bpf: offload: add infrastructure for loading programs for a specific netdev

The fact that we don't know which device the program is going
to be used on is quite limiting in current eBPF infrastructure.
We have to reverse or limit the changes which kernel makes to
the loaded bytecode if we want it to be offloaded to a networking
device.  We also have to invent new APIs for debugging and
troubleshooting support.

Make it possible to load programs for a specific netdev.  This
helps us to bring the debug information closer to the core
eBPF infrastructure (e.g. we will be able to reuse the verifer
log in device JIT).  It allows device JITs to perform translation
on the original bytecode.

__bpf_prog_get() when called to get a reference for an attachment
point will now refuse to give it if program has a device assigned.
Following patches will add a version of that function which passes
the expected netdev in. @type argument in __bpf_prog_get() is
renamed to attach_type to make it clearer that it's only set on
attachment.

All calls to ndo_bpf are protected by rtnl, only verifier callbacks
are not.  We need a wait queue to make sure netdev doesn't get
destroyed while verifier is still running and calling its driver.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 4 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 323be2473c4b..1574b9f0f24e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -824,7 +824,10 @@ static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
         if (type >= ARRAY_SIZE(bpf_prog_types) || !bpf_prog_types[type])
                 return -EINVAL;
 
-        prog->aux->ops = bpf_prog_types[type];
+        if (!bpf_prog_is_dev_bound(prog->aux))
+                prog->aux->ops = bpf_prog_types[type];
+        else
+                prog->aux->ops = &bpf_offload_prog_ops;
         prog->type = type;
         return 0;
 }
@@ -1054,7 +1057,7 @@ struct bpf_prog *bpf_prog_inc_not_zero(struct bpf_prog *prog)
 }
 EXPORT_SYMBOL_GPL(bpf_prog_inc_not_zero);
 
-static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *type)
+static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *attach_type)
 {
         struct fd f = fdget(ufd);
         struct bpf_prog *prog;
@@ -1062,7 +1065,7 @@ static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *type)
         prog = ____bpf_prog_get(f);
         if (IS_ERR(prog))
                 return prog;
-        if (type && prog->type != *type) {
+        if (attach_type && (prog->type != *attach_type || prog->aux->offload)) {
                 prog = ERR_PTR(-EINVAL);
                 goto out;
         }
@@ -1089,7 +1092,7 @@ struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type)
 EXPORT_SYMBOL_GPL(bpf_prog_get_type);
 
 /* last field in 'union bpf_attr' used by this command */
-#define BPF_PROG_LOAD_LAST_FIELD prog_name
+#define BPF_PROG_LOAD_LAST_FIELD prog_target_ifindex
 
 static int bpf_prog_load(union bpf_attr *attr)
 {
@@ -1152,6 +1155,12 @@ static int bpf_prog_load(union bpf_attr *attr)
         atomic_set(&prog->aux->refcnt, 1);
         prog->gpl_compatible = is_gpl ? 1 : 0;
 
+        if (attr->prog_target_ifindex) {
+                err = bpf_prog_offload_init(prog, attr);
+                if (err)
+                        goto free_prog;
+        }
+
         /* find program type: socket_filter vs tracing_filter */
         err = find_prog_type(type, prog);
         if (err < 0)