@@ -3761,6 +3761,19 @@ struct xdp_md {
__u32 egress_ifindex; /* txq->dev->ifindex */
};
+/* DEVMAP map-value layout
+ *
+ * The struct data-layout of map-value is a configuration interface.
+ * New members can only be added to the end of this structure.
+ */
+struct bpf_devmap_val {
+ __u32 ifindex; /* device index */
+ union {
+ int fd; /* prog fd on map write */
+ __u32 id; /* prog id on map read */
+ } bpf_prog;
+};
+
enum sk_action {
SK_DROP = 0,
SK_PASS,
@@ -60,15 +60,6 @@ struct xdp_dev_bulk_queue {
unsigned int count;
};
-/* DEVMAP values */
-struct bpf_devmap_val {
- u32 ifindex; /* device index */
- union {
- int fd; /* prog fd on map write */
- u32 id; /* prog id on map read */
- } bpf_prog;
-};
-
struct bpf_dtab_netdev {
struct net_device *dev; /* must be first member, due to tracepoint */
struct hlist_node index_hlist;
@@ -618,7 +609,7 @@ static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
if (!dev->dev)
goto err_out;
- if (val->bpf_prog.fd >= 0) {
+ if (val->bpf_prog.fd > 0) {
prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
BPF_PROG_TYPE_XDP, false);
if (IS_ERR(prog))
@@ -652,8 +643,8 @@ static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
void *key, void *value, u64 map_flags)
{
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
- struct bpf_devmap_val val = { .bpf_prog.fd = -1 };
struct bpf_dtab_netdev *dev, *old_dev;
+ struct bpf_devmap_val val = {};
u32 i = *(u32 *)key;
if (unlikely(map_flags > BPF_EXIST))
@@ -669,7 +660,7 @@ static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
if (!val.ifindex) {
dev = NULL;
/* can not specify fd if ifindex is 0 */
- if (val.bpf_prog.fd != -1)
+ if (val.bpf_prog.fd > 0)
return -EINVAL;
} else {
dev = __dev_map_alloc_node(net, dtab, &val, i);
@@ -699,8 +690,8 @@ static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
void *key, void *value, u64 map_flags)
{
struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
- struct bpf_devmap_val val = { .bpf_prog.fd = -1 };
struct bpf_dtab_netdev *dev, *old_dev;
+ struct bpf_devmap_val val = {};
u32 idx = *(u32 *)key;
unsigned long flags;
int err = -EEXIST;
V2: - Defer changing BPF-syscall to start at file-descriptor 1 - Use {} to zero initialise struct. The recent commit fbee97feed9b ("bpf: Add support to attach bpf program to a devmap entry"), introduced ability to attach (and run) a separate XDP bpf_prog for each devmap entry. A bpf_prog is added via a file-descriptor. As zero were a valid FD, not using the feature requires using value minus-1. The UAPI is extended via tail-extending struct bpf_devmap_val and using map->value_size to determine the feature set. This will break older userspace applications not using the bpf_prog feature. Consider an old userspace app that is compiled against newer kernel uapi/bpf.h, it will not know that it need to initialise the member bpf_prog.fd to minus-1. Thus, users will be forced to update source code to get program running on newer kernels. This patch remove the minus-1 checks, and have zero mean feature isn't used. Followup patches either for kernel or libbpf should handle and avoid returning file-descriptor zero in the first place. Fixes: fbee97feed9b ("bpf: Add support to attach bpf program to a devmap entry") Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> --- include/uapi/linux/bpf.h | 13 +++++++++++++ kernel/bpf/devmap.c | 17 ++++------------- 2 files changed, 17 insertions(+), 13 deletions(-)