Merge branch 'bpf-fd-array-release'

Daniel Borkmann says:

====================
bpf: improve fd array release

This set improves BPF perf fd array map release wrt to purging
entries, first two extend the API as needed. Please see individual
patches for more details.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 82 insertions, 34 deletions

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 76d5a794e426..5af30732697b 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -328,8 +328,8 @@ static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
 }
 
 /* only called from syscall */
-static int fd_array_map_update_elem(struct bpf_map *map, void *key,
-				    void *value, u64 map_flags)
+int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
+				 void *key, void *value, u64 map_flags)
 {
 	struct bpf_array *array = container_of(map, struct bpf_array, map);
 	void *new_ptr, *old_ptr;
@@ -342,7 +342,7 @@ static int fd_array_map_update_elem(struct bpf_map *map, void *key,
 		return -E2BIG;
 
 	ufd = *(u32 *)value;
-	new_ptr = map->ops->map_fd_get_ptr(map, ufd);
+	new_ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
 	if (IS_ERR(new_ptr))
 		return PTR_ERR(new_ptr);
 
@@ -371,10 +371,12 @@ static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
 	}
 }
 
-static void *prog_fd_array_get_ptr(struct bpf_map *map, int fd)
+static void *prog_fd_array_get_ptr(struct bpf_map *map,
+				   struct file *map_file, int fd)
 {
 	struct bpf_array *array = container_of(map, struct bpf_array, map);
 	struct bpf_prog *prog = bpf_prog_get(fd);
+
 	if (IS_ERR(prog))
 		return prog;
 
@@ -382,6 +384,7 @@ static void *prog_fd_array_get_ptr(struct bpf_map *map, int fd)
 		bpf_prog_put(prog);
 		return ERR_PTR(-EINVAL);
 	}
+
 	return prog;
 }
 
@@ -407,7 +410,6 @@ static const struct bpf_map_ops prog_array_ops = {
 	.map_free = fd_array_map_free,
 	.map_get_next_key = array_map_get_next_key,
 	.map_lookup_elem = fd_array_map_lookup_elem,
-	.map_update_elem = fd_array_map_update_elem,
 	.map_delete_elem = fd_array_map_delete_elem,
 	.map_fd_get_ptr = prog_fd_array_get_ptr,
 	.map_fd_put_ptr = prog_fd_array_put_ptr,
@@ -425,59 +427,105 @@ static int __init register_prog_array_map(void)
 }
 late_initcall(register_prog_array_map);
 
-static void perf_event_array_map_free(struct bpf_map *map)
+static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
+						   struct file *map_file)
 {
-	bpf_fd_array_map_clear(map);
-	fd_array_map_free(map);
+	struct bpf_event_entry *ee;
+
+	ee = kzalloc(sizeof(*ee), GFP_KERNEL);
+	if (ee) {
+		ee->event = perf_file->private_data;
+		ee->perf_file = perf_file;
+		ee->map_file = map_file;
+	}
+
+	return ee;
 }
 
-static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
+static void __bpf_event_entry_free(struct rcu_head *rcu)
 {
-	struct perf_event *event;
-	const struct perf_event_attr *attr;
-	struct file *file;
+	struct bpf_event_entry *ee;
 
-	file = perf_event_get(fd);
-	if (IS_ERR(file))
-		return file;
+	ee = container_of(rcu, struct bpf_event_entry, rcu);
+	fput(ee->perf_file);
+	kfree(ee);
+}
 
-	event = file->private_data;
+static void bpf_event_entry_free_rcu(struct bpf_event_entry *ee)
+{
+	call_rcu(&ee->rcu, __bpf_event_entry_free);
+}
 
-	attr = perf_event_attrs(event);
-	if (IS_ERR(attr))
-		goto err;
+static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
+					 struct file *map_file, int fd)
+{
+	const struct perf_event_attr *attr;
+	struct bpf_event_entry *ee;
+	struct perf_event *event;
+	struct file *perf_file;
 
-	if (attr->inherit)
-		goto err;
+	perf_file = perf_event_get(fd);
+	if (IS_ERR(perf_file))
+		return perf_file;
 
-	if (attr->type == PERF_TYPE_RAW)
-		return file;
+	event = perf_file->private_data;
+	ee = ERR_PTR(-EINVAL);
 
-	if (attr->type == PERF_TYPE_HARDWARE)
-		return file;
+	attr = perf_event_attrs(event);
+	if (IS_ERR(attr) || attr->inherit)
+		goto err_out;
+
+	switch (attr->type) {
+	case PERF_TYPE_SOFTWARE:
+		if (attr->config != PERF_COUNT_SW_BPF_OUTPUT)
+			goto err_out;
+		/* fall-through */
+	case PERF_TYPE_RAW:
+	case PERF_TYPE_HARDWARE:
+		ee = bpf_event_entry_gen(perf_file, map_file);
+		if (ee)
+			return ee;
+		ee = ERR_PTR(-ENOMEM);
+		/* fall-through */
+	default:
+		break;
+	}
 
-	if (attr->type == PERF_TYPE_SOFTWARE &&
-	    attr->config == PERF_COUNT_SW_BPF_OUTPUT)
-		return file;
-err:
-	fput(file);
-	return ERR_PTR(-EINVAL);
+err_out:
+	fput(perf_file);
+	return ee;
 }
 
 static void perf_event_fd_array_put_ptr(void *ptr)
 {
-	fput((struct file *)ptr);
+	bpf_event_entry_free_rcu(ptr);
+}
+
+static void perf_event_fd_array_release(struct bpf_map *map,
+					struct file *map_file)
+{
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+	struct bpf_event_entry *ee;
+	int i;
+
+	rcu_read_lock();
+	for (i = 0; i < array->map.max_entries; i++) {
+		ee = READ_ONCE(array->ptrs[i]);
+		if (ee && ee->map_file == map_file)
+			fd_array_map_delete_elem(map, &i);
+	}
+	rcu_read_unlock();
 }
 
 static const struct bpf_map_ops perf_event_array_ops = {
 	.map_alloc = fd_array_map_alloc,
-	.map_free = perf_event_array_map_free,
+	.map_free = fd_array_map_free,
 	.map_get_next_key = array_map_get_next_key,
 	.map_lookup_elem = fd_array_map_lookup_elem,
-	.map_update_elem = fd_array_map_update_elem,
 	.map_delete_elem = fd_array_map_delete_elem,
 	.map_fd_get_ptr = perf_event_fd_array_get_ptr,
 	.map_fd_put_ptr = perf_event_fd_array_put_ptr,
+	.map_release = perf_event_fd_array_release,
 };
 
 static struct bpf_map_type_list perf_event_array_type __read_mostly = {