On Wed, 7 Nov 2018 11:35:52 -0800, Stanislav Fomichev wrote:
> This commit adds support for loading/attaching/detaching flow
> dissector program. The structure of the flow dissector program is
> assumed to be the same as in the selftests:
>
> * flow_dissector section with the main entry point
> * a bunch of tail call progs
> * a jmp_table map that is populated with the tail call progs
>
> When `bpftool load` is called with a flow_dissector prog (i.e. when the
> first section is flow_dissector of 'type flow_dissector' argument is
> passed), we load and pin all the programs and build the jump table.
>
> The last argument of `bpftool attach` is made optional for this use
> case.
>
> Example:
> bpftool prog load tools/testing/selftests/bpf/bpf_flow.o \
> /sys/fs/bpf/flow type flow_dissector
> bpftool prog attach pinned /sys/fs/bpf/flow/flow_dissector/0 flow_dissector
>
> Tested by using the above two lines to load the prog in
> the test_flow_dissector.sh selftest.
>
> Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> ---
> .../bpftool/Documentation/bpftool-prog.rst | 16 ++-
> tools/bpf/bpftool/common.c | 32 +++--
> tools/bpf/bpftool/main.h | 1 +
> tools/bpf/bpftool/prog.c | 135 +++++++++++++++---
Please add the new attach type to bash completions.
> 4 files changed, 141 insertions(+), 43 deletions(-)
>
> diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
> index ac4e904b10fb..3caa9153435b 100644
> --- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst
> +++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
> @@ -25,8 +25,8 @@ MAP COMMANDS
> | **bpftool** **prog dump jited** *PROG* [{**file** *FILE* | **opcodes**}]
> | **bpftool** **prog pin** *PROG* *FILE*
> | **bpftool** **prog load** *OBJ* *FILE* [**type** *TYPE*] [**map** {**idx** *IDX* | **name** *NAME*} *MAP*] [**dev** *NAME*]
> -| **bpftool** **prog attach** *PROG* *ATTACH_TYPE* *MAP*
> -| **bpftool** **prog detach** *PROG* *ATTACH_TYPE* *MAP*
> +| **bpftool** **prog attach** *PROG* *ATTACH_TYPE* [*MAP*]
> +| **bpftool** **prog detach** *PROG* *ATTACH_TYPE* [*MAP*]
> | **bpftool** **prog help**
> |
> | *MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
> @@ -39,7 +39,9 @@ MAP COMMANDS
> | **cgroup/bind4** | **cgroup/bind6** | **cgroup/post_bind4** | **cgroup/post_bind6** |
> | **cgroup/connect4** | **cgroup/connect6** | **cgroup/sendmsg4** | **cgroup/sendmsg6**
> | }
> -| *ATTACH_TYPE* := { **msg_verdict** | **skb_verdict** | **skb_parse** }
> +| *ATTACH_TYPE* := {
> +| | **msg_verdict** | **skb_verdict** | **skb_parse** | **flow_dissector**
> +| }
>
>
> DESCRIPTION
> @@ -97,13 +99,13 @@ DESCRIPTION
> contain a dot character ('.'), which is reserved for future
> extensions of *bpffs*.
>
> - **bpftool prog attach** *PROG* *ATTACH_TYPE* *MAP*
> + **bpftool prog attach** *PROG* *ATTACH_TYPE* [*MAP*]
> Attach bpf program *PROG* (with type specified by *ATTACH_TYPE*)
> - to the map *MAP*.
> + to the optional map *MAP*.
Perhaps we can do better on help? Attach BPF program *PROG* (with type
specified by *ATTACH_TYPE*). Most *ATTACH_TYPEs* require a *MAP*
parameter, with the exception of *flow_dissector* which is attached to
current networking name space.
> - **bpftool prog detach** *PROG* *ATTACH_TYPE* *MAP*
> + **bpftool prog detach** *PROG* *ATTACH_TYPE* [*MAP*]
> Detach bpf program *PROG* (with type specified by *ATTACH_TYPE*)
> - from the map *MAP*.
> + from the optional map *MAP*.
>
> **bpftool prog help**
> Print short help message.
> diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
> index 25af85304ebe..963881142dfb 100644
> --- a/tools/bpf/bpftool/common.c
> +++ b/tools/bpf/bpftool/common.c
> @@ -204,10 +194,22 @@ int do_pin_fd(int fd, const char *name)
>
> out_free:
> free(file);
> -out:
> return err;
> }
>
> +int do_pin_fd(int fd, const char *name)
> +{
> + int err = mount_bpffs_for_pin(name);
Please don't initialize the error variable with a non-trivial function
call.
> + if (err) {
> + p_err("can't mount bpffs for pin %s: %s",
> + name, strerror(errno));
I think mount_bpffs_for_pin() will already print an error. We can't
print two errors, because it will break JSON output.
> + return err;
> + }
> +
> + return bpf_obj_pin(fd, name);
> +}
> +
> int do_pin_any(int argc, char **argv, int (*get_fd_by_id)(__u32))
> {
> unsigned int id;
> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
> index 5302ee282409..f3a07ec3a444 100644
> --- a/tools/bpf/bpftool/prog.c
> +++ b/tools/bpf/bpftool/prog.c
> @@ -81,6 +81,7 @@ static const char * const attach_type_strings[] = {
> [BPF_SK_SKB_STREAM_PARSER] = "stream_parser",
> [BPF_SK_SKB_STREAM_VERDICT] = "stream_verdict",
> [BPF_SK_MSG_VERDICT] = "msg_verdict",
> + [BPF_FLOW_DISSECTOR] = "flow_dissector",
> [__MAX_BPF_ATTACH_TYPE] = NULL,
> };
>
> @@ -724,9 +725,10 @@ int map_replace_compar(const void *p1, const void *p2)
> static int do_attach(int argc, char **argv)
> {
> enum bpf_attach_type attach_type;
> - int err, mapfd, progfd;
> + int err, progfd;
> + int mapfd = 0;
>
> - if (!REQ_ARGS(5)) {
> + if (!REQ_ARGS(3)) {
> p_err("too few parameters for map attach");
> return -EINVAL;
> }
> @@ -741,10 +743,11 @@ static int do_attach(int argc, char **argv)
> return -EINVAL;
> }
> NEXT_ARG();
> -
> - mapfd = map_parse_fd(&argc, &argv);
> - if (mapfd < 0)
> - return mapfd;
> + if (argc > 0) {
Flow dissector can't need a map right? I think explicitly checking for
the correct number of arguments once attach type is known would be good.
> + mapfd = map_parse_fd(&argc, &argv);
> + if (mapfd < 0)
> + return mapfd;
> + }
>
> err = bpf_prog_attach(progfd, mapfd, attach_type, 0);
> if (err) {
> @@ -760,9 +763,10 @@ static int do_attach(int argc, char **argv)
> static int do_detach(int argc, char **argv)
> {
> enum bpf_attach_type attach_type;
> - int err, mapfd, progfd;
> + int err, progfd;
> + int mapfd = 0;
>
> - if (!REQ_ARGS(5)) {
> + if (!REQ_ARGS(3)) {
> p_err("too few parameters for map detach");
> return -EINVAL;
> }
> @@ -777,10 +781,11 @@ static int do_detach(int argc, char **argv)
> return -EINVAL;
> }
> NEXT_ARG();
> -
> - mapfd = map_parse_fd(&argc, &argv);
> - if (mapfd < 0)
> - return mapfd;
> + if (argc > 0) {
> + mapfd = map_parse_fd(&argc, &argv);
> + if (mapfd < 0)
> + return mapfd;
> + }
>
> err = bpf_prog_detach2(progfd, mapfd, attach_type);
> if (err) {
> @@ -792,6 +797,56 @@ static int do_detach(int argc, char **argv)
> jsonw_null(json_wtr);
> return 0;
> }
> +
> +/* Flow dissector consists of a main program and a jump table for each
> + * supported protocol. The assumption here is that the first prog is the main
> + * one and the other progs are used in the tail calls. In this routine we
> + * build the jump table for the non-main progs.
> + */
> +static int build_flow_dissector_jmp_table(struct bpf_object *obj,
> + struct bpf_program *prog,
> + const char *jmp_table_map)
> +{
> + struct bpf_map *jmp_table;
> + struct bpf_program *pos;
> + int i = 0;
> + int prog_fd, jmp_table_fd, fd;
Please order variables longest to shortest.
> + prog_fd = bpf_program__fd(prog);
> + if (prog_fd < 0) {
> + p_err("failed to get fd of main prog");
> + return prog_fd;
> + }
> +
> + jmp_table = bpf_object__find_map_by_name(obj, jmp_table_map);
> + if (jmp_table == NULL) {
nit: !jmp_table
> + p_err("failed to find '%s' map", jmp_table_map);
> + return -1;
> + }
> +
> + jmp_table_fd = bpf_map__fd(jmp_table);
> + if (jmp_table_fd < 0) {
> + p_err("failed to get fd of jmp_table");
> + return jmp_table_fd;
> + }
> +
> + bpf_object__for_each_program(pos, obj) {
> + fd = bpf_program__fd(pos);
> + if (fd < 0) {
> + p_err("failed to get fd of '%s'",
> + bpf_program__title(pos, false));
> + return fd;
> + }
> +
> + if (fd != prog_fd) {
> + bpf_map_update_elem(jmp_table_fd, &i, &fd, BPF_ANY);
> + ++i;
> + }
> + }
> +
> + return 0;
> +}
> +
> static int do_load(int argc, char **argv)
> {
> enum bpf_attach_type expected_attach_type;
> @@ -800,7 +855,7 @@ static int do_load(int argc, char **argv)
> };
> struct map_replace *map_replace = NULL;
> unsigned int old_map_fds = 0;
> - struct bpf_program *prog;
> + struct bpf_program *prog, *pos;
variable order
> struct bpf_object *obj;
> struct bpf_map *map;
> const char *pinfile;
> @@ -918,13 +973,19 @@ static int do_load(int argc, char **argv)
> goto err_free_reuse_maps;
> }
>
> - prog = bpf_program__next(NULL, obj);
> + if (attr.prog_type == BPF_PROG_TYPE_FLOW_DISSECTOR) {
> + /* for the flow dissector type, the entry point is in the
> + * section flow_dissector; other progs are tail calls
> + */
> + prog = bpf_object__find_program_by_title(obj, "flow_dissector");
> + } else {
> + prog = bpf_program__next(NULL, obj);
> + }
> if (!prog) {
> p_err("object file doesn't contain any bpf program");
> goto err_close_obj;
> }
>
> - bpf_program__set_ifindex(prog, ifindex);
> if (attr.prog_type == BPF_PROG_TYPE_UNSPEC) {
> const char *sec_name = bpf_program__title(prog, false);
>
> @@ -936,8 +997,13 @@ static int do_load(int argc, char **argv)
> goto err_close_obj;
> }
> }
> - bpf_program__set_type(prog, attr.prog_type);
> - bpf_program__set_expected_attach_type(prog, expected_attach_type);
> +
> + bpf_object__for_each_program(pos, obj) {
> + bpf_program__set_ifindex(pos, ifindex);
> + bpf_program__set_type(pos, attr.prog_type);
> + bpf_program__set_expected_attach_type(pos,
> + expected_attach_type);
> + }
>
> qsort(map_replace, old_map_fds, sizeof(*map_replace),
> map_replace_compar);
> @@ -1001,8 +1067,34 @@ static int do_load(int argc, char **argv)
> goto err_close_obj;
> }
>
> - if (do_pin_fd(bpf_program__fd(prog), pinfile))
> + err = mount_bpffs_for_pin(pinfile);
> + if (err) {
> + p_err("failed to mount bpffs for pin '%s'", pinfile);
Probably would be a duplicated error again?
> goto err_close_obj;
> + }
> +
> + if (attr.prog_type == BPF_PROG_TYPE_FLOW_DISSECTOR) {
> + err = build_flow_dissector_jmp_table(obj, prog, "jmp_table");
> + if (err) {
> + p_err("failed to build flow dissector jump table");
> + goto err_close_obj;
> + }
> + /* flow dissector consist of multiple programs,
> + * we want to pin them all
Why pin them all shouldn't the main program be the only one pinned?
> + */
> + err = bpf_object__pin(obj, pinfile);
> + if (err) {
> + p_err("failed to pin flow dissector object");
> + goto err_close_obj;
> + }
> + } else {
> + err = bpf_obj_pin(bpf_program__fd(prog), pinfile);
> + if (err) {
> + p_err("failed to pin program %s",
> + bpf_program__title(prog, false));
> + goto err_close_obj;
> + }
> + }
