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@redhat.com Signed-off-by: Kumar Kartikeya Dwivedi memxor@gmail.com --- 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;