[RFC] bpf: change bpf syacall to use u64 temp variables
From: yalin wang <hidden>
Date: 2015-10-19 07:10:58
Also in:
lkml
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
This patch change map_lookup_elem() and map_update_elem() function to use u64 temp variable if the key_size or value_size is less than u64, we don't need use kmalloc() for these small variables. Signed-off-by: yalin wang <redacted> --- kernel/bpf/syscall.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index f640e5f..c82d7bf 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c@@ -189,7 +189,8 @@ static int map_lookup_elem(union bpf_attr *attr) void __user *uvalue = u64_to_ptr(attr->value); int ufd = attr->map_fd; struct bpf_map *map; - void *key, *value, *ptr; + u64 key_buf, value_buf; + void *key = &key_buf, *value = &value_buf, *ptr; struct fd f; int err;
@@ -202,7 +203,8 @@ static int map_lookup_elem(union bpf_attr *attr) return PTR_ERR(map); err = -ENOMEM; - key = kmalloc(map->key_size, GFP_USER); + if (map->key_size > sizeof(u64)) + key = kmalloc(map->key_size, GFP_USER); if (!key) goto err_put;
@@ -211,7 +213,8 @@ static int map_lookup_elem(union bpf_attr *attr) goto free_key; err = -ENOMEM; - value = kmalloc(map->value_size, GFP_USER); + if (map->value_size > sizeof(u64)) + value = kmalloc(map->value_size, GFP_USER); if (!value) goto free_key;
@@ -232,9 +235,11 @@ static int map_lookup_elem(union bpf_attr *attr) err = 0; free_value: - kfree(value); + if (value != &value_buf) + kfree(value); free_key: - kfree(key); + if (key != &key_buf) + kfree(key); err_put: fdput(f); return err;
@@ -248,7 +253,8 @@ static int map_update_elem(union bpf_attr *attr) void __user *uvalue = u64_to_ptr(attr->value); int ufd = attr->map_fd; struct bpf_map *map; - void *key, *value; + u64 key_buf, value_buf; + void *key = &key_buf, *value = &value_buf; struct fd f; int err;
@@ -261,7 +267,8 @@ static int map_update_elem(union bpf_attr *attr) return PTR_ERR(map); err = -ENOMEM; - key = kmalloc(map->key_size, GFP_USER); + if (map->key_size > sizeof(u64)) + key = kmalloc(map->key_size, GFP_USER); if (!key) goto err_put;
@@ -270,7 +277,8 @@ static int map_update_elem(union bpf_attr *attr) goto free_key; err = -ENOMEM; - value = kmalloc(map->value_size, GFP_USER); + if (map->value_size > sizeof(u64)) + value = kmalloc(map->value_size, GFP_USER); if (!value) goto free_key;
@@ -286,9 +294,11 @@ static int map_update_elem(union bpf_attr *attr) rcu_read_unlock(); free_value: - kfree(value); + if (value != &value_buf) + kfree(value); free_key: - kfree(key); + if (key != &key_buf) + kfree(key); err_put: fdput(f); return err;
--
1.9.1