* [PATCH v2 bpf-next 1/5] bpf: add support for forced LINK_DETACH command
2020-07-31 18:28 [PATCH v2 bpf-next 0/5] BPF link force-detach support Andrii Nakryiko
@ 2020-07-31 18:28 ` Andrii Nakryiko
2020-07-31 23:19 ` John Fastabend
2020-07-31 18:28 ` [PATCH v2 bpf-next 2/5] libbpf: add bpf_link detach APIs Andrii Nakryiko
` (4 subsequent siblings)
5 siblings, 1 reply; 12+ messages in thread
From: Andrii Nakryiko @ 2020-07-31 18:28 UTC (permalink / raw)
To: bpf, netdev, ast, daniel
Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko, Song Liu
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.
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 5 +++++
kernel/bpf/cgroup.c | 15 ++++++++++++++-
kernel/bpf/net_namespace.c | 8 ++++++++
kernel/bpf/syscall.c | 26 ++++++++++++++++++++++++++
net/core/dev.c | 11 ++++++++++-
6 files changed, 64 insertions(+), 2 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 40c5e206ecf2..cef4ef0d2b4e 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -793,6 +793,7 @@ struct bpf_link {
struct bpf_link_ops {
void (*release)(struct bpf_link *link);
void (*dealloc)(struct bpf_link *link);
+ int (*detach)(struct bpf_link *link);
int (*update_prog)(struct bpf_link *link, struct bpf_prog *new_prog,
struct bpf_prog *old_prog);
void (*show_fdinfo)(const struct bpf_link *link, struct seq_file *seq);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index eb5e0c38eb2c..b134e679e9db 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -117,6 +117,7 @@ enum bpf_cmd {
BPF_LINK_GET_NEXT_ID,
BPF_ENABLE_STATS,
BPF_ITER_CREATE,
+ BPF_LINK_DETACH,
};
enum bpf_map_type {
@@ -634,6 +635,10 @@ union bpf_attr {
__u32 old_prog_fd;
} link_update;
+ struct {
+ __u32 link_fd;
+ } link_detach;
+
struct { /* struct used by BPF_ENABLE_STATS command */
__u32 type;
} enable_stats;
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 957cce1d5168..83ff127ef7ae 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -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,
diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c
index 71405edd667c..542f275bf252 100644
--- a/kernel/bpf/net_namespace.c
+++ b/kernel/bpf/net_namespace.c
@@ -142,9 +142,16 @@ static void bpf_netns_link_release(struct bpf_link *link)
bpf_prog_array_free(old_array);
out_unlock:
+ net_link->net = NULL;
mutex_unlock(&netns_bpf_mutex);
}
+static int bpf_netns_link_detach(struct bpf_link *link)
+{
+ bpf_netns_link_release(link);
+ return 0;
+}
+
static void bpf_netns_link_dealloc(struct bpf_link *link)
{
struct bpf_netns_link *net_link =
@@ -228,6 +235,7 @@ static void bpf_netns_link_show_fdinfo(const struct bpf_link *link,
static const struct bpf_link_ops bpf_netns_link_ops = {
.release = bpf_netns_link_release,
.dealloc = bpf_netns_link_dealloc,
+ .detach = bpf_netns_link_detach,
.update_prog = bpf_netns_link_update_prog,
.fill_link_info = bpf_netns_link_fill_info,
.show_fdinfo = bpf_netns_link_show_fdinfo,
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index cd3d599e9e90..2f343ce15747 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3991,6 +3991,29 @@ static int link_update(union bpf_attr *attr)
return ret;
}
+#define BPF_LINK_DETACH_LAST_FIELD link_detach.link_fd
+
+static int link_detach(union bpf_attr *attr)
+{
+ struct bpf_link *link;
+ int ret;
+
+ if (CHECK_ATTR(BPF_LINK_DETACH))
+ return -EINVAL;
+
+ link = bpf_link_get_from_fd(attr->link_detach.link_fd);
+ if (IS_ERR(link))
+ return PTR_ERR(link);
+
+ if (link->ops->detach)
+ ret = link->ops->detach(link);
+ else
+ ret = -EOPNOTSUPP;
+
+ bpf_link_put(link);
+ return ret;
+}
+
static int bpf_link_inc_not_zero(struct bpf_link *link)
{
return atomic64_fetch_add_unless(&link->refcnt, 1, 0) ? 0 : -ENOENT;
@@ -4240,6 +4263,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
case BPF_ITER_CREATE:
err = bpf_iter_create(&attr);
break;
+ case BPF_LINK_DETACH:
+ err = link_detach(&attr);
+ break;
default:
err = -EINVAL;
break;
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 @@ static int bpf_xdp_link_update(struct bpf_link *link, struct bpf_prog *new_prog,
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,
--
2.24.1
^ permalink raw reply related [flat|nested] 12+ messages in thread* RE: [PATCH v2 bpf-next 1/5] bpf: add support for forced LINK_DETACH command
2020-07-31 18:28 ` [PATCH v2 bpf-next 1/5] bpf: add support for forced LINK_DETACH command Andrii Nakryiko
@ 2020-07-31 23:19 ` John Fastabend
0 siblings, 0 replies; 12+ messages in thread
From: John Fastabend @ 2020-07-31 23:19 UTC (permalink / raw)
To: Andrii Nakryiko, bpf, netdev, ast, daniel
Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko, Song Liu
Andrii Nakryiko wrote:
> 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.
>
> Acked-by: Song Liu <songliubraving@fb.com>
> Signed-off-by: Andrii Nakryiko <andriin@fb.com>
> ---
Looks necessary otherwise we have no way, as far as I read it, to delete
an XDP program and go back the no prog state after link_{create|update}.
Acked-by: John Fastabend <john.fastabend@gmail.com>
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH v2 bpf-next 2/5] libbpf: add bpf_link detach APIs
2020-07-31 18:28 [PATCH v2 bpf-next 0/5] BPF link force-detach support Andrii Nakryiko
2020-07-31 18:28 ` [PATCH v2 bpf-next 1/5] bpf: add support for forced LINK_DETACH command Andrii Nakryiko
@ 2020-07-31 18:28 ` Andrii Nakryiko
2020-07-31 23:22 ` John Fastabend
2020-07-31 18:28 ` [PATCH v2 bpf-next 3/5] selftests/bpf: add link detach tests for cgroup, netns, and xdp bpf_links Andrii Nakryiko
` (3 subsequent siblings)
5 siblings, 1 reply; 12+ messages in thread
From: Andrii Nakryiko @ 2020-07-31 18:28 UTC (permalink / raw)
To: bpf, netdev, ast, daniel
Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko, Song Liu
Add low-level bpf_link_detach() API. Also add higher-level bpf_link__detach()
one.
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
tools/include/uapi/linux/bpf.h | 5 +++++
tools/lib/bpf/bpf.c | 10 ++++++++++
tools/lib/bpf/bpf.h | 2 ++
tools/lib/bpf/libbpf.c | 5 +++++
tools/lib/bpf/libbpf.h | 1 +
tools/lib/bpf/libbpf.map | 2 ++
6 files changed, 25 insertions(+)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index eb5e0c38eb2c..b134e679e9db 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -117,6 +117,7 @@ enum bpf_cmd {
BPF_LINK_GET_NEXT_ID,
BPF_ENABLE_STATS,
BPF_ITER_CREATE,
+ BPF_LINK_DETACH,
};
enum bpf_map_type {
@@ -634,6 +635,10 @@ union bpf_attr {
__u32 old_prog_fd;
} link_update;
+ struct {
+ __u32 link_fd;
+ } link_detach;
+
struct { /* struct used by BPF_ENABLE_STATS command */
__u32 type;
} enable_stats;
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index e1bdf214f75f..eab14c97c15d 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -603,6 +603,16 @@ int bpf_link_create(int prog_fd, int target_fd,
return sys_bpf(BPF_LINK_CREATE, &attr, sizeof(attr));
}
+int bpf_link_detach(int link_fd)
+{
+ union bpf_attr attr;
+
+ memset(&attr, 0, sizeof(attr));
+ attr.link_detach.link_fd = link_fd;
+
+ return sys_bpf(BPF_LINK_DETACH, &attr, sizeof(attr));
+}
+
int bpf_link_update(int link_fd, int new_prog_fd,
const struct bpf_link_update_opts *opts)
{
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 6d367e01d05e..28855fd5b5f4 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -178,6 +178,8 @@ LIBBPF_API int bpf_link_create(int prog_fd, int target_fd,
enum bpf_attach_type attach_type,
const struct bpf_link_create_opts *opts);
+LIBBPF_API int bpf_link_detach(int link_fd);
+
struct bpf_link_update_opts {
size_t sz; /* size of this struct for forward/backward compatibility */
__u32 flags; /* extra flags */
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b9f11f854985..7be04e45d29c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -7748,6 +7748,11 @@ struct bpf_link *bpf_link__open(const char *path)
return link;
}
+int bpf_link__detach(struct bpf_link *link)
+{
+ return bpf_link_detach(link->fd) ? -errno : 0;
+}
+
int bpf_link__pin(struct bpf_link *link, const char *path)
{
int err;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 9924385462ab..3ed1399bfbbc 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -229,6 +229,7 @@ LIBBPF_API int bpf_link__unpin(struct bpf_link *link);
LIBBPF_API int bpf_link__update_program(struct bpf_link *link,
struct bpf_program *prog);
LIBBPF_API void bpf_link__disconnect(struct bpf_link *link);
+LIBBPF_API int bpf_link__detach(struct bpf_link *link);
LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
LIBBPF_API struct bpf_link *
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index ca49a6a7e5b2..099863411f7d 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -273,6 +273,8 @@ LIBBPF_0.0.9 {
LIBBPF_0.1.0 {
global:
+ bpf_link__detach;
+ bpf_link_detach;
bpf_map__ifindex;
bpf_map__key_size;
bpf_map__map_flags;
--
2.24.1
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v2 bpf-next 3/5] selftests/bpf: add link detach tests for cgroup, netns, and xdp bpf_links
2020-07-31 18:28 [PATCH v2 bpf-next 0/5] BPF link force-detach support Andrii Nakryiko
2020-07-31 18:28 ` [PATCH v2 bpf-next 1/5] bpf: add support for forced LINK_DETACH command Andrii Nakryiko
2020-07-31 18:28 ` [PATCH v2 bpf-next 2/5] libbpf: add bpf_link detach APIs Andrii Nakryiko
@ 2020-07-31 18:28 ` Andrii Nakryiko
2020-07-31 23:29 ` John Fastabend
2020-07-31 18:28 ` [PATCH v2 bpf-next 4/5] tools/bpftool: add `link detach` subcommand Andrii Nakryiko
` (2 subsequent siblings)
5 siblings, 1 reply; 12+ messages in thread
From: Andrii Nakryiko @ 2020-07-31 18:28 UTC (permalink / raw)
To: bpf, netdev, ast, daniel
Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko, Song Liu
Add bpf_link__detach() testing to selftests for cgroup, netns, and xdp
bpf_links.
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
.../selftests/bpf/prog_tests/cgroup_link.c | 20 +++++++-
.../selftests/bpf/prog_tests/sk_lookup.c | 51 +++++++++----------
.../selftests/bpf/prog_tests/xdp_link.c | 14 +++++
tools/testing/selftests/bpf/testing_helpers.c | 14 +++++
tools/testing/selftests/bpf/testing_helpers.h | 3 ++
5 files changed, 73 insertions(+), 29 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_link.c b/tools/testing/selftests/bpf/prog_tests/cgroup_link.c
index 6e04f8d1d15b..4d9b514b3fd9 100644
--- a/tools/testing/selftests/bpf/prog_tests/cgroup_link.c
+++ b/tools/testing/selftests/bpf/prog_tests/cgroup_link.c
@@ -2,6 +2,7 @@
#include <test_progs.h>
#include "cgroup_helpers.h"
+#include "testing_helpers.h"
#include "test_cgroup_link.skel.h"
static __u32 duration = 0;
@@ -37,7 +38,8 @@ void test_cgroup_link(void)
int last_cg = ARRAY_SIZE(cgs) - 1, cg_nr = ARRAY_SIZE(cgs);
DECLARE_LIBBPF_OPTS(bpf_link_update_opts, link_upd_opts);
struct bpf_link *links[ARRAY_SIZE(cgs)] = {}, *tmp_link;
- __u32 prog_ids[ARRAY_SIZE(cgs)], prog_cnt = 0, attach_flags;
+ __u32 prog_ids[ARRAY_SIZE(cgs)], prog_cnt = 0, attach_flags, prog_id;
+ struct bpf_link_info info;
int i = 0, err, prog_fd;
bool detach_legacy = false;
@@ -219,6 +221,22 @@ void test_cgroup_link(void)
/* BPF programs should still get called */
ping_and_check(0, cg_nr);
+ prog_id = link_info_prog_id(links[0], &info);
+ CHECK(prog_id == 0, "link_info", "failed\n");
+ CHECK(info.cgroup.cgroup_id == 0, "cgroup_id", "unexpected %llu\n", info.cgroup.cgroup_id);
+
+ err = bpf_link__detach(links[0]);
+ if (CHECK(err, "link_detach", "failed %d\n", err))
+ goto cleanup;
+
+ /* cgroup_id should be zero in link_info */
+ prog_id = link_info_prog_id(links[0], &info);
+ CHECK(prog_id == 0, "link_info", "failed\n");
+ CHECK(info.cgroup.cgroup_id != 0, "cgroup_id", "unexpected %llu\n", info.cgroup.cgroup_id);
+
+ /* First BPF program shouldn't be called anymore */
+ ping_and_check(0, cg_nr - 1);
+
/* leave cgroup and remove them, don't detach programs */
cleanup_cgroup_environment();
diff --git a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
index 379da6f10ee9..c571584c00f5 100644
--- a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
+++ b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c
@@ -34,6 +34,7 @@
#include "bpf_util.h"
#include "cgroup_helpers.h"
#include "network_helpers.h"
+#include "testing_helpers.h"
#include "test_sk_lookup.skel.h"
/* External (address, port) pairs the client sends packets to. */
@@ -469,34 +470,10 @@ static int update_lookup_map(struct bpf_map *map, int index, int sock_fd)
return 0;
}
-static __u32 link_info_prog_id(struct bpf_link *link)
-{
- struct bpf_link_info info = {};
- __u32 info_len = sizeof(info);
- int link_fd, err;
-
- link_fd = bpf_link__fd(link);
- if (CHECK(link_fd < 0, "bpf_link__fd", "failed\n")) {
- errno = -link_fd;
- log_err("bpf_link__fd failed");
- return 0;
- }
-
- err = bpf_obj_get_info_by_fd(link_fd, &info, &info_len);
- if (CHECK(err, "bpf_obj_get_info_by_fd", "failed\n")) {
- log_err("bpf_obj_get_info_by_fd");
- return 0;
- }
- if (CHECK(info_len != sizeof(info), "bpf_obj_get_info_by_fd",
- "unexpected info len %u\n", info_len))
- return 0;
-
- return info.prog_id;
-}
-
static void query_lookup_prog(struct test_sk_lookup *skel)
{
struct bpf_link *link[3] = {};
+ struct bpf_link_info info;
__u32 attach_flags = 0;
__u32 prog_ids[3] = {};
__u32 prog_cnt = 3;
@@ -534,18 +511,36 @@ static void query_lookup_prog(struct test_sk_lookup *skel)
if (CHECK(prog_cnt != 3, "bpf_prog_query",
"wrong program count on query: %u", prog_cnt))
goto detach;
- prog_id = link_info_prog_id(link[0]);
+ prog_id = link_info_prog_id(link[0], &info);
CHECK(prog_ids[0] != prog_id, "bpf_prog_query",
"invalid program #0 id on query: %u != %u\n",
prog_ids[0], prog_id);
- prog_id = link_info_prog_id(link[1]);
+ CHECK(info.netns.netns_ino == 0, "netns_ino",
+ "unexpected netns_ino: %u\n", info.netns.netns_ino);
+ prog_id = link_info_prog_id(link[1], &info);
CHECK(prog_ids[1] != prog_id, "bpf_prog_query",
"invalid program #1 id on query: %u != %u\n",
prog_ids[1], prog_id);
- prog_id = link_info_prog_id(link[2]);
+ CHECK(info.netns.netns_ino == 0, "netns_ino",
+ "unexpected netns_ino: %u\n", info.netns.netns_ino);
+ prog_id = link_info_prog_id(link[2], &info);
CHECK(prog_ids[2] != prog_id, "bpf_prog_query",
"invalid program #2 id on query: %u != %u\n",
prog_ids[2], prog_id);
+ CHECK(info.netns.netns_ino == 0, "netns_ino",
+ "unexpected netns_ino: %u\n", info.netns.netns_ino);
+
+ err = bpf_link__detach(link[0]);
+ if (CHECK(err, "link_detach", "failed %d\n", err))
+ goto detach;
+
+ /* prog id is still there, but netns_ino is zeroed out */
+ prog_id = link_info_prog_id(link[0], &info);
+ CHECK(prog_ids[0] != prog_id, "bpf_prog_query",
+ "invalid program #0 id on query: %u != %u\n",
+ prog_ids[0], prog_id);
+ CHECK(info.netns.netns_ino != 0, "netns_ino",
+ "unexpected netns_ino: %u\n", info.netns.netns_ino);
detach:
if (link[2])
diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_link.c b/tools/testing/selftests/bpf/prog_tests/xdp_link.c
index 52cba6795d40..6f814999b395 100644
--- a/tools/testing/selftests/bpf/prog_tests/xdp_link.c
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_link.c
@@ -131,6 +131,20 @@ void test_xdp_link(void)
CHECK(link_info.xdp.ifindex != IFINDEX_LO, "link_ifindex",
"got %u != exp %u\n", link_info.xdp.ifindex, IFINDEX_LO);
+ err = bpf_link__detach(link);
+ if (CHECK(err, "link_detach", "failed %d\n", err))
+ goto cleanup;
+
+ memset(&link_info, 0, sizeof(link_info));
+ err = bpf_obj_get_info_by_fd(bpf_link__fd(link), &link_info, &link_info_len);
+ if (CHECK(err, "link_info", "failed: %d\n", err))
+ goto cleanup;
+ CHECK(link_info.prog_id != id1, "link_prog_id",
+ "got %u != exp %u\n", link_info.prog_id, id1);
+ /* ifindex should be zeroed out */
+ CHECK(link_info.xdp.ifindex != 0, "link_ifindex",
+ "got %u != exp %u\n", link_info.xdp.ifindex, 0);
+
cleanup:
test_xdp_link__destroy(skel1);
test_xdp_link__destroy(skel2);
diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c
index 0af6337a8962..800d503e5cb4 100644
--- a/tools/testing/selftests/bpf/testing_helpers.c
+++ b/tools/testing/selftests/bpf/testing_helpers.c
@@ -64,3 +64,17 @@ int parse_num_list(const char *s, bool **num_set, int *num_set_len)
return 0;
}
+
+__u32 link_info_prog_id(const struct bpf_link *link, struct bpf_link_info *info)
+{
+ __u32 info_len = sizeof(*info);
+ int err;
+
+ memset(info, 0, sizeof(*info));
+ err = bpf_obj_get_info_by_fd(bpf_link__fd(link), info, &info_len);
+ if (err) {
+ printf("failed to get link info: %d\n", -errno);
+ return 0;
+ }
+ return info->prog_id;
+}
diff --git a/tools/testing/selftests/bpf/testing_helpers.h b/tools/testing/selftests/bpf/testing_helpers.h
index 923b51762759..d4f8e749611b 100644
--- a/tools/testing/selftests/bpf/testing_helpers.h
+++ b/tools/testing/selftests/bpf/testing_helpers.h
@@ -1,5 +1,8 @@
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
/* Copyright (C) 2020 Facebook, Inc. */
#include <stdbool.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
int parse_num_list(const char *s, bool **set, int *set_len);
+__u32 link_info_prog_id(const struct bpf_link *link, struct bpf_link_info *info);
--
2.24.1
^ permalink raw reply related [flat|nested] 12+ messages in thread* RE: [PATCH v2 bpf-next 3/5] selftests/bpf: add link detach tests for cgroup, netns, and xdp bpf_links
2020-07-31 18:28 ` [PATCH v2 bpf-next 3/5] selftests/bpf: add link detach tests for cgroup, netns, and xdp bpf_links Andrii Nakryiko
@ 2020-07-31 23:29 ` John Fastabend
0 siblings, 0 replies; 12+ messages in thread
From: John Fastabend @ 2020-07-31 23:29 UTC (permalink / raw)
To: Andrii Nakryiko, bpf, netdev, ast, daniel
Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko, Song Liu
Andrii Nakryiko wrote:
> Add bpf_link__detach() testing to selftests for cgroup, netns, and xdp
> bpf_links.
>
> Acked-by: Song Liu <songliubraving@fb.com>
> Signed-off-by: Andrii Nakryiko <andriin@fb.com>
> ---
Acked-by: John Fastabend <john.fastabend@gmail.com>
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH v2 bpf-next 4/5] tools/bpftool: add `link detach` subcommand
2020-07-31 18:28 [PATCH v2 bpf-next 0/5] BPF link force-detach support Andrii Nakryiko
` (2 preceding siblings ...)
2020-07-31 18:28 ` [PATCH v2 bpf-next 3/5] selftests/bpf: add link detach tests for cgroup, netns, and xdp bpf_links Andrii Nakryiko
@ 2020-07-31 18:28 ` Andrii Nakryiko
2020-07-31 23:32 ` John Fastabend
2020-07-31 18:28 ` [PATCH v2 bpf-next 5/5] tools/bpftool: add documentation and bash-completion for `link detach` Andrii Nakryiko
2020-08-02 3:48 ` [PATCH v2 bpf-next 0/5] BPF link force-detach support Alexei Starovoitov
5 siblings, 1 reply; 12+ messages in thread
From: Andrii Nakryiko @ 2020-07-31 18:28 UTC (permalink / raw)
To: bpf, netdev, ast, daniel
Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko, Song Liu
Add ability to force-detach BPF link. Also add missing error message, if
specified link ID is wrong.
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
tools/bpf/bpftool/link.c | 37 ++++++++++++++++++++++++++++++++++++-
1 file changed, 36 insertions(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
index 326b8fdf0243..1b793759170e 100644
--- a/tools/bpf/bpftool/link.c
+++ b/tools/bpf/bpftool/link.c
@@ -22,6 +22,8 @@ static const char * const link_type_name[] = {
static int link_parse_fd(int *argc, char ***argv)
{
+ int fd;
+
if (is_prefix(**argv, "id")) {
unsigned int id;
char *endptr;
@@ -35,7 +37,10 @@ static int link_parse_fd(int *argc, char ***argv)
}
NEXT_ARGP();
- return bpf_link_get_fd_by_id(id);
+ fd = bpf_link_get_fd_by_id(id);
+ if (fd < 0)
+ p_err("failed to get link with ID %d: %s", id, strerror(errno));
+ return fd;
} else if (is_prefix(**argv, "pinned")) {
char *path;
@@ -316,6 +321,34 @@ static int do_pin(int argc, char **argv)
return err;
}
+static int do_detach(int argc, char **argv)
+{
+ int err, fd;
+
+ if (argc != 2) {
+ p_err("link specifier is invalid or missing\n");
+ return 1;
+ }
+
+ fd = link_parse_fd(&argc, &argv);
+ if (fd < 0)
+ return 1;
+
+ err = bpf_link_detach(fd);
+ if (err)
+ err = -errno;
+ close(fd);
+ if (err) {
+ p_err("failed link detach: %s", strerror(-err));
+ return 1;
+ }
+
+ if (json_output)
+ jsonw_null(json_wtr);
+
+ return 0;
+}
+
static int do_help(int argc, char **argv)
{
if (json_output) {
@@ -326,6 +359,7 @@ static int do_help(int argc, char **argv)
fprintf(stderr,
"Usage: %1$s %2$s { show | list } [LINK]\n"
" %1$s %2$s pin LINK FILE\n"
+ " %1$s %2$s detach LINK\n"
" %1$s %2$s help\n"
"\n"
" " HELP_SPEC_LINK "\n"
@@ -341,6 +375,7 @@ static const struct cmd cmds[] = {
{ "list", do_show },
{ "help", do_help },
{ "pin", do_pin },
+ { "detach", do_detach },
{ 0 }
};
--
2.24.1
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v2 bpf-next 5/5] tools/bpftool: add documentation and bash-completion for `link detach`
2020-07-31 18:28 [PATCH v2 bpf-next 0/5] BPF link force-detach support Andrii Nakryiko
` (3 preceding siblings ...)
2020-07-31 18:28 ` [PATCH v2 bpf-next 4/5] tools/bpftool: add `link detach` subcommand Andrii Nakryiko
@ 2020-07-31 18:28 ` Andrii Nakryiko
2020-07-31 23:35 ` John Fastabend
2020-08-02 3:48 ` [PATCH v2 bpf-next 0/5] BPF link force-detach support Alexei Starovoitov
5 siblings, 1 reply; 12+ messages in thread
From: Andrii Nakryiko @ 2020-07-31 18:28 UTC (permalink / raw)
To: bpf, netdev, ast, daniel
Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko, Song Liu
Add info on link detach sub-command to man page. Add detach to bash-completion
as well.
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
tools/bpf/bpftool/Documentation/bpftool-link.rst | 8 ++++++++
tools/bpf/bpftool/bash-completion/bpftool | 4 ++--
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/tools/bpf/bpftool/Documentation/bpftool-link.rst b/tools/bpf/bpftool/Documentation/bpftool-link.rst
index 38b0949a185b..4a52e7a93339 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-link.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-link.rst
@@ -21,6 +21,7 @@ LINK COMMANDS
| **bpftool** **link { show | list }** [*LINK*]
| **bpftool** **link pin** *LINK* *FILE*
+| **bpftool** **link detach *LINK*
| **bpftool** **link help**
|
| *LINK* := { **id** *LINK_ID* | **pinned** *FILE* }
@@ -49,6 +50,13 @@ DESCRIPTION
contain a dot character ('.'), which is reserved for future
extensions of *bpffs*.
+ **bpftool link detach** *LINK*
+ Force-detach link *LINK*. BPF link and its underlying BPF
+ program will stay valid, but they will be detached from the
+ respective BPF hook and BPF link will transition into
+ a defunct state until last open file descriptor for that
+ link is closed.
+
**bpftool link help**
Print short help message.
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index 257fa310ea2b..f53ed2f1a4aa 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -1122,7 +1122,7 @@ _bpftool()
;;
link)
case $command in
- show|list|pin)
+ show|list|pin|detach)
case $prev in
id)
_bpftool_get_link_ids
@@ -1139,7 +1139,7 @@ _bpftool()
COMPREPLY=( $( compgen -W "$LINK_TYPE" -- "$cur" ) )
return 0
;;
- pin)
+ pin|detach)
if [[ $prev == "$command" ]]; then
COMPREPLY=( $( compgen -W "$LINK_TYPE" -- "$cur" ) )
else
--
2.24.1
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re: [PATCH v2 bpf-next 0/5] BPF link force-detach support
2020-07-31 18:28 [PATCH v2 bpf-next 0/5] BPF link force-detach support Andrii Nakryiko
` (4 preceding siblings ...)
2020-07-31 18:28 ` [PATCH v2 bpf-next 5/5] tools/bpftool: add documentation and bash-completion for `link detach` Andrii Nakryiko
@ 2020-08-02 3:48 ` Alexei Starovoitov
5 siblings, 0 replies; 12+ messages in thread
From: Alexei Starovoitov @ 2020-08-02 3:48 UTC (permalink / raw)
To: Andrii Nakryiko
Cc: bpf, Network Development, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Kernel Team
On Fri, Jul 31, 2020 at 11:29 AM Andrii Nakryiko <andriin@fb.com> wrote:
>
> This patch set adds new BPF link operation, LINK_DETACH, allowing processes
> with BPF link FD to force-detach it from respective BPF hook, similarly how
> BPF link is auto-detached when such BPF hook (e.g., cgroup, net_device, netns,
> etc) is removed. This facility allows admin to forcefully undo BPF link
> attachment, while process that created BPF link in the first place is left
> intact.
>
> Once force-detached, BPF link stays valid in the kernel as long as there is at
> least one FD open against it. It goes into defunct state, just like
> auto-detached BPF link.
>
> bpftool also got `link detach` command to allow triggering this in
> non-programmatic fashion.
>
> v1->v2:
> - improve error reporting in `bpftool link detach` (Song).
Applied. Thanks
^ permalink raw reply [flat|nested] 12+ messages in thread