[PATCH net-next 2/5] bpf: Add map_name to bpf_map_info

[Martin KaFai Lau]

This patch allows userspace to specify a name for a map
during BPF_MAP_CREATE.

The map's name can later be exported to user space
via BPF_OBJ_GET_INFO_BY_FD.

Signed-off-by: Martin KaFai Lau <ka...@fb.com>
Acked-by: Alexei Starovoitov <a...@fb.com>
Acked-by: Daniel Borkmann <dan...@iogearbox.net>
---
 include/linux/bpf.h      | 1 +
 include/uapi/linux/bpf.h | 2 ++
 kernel/bpf/syscall.c     | 7 ++++++-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 33ccc474fb04..252f4bc9eb25 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -56,6 +56,7 @@ struct bpf_map {
        struct work_struct work;
        atomic_t usercnt;
        struct bpf_map *inner_map_meta;
+       u8 name[BPF_OBJ_NAME_LEN];
 };
 
 /* function argument constraints */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index bd6348269bf5..6d2137b4cf38 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -190,6 +190,7 @@ union bpf_attr {
                __u32   numa_node;      /* numa node (effective only if
                                         * BPF_F_NUMA_NODE is set).
                                         */
+               __u8    map_name[BPF_OBJ_NAME_LEN];
        };
 
        struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
@@ -829,6 +830,7 @@ struct bpf_map_info {
        __u32 value_size;
        __u32 max_entries;
        __u32 map_flags;
+       __u8  name[BPF_OBJ_NAME_LEN];
 } __attribute__((aligned(8)));
 
 /* User bpf_sock_ops struct to access socket values and specify request ops
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 45970df3f820..11a7f82a55d1 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -339,7 +339,7 @@ static int bpf_obj_name_cpy(char *dst, const char *src)
        return 0;
 }
 
-#define BPF_MAP_CREATE_LAST_FIELD numa_node
+#define BPF_MAP_CREATE_LAST_FIELD map_name
 /* called via syscall */
 static int map_create(union bpf_attr *attr)
 {
@@ -361,6 +361,10 @@ static int map_create(union bpf_attr *attr)
        if (IS_ERR(map))
                return PTR_ERR(map);
 
+       err = bpf_obj_name_cpy(map->name, attr->map_name);
+       if (err)
+               goto free_map_nouncharge;
+
        atomic_set(&map->refcnt, 1);
        atomic_set(&map->usercnt, 1);
 
@@ -1462,6 +1466,7 @@ static int bpf_map_get_info_by_fd(struct bpf_map *map,
        info.value_size = map->value_size;
        info.max_entries = map->max_entries;
        info.map_flags = map->map_flags;
+       memcpy(info.name, map->name, sizeof(map->name));
 
        if (copy_to_user(uinfo, &info, info_len) ||
            put_user(info_len, &uattr->info.info_len))
-- 
2.9.5