netdev - [PATCH bpf-next] bpf: add support for other map types to bpf_map_lookup_and_delete

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Date:   Thu, 17 Sep 2020 15:57:00 +0200
From:   Luka Oreskovic <luka.oreskovic@...tura.hr>
To:     ast@...nel.org, daniel@...earbox.net
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        Luka Oreskovic <luka.oreskovic@...tura.hr>,
        Juraj Vijtiuk <juraj.vijtiuk@...tura.hr>,
        Luka Perkov <luka.perkov@...tura.hr>
Subject: [PATCH bpf-next] bpf: add support for other map types to bpf_map_lookup_and_delete_elem

Since this function already exists, it made sense to implement it for
map types other than stack and queue. This patch adds the necessary parts
from bpf_map_lookup_elem and bpf_map_delete_elem so it works as expected
for all map types.

Signed-off-by: Luka Oreskovic <luka.oreskovic@...tura.hr>
CC: Juraj Vijtiuk <juraj.vijtiuk@...tura.hr>
CC: Luka Perkov <luka.perkov@...tura.hr>
---
 kernel/bpf/syscall.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2ce32cad5c8e..955de6ca8c45 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1475,6 +1475,9 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
 	if (CHECK_ATTR(BPF_MAP_LOOKUP_AND_DELETE_ELEM))
 		return -EINVAL;
 
+	if (attr->flags & ~BPF_F_LOCK)
+		return -EINVAL;
+
 	f = fdget(ufd);
 	map = __bpf_map_get(f);
 	if (IS_ERR(map))
@@ -1485,13 +1488,19 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
 		goto err_put;
 	}
 
+	if ((attr->flags & BPF_F_LOCK) &&
+	    !map_value_has_spin_lock(map)) {
+		err = -EINVAL;
+		goto err_put;
+	}
+
 	key = __bpf_copy_key(ukey, map->key_size);
 	if (IS_ERR(key)) {
 		err = PTR_ERR(key);
 		goto err_put;
 	}
 
-	value_size = map->value_size;
+	value_size = bpf_map_value_size(map);
 
 	err = -ENOMEM;
 	value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
@@ -1502,7 +1511,24 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
 	    map->map_type == BPF_MAP_TYPE_STACK) {
 		err = map->ops->map_pop_elem(map, value);
 	} else {
-		err = -ENOTSUPP;
+		err = bpf_map_copy_value(map, key, value, attr->flags);
+		if (err)
+			goto free_value;
+
+		if (bpf_map_is_dev_bound(map)) {
+			err = bpf_map_offload_delete_elem(map, key);
+		} else if (IS_FD_PROG_ARRAY(map) ||
+			   map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
+			/* These maps require sleepable context */
+			err = map->ops->map_delete_elem(map, key);
+		} else {
+			bpf_disable_instrumentation();
+			rcu_read_lock();
+			err = map->ops->map_delete_elem(map, key);
+			rcu_read_unlock();
+			bpf_enable_instrumentation();
+			maybe_wait_bpf_programs(map);
+		}
 	}
 
 	if (err)
-- 
2.26.2