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bpf/syscall: allow key to be null in map functions 

This commit adds the required logic to allow key being NULL
in case the key_size of the map is 0.

A new __bpf_copy_key function helper only copies the key from
userpsace when key_size != 0, otherwise it enforces that key must be
null.

Signed-off-by: Mauricio Vasquez B <mauricio.vasquez@polito.it>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Mauricio Vasquez B 2018-10-18 15:16:14 +02:00 committed by Alexei Starovoitov
parent 144991602e
commit c9d29f4658
1 changed files with 15 additions and 4 deletions
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19
kernel/bpf/syscall.c
View File

@ -651,6 +651,17 @@ int __weak bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
return -ENOTSUPP;
}
static void *__bpf_copy_key(void __user *ukey, u64 key_size)
{
if (key_size)
return memdup_user(ukey, key_size);
if (ukey)
return ERR_PTR(-EINVAL);
return NULL;
}
/* last field in 'union bpf_attr' used by this command */
#define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value
@ -678,7 +689,7 @@ static int map_lookup_elem(union bpf_attr *attr)
goto err_put;
}
key = memdup_user(ukey, map->key_size);
key = __bpf_copy_key(ukey, map->key_size);
if (IS_ERR(key)) {
err = PTR_ERR(key);
goto err_put;
@ -785,7 +796,7 @@ static int map_update_elem(union bpf_attr *attr)
goto err_put;
}
key = memdup_user(ukey, map->key_size);
key = __bpf_copy_key(ukey, map->key_size);
if (IS_ERR(key)) {
err = PTR_ERR(key);
goto err_put;
@ -888,7 +899,7 @@ static int map_delete_elem(union bpf_attr *attr)
goto err_put;
}
key = memdup_user(ukey, map->key_size);
key = __bpf_copy_key(ukey, map->key_size);
if (IS_ERR(key)) {
err = PTR_ERR(key);
goto err_put;
@ -941,7 +952,7 @@ static int map_get_next_key(union bpf_attr *attr)
}
if (ukey) {
key = memdup_user(ukey, map->key_size);
key = __bpf_copy_key(ukey, map->key_size);
if (IS_ERR(key)) {
err = PTR_ERR(key);
goto err_put;