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Message-Id: <cd0871f11c476f8d7fee1cb356940a13cf7d4807.1480370617.git.daniel@iogearbox.net>
Date: Mon, 28 Nov 2016 23:16:54 +0100
From: Daniel Borkmann <daniel@...earbox.net>
To: davem@...emloft.net
Cc: alexei.starovoitov@...il.com, netdev@...r.kernel.org,
Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH net-next] bpf, xdp: allow to pass flags to dev_change_xdp_fd
Add an IFLA_XDP_FLAGS attribute that can be passed for setting up
XDP along with IFLA_XDP_FD, which eventually allows user space to
implement typical add/replace/delete logic for programs. Right now,
calling into dev_change_xdp_fd() will always replace previous programs.
When passed XDP_FLAGS_UPDATE_IF_NOEXIST, we can handle this more
graceful when requested by returning -EBUSY in case we try to
attach a new program, but we find that another one is already
attached. This will be used by upcoming front-end for iproute2 as
well.
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Alexei Starovoitov <ast@...nel.org>
---
include/linux/netdevice.h | 2 +-
include/uapi/linux/if_link.h | 4 ++++
net/core/dev.c | 20 ++++++++++++++++++--
net/core/rtnetlink.c | 14 +++++++++++++-
4 files changed, 36 insertions(+), 4 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 4ffcd87..3755317 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3253,7 +3253,7 @@ int dev_get_phys_port_id(struct net_device *dev,
int dev_get_phys_port_name(struct net_device *dev,
char *name, size_t len);
int dev_change_proto_down(struct net_device *dev, bool proto_down);
-int dev_change_xdp_fd(struct net_device *dev, int fd);
+int dev_change_xdp_fd(struct net_device *dev, int fd, u32 flags);
struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *dev);
struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
struct netdev_queue *txq, int *ret);
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 92b2d49..6b13e59 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -876,10 +876,14 @@ enum {
/* XDP section */
+#define XDP_FLAGS_UPDATE_IF_NOEXIST (1U << 0)
+#define XDP_FLAGS_MASK (XDP_FLAGS_UPDATE_IF_NOEXIST)
+
enum {
IFLA_XDP_UNSPEC,
IFLA_XDP_FD,
IFLA_XDP_ATTACHED,
+ IFLA_XDP_FLAGS,
__IFLA_XDP_MAX,
};
diff --git a/net/core/dev.c b/net/core/dev.c
index 048b46b..a44aefe 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6692,26 +6692,42 @@ int dev_change_proto_down(struct net_device *dev, bool proto_down)
* dev_change_xdp_fd - set or clear a bpf program for a device rx path
* @dev: device
* @fd: new program fd or negative value to clear
+ * @flags: xdp-related flags
*
* Set or clear a bpf program for a device
*/
-int dev_change_xdp_fd(struct net_device *dev, int fd)
+int dev_change_xdp_fd(struct net_device *dev, int fd, u32 flags)
{
const struct net_device_ops *ops = dev->netdev_ops;
struct bpf_prog *prog = NULL;
- struct netdev_xdp xdp = {};
+ struct netdev_xdp xdp;
int err;
+ ASSERT_RTNL();
+
if (!ops->ndo_xdp)
return -EOPNOTSUPP;
if (fd >= 0) {
+ if (flags & XDP_FLAGS_UPDATE_IF_NOEXIST) {
+ memset(&xdp, 0, sizeof(xdp));
+ xdp.command = XDP_QUERY_PROG;
+
+ err = ops->ndo_xdp(dev, &xdp);
+ if (err < 0)
+ return err;
+ if (xdp.prog_attached)
+ return -EBUSY;
+ }
+
prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_XDP);
if (IS_ERR(prog))
return PTR_ERR(prog);
}
+ memset(&xdp, 0, sizeof(xdp));
xdp.command = XDP_SETUP_PROG;
xdp.prog = prog;
+
err = ops->ndo_xdp(dev, &xdp);
if (err < 0 && prog)
bpf_prog_put(prog);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 4e60525..bd85570 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1505,6 +1505,7 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
static const struct nla_policy ifla_xdp_policy[IFLA_XDP_MAX + 1] = {
[IFLA_XDP_FD] = { .type = NLA_S32 },
[IFLA_XDP_ATTACHED] = { .type = NLA_U8 },
+ [IFLA_XDP_FLAGS] = { .type = NLA_U32 },
};
static const struct rtnl_link_ops *linkinfo_to_kind_ops(const struct nlattr *nla)
@@ -2164,6 +2165,7 @@ static int do_setlink(const struct sk_buff *skb,
if (tb[IFLA_XDP]) {
struct nlattr *xdp[IFLA_XDP_MAX + 1];
+ u32 xdp_flags = 0;
err = nla_parse_nested(xdp, IFLA_XDP_MAX, tb[IFLA_XDP],
ifla_xdp_policy);
@@ -2174,9 +2176,19 @@ static int do_setlink(const struct sk_buff *skb,
err = -EINVAL;
goto errout;
}
+
+ if (xdp[IFLA_XDP_FLAGS]) {
+ xdp_flags = nla_get_u32(xdp[IFLA_XDP_FLAGS]);
+ if (xdp_flags & ~XDP_FLAGS_MASK) {
+ err = -EINVAL;
+ goto errout;
+ }
+ }
+
if (xdp[IFLA_XDP_FD]) {
err = dev_change_xdp_fd(dev,
- nla_get_s32(xdp[IFLA_XDP_FD]));
+ nla_get_s32(xdp[IFLA_XDP_FD]),
+ xdp_flags);
if (err)
goto errout;
status |= DO_SETLINK_NOTIFY;
--
1.9.3
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