An upper device installs its XDP program on each lower with dev_xdp_propagate(), which calls ndo_bpf() directly and records nothing in the lower's xdp_state[]. netif_xdp_propagate() open-codes two of the checks dev_xdp_install() makes, but the lower still looks program-free to everything else, so the checks made in the opposite direction miss it entirely:
ethtool -G $slave tcp-data-split on is refused by dev_xdp_sb_prog_count() for a device running a single-buffer XDP program, but not for a bond slave running the bond's, even though netif_xdp_propagate() would have refused to install that same program had header-data split been on already. Binding a memory provider has the same asymmetry. The lower does not report the program over rtnetlink either, so it is invisible to userspace as well. Install it into xdp_state[] like any other program and mark it with xdp_from_upper, rather than tracking it separately. Every existing user of dev_xdp_prog_count() and dev_xdp_sb_prog_count() then gets the right answer with no changes. The flag is only needed where the owner matters: bonding reads it to tell a slave's own program apart from the one it pushed down, both to refuse enslaving such a device and to let the bond-wide program be replaced, and dev_xdp_attach() reads it to keep the program from being replaced or removed behind the upper's back. The lower now holds its own reference, as it does for a program of its own; the upper's per-lower reference for the driver is unchanged. While here, refuse to propagate onto a device which has a program of its own, matching dev_xdp_install(). Bonding checks this before enslaving and before installing, netvsc does not and would silently replace the VF's program. Signed-off-by: Jakub Kicinski <[email protected]> --- include/linux/netdevice.h | 7 +++ drivers/net/bonding/bond_main.c | 4 +- net/core/dev.c | 101 +++++++++++++++++++++++--------- 3 files changed, 81 insertions(+), 31 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index d037faff7c44..512e3a21d0bd 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2517,6 +2517,12 @@ struct net_device { unsigned long change_proto_down:1; unsigned long netns_immutable:1; unsigned long fcoe_mtu:1; + /** + * @xdp_from_upper: the program in @xdp_state was installed by an + * upper device with netif_xdp_propagate(); it belongs to the + * upper and can't be replaced or removed through this device. + */ + unsigned long xdp_from_upper:1; struct list_head net_notifier_list; @@ -4418,6 +4424,7 @@ struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev, int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog); u8 dev_xdp_prog_count(struct net_device *dev); +bool dev_xdp_has_own_prog(struct net_device *dev); int netif_xdp_propagate(struct net_device *dev, struct netdev_bpf *bpf); int dev_xdp_propagate(struct net_device *dev, struct netdev_bpf *bpf); u8 dev_xdp_sb_prog_count(struct net_device *dev); diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index de2489c3d9bf..a62fff94fea3 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2315,7 +2315,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev, .extack = extack, }; - if (dev_xdp_prog_count(slave_dev) > 0) { + if (dev_xdp_has_own_prog(slave_dev)) { SLAVE_NL_ERR(bond_dev, slave_dev, extack, "Slave has XDP program loaded, please unload before enslaving"); res = -EOPNOTSUPP; @@ -5715,7 +5715,7 @@ static int bond_xdp_set(struct net_device *dev, struct bpf_prog *prog, goto err; } - if (dev_xdp_prog_count(slave_dev) > 0) { + if (dev_xdp_has_own_prog(slave_dev)) { SLAVE_NL_ERR(dev, slave_dev, extack, "Slave has XDP program loaded, please unload before enslaving"); err = -EOPNOTSUPP; diff --git a/net/core/dev.c b/net/core/dev.c index f660fccfc0db..096d1dedebfd 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -10330,6 +10330,15 @@ u8 dev_xdp_prog_count(struct net_device *dev) } EXPORT_SYMBOL_GPL(dev_xdp_prog_count); +/* Does the device have an XDP program, and was it installed directly on the + * device rather than propagated down by an upper with netif_xdp_propagate()? + */ +bool dev_xdp_has_own_prog(struct net_device *dev) +{ + return dev_xdp_prog_count(dev) && !dev->xdp_from_upper; +} +EXPORT_SYMBOL_GPL(dev_xdp_has_own_prog); + u8 dev_xdp_sb_prog_count(struct net_device *dev) { u8 count = 0; @@ -10342,35 +10351,6 @@ u8 dev_xdp_sb_prog_count(struct net_device *dev) return count; } -int netif_xdp_propagate(struct net_device *dev, struct netdev_bpf *bpf) -{ - if (!dev->netdev_ops->ndo_bpf) - return -EOPNOTSUPP; - - if (dev->cfg->hds_config == ETHTOOL_TCP_DATA_SPLIT_ENABLED && - bpf->command == XDP_SETUP_PROG && - bpf->prog && !bpf->prog->aux->xdp_has_frags) { - NL_SET_ERR_MSG(bpf->extack, - "unable to propagate XDP to device using tcp-data-split"); - return -EBUSY; - } - - if (dev_get_min_mp_channel_count(dev)) { - NL_SET_ERR_MSG(bpf->extack, "unable to propagate XDP to device using memory provider"); - return -EBUSY; - } - - return dev->netdev_ops->ndo_bpf(dev, bpf); -} -EXPORT_SYMBOL_GPL(netif_xdp_propagate); - -u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode) -{ - struct bpf_prog *prog = dev_xdp_prog(dev, mode); - - return prog ? prog->aux->id : 0; -} - static void dev_xdp_set_link(struct net_device *dev, enum bpf_xdp_mode mode, struct bpf_xdp_link *link) { @@ -10385,6 +10365,63 @@ static void dev_xdp_set_prog(struct net_device *dev, enum bpf_xdp_mode mode, dev->xdp_state[mode].prog = prog; } +int netif_xdp_propagate(struct net_device *dev, struct netdev_bpf *bpf) +{ + struct bpf_prog *old_prog; + int err; + + if (!dev->netdev_ops->ndo_bpf) + return -EOPNOTSUPP; + + /* we have more work to do for setup, bypass for other commands */ + if (bpf->command != XDP_SETUP_PROG) + return dev->netdev_ops->ndo_bpf(dev, bpf); + + if (bpf->prog && dev_xdp_has_own_prog(dev)) { + NL_SET_ERR_MSG(bpf->extack, + "unable to propagate XDP to device with an XDP program of its own"); + return -EBUSY; + } + + if (dev->cfg->hds_config == ETHTOOL_TCP_DATA_SPLIT_ENABLED && + bpf->prog && !bpf->prog->aux->xdp_has_frags) { + NL_SET_ERR_MSG(bpf->extack, + "unable to propagate XDP to device using tcp-data-split"); + return -EBUSY; + } + + if (dev_get_min_mp_channel_count(dev)) { + NL_SET_ERR_MSG(bpf->extack, "unable to propagate XDP to device using memory provider"); + return -EBUSY; + } + + err = dev->netdev_ops->ndo_bpf(dev, bpf); + if (err) + return err; + + /* Record it like a program of our own, so that everything which asks + * whether XDP is running here gets the right answer. @xdp_from_upper + * keeps the two apart where it matters. + */ + old_prog = dev_xdp_prog(dev, XDP_MODE_DRV); + if (bpf->prog) + bpf_prog_inc(bpf->prog); + dev_xdp_set_prog(dev, XDP_MODE_DRV, bpf->prog); + dev->xdp_from_upper = !!bpf->prog; + if (old_prog) + bpf_prog_put(old_prog); + + return 0; +} +EXPORT_SYMBOL_GPL(netif_xdp_propagate); + +u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode) +{ + struct bpf_prog *prog = dev_xdp_prog(dev, mode); + + return prog ? prog->aux->id : 0; +} + static int dev_xdp_install(struct net_device *dev, enum bpf_xdp_mode mode, bpf_op_t bpf_op, struct netlink_ext_ack *extack, u32 flags, struct bpf_prog *prog) @@ -10492,6 +10529,7 @@ static void dev_xdp_uninstall(struct net_device *dev) dev_xdp_set_link(dev, mode, NULL); } + dev->xdp_from_upper = 0; } static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack, @@ -10532,6 +10570,11 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack NL_SET_ERR_MSG(extack, "XDP_FLAGS_REPLACE is not specified"); return -EINVAL; } + /* the program belongs to an upper device */ + if (dev->xdp_from_upper) { + NL_SET_ERR_MSG(extack, "Can't replace an XDP program installed by an upper device"); + return -EBUSY; + } mode = dev_xdp_mode(dev, flags); /* can't replace attached link */ -- 2.55.0
