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authorMaxim Mikityanskiy <maximmi@mellanox.com>2019-08-14 14:34:06 +0000
committerDaniel Borkmann <daniel@iogearbox.net>2019-08-17 23:11:54 +0200
commitc14a9f633d9eb5c0fdd0cb4135b6be978fd538f3 (patch)
tree8d73f79c672dad6f43baa35a818756160f84a850 /net/core
parentc8186c8064c4c234a3d2e3d60e25c1f55ec4f8b3 (diff)
downloadlinux-c14a9f633d9eb5c0fdd0cb4135b6be978fd538f3.tar.bz2
net: Don't call XDP_SETUP_PROG when nothing is changed
Don't uninstall an XDP program when none is installed, and don't install an XDP program that has the same ID as the one already installed. dev_change_xdp_fd doesn't perform any checks in case it uninstalls an XDP program. It means that the driver's ndo_bpf can be called with XDP_SETUP_PROG asking to set it to NULL even if it's already NULL. This case happens if the user runs `ip link set eth0 xdp off` when there is no XDP program attached. The symmetrical case is possible when the user tries to set the program that is already set. The drivers typically perform some heavy operations on XDP_SETUP_PROG, so they all have to handle these cases internally to return early if they happen. This patch puts this check into the kernel code, so that all drivers will benefit from it. Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com> Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com> Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/dev.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 49589ed2018d..b1afafee3e2a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8126,12 +8126,15 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
bpf_chk = generic_xdp_install;
if (fd >= 0) {
+ u32 prog_id;
+
if (!offload && __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG)) {
NL_SET_ERR_MSG(extack, "native and generic XDP can't be active at the same time");
return -EEXIST;
}
- if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) &&
- __dev_xdp_query(dev, bpf_op, query)) {
+
+ prog_id = __dev_xdp_query(dev, bpf_op, query);
+ if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && prog_id) {
NL_SET_ERR_MSG(extack, "XDP program already attached");
return -EBUSY;
}
@@ -8146,6 +8149,14 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
bpf_prog_put(prog);
return -EINVAL;
}
+
+ if (prog->aux->id == prog_id) {
+ bpf_prog_put(prog);
+ return 0;
+ }
+ } else {
+ if (!__dev_xdp_query(dev, bpf_op, query))
+ return 0;
}
err = dev_xdp_install(dev, bpf_op, extack, flags, prog);