[PATCH bpf-next v6 6/8] tools/libbpf: Add support for BPF_PROG_TYPE_LSM

KP Singh
2020-03-25T15:27:10Z

From: KP Singh <kpsingh@google.com>

Since BPF_PROG_TYPE_LSM uses the same attaching mechanism as
BPF_PROG_TYPE_TRACING, the common logic is refactored into a static
function bpf_program__attach_btf_id.

A new API call bpf_program__attach_lsm is still added to avoid userspace
conflicts if this ever changes in the future.

Signed-off-by: KP Singh <kpsingh@google.com>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Florent Revest <revest@google.com>
Acked-by: Yonghong Song <yhs@fb.com>
---
tools/lib/bpf/bpf.c | 3 ++-
tools/lib/bpf/libbpf.c | 39 +++++++++++++++++++++++++++++++++++----
tools/lib/bpf/libbpf.h | 4 ++++
tools/lib/bpf/libbpf.map | 3 +++
4 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index c6dafe563176..73220176728d 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -235,7 +235,8 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
memset(&attr, 0, sizeof(attr));
attr.prog_type = load_attr->prog_type;
attr.expected_attach_type = load_attr->expected_attach_type;
- if (attr.prog_type == BPF_PROG_TYPE_STRUCT_OPS) {
+ if (attr.prog_type == BPF_PROG_TYPE_STRUCT_OPS ||
+ attr.prog_type == BPF_PROG_TYPE_LSM) {
attr.attach_btf_id = load_attr->attach_btf_id;
} else if (attr.prog_type == BPF_PROG_TYPE_TRACING ||
attr.prog_type == BPF_PROG_TYPE_EXT) {
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 085e41f9b68e..ba605e5a9c44 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2362,7 +2362,8 @@ static int bpf_object__finalize_btf(struct bpf_object *obj)

static inline bool libbpf_prog_needs_vmlinux_btf(struct bpf_program *prog)
{
- if (prog->type == BPF_PROG_TYPE_STRUCT_OPS)
+ if (prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
+ prog->type == BPF_PROG_TYPE_LSM)
return true;

/* BPF_PROG_TYPE_TRACING programs which do not attach to other programs
@@ -4870,7 +4871,8 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
load_attr.insns = insns;
load_attr.insns_cnt = insns_cnt;
load_attr.license = license;
- if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) {
+ if (prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
+ prog->type == BPF_PROG_TYPE_LSM) {
load_attr.attach_btf_id = prog->attach_btf_id;
} else if (prog->type == BPF_PROG_TYPE_TRACING ||
prog->type == BPF_PROG_TYPE_EXT) {
@@ -4955,6 +4957,7 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
int err = 0, fd, i, btf_id;

if ((prog->type == BPF_PROG_TYPE_TRACING ||
+ prog->type == BPF_PROG_TYPE_LSM ||
prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) {
btf_id = libbpf_find_attach_btf_id(prog);
if (btf_id <= 0)
@@ -6194,6 +6197,7 @@ bool bpf_program__is_##NAME(const struct bpf_program *prog) \
} \

BPF_PROG_TYPE_FNS(socket_filter, BPF_PROG_TYPE_SOCKET_FILTER);
+BPF_PROG_TYPE_FNS(lsm, BPF_PROG_TYPE_LSM);
BPF_PROG_TYPE_FNS(kprobe, BPF_PROG_TYPE_KPROBE);
BPF_PROG_TYPE_FNS(sched_cls, BPF_PROG_TYPE_SCHED_CLS);
BPF_PROG_TYPE_FNS(sched_act, BPF_PROG_TYPE_SCHED_ACT);
@@ -6260,6 +6264,8 @@ static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec,
struct bpf_program *prog);
static struct bpf_link *attach_trace(const struct bpf_sec_def *sec,
struct bpf_program *prog);
+static struct bpf_link *attach_lsm(const struct bpf_sec_def *sec,
+ struct bpf_program *prog);

struct bpf_sec_def {
const char *sec;
@@ -6310,6 +6316,10 @@ static const struct bpf_sec_def section_defs[] = {
SEC_DEF("freplace/", EXT,
.is_attach_btf = true,
.attach_fn = attach_trace),
+ SEC_DEF("lsm/", LSM,
+ .is_attach_btf = true,
+ .expected_attach_type = BPF_LSM_MAC,
+ .attach_fn = attach_lsm),
BPF_PROG_SEC("xdp", BPF_PROG_TYPE_XDP),
BPF_PROG_SEC("perf_event", BPF_PROG_TYPE_PERF_EVENT),
BPF_PROG_SEC("lwt_in", BPF_PROG_TYPE_LWT_IN),
@@ -6572,6 +6582,7 @@ static int bpf_object__collect_struct_ops_map_reloc(struct bpf_object *obj,
}

#define BTF_TRACE_PREFIX "btf_trace_"
+#define BTF_LSM_PREFIX "bpf_lsm_"
#define BTF_MAX_NAME_SIZE 128

static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
@@ -6599,6 +6610,9 @@ static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name,
if (attach_type == BPF_TRACE_RAW_TP)
err = find_btf_by_prefix_kind(btf, BTF_TRACE_PREFIX, name,
BTF_KIND_TYPEDEF);
+ else if (attach_type == BPF_LSM_MAC)
+ err = find_btf_by_prefix_kind(btf, BTF_LSM_PREFIX, name,
+ BTF_KIND_FUNC);
else
err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);

@@ -7452,7 +7466,8 @@ static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec,
return bpf_program__attach_raw_tracepoint(prog, tp_name);
}

-struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
+/* Common logic for all BPF program types that attach to a btf_id */
+static struct bpf_link *bpf_program__attach_btf_id(struct bpf_program *prog)
{
char errmsg[STRERR_BUFSIZE];
struct bpf_link *link;
@@ -7474,7 +7489,7 @@ struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
if (pfd < 0) {
pfd = -errno;
free(link);
- pr_warn("program '%s': failed to attach to trace: %s\n",
+ pr_warn("program '%s': failed to attach: %s\n",
bpf_program__title(prog, false),
libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return ERR_PTR(pfd);
@@ -7483,12 +7498,28 @@ struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
return (struct bpf_link *)link;
}

+struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
+{
+ return bpf_program__attach_btf_id(prog);
+}
+
+struct bpf_link *bpf_program__attach_lsm(struct bpf_program *prog)
+{
+ return bpf_program__attach_btf_id(prog);
+}
+
static struct bpf_link *attach_trace(const struct bpf_sec_def *sec,
struct bpf_program *prog)
{
return bpf_program__attach_trace(prog);
}

+static struct bpf_link *attach_lsm(const struct bpf_sec_def *sec,
+ struct bpf_program *prog)
+{
+ return bpf_program__attach_lsm(prog);
+}
+
struct bpf_link *bpf_program__attach(struct bpf_program *prog)
{
const struct bpf_sec_def *sec_def;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index d38d7a629417..df1be44c8118 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -248,6 +248,8 @@ bpf_program__attach_raw_tracepoint(struct bpf_program *prog,

LIBBPF_API struct bpf_link *
bpf_program__attach_trace(struct bpf_program *prog);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_lsm(struct bpf_program *prog);
struct bpf_map;
LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map);
struct bpf_insn;
@@ -321,6 +323,7 @@ LIBBPF_API int bpf_program__set_socket_filter(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_tracepoint(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_raw_tracepoint(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_kprobe(struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_lsm(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_sched_cls(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_sched_act(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_xdp(struct bpf_program *prog);
@@ -347,6 +350,7 @@ LIBBPF_API bool bpf_program__is_socket_filter(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_tracepoint(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_raw_tracepoint(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_kprobe(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__is_lsm(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_sched_cls(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_sched_act(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_xdp(const struct bpf_program *prog);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 5129283c0284..ec29d3aa2700 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -243,5 +243,8 @@ LIBBPF_0.0.8 {
bpf_link__pin;
bpf_link__pin_path;
bpf_link__unpin;
+ bpf_program__attach_lsm;
+ bpf_program__is_lsm;
bpf_program__set_attach_target;
+ bpf_program__set_lsm;
} LIBBPF_0.0.7;
--
2.20.1