A high level API is provided using the aforementioned routines internally,
and these return a bpf_link object to the user. These are limited to just
attach for now, and can be extended to change/replace if the use case
arises in the future. It is also possible to call bpf_link__disconnect
on the link and switch to managing the filter/action manually if the
need arises. In most cases, the higher level API should suffice.
Example:
struct bpf_tc_cls_info info = {};
struct bpf_object *obj;
struct bpf_program *p;
struct bpf_link *link;
__u32 index;
int fd, r;
obj = bpf_object_open("foo.o");
if (IS_ERR_OR_NULL(obj))
return PTR_ERR(obj);
p = bpf_object__find_program_by_title(obj, "classifier");
if (IS_ERR_OR_NULL(p))
return PTR_ERR(p);
DECLARE_LIBBPF_OPTS(bpf_tc_cls_opts, opts, .handle = 1);
link = bpf_program__attach_tc_cls_dev(p, if_nametoindex("lo"),
BPF_TC_CLSACT_INGRESS,
ETH_P_IP, &opts);
if (IS_ERR_OR_NULL(link))
return PTR_ERR(link);
/* We want to take ownership of the filter, so we disconnect the
* link and detach it on our own
*/
bpf_link__disconnect(link);
r = bpf_tc_cls_get_info_dev(bpf_program__fd(fd),
if_nametoindex("lo"),
BPF_TC_CLSACT_INGRESS,
ETH_P_IP, &opts, &info);
if (r < 0)
return r;
/* We get the attach_id in the info struct, pass it to detach */
bpf_tc_cls_detach_dev(&info.id);
bpf_link__destroy(link);
Example:
struct bpf_object *obj;
struct bpf_program *p;
struct bpf_link *link;
__u32 index;
int fd, r;
obj = bpf_object_open("foo.o");
if (IS_ERR_OR_NULL(obj))
return PTR_ERR(obj);
p = bpf_object__find_program_by_title(obj, "action");
if (IS_ERR_OR_NULL(p))
return PTR_ERR(p);
/* A simple example that attaches a SCHED_ACT prog */
link = bpf_program__attach_tc_act(p, NULL);
if (IS_ERR_OR_NULL(link))
return PTR_ERR(link);
bpf_link__destroy(link);
Reviewed-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 110 ++++++++++++++++++++++++++++++++++++++-
tools/lib/bpf/libbpf.h | 15 ++++++
tools/lib/bpf/libbpf.map | 3 ++
3 files changed, 127 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 058b643cbcb1..cc5c200a661d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -33,6 +33,7 @@
#include <linux/filter.h>
#include <linux/list.h>
#include <linux/limits.h>
+#include <linux/rtnetlink.h>
#include <linux/perf_event.h>
#include <linux/ring_buffer.h>
#include <linux/version.h>
@@ -6847,7 +6848,7 @@ static int bpf_object__collect_relos(struct bpf_object *obj)
for (i = 0; i < obj->nr_programs; i++) {
struct bpf_program *p = &obj->programs[i];
-
+
if (!p->nr_reloc)
continue;
@@ -9443,6 +9444,10 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
struct bpf_link {
int (*detach)(struct bpf_link *link);
int (*destroy)(struct bpf_link *link);
+ union {
+ struct bpf_tc_cls_attach_id *tc_cls_id;
+ __u32 tc_act_index;
+ };
char *pin_path; /* NULL, if not pinned */
int fd; /* hook FD, -1 if not applicable */
bool disconnected;
@@ -10199,6 +10204,109 @@ struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map)
return link;
}
+static int bpf_link__detach_tc_cls(struct bpf_link *link)
+{
+ return bpf_tc_cls_detach_dev(link->tc_cls_id);
+}
+
+static int bpf_link__destroy_tc_cls(struct bpf_link *link)
+{
+ zfree(&link->tc_cls_id);
+ return 0;
+}
+
+struct bpf_link *bpf_program__attach_tc_cls_dev(struct bpf_program *prog,
+ __u32 ifindex, __u32 parent_id,
+ __u32 protocol,
+ const struct bpf_tc_cls_opts *opts)
+{
+ struct bpf_tc_cls_attach_id *id = NULL;
+ struct bpf_link *link = NULL;
+ char errmsg[STRERR_BUFSIZE];
+ int prog_fd, err;
+
+ prog_fd = bpf_program__fd(prog);
+ if (prog_fd < 0) {
+ pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+ return ERR_PTR(-EINVAL);
+ }
+
+ link = calloc(1, sizeof(*link));
+ if (!link)
+ return ERR_PTR(-ENOMEM);
+ link->detach = &bpf_link__detach_tc_cls;
+ link->destroy = &bpf_link__destroy_tc_cls;
+ link->fd = -1;
+
+ id = calloc(1, sizeof(*id));
+ if (!id) {
+ err = -ENOMEM;
+ goto end;
+ }
+
+ err = bpf_tc_cls_attach_dev(prog_fd, ifindex, parent_id, protocol, opts, id);
+ if (err < 0) {
+ pr_warn("prog '%s': failed to attach classifier: %s\n",
+ prog->name,
+ libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+ goto end;
+ }
+
+ link->tc_cls_id = id;
+ return link;
+
+end:
+ free(id);
+ free(link);
+ return ERR_PTR(err);
+}
+
+struct bpf_link *bpf_program__attach_tc_cls_block(struct bpf_program *prog,
+ __u32 block_index, __u32 protocol,
+ const struct bpf_tc_cls_opts *opts)
+{
+ return bpf_program__attach_tc_cls_dev(prog, TCM_IFINDEX_MAGIC_BLOCK, block_index,
+ protocol, opts);
+}
+
+static int bpf_link__detach_tc_act(struct bpf_link *link)
+{
+ return bpf_tc_act_detach(link->tc_act_index);
+}
+
+struct bpf_link *bpf_program__attach_tc_act(struct bpf_program *prog,
+ const struct bpf_tc_act_opts *opts)
+{
+ struct bpf_link *link = NULL;
+ char errmsg[STRERR_BUFSIZE];
+ int prog_fd, err;
+
+ prog_fd = bpf_program__fd(prog);
+ if (prog_fd < 0) {
+ pr_warn("prog '%s': can't attach before loading\n", prog->name);
+ return ERR_PTR(-EINVAL);
+ }
+
+ link = calloc(1, sizeof(*link));
+ if (!link)
+ return ERR_PTR(-ENOMEM);
+ link->detach = &bpf_link__detach_tc_act;
+ link->fd = -1;
+
+ err = bpf_tc_act_attach(prog_fd, opts, &link->tc_act_index);
+ if (err < 0) {
+ pr_warn("prog '%s': failed to attach action: %s\n", prog->name,
+ libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+ goto end;
+ }
+
+ return link;
+
+end:
+ free(link);
+ return ERR_PTR(err);
+}
+
enum bpf_perf_event_ret
bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
void **copy_mem, size_t *copy_size,
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 63baef6045b1..e33720d0b672 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -268,6 +268,21 @@ LIBBPF_API struct bpf_link *
bpf_program__attach_freplace(struct bpf_program *prog,
int target_fd, const char *attach_func_name);
+struct bpf_tc_cls_opts;
+struct bpf_tc_act_opts;
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tc_cls_dev(struct bpf_program *prog, __u32 ifindex,
+ __u32 parent_id, __u32 protocol,
+ const struct bpf_tc_cls_opts *opts);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tc_cls_block(struct bpf_program *prog, __u32 block_index,
+ __u32 protocol,
+ const struct bpf_tc_cls_opts *opts);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tc_act(struct bpf_program *prog,
+ const struct bpf_tc_act_opts *opts);
+
struct bpf_map;
LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 72022b45a8b9..2e1390e4ebf0 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -373,4 +373,7 @@ LIBBPF_0.4.0 {
bpf_tc_cls_replace_dev;
bpf_tc_cls_get_info_dev;
bpf_tc_cls_get_info_block;
+ bpf_program__attach_tc_cls_dev;
+ bpf_program__attach_tc_cls_block;
+ bpf_program__attach_tc_act;
} LIBBPF_0.3.0;
--
2.30.2
