From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Fri, 3 Nov 2017 13:56:20 -0700
Subject: xdp: allow attaching programs loaded for specific device
Patch-mainline: v4.15-rc1
Git-commit: 248f346ffe9508dee0039db4ac839cb31ba3bdec
References: bsc#1109837

Pass the netdev pointer to bpf_prog_get_type().  This way
BPF code can decide whether the device matches what the
code was loaded/translated for.

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>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/linux/bpf.h  |   10 ++++++++++
 kernel/bpf/syscall.c |   33 +++++++++++++++++++++++++++++----
 net/core/dev.c       |    6 +++++-
 3 files changed, 44 insertions(+), 5 deletions(-)

--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -306,6 +306,8 @@ extern const struct bpf_verifier_ops xdp
 
 struct bpf_prog *bpf_prog_get(u32 ufd);
 struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type);
+struct bpf_prog *bpf_prog_get_type_dev(u32 ufd, enum bpf_prog_type type,
+				       struct net_device *netdev);
 struct bpf_prog * __must_check bpf_prog_add(struct bpf_prog *prog, int i);
 void bpf_prog_sub(struct bpf_prog *prog, int i);
 struct bpf_prog * __must_check bpf_prog_inc(struct bpf_prog *prog);
@@ -399,6 +401,14 @@ static inline struct bpf_prog *bpf_prog_
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }
+
+static inline struct bpf_prog *bpf_prog_get_type_dev(u32 ufd,
+						     enum bpf_prog_type type,
+						     struct net_device *netdev)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
 static inline struct bpf_prog * __must_check bpf_prog_add(struct bpf_prog *prog,
 							  int i)
 {
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1037,7 +1037,22 @@ struct bpf_prog *bpf_prog_inc_not_zero(s
 }
 EXPORT_SYMBOL_GPL(bpf_prog_inc_not_zero);
 
-static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *attach_type)
+static bool bpf_prog_can_attach(struct bpf_prog *prog,
+				enum bpf_prog_type *attach_type,
+				struct net_device *netdev)
+{
+	struct bpf_dev_offload *offload = prog->aux->offload;
+
+	if (prog->type != *attach_type)
+		return false;
+	if (offload && offload->netdev != netdev)
+		return false;
+
+	return true;
+}
+
+static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *attach_type,
+				       struct net_device *netdev)
 {
 	struct fd f = fdget(ufd);
 	struct bpf_prog *prog;
@@ -1045,7 +1060,7 @@ static struct bpf_prog *__bpf_prog_get(u
 	prog = ____bpf_prog_get(f);
 	if (IS_ERR(prog))
 		return prog;
-	if (attach_type && (prog->type != *attach_type || prog->aux->offload)) {
+	if (attach_type && !bpf_prog_can_attach(prog, attach_type, netdev)) {
 		prog = ERR_PTR(-EINVAL);
 		goto out;
 	}
@@ -1058,12 +1073,12 @@ out:
 
 struct bpf_prog *bpf_prog_get(u32 ufd)
 {
-	return __bpf_prog_get(ufd, NULL);
+	return __bpf_prog_get(ufd, NULL, NULL);
 }
 
 struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type)
 {
-	struct bpf_prog *prog = __bpf_prog_get(ufd, &type);
+	struct bpf_prog *prog = __bpf_prog_get(ufd, &type, NULL);
 
 	if (!IS_ERR(prog))
 		trace_bpf_prog_get_type(prog);
@@ -1071,6 +1086,16 @@ struct bpf_prog *bpf_prog_get_type(u32 u
 }
 EXPORT_SYMBOL_GPL(bpf_prog_get_type);
 
+struct bpf_prog *bpf_prog_get_type_dev(u32 ufd, enum bpf_prog_type type,
+				       struct net_device *netdev)
+{
+	struct bpf_prog *prog = __bpf_prog_get(ufd, &type, netdev);
+
+	if (!IS_ERR(prog))
+		trace_bpf_prog_get_type(prog);
+	return prog;
+}
+
 /* last field in 'union bpf_attr' used by this command */
 #define	BPF_PROG_LOAD_LAST_FIELD prog_target_ifindex
 
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7130,7 +7130,11 @@ int dev_change_xdp_fd(struct net_device
 		    __dev_xdp_attached(dev, bpf_op, NULL))
 			return -EBUSY;
 
-		prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_XDP);
+		if (bpf_op == ops->ndo_bpf)
+			prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
+						     dev);
+		else
+			prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_XDP);
 		if (IS_ERR(prog))
 			return PTR_ERR(prog);
 	}