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bpf, xdp: allow to pass flags to dev_change_xdp_fd

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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@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2016-11-28 23:16:54 +01:00 committed by David S. Miller
parent 0f29f05bd7
commit 85de8576a0
4 changed files with 36 additions and 4 deletions
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2
include/linux/netdevice.h
View file

@ -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);

4
include/uapi/linux/if_link.h
View file

@ -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,
};

20
net/core/dev.c
View file

@ -6692,26 +6692,42 @@ EXPORT_SYMBOL(dev_change_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);

14
net/core/rtnetlink.c
View file

@ -1505,6 +1505,7 @@ static const struct nla_policy ifla_port_policy[IFLA_PORT_MAX+1] = {
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;