xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

bpf: Add support for forced LINK_DETACH command

Browse Source 
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
This commit is contained in:
Andrii Nakryiko
2020-07-31 11:28:26 -07:00
committed by Alexei Starovoitov
parent 4939b2847d
commit 73b11c2ab0
6 changed files with 64 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
kernel/bpf/cgroup.c
View File

@@ -814,6 +814,7 @@ static void bpf_cgroup_link_release(struct bpf_link *link)
{
struct bpf_cgroup_link *cg_link =
container_of(link, struct bpf_cgroup_link, link);
struct cgroup *cg;
/* link might have been auto-detached by dying cgroup already,
* in that case our work is done here
@@ -832,8 +833,12 @@ static void bpf_cgroup_link_release(struct bpf_link *link)
WARN_ON(__cgroup_bpf_detach(cg_link->cgroup, NULL, cg_link,
cg_link->type));
cg = cg_link->cgroup;
cg_link->cgroup = NULL;
mutex_unlock(&cgroup_mutex);
cgroup_put(cg_link->cgroup);
cgroup_put(cg);
}
static void bpf_cgroup_link_dealloc(struct bpf_link *link)
@@ -844,6 +849,13 @@ static void bpf_cgroup_link_dealloc(struct bpf_link *link)
kfree(cg_link);
}
static int bpf_cgroup_link_detach(struct bpf_link *link)
{
bpf_cgroup_link_release(link);
return 0;
}
static void bpf_cgroup_link_show_fdinfo(const struct bpf_link *link,
struct seq_file *seq)
{
@@ -883,6 +895,7 @@ static int bpf_cgroup_link_fill_link_info(const struct bpf_link *link,
static const struct bpf_link_ops bpf_cgroup_link_lops = {
.release = bpf_cgroup_link_release,
.dealloc = bpf_cgroup_link_dealloc,
.detach = bpf_cgroup_link_detach,
.update_prog = cgroup_bpf_replace,
.show_fdinfo = bpf_cgroup_link_show_fdinfo,
.fill_link_info = bpf_cgroup_link_fill_link_info,