On Mon, Jul 10, 2023 at 1:12 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
Implement tcx BPF link support for libbpf.
The bpf_program__attach_fd() API has been refactored slightly in order to pass
bpf_link_create_opts pointer as input.
A new bpf_program__attach_tcx() has been added on top of this which allows for
passing all relevant data via extensible struct bpf_tcx_opts.
The program sections tcx/ingress and tcx/egress correspond to the hook locations
for tc ingress and egress, respectively.
For concrete usage examples, see the extensive selftests that have been
developed as part of this series.
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
---
tools/lib/bpf/bpf.c | 19 ++++++++++--
tools/lib/bpf/bpf.h | 5 ++++
tools/lib/bpf/libbpf.c | 62 ++++++++++++++++++++++++++++++++++------
tools/lib/bpf/libbpf.h | 16 +++++++++++
tools/lib/bpf/libbpf.map | 1 +
5 files changed, 92 insertions(+), 11 deletions(-)
Pretty minor nits, I think ifindex move to be mandatory argument is
the most consequential, as it's an API. With that addressed, please
add my ack for next rev
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 3dfc43b477c3..d513c226b9aa 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -717,9 +717,9 @@ int bpf_link_create(int prog_fd, int target_fd,
const struct bpf_link_create_opts *opts)
{
const size_t attr_sz = offsetofend(union bpf_attr, link_create);
- __u32 target_btf_id, iter_info_len;
+ __u32 target_btf_id, iter_info_len, relative_id;
+ int fd, err, relative;
nit: maybe make these new vars local to the TCX cases branch below?
union bpf_attr attr;
- int fd, err;
if (!OPTS_VALID(opts, bpf_link_create_opts))
return libbpf_err(-EINVAL);
@@ -781,6 +781,21 @@ int bpf_link_create(int prog_fd, int target_fd,
if (!OPTS_ZEROED(opts, netfilter))
return libbpf_err(-EINVAL);
break;
+ case BPF_TCX_INGRESS:
+ case BPF_TCX_EGRESS:
+ relative = OPTS_GET(opts, tcx.relative_fd, 0);
+ relative_id = OPTS_GET(opts, tcx.relative_id, 0);
+ if (relative > 0 && relative_id)
+ return libbpf_err(-EINVAL);
+ if (relative_id) {
+ relative = relative_id;
+ attr.link_create.flags |= BPF_F_ID;
+ }
Well, I have the same nit as in the previous patch, this "relative =
relative_id" is both confusing because of naming asymmetry (no
relative_fd throws me off), and also unnecessary updating of the
state. link_create.flags |= BPF_F_ID is inevitable, but the rest can
be more straightforward, IMO
+ attr.link_create.tcx.relative_fd = relative;
+ attr.link_create.tcx.expected_revision = OPTS_GET(opts, tcx.expected_revision, 0);
+ if (!OPTS_ZEROED(opts, tcx))
+ return libbpf_err(-EINVAL);
+ break;
default:
if (!OPTS_ZEROED(opts, flags))
return libbpf_err(-EINVAL);
[...]
+struct bpf_link *
+bpf_program__attach_tcx(const struct bpf_program *prog,
+ const struct bpf_tcx_opts *opts)
+{
+ LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
+ __u32 relative_id, flags;
+ int ifindex, relative_fd;
+
+ if (!OPTS_VALID(opts, bpf_tcx_opts))
+ return libbpf_err_ptr(-EINVAL);
+
+ relative_id = OPTS_GET(opts, relative_id, 0);
+ relative_fd = OPTS_GET(opts, relative_fd, 0);
+ flags = OPTS_GET(opts, flags, 0);
+ ifindex = OPTS_GET(opts, ifindex, 0);
+
+ /* validate we don't have unexpected combinations of non-zero fields */
+ if (!ifindex) {
+ pr_warn("prog '%s': target netdevice ifindex cannot be zero\n",
+ prog->name);
+ return libbpf_err_ptr(-EINVAL);
+ }
given ifindex is non-optional, then it makes more sense to have it as
a mandatory argument between prog and opts in
bpf_program__attach_tcx(), instead of as a field of an opts struct
+ if (relative_fd > 0 && relative_id) {
this asymmetrical check is a bit distracting. And also, if someone
specifies negative FD and positive ID, that's also a bad combo and we
shouldn't just ignore invalid FD, right? So I'd have a nice and clean
if (relative_fd && relative_id) { /* bad */ }
+ pr_warn("prog '%s': relative_fd and relative_id cannot be set at the same time\n",
+ prog->name);
+ return libbpf_err_ptr(-EINVAL);
+ }
+ if (relative_id)
+ flags |= BPF_F_ID;
I think bpf_link_create() will add this flag anyways, so can drop this
adjustment logic here?
+
+ link_create_opts.tcx.expected_revision = OPTS_GET(opts, expected_revision, 0);
+ link_create_opts.tcx.relative_fd = relative_fd;
+ link_create_opts.tcx.relative_id = relative_id;
+ link_create_opts.flags = flags;
+
+ /* target_fd/target_ifindex use the same field in LINK_CREATE */
+ return bpf_program_attach_fd(prog, ifindex, "tc", &link_create_opts);
s/tc/tcx/ ?
}
struct bpf_link *bpf_program__attach_freplace(const struct bpf_program *prog,
@@ -11917,11 +11956,16 @@ struct bpf_link *bpf_program__attach_freplace(const struct bpf_program *prog,
}
if (target_fd) {
+ LIBBPF_OPTS(bpf_link_create_opts, target_opts);
+
btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd);
if (btf_id < 0)
return libbpf_err_ptr(btf_id);
- return bpf_program__attach_fd(prog, target_fd, btf_id, "freplace");
+ target_opts.target_btf_id = btf_id;
+
+ return bpf_program_attach_fd(prog, target_fd, "freplace",
+ &target_opts);
} else {
/* no target, so use raw_tracepoint_open for compatibility
* with old kernels
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 10642ad69d76..33f60a318e81 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -733,6 +733,22 @@ LIBBPF_API struct bpf_link *
bpf_program__attach_netfilter(const struct bpf_program *prog,
const struct bpf_netfilter_opts *opts);
+struct bpf_tcx_opts {
+ /* size of this struct, for forward/backward compatibility */
+ size_t sz;
+ int ifindex;
is ifindex optional or it's expected to always be specified? If the
latter, then I'd move ifindex out of opts and make it second arg of
bpf_program__attach_tcx, between prog and opts
+ __u32 flags;
+ __u32 relative_fd;
+ __u32 relative_id;
+ __u64 expected_revision;
+ size_t :0;
+};
+#define bpf_tcx_opts__last_field expected_revision
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tcx(const struct bpf_program *prog,
+ const struct bpf_tcx_opts *opts);
+
struct bpf_map;
LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index a95d39bbef90..2a2db5c78048 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -397,4 +397,5 @@ LIBBPF_1.3.0 {
bpf_obj_pin_opts;
bpf_program__attach_netfilter;
bpf_prog_detach_opts;
+ bpf_program__attach_tcx;
heh, now we definitely screwed up sorting ;)
} LIBBPF_1.2.0;
--
2.34.1
