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authorAndrii Nakryiko <andriin@fb.com>2020-07-31 11:28:26 -0700
committerAlexei Starovoitov <ast@kernel.org>2020-08-01 20:38:28 -0700
commit73b11c2ab072d5b0599d1e12cc126f55ee306daf (patch)
tree0b005d7d70f073d7d908e0d2a1fb263405f3971b /net
parent4939b2847d26c025e2e2118744226967f239a1ac (diff)
downloadlinux-73b11c2ab072d5b0599d1e12cc126f55ee306daf.tar.bz2
bpf: Add support for forced LINK_DETACH command
Add LINK_DETACH command to force-detach bpf_link without destroying it. It has the same behavior as auto-detaching of bpf_link due to cgroup dying for bpf_cgroup_link or net_device being destroyed for bpf_xdp_link. In such case, bpf_link is still a valid kernel object, but is defuncts and doesn't hold BPF program attached to corresponding BPF hook. This functionality allows users with enough access rights to manually force-detach attached bpf_link without killing respective owner process. This patch implements LINK_DETACH for cgroup, xdp, and netns links, mostly re-using existing link release handling code. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20200731182830.286260-2-andriin@fb.com
Diffstat (limited to 'net')
-rw-r--r--net/core/dev.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index a2a57988880a..c8b911b10187 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8979,12 +8979,20 @@ static void bpf_xdp_link_release(struct bpf_link *link)
/* if racing with net_device's tear down, xdp_link->dev might be
* already NULL, in which case link was already auto-detached
*/
- if (xdp_link->dev)
+ if (xdp_link->dev) {
WARN_ON(dev_xdp_detach_link(xdp_link->dev, NULL, xdp_link));
+ xdp_link->dev = NULL;
+ }
rtnl_unlock();
}
+static int bpf_xdp_link_detach(struct bpf_link *link)
+{
+ bpf_xdp_link_release(link);
+ return 0;
+}
+
static void bpf_xdp_link_dealloc(struct bpf_link *link)
{
struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
@@ -9066,6 +9074,7 @@ out_unlock:
static const struct bpf_link_ops bpf_xdp_link_lops = {
.release = bpf_xdp_link_release,
.dealloc = bpf_xdp_link_dealloc,
+ .detach = bpf_xdp_link_detach,
.show_fdinfo = bpf_xdp_link_show_fdinfo,
.fill_link_info = bpf_xdp_link_fill_link_info,
.update_prog = bpf_xdp_link_update,