *mut c_void,
+            )
+        };
+
+        if ret == 0 {
+            Ok(true)
+        } else {
+            let err = io::Error::last_os_error();
+            if err.kind() == io::ErrorKind::NotFound {
+                Ok(false)
+            } else {
+                Err(Error::from(err))
+            }
+        }
+    }
+
     /// Returns one value per cpu as `Vec` of `Vec` of `u8` for per per-cpu maps.
     ///
     /// For normal maps, [`MapHandle::lookup()`] must be used.
@@ -1009,6 +1040,17 @@ impl MapType {
         )
     }
 
+    /// Returns if the map is keyless map type as per documentation of libbpf
+    /// Keyless map types are: Queues, Stacks and Bloom Filters
+    fn is_keyless(&self) -> bool {
+        matches!(self, MapType::Queue | MapType::Stack | MapType::BloomFilter)
+    }
+
+    /// Returns if the map is of bloom filter type
+    pub fn is_bloom_filter(&self) -> bool {
+        MapType::BloomFilter.eq(self)
+    }
+
     /// Detects if host kernel supports this BPF map type.
     ///
     /// Make sure the process has required set of CAP_* permissions (or runs as

libbpf-rs/tests/bin/src/tracepoint.bpf.c

@@ -65,4 +65,10 @@ struct {
     __type(value, __u32);
 } stack SEC(".maps");
 
+struct {
+    __uint(type, BPF_MAP_TYPE_BLOOM_FILTER);
+    __uint(max_entries, 5);
+    __type(value, __u32);
+} bloom_filter SEC(".maps");
+
 char LICENSE[] SEC("license") = "GPL";

libbpf-rs/tests/bin/tracepoint.bpf.o

@@ -527,6 +527,58 @@ fn test_sudo_object_map_queue_crud() {
         .is_none());
 }
 
+/// Test CRUD operations on map of type bloomfilter.
+#[test]
+fn test_sudo_object_map_bloom_filter_crud() {
+    bump_rlimit_mlock();
+
+    let obj = get_test_object("tracepoint.bpf.o");
+    let bloom_filter = obj
+        .map("bloom_filter")
+        .expect("failed to find bloom_filter map");
+
+    let key: [u8; 0] = [];
+    let value1 = 1337u32.to_ne_bytes();
+    let value2 = 2674u32.to_ne_bytes();
+
+    bloom_filter
+        .update(&key, &value1, MapFlags::ANY)
+        .expect("failed to add entry value1 to bloom filter");
+
+    bloom_filter
+        .update(&key, &value2, MapFlags::ANY)
+        .expect("failed to add entry value2 in bloom filter");
+
+    // Non empty keys should result in an error
+    bloom_filter
+        .update(&value1, &value1, MapFlags::ANY)
+        .expect_err("Non empty key should return an error");
+
+    for inserted_value in [value1, value2] {
+        let val = bloom_filter
+            .lookup_bloom_filter(&inserted_value)
+            .expect("failed retrieve item from bloom filter");
+
+        assert!(val);
+    }
+    // Test non existing element
+    let enoent_found = bloom_filter
+        .lookup_bloom_filter(&[1, 2, 3, 4])
+        .expect("failed retrieve item from bloom filter");
+
+    assert!(!enoent_found);
+
+    // Calling lookup should result in an error
+    bloom_filter
+        .lookup(&[1, 2, 3, 4], MapFlags::ANY)
+        .expect_err("lookup should fail since we should use lookup_bloom_filter");
+
+    // Deleting should not be possible
+    bloom_filter
+        .lookup_and_delete(&key)
+        .expect_err("Expect delete to fail");
+}
+
 /// Test CRUD operations on map of type stack.
 #[test]
 fn test_sudo_object_map_stack_crud() {
@@ -550,6 +602,7 @@ fn test_sudo_object_map_stack_crud() {
         .lookup(&key, MapFlags::ANY)
         .expect("failed to pop from stack")
         .expect("failed to retrieve value");
+
     assert_eq!(val.len(), 4);
     assert_eq!(&val, &value2);