[PATCH v2 bpf-next 23/30] libbpf: move feature detection code into its own file
Andrii Nakryiko
andrii at kernel.org
Wed Jan 24 02:21:20 UTC 2024
It's quite a lot of well isolated code, so it seems like a good
candidate to move it out of libbpf.c to reduce its size.
Acked-by: John Fastabend <john.fastabend at gmail.com>
Signed-off-by: Andrii Nakryiko <andrii at kernel.org>
---
tools/lib/bpf/Build | 2 +-
tools/lib/bpf/elf.c | 2 -
tools/lib/bpf/features.c | 463 ++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf.c | 463 +-------------------------------
tools/lib/bpf/libbpf_internal.h | 14 +-
tools/lib/bpf/str_error.h | 3 +
6 files changed, 481 insertions(+), 466 deletions(-)
create mode 100644 tools/lib/bpf/features.c
diff --git a/tools/lib/bpf/Build b/tools/lib/bpf/Build
index 2d0c282c8588..b6619199a706 100644
--- a/tools/lib/bpf/Build
+++ b/tools/lib/bpf/Build
@@ -1,4 +1,4 @@
libbpf-y := libbpf.o bpf.o nlattr.o btf.o libbpf_errno.o str_error.o \
netlink.o bpf_prog_linfo.o libbpf_probes.o hashmap.o \
btf_dump.o ringbuf.o strset.o linker.o gen_loader.o relo_core.o \
- usdt.o zip.o elf.o
+ usdt.o zip.o elf.o features.o
diff --git a/tools/lib/bpf/elf.c b/tools/lib/bpf/elf.c
index b02faec748a5..c92e02394159 100644
--- a/tools/lib/bpf/elf.c
+++ b/tools/lib/bpf/elf.c
@@ -11,8 +11,6 @@
#include "libbpf_internal.h"
#include "str_error.h"
-#define STRERR_BUFSIZE 128
-
/* A SHT_GNU_versym section holds 16-bit words. This bit is set if
* the symbol is hidden and can only be seen when referenced using an
* explicit version number. This is a GNU extension.
diff --git a/tools/lib/bpf/features.c b/tools/lib/bpf/features.c
new file mode 100644
index 000000000000..a4664526ab7f
--- /dev/null
+++ b/tools/lib/bpf/features.c
@@ -0,0 +1,463 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+#include <linux/kernel.h>
+#include <linux/filter.h>
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_common.h"
+#include "libbpf_internal.h"
+#include "str_error.h"
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+ return (__u64)(unsigned long)ptr;
+}
+
+int probe_fd(int fd)
+{
+ if (fd >= 0)
+ close(fd);
+ return fd >= 0;
+}
+
+static int probe_kern_prog_name(void)
+{
+ const size_t attr_sz = offsetofend(union bpf_attr, prog_name);
+ struct bpf_insn insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ union bpf_attr attr;
+ int ret;
+
+ memset(&attr, 0, attr_sz);
+ attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+ attr.license = ptr_to_u64("GPL");
+ attr.insns = ptr_to_u64(insns);
+ attr.insn_cnt = (__u32)ARRAY_SIZE(insns);
+ libbpf_strlcpy(attr.prog_name, "libbpf_nametest", sizeof(attr.prog_name));
+
+ /* make sure loading with name works */
+ ret = sys_bpf_prog_load(&attr, attr_sz, PROG_LOAD_ATTEMPTS);
+ return probe_fd(ret);
+}
+
+static int probe_kern_global_data(void)
+{
+ char *cp, errmsg[STRERR_BUFSIZE];
+ struct bpf_insn insns[] = {
+ BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16),
+ BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ int ret, map, insn_cnt = ARRAY_SIZE(insns);
+
+ map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_global", sizeof(int), 32, 1, NULL);
+ if (map < 0) {
+ ret = -errno;
+ cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
+ pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
+ __func__, cp, -ret);
+ return ret;
+ }
+
+ insns[0].imm = map;
+
+ ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
+ close(map);
+ return probe_fd(ret);
+}
+
+static int probe_kern_btf(void)
+{
+ static const char strs[] = "\0int";
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
+ };
+
+ return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_func(void)
+{
+ static const char strs[] = "\0int\0x\0a";
+ /* void x(int a) {} */
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
+ /* FUNC_PROTO */ /* [2] */
+ BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
+ BTF_PARAM_ENC(7, 1),
+ /* FUNC x */ /* [3] */
+ BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2),
+ };
+
+ return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_func_global(void)
+{
+ static const char strs[] = "\0int\0x\0a";
+ /* static void x(int a) {} */
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
+ /* FUNC_PROTO */ /* [2] */
+ BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
+ BTF_PARAM_ENC(7, 1),
+ /* FUNC x BTF_FUNC_GLOBAL */ /* [3] */
+ BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2),
+ };
+
+ return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_datasec(void)
+{
+ static const char strs[] = "\0x\0.data";
+ /* static int a; */
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
+ /* VAR x */ /* [2] */
+ BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
+ BTF_VAR_STATIC,
+ /* DATASEC val */ /* [3] */
+ BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
+ BTF_VAR_SECINFO_ENC(2, 0, 4),
+ };
+
+ return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_float(void)
+{
+ static const char strs[] = "\0float";
+ __u32 types[] = {
+ /* float */
+ BTF_TYPE_FLOAT_ENC(1, 4),
+ };
+
+ return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_decl_tag(void)
+{
+ static const char strs[] = "\0tag";
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
+ /* VAR x */ /* [2] */
+ BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
+ BTF_VAR_STATIC,
+ /* attr */
+ BTF_TYPE_DECL_TAG_ENC(1, 2, -1),
+ };
+
+ return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs)));
+}
+
+static int probe_kern_btf_type_tag(void)
+{
+ static const char strs[] = "\0tag";
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
+ /* attr */
+ BTF_TYPE_TYPE_TAG_ENC(1, 1), /* [2] */
+ /* ptr */
+ BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2), /* [3] */
+ };
+
+ return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs)));
+}
+
+static int probe_kern_array_mmap(void)
+{
+ LIBBPF_OPTS(bpf_map_create_opts, opts, .map_flags = BPF_F_MMAPABLE);
+ int fd;
+
+ fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_mmap", sizeof(int), sizeof(int), 1, &opts);
+ return probe_fd(fd);
+}
+
+static int probe_kern_exp_attach_type(void)
+{
+ LIBBPF_OPTS(bpf_prog_load_opts, opts, .expected_attach_type = BPF_CGROUP_INET_SOCK_CREATE);
+ struct bpf_insn insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ int fd, insn_cnt = ARRAY_SIZE(insns);
+
+ /* use any valid combination of program type and (optional)
+ * non-zero expected attach type (i.e., not a BPF_CGROUP_INET_INGRESS)
+ * to see if kernel supports expected_attach_type field for
+ * BPF_PROG_LOAD command
+ */
+ fd = bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCK, NULL, "GPL", insns, insn_cnt, &opts);
+ return probe_fd(fd);
+}
+
+static int probe_kern_probe_read_kernel(void)
+{
+ struct bpf_insn insns[] = {
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), /* r1 = r10 (fp) */
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8), /* r1 += -8 */
+ BPF_MOV64_IMM(BPF_REG_2, 8), /* r2 = 8 */
+ BPF_MOV64_IMM(BPF_REG_3, 0), /* r3 = 0 */
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_probe_read_kernel),
+ BPF_EXIT_INSN(),
+ };
+ int fd, insn_cnt = ARRAY_SIZE(insns);
+
+ fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, NULL);
+ return probe_fd(fd);
+}
+
+static int probe_prog_bind_map(void)
+{
+ char *cp, errmsg[STRERR_BUFSIZE];
+ struct bpf_insn insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ int ret, map, prog, insn_cnt = ARRAY_SIZE(insns);
+
+ map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_det_bind", sizeof(int), 32, 1, NULL);
+ if (map < 0) {
+ ret = -errno;
+ cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
+ pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
+ __func__, cp, -ret);
+ return ret;
+ }
+
+ prog = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
+ if (prog < 0) {
+ close(map);
+ return 0;
+ }
+
+ ret = bpf_prog_bind_map(prog, map, NULL);
+
+ close(map);
+ close(prog);
+
+ return ret >= 0;
+}
+
+static int probe_module_btf(void)
+{
+ static const char strs[] = "\0int";
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
+ };
+ struct bpf_btf_info info;
+ __u32 len = sizeof(info);
+ char name[16];
+ int fd, err;
+
+ fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs));
+ if (fd < 0)
+ return 0; /* BTF not supported at all */
+
+ memset(&info, 0, sizeof(info));
+ info.name = ptr_to_u64(name);
+ info.name_len = sizeof(name);
+
+ /* check that BPF_OBJ_GET_INFO_BY_FD supports specifying name pointer;
+ * kernel's module BTF support coincides with support for
+ * name/name_len fields in struct bpf_btf_info.
+ */
+ err = bpf_btf_get_info_by_fd(fd, &info, &len);
+ close(fd);
+ return !err;
+}
+
+static int probe_perf_link(void)
+{
+ struct bpf_insn insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ int prog_fd, link_fd, err;
+
+ prog_fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL",
+ insns, ARRAY_SIZE(insns), NULL);
+ if (prog_fd < 0)
+ return -errno;
+
+ /* use invalid perf_event FD to get EBADF, if link is supported;
+ * otherwise EINVAL should be returned
+ */
+ link_fd = bpf_link_create(prog_fd, -1, BPF_PERF_EVENT, NULL);
+ err = -errno; /* close() can clobber errno */
+
+ if (link_fd >= 0)
+ close(link_fd);
+ close(prog_fd);
+
+ return link_fd < 0 && err == -EBADF;
+}
+
+static int probe_uprobe_multi_link(void)
+{
+ LIBBPF_OPTS(bpf_prog_load_opts, load_opts,
+ .expected_attach_type = BPF_TRACE_UPROBE_MULTI,
+ );
+ LIBBPF_OPTS(bpf_link_create_opts, link_opts);
+ struct bpf_insn insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ int prog_fd, link_fd, err;
+ unsigned long offset = 0;
+
+ prog_fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL",
+ insns, ARRAY_SIZE(insns), &load_opts);
+ if (prog_fd < 0)
+ return -errno;
+
+ /* Creating uprobe in '/' binary should fail with -EBADF. */
+ link_opts.uprobe_multi.path = "/";
+ link_opts.uprobe_multi.offsets = &offset;
+ link_opts.uprobe_multi.cnt = 1;
+
+ link_fd = bpf_link_create(prog_fd, -1, BPF_TRACE_UPROBE_MULTI, &link_opts);
+ err = -errno; /* close() can clobber errno */
+
+ if (link_fd >= 0)
+ close(link_fd);
+ close(prog_fd);
+
+ return link_fd < 0 && err == -EBADF;
+}
+
+static int probe_kern_bpf_cookie(void)
+{
+ struct bpf_insn insns[] = {
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_attach_cookie),
+ BPF_EXIT_INSN(),
+ };
+ int ret, insn_cnt = ARRAY_SIZE(insns);
+
+ ret = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", insns, insn_cnt, NULL);
+ return probe_fd(ret);
+}
+
+static int probe_kern_btf_enum64(void)
+{
+ static const char strs[] = "\0enum64";
+ __u32 types[] = {
+ BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_ENUM64, 0, 0), 8),
+ };
+
+ return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs)));
+}
+
+typedef int (*feature_probe_fn)(void);
+
+static struct kern_feature_cache feature_cache;
+
+static struct kern_feature_desc {
+ const char *desc;
+ feature_probe_fn probe;
+} feature_probes[__FEAT_CNT] = {
+ [FEAT_PROG_NAME] = {
+ "BPF program name", probe_kern_prog_name,
+ },
+ [FEAT_GLOBAL_DATA] = {
+ "global variables", probe_kern_global_data,
+ },
+ [FEAT_BTF] = {
+ "minimal BTF", probe_kern_btf,
+ },
+ [FEAT_BTF_FUNC] = {
+ "BTF functions", probe_kern_btf_func,
+ },
+ [FEAT_BTF_GLOBAL_FUNC] = {
+ "BTF global function", probe_kern_btf_func_global,
+ },
+ [FEAT_BTF_DATASEC] = {
+ "BTF data section and variable", probe_kern_btf_datasec,
+ },
+ [FEAT_ARRAY_MMAP] = {
+ "ARRAY map mmap()", probe_kern_array_mmap,
+ },
+ [FEAT_EXP_ATTACH_TYPE] = {
+ "BPF_PROG_LOAD expected_attach_type attribute",
+ probe_kern_exp_attach_type,
+ },
+ [FEAT_PROBE_READ_KERN] = {
+ "bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel,
+ },
+ [FEAT_PROG_BIND_MAP] = {
+ "BPF_PROG_BIND_MAP support", probe_prog_bind_map,
+ },
+ [FEAT_MODULE_BTF] = {
+ "module BTF support", probe_module_btf,
+ },
+ [FEAT_BTF_FLOAT] = {
+ "BTF_KIND_FLOAT support", probe_kern_btf_float,
+ },
+ [FEAT_PERF_LINK] = {
+ "BPF perf link support", probe_perf_link,
+ },
+ [FEAT_BTF_DECL_TAG] = {
+ "BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag,
+ },
+ [FEAT_BTF_TYPE_TAG] = {
+ "BTF_KIND_TYPE_TAG support", probe_kern_btf_type_tag,
+ },
+ [FEAT_MEMCG_ACCOUNT] = {
+ "memcg-based memory accounting", probe_memcg_account,
+ },
+ [FEAT_BPF_COOKIE] = {
+ "BPF cookie support", probe_kern_bpf_cookie,
+ },
+ [FEAT_BTF_ENUM64] = {
+ "BTF_KIND_ENUM64 support", probe_kern_btf_enum64,
+ },
+ [FEAT_SYSCALL_WRAPPER] = {
+ "Kernel using syscall wrapper", probe_kern_syscall_wrapper,
+ },
+ [FEAT_UPROBE_MULTI_LINK] = {
+ "BPF multi-uprobe link support", probe_uprobe_multi_link,
+ },
+};
+
+bool feat_supported(struct kern_feature_cache *cache, enum kern_feature_id feat_id)
+{
+ struct kern_feature_desc *feat = &feature_probes[feat_id];
+ int ret;
+
+ /* assume global feature cache, unless custom one is provided */
+ if (!cache)
+ cache = &feature_cache;
+
+ if (READ_ONCE(cache->res[feat_id]) == FEAT_UNKNOWN) {
+ ret = feat->probe();
+ if (ret > 0) {
+ WRITE_ONCE(cache->res[feat_id], FEAT_SUPPORTED);
+ } else if (ret == 0) {
+ WRITE_ONCE(cache->res[feat_id], FEAT_MISSING);
+ } else {
+ pr_warn("Detection of kernel %s support failed: %d\n", feat->desc, ret);
+ WRITE_ONCE(cache->res[feat_id], FEAT_MISSING);
+ }
+ }
+
+ return READ_ONCE(cache->res[feat_id]) == FEAT_SUPPORTED;
+}
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 4bfc504815d5..5c441737db98 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4582,467 +4582,6 @@ bpf_object__probe_loading(struct bpf_object *obj)
return 0;
}
-static int probe_fd(int fd)
-{
- if (fd >= 0)
- close(fd);
- return fd >= 0;
-}
-
-static int probe_kern_prog_name(void)
-{
- const size_t attr_sz = offsetofend(union bpf_attr, prog_name);
- struct bpf_insn insns[] = {
- BPF_MOV64_IMM(BPF_REG_0, 0),
- BPF_EXIT_INSN(),
- };
- union bpf_attr attr;
- int ret;
-
- memset(&attr, 0, attr_sz);
- attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
- attr.license = ptr_to_u64("GPL");
- attr.insns = ptr_to_u64(insns);
- attr.insn_cnt = (__u32)ARRAY_SIZE(insns);
- libbpf_strlcpy(attr.prog_name, "libbpf_nametest", sizeof(attr.prog_name));
-
- /* make sure loading with name works */
- ret = sys_bpf_prog_load(&attr, attr_sz, PROG_LOAD_ATTEMPTS);
- return probe_fd(ret);
-}
-
-static int probe_kern_global_data(void)
-{
- char *cp, errmsg[STRERR_BUFSIZE];
- struct bpf_insn insns[] = {
- BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16),
- BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42),
- BPF_MOV64_IMM(BPF_REG_0, 0),
- BPF_EXIT_INSN(),
- };
- int ret, map, insn_cnt = ARRAY_SIZE(insns);
-
- map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_global", sizeof(int), 32, 1, NULL);
- if (map < 0) {
- ret = -errno;
- cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
- pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
- __func__, cp, -ret);
- return ret;
- }
-
- insns[0].imm = map;
-
- ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
- close(map);
- return probe_fd(ret);
-}
-
-static int probe_kern_btf(void)
-{
- static const char strs[] = "\0int";
- __u32 types[] = {
- /* int */
- BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
- };
-
- return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
- strs, sizeof(strs)));
-}
-
-static int probe_kern_btf_func(void)
-{
- static const char strs[] = "\0int\0x\0a";
- /* void x(int a) {} */
- __u32 types[] = {
- /* int */
- BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
- /* FUNC_PROTO */ /* [2] */
- BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
- BTF_PARAM_ENC(7, 1),
- /* FUNC x */ /* [3] */
- BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2),
- };
-
- return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
- strs, sizeof(strs)));
-}
-
-static int probe_kern_btf_func_global(void)
-{
- static const char strs[] = "\0int\0x\0a";
- /* static void x(int a) {} */
- __u32 types[] = {
- /* int */
- BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
- /* FUNC_PROTO */ /* [2] */
- BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
- BTF_PARAM_ENC(7, 1),
- /* FUNC x BTF_FUNC_GLOBAL */ /* [3] */
- BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2),
- };
-
- return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
- strs, sizeof(strs)));
-}
-
-static int probe_kern_btf_datasec(void)
-{
- static const char strs[] = "\0x\0.data";
- /* static int a; */
- __u32 types[] = {
- /* int */
- BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
- /* VAR x */ /* [2] */
- BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
- BTF_VAR_STATIC,
- /* DATASEC val */ /* [3] */
- BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
- BTF_VAR_SECINFO_ENC(2, 0, 4),
- };
-
- return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
- strs, sizeof(strs)));
-}
-
-static int probe_kern_btf_float(void)
-{
- static const char strs[] = "\0float";
- __u32 types[] = {
- /* float */
- BTF_TYPE_FLOAT_ENC(1, 4),
- };
-
- return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
- strs, sizeof(strs)));
-}
-
-static int probe_kern_btf_decl_tag(void)
-{
- static const char strs[] = "\0tag";
- __u32 types[] = {
- /* int */
- BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
- /* VAR x */ /* [2] */
- BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
- BTF_VAR_STATIC,
- /* attr */
- BTF_TYPE_DECL_TAG_ENC(1, 2, -1),
- };
-
- return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
- strs, sizeof(strs)));
-}
-
-static int probe_kern_btf_type_tag(void)
-{
- static const char strs[] = "\0tag";
- __u32 types[] = {
- /* int */
- BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
- /* attr */
- BTF_TYPE_TYPE_TAG_ENC(1, 1), /* [2] */
- /* ptr */
- BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2), /* [3] */
- };
-
- return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
- strs, sizeof(strs)));
-}
-
-static int probe_kern_array_mmap(void)
-{
- LIBBPF_OPTS(bpf_map_create_opts, opts, .map_flags = BPF_F_MMAPABLE);
- int fd;
-
- fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_mmap", sizeof(int), sizeof(int), 1, &opts);
- return probe_fd(fd);
-}
-
-static int probe_kern_exp_attach_type(void)
-{
- LIBBPF_OPTS(bpf_prog_load_opts, opts, .expected_attach_type = BPF_CGROUP_INET_SOCK_CREATE);
- struct bpf_insn insns[] = {
- BPF_MOV64_IMM(BPF_REG_0, 0),
- BPF_EXIT_INSN(),
- };
- int fd, insn_cnt = ARRAY_SIZE(insns);
-
- /* use any valid combination of program type and (optional)
- * non-zero expected attach type (i.e., not a BPF_CGROUP_INET_INGRESS)
- * to see if kernel supports expected_attach_type field for
- * BPF_PROG_LOAD command
- */
- fd = bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCK, NULL, "GPL", insns, insn_cnt, &opts);
- return probe_fd(fd);
-}
-
-static int probe_kern_probe_read_kernel(void)
-{
- struct bpf_insn insns[] = {
- BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), /* r1 = r10 (fp) */
- BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8), /* r1 += -8 */
- BPF_MOV64_IMM(BPF_REG_2, 8), /* r2 = 8 */
- BPF_MOV64_IMM(BPF_REG_3, 0), /* r3 = 0 */
- BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_probe_read_kernel),
- BPF_EXIT_INSN(),
- };
- int fd, insn_cnt = ARRAY_SIZE(insns);
-
- fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, NULL);
- return probe_fd(fd);
-}
-
-static int probe_prog_bind_map(void)
-{
- char *cp, errmsg[STRERR_BUFSIZE];
- struct bpf_insn insns[] = {
- BPF_MOV64_IMM(BPF_REG_0, 0),
- BPF_EXIT_INSN(),
- };
- int ret, map, prog, insn_cnt = ARRAY_SIZE(insns);
-
- map = bpf_map_create(BPF_MAP_TYPE_ARRAY, "libbpf_det_bind", sizeof(int), 32, 1, NULL);
- if (map < 0) {
- ret = -errno;
- cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
- pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
- __func__, cp, -ret);
- return ret;
- }
-
- prog = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, NULL);
- if (prog < 0) {
- close(map);
- return 0;
- }
-
- ret = bpf_prog_bind_map(prog, map, NULL);
-
- close(map);
- close(prog);
-
- return ret >= 0;
-}
-
-static int probe_module_btf(void)
-{
- static const char strs[] = "\0int";
- __u32 types[] = {
- /* int */
- BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
- };
- struct bpf_btf_info info;
- __u32 len = sizeof(info);
- char name[16];
- int fd, err;
-
- fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs));
- if (fd < 0)
- return 0; /* BTF not supported at all */
-
- memset(&info, 0, sizeof(info));
- info.name = ptr_to_u64(name);
- info.name_len = sizeof(name);
-
- /* check that BPF_OBJ_GET_INFO_BY_FD supports specifying name pointer;
- * kernel's module BTF support coincides with support for
- * name/name_len fields in struct bpf_btf_info.
- */
- err = bpf_btf_get_info_by_fd(fd, &info, &len);
- close(fd);
- return !err;
-}
-
-static int probe_perf_link(void)
-{
- struct bpf_insn insns[] = {
- BPF_MOV64_IMM(BPF_REG_0, 0),
- BPF_EXIT_INSN(),
- };
- int prog_fd, link_fd, err;
-
- prog_fd = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL",
- insns, ARRAY_SIZE(insns), NULL);
- if (prog_fd < 0)
- return -errno;
-
- /* use invalid perf_event FD to get EBADF, if link is supported;
- * otherwise EINVAL should be returned
- */
- link_fd = bpf_link_create(prog_fd, -1, BPF_PERF_EVENT, NULL);
- err = -errno; /* close() can clobber errno */
-
- if (link_fd >= 0)
- close(link_fd);
- close(prog_fd);
-
- return link_fd < 0 && err == -EBADF;
-}
-
-static int probe_uprobe_multi_link(void)
-{
- LIBBPF_OPTS(bpf_prog_load_opts, load_opts,
- .expected_attach_type = BPF_TRACE_UPROBE_MULTI,
- );
- LIBBPF_OPTS(bpf_link_create_opts, link_opts);
- struct bpf_insn insns[] = {
- BPF_MOV64_IMM(BPF_REG_0, 0),
- BPF_EXIT_INSN(),
- };
- int prog_fd, link_fd, err;
- unsigned long offset = 0;
-
- prog_fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL",
- insns, ARRAY_SIZE(insns), &load_opts);
- if (prog_fd < 0)
- return -errno;
-
- /* Creating uprobe in '/' binary should fail with -EBADF. */
- link_opts.uprobe_multi.path = "/";
- link_opts.uprobe_multi.offsets = &offset;
- link_opts.uprobe_multi.cnt = 1;
-
- link_fd = bpf_link_create(prog_fd, -1, BPF_TRACE_UPROBE_MULTI, &link_opts);
- err = -errno; /* close() can clobber errno */
-
- if (link_fd >= 0)
- close(link_fd);
- close(prog_fd);
-
- return link_fd < 0 && err == -EBADF;
-}
-
-static int probe_kern_bpf_cookie(void)
-{
- struct bpf_insn insns[] = {
- BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_attach_cookie),
- BPF_EXIT_INSN(),
- };
- int ret, insn_cnt = ARRAY_SIZE(insns);
-
- ret = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", insns, insn_cnt, NULL);
- return probe_fd(ret);
-}
-
-static int probe_kern_btf_enum64(void)
-{
- static const char strs[] = "\0enum64";
- __u32 types[] = {
- BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_ENUM64, 0, 0), 8),
- };
-
- return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
- strs, sizeof(strs)));
-}
-
-static int probe_kern_syscall_wrapper(void);
-
-enum kern_feature_result {
- FEAT_UNKNOWN = 0,
- FEAT_SUPPORTED = 1,
- FEAT_MISSING = 2,
-};
-
-struct kern_feature_cache {
- enum kern_feature_result res[__FEAT_CNT];
-};
-
-typedef int (*feature_probe_fn)(void);
-
-static struct kern_feature_cache feature_cache;
-
-static struct kern_feature_desc {
- const char *desc;
- feature_probe_fn probe;
-} feature_probes[__FEAT_CNT] = {
- [FEAT_PROG_NAME] = {
- "BPF program name", probe_kern_prog_name,
- },
- [FEAT_GLOBAL_DATA] = {
- "global variables", probe_kern_global_data,
- },
- [FEAT_BTF] = {
- "minimal BTF", probe_kern_btf,
- },
- [FEAT_BTF_FUNC] = {
- "BTF functions", probe_kern_btf_func,
- },
- [FEAT_BTF_GLOBAL_FUNC] = {
- "BTF global function", probe_kern_btf_func_global,
- },
- [FEAT_BTF_DATASEC] = {
- "BTF data section and variable", probe_kern_btf_datasec,
- },
- [FEAT_ARRAY_MMAP] = {
- "ARRAY map mmap()", probe_kern_array_mmap,
- },
- [FEAT_EXP_ATTACH_TYPE] = {
- "BPF_PROG_LOAD expected_attach_type attribute",
- probe_kern_exp_attach_type,
- },
- [FEAT_PROBE_READ_KERN] = {
- "bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel,
- },
- [FEAT_PROG_BIND_MAP] = {
- "BPF_PROG_BIND_MAP support", probe_prog_bind_map,
- },
- [FEAT_MODULE_BTF] = {
- "module BTF support", probe_module_btf,
- },
- [FEAT_BTF_FLOAT] = {
- "BTF_KIND_FLOAT support", probe_kern_btf_float,
- },
- [FEAT_PERF_LINK] = {
- "BPF perf link support", probe_perf_link,
- },
- [FEAT_BTF_DECL_TAG] = {
- "BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag,
- },
- [FEAT_BTF_TYPE_TAG] = {
- "BTF_KIND_TYPE_TAG support", probe_kern_btf_type_tag,
- },
- [FEAT_MEMCG_ACCOUNT] = {
- "memcg-based memory accounting", probe_memcg_account,
- },
- [FEAT_BPF_COOKIE] = {
- "BPF cookie support", probe_kern_bpf_cookie,
- },
- [FEAT_BTF_ENUM64] = {
- "BTF_KIND_ENUM64 support", probe_kern_btf_enum64,
- },
- [FEAT_SYSCALL_WRAPPER] = {
- "Kernel using syscall wrapper", probe_kern_syscall_wrapper,
- },
- [FEAT_UPROBE_MULTI_LINK] = {
- "BPF multi-uprobe link support", probe_uprobe_multi_link,
- },
-};
-
-bool feat_supported(struct kern_feature_cache *cache, enum kern_feature_id feat_id)
-{
- struct kern_feature_desc *feat = &feature_probes[feat_id];
- int ret;
-
- /* assume global feature cache, unless custom one is provided */
- if (!cache)
- cache = &feature_cache;
-
- if (READ_ONCE(cache->res[feat_id]) == FEAT_UNKNOWN) {
- ret = feat->probe();
- if (ret > 0) {
- WRITE_ONCE(cache->res[feat_id], FEAT_SUPPORTED);
- } else if (ret == 0) {
- WRITE_ONCE(cache->res[feat_id], FEAT_MISSING);
- } else {
- pr_warn("Detection of kernel %s support failed: %d\n", feat->desc, ret);
- WRITE_ONCE(cache->res[feat_id], FEAT_MISSING);
- }
- }
-
- return READ_ONCE(cache->res[feat_id]) == FEAT_SUPPORTED;
-}
-
bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)
{
if (obj && obj->gen_loader)
@@ -11046,7 +10585,7 @@ static const char *arch_specific_syscall_pfx(void)
#endif
}
-static int probe_kern_syscall_wrapper(void)
+int probe_kern_syscall_wrapper(void)
{
char syscall_name[64];
const char *ksys_pfx;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 622892fc841d..fa25e1232bc8 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -361,10 +361,20 @@ enum kern_feature_id {
__FEAT_CNT,
};
-struct kern_feature_cache;
+enum kern_feature_result {
+ FEAT_UNKNOWN = 0,
+ FEAT_SUPPORTED = 1,
+ FEAT_MISSING = 2,
+};
+
+struct kern_feature_cache {
+ enum kern_feature_result res[__FEAT_CNT];
+};
+
bool feat_supported(struct kern_feature_cache *cache, enum kern_feature_id feat_id);
bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id);
+int probe_kern_syscall_wrapper(void);
int probe_memcg_account(void);
int bump_rlimit_memlock(void);
@@ -626,4 +636,6 @@ int elf_resolve_syms_offsets(const char *binary_path, int cnt,
int elf_resolve_pattern_offsets(const char *binary_path, const char *pattern,
unsigned long **poffsets, size_t *pcnt);
+int probe_fd(int fd);
+
#endif /* __LIBBPF_LIBBPF_INTERNAL_H */
diff --git a/tools/lib/bpf/str_error.h b/tools/lib/bpf/str_error.h
index a139334d57b6..626d7ffb03d6 100644
--- a/tools/lib/bpf/str_error.h
+++ b/tools/lib/bpf/str_error.h
@@ -2,5 +2,8 @@
#ifndef __LIBBPF_STR_ERROR_H
#define __LIBBPF_STR_ERROR_H
+#define STRERR_BUFSIZE 128
+
char *libbpf_strerror_r(int err, char *dst, int len);
+
#endif /* __LIBBPF_STR_ERROR_H */
--
2.34.1
More information about the Linux-security-module-archive
mailing list