Re: [PATCH bpf-next v2 2/7] bpf/syscall: allow key to be null in map functions
From: Song Liu <hidden>
Date: 2018-10-10 23:32:22
On Wed, Oct 10, 2018 at 7:06 AM Mauricio Vasquez B [off-list ref] wrote:
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 <redacted>
Acked-by: Song Liu <redacted>
quoted hunk ↗ jump to hunk
--- kernel/bpf/syscall.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-)diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 4f416234251f..f36c080ad356 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c@@ -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;@@ -774,7 +785,7 @@ 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;@@ -876,7 +887,7 @@ 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;@@ -928,7 +939,7 @@ 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;