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-rw-r--r--tools/lib/bpf/libbpf.h52
-rw-r--r--tools/lib/bpf/libbpf.map3
-rw-r--r--tools/lib/bpf/libbpf_probes.c235
3 files changed, 236 insertions, 54 deletions
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 42b2f36fd9f0..85dfef88b3d2 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1052,13 +1052,57 @@ bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
* user, causing subsequent probes to fail. In this case, the caller may want
* to adjust that limit with setrlimit().
*/
-LIBBPF_API bool bpf_probe_prog_type(enum bpf_prog_type prog_type,
- __u32 ifindex);
+LIBBPF_DEPRECATED_SINCE(0, 8, "use libbpf_probe_bpf_prog_type() instead")
+LIBBPF_API bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex);
+LIBBPF_DEPRECATED_SINCE(0, 8, "use libbpf_probe_bpf_map_type() instead")
LIBBPF_API bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex);
-LIBBPF_API bool bpf_probe_helper(enum bpf_func_id id,
- enum bpf_prog_type prog_type, __u32 ifindex);
+LIBBPF_DEPRECATED_SINCE(0, 8, "use libbpf_probe_bpf_helper() instead")
+LIBBPF_API bool bpf_probe_helper(enum bpf_func_id id, enum bpf_prog_type prog_type, __u32 ifindex);
+LIBBPF_DEPRECATED_SINCE(0, 8, "implement your own or use bpftool for feature detection")
LIBBPF_API bool bpf_probe_large_insn_limit(__u32 ifindex);
+/**
+ * @brief **libbpf_probe_bpf_prog_type()** detects if host kernel supports
+ * BPF programs of a given type.
+ * @param prog_type BPF program type to detect kernel support for
+ * @param opts reserved for future extensibility, should be NULL
+ * @return 1, if given program type is supported; 0, if given program type is
+ * not supported; negative error code if feature detection failed or can't be
+ * performed
+ *
+ * Make sure the process has required set of CAP_* permissions (or runs as
+ * root) when performing feature checking.
+ */
+LIBBPF_API int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts);
+/**
+ * @brief **libbpf_probe_bpf_map_type()** detects if host kernel supports
+ * BPF maps of a given type.
+ * @param map_type BPF map type to detect kernel support for
+ * @param opts reserved for future extensibility, should be NULL
+ * @return 1, if given map type is supported; 0, if given map type is
+ * not supported; negative error code if feature detection failed or can't be
+ * performed
+ *
+ * Make sure the process has required set of CAP_* permissions (or runs as
+ * root) when performing feature checking.
+ */
+LIBBPF_API int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts);
+/**
+ * @brief **libbpf_probe_bpf_helper()** detects if host kernel supports the
+ * use of a given BPF helper from specified BPF program type.
+ * @param prog_type BPF program type used to check the support of BPF helper
+ * @param helper_id BPF helper ID (enum bpf_func_id) to check support for
+ * @param opts reserved for future extensibility, should be NULL
+ * @return 1, if given combination of program type and helper is supported; 0,
+ * if the combination is not supported; negative error code if feature
+ * detection for provided input arguments failed or can't be performed
+ *
+ * Make sure the process has required set of CAP_* permissions (or runs as
+ * root) when performing feature checking.
+ */
+LIBBPF_API int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type,
+ enum bpf_func_id helper_id, const void *opts);
+
/*
* Get bpf_prog_info in continuous memory
*
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index b3938b3f8fc9..529783967793 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -427,5 +427,8 @@ LIBBPF_0.7.0 {
bpf_program__log_level;
bpf_program__set_log_buf;
bpf_program__set_log_level;
+ libbpf_probe_bpf_helper;
+ libbpf_probe_bpf_map_type;
+ libbpf_probe_bpf_prog_type;
libbpf_set_memlock_rlim_max;
};
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index 4bdec69523a7..9d3985283dfc 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -64,12 +64,20 @@ static int get_kernel_version(void)
return (version << 16) + (subversion << 8) + patchlevel;
}
-static void
-probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
- size_t insns_cnt, char *buf, size_t buf_len, __u32 ifindex)
+static int probe_prog_load(enum bpf_prog_type prog_type,
+ const struct bpf_insn *insns, size_t insns_cnt,
+ char *log_buf, size_t log_buf_sz,
+ __u32 ifindex)
{
- LIBBPF_OPTS(bpf_prog_load_opts, opts);
- int fd;
+ LIBBPF_OPTS(bpf_prog_load_opts, opts,
+ .log_buf = log_buf,
+ .log_size = log_buf_sz,
+ .log_level = log_buf ? 1 : 0,
+ .prog_ifindex = ifindex,
+ );
+ int fd, err, exp_err = 0;
+ const char *exp_msg = NULL;
+ char buf[4096];
switch (prog_type) {
case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
@@ -84,6 +92,38 @@ probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
case BPF_PROG_TYPE_KPROBE:
opts.kern_version = get_kernel_version();
break;
+ case BPF_PROG_TYPE_LIRC_MODE2:
+ opts.expected_attach_type = BPF_LIRC_MODE2;
+ break;
+ case BPF_PROG_TYPE_TRACING:
+ case BPF_PROG_TYPE_LSM:
+ opts.log_buf = buf;
+ opts.log_size = sizeof(buf);
+ opts.log_level = 1;
+ if (prog_type == BPF_PROG_TYPE_TRACING)
+ opts.expected_attach_type = BPF_TRACE_FENTRY;
+ else
+ opts.expected_attach_type = BPF_MODIFY_RETURN;
+ opts.attach_btf_id = 1;
+
+ exp_err = -EINVAL;
+ exp_msg = "attach_btf_id 1 is not a function";
+ break;
+ case BPF_PROG_TYPE_EXT:
+ opts.log_buf = buf;
+ opts.log_size = sizeof(buf);
+ opts.log_level = 1;
+ opts.attach_btf_id = 1;
+
+ exp_err = -EINVAL;
+ exp_msg = "Cannot replace kernel functions";
+ break;
+ case BPF_PROG_TYPE_SYSCALL:
+ opts.prog_flags = BPF_F_SLEEPABLE;
+ break;
+ case BPF_PROG_TYPE_STRUCT_OPS:
+ exp_err = -524; /* -ENOTSUPP */
+ break;
case BPF_PROG_TYPE_UNSPEC:
case BPF_PROG_TYPE_SOCKET_FILTER:
case BPF_PROG_TYPE_SCHED_CLS:
@@ -103,25 +143,42 @@ probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
case BPF_PROG_TYPE_RAW_TRACEPOINT:
case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
case BPF_PROG_TYPE_LWT_SEG6LOCAL:
- case BPF_PROG_TYPE_LIRC_MODE2:
case BPF_PROG_TYPE_SK_REUSEPORT:
case BPF_PROG_TYPE_FLOW_DISSECTOR:
case BPF_PROG_TYPE_CGROUP_SYSCTL:
- case BPF_PROG_TYPE_TRACING:
- case BPF_PROG_TYPE_STRUCT_OPS:
- case BPF_PROG_TYPE_EXT:
- case BPF_PROG_TYPE_LSM:
- default:
break;
+ default:
+ return -EOPNOTSUPP;
}
- opts.prog_ifindex = ifindex;
- opts.log_buf = buf;
- opts.log_size = buf_len;
-
- fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, NULL);
+ fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts);
+ err = -errno;
if (fd >= 0)
close(fd);
+ if (exp_err) {
+ if (fd >= 0 || err != exp_err)
+ return 0;
+ if (exp_msg && !strstr(buf, exp_msg))
+ return 0;
+ return 1;
+ }
+ return fd >= 0 ? 1 : 0;
+}
+
+int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts)
+{
+ struct bpf_insn insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN()
+ };
+ const size_t insn_cnt = ARRAY_SIZE(insns);
+ int ret;
+
+ if (opts)
+ return libbpf_err(-EINVAL);
+
+ ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, 0, 0);
+ return libbpf_err(ret);
}
bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex)
@@ -131,12 +188,16 @@ bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex)
BPF_EXIT_INSN()
};
+ /* prefer libbpf_probe_bpf_prog_type() unless offload is requested */
+ if (ifindex == 0)
+ return libbpf_probe_bpf_prog_type(prog_type, NULL) == 1;
+
if (ifindex && prog_type == BPF_PROG_TYPE_SCHED_CLS)
/* nfp returns -EINVAL on exit(0) with TC offload */
insns[0].imm = 2;
errno = 0;
- probe_load(prog_type, insns, ARRAY_SIZE(insns), NULL, 0, ifindex);
+ probe_prog_load(prog_type, insns, ARRAY_SIZE(insns), NULL, 0, ifindex);
return errno != EINVAL && errno != EOPNOTSUPP;
}
@@ -197,16 +258,18 @@ static int load_local_storage_btf(void)
strs, sizeof(strs));
}
-bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
+static int probe_map_create(enum bpf_map_type map_type, __u32 ifindex)
{
- int key_size, value_size, max_entries, map_flags;
+ LIBBPF_OPTS(bpf_map_create_opts, opts);
+ int key_size, value_size, max_entries;
__u32 btf_key_type_id = 0, btf_value_type_id = 0;
- int fd = -1, btf_fd = -1, fd_inner;
+ int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err;
+
+ opts.map_ifindex = ifindex;
key_size = sizeof(__u32);
value_size = sizeof(__u32);
max_entries = 1;
- map_flags = 0;
switch (map_type) {
case BPF_MAP_TYPE_STACK_TRACE:
@@ -215,7 +278,7 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
case BPF_MAP_TYPE_LPM_TRIE:
key_size = sizeof(__u64);
value_size = sizeof(__u64);
- map_flags = BPF_F_NO_PREALLOC;
+ opts.map_flags = BPF_F_NO_PREALLOC;
break;
case BPF_MAP_TYPE_CGROUP_STORAGE:
case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
@@ -234,17 +297,25 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
btf_value_type_id = 3;
value_size = 8;
max_entries = 0;
- map_flags = BPF_F_NO_PREALLOC;
+ opts.map_flags = BPF_F_NO_PREALLOC;
btf_fd = load_local_storage_btf();
if (btf_fd < 0)
- return false;
+ return btf_fd;
break;
case BPF_MAP_TYPE_RINGBUF:
key_size = 0;
value_size = 0;
max_entries = 4096;
break;
- case BPF_MAP_TYPE_UNSPEC:
+ case BPF_MAP_TYPE_STRUCT_OPS:
+ /* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */
+ opts.btf_vmlinux_value_type_id = 1;
+ exp_err = -524; /* -ENOTSUPP */
+ break;
+ case BPF_MAP_TYPE_BLOOM_FILTER:
+ key_size = 0;
+ max_entries = 1;
+ break;
case BPF_MAP_TYPE_HASH:
case BPF_MAP_TYPE_ARRAY:
case BPF_MAP_TYPE_PROG_ARRAY:
@@ -263,49 +334,114 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
case BPF_MAP_TYPE_XSKMAP:
case BPF_MAP_TYPE_SOCKHASH:
case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
- case BPF_MAP_TYPE_STRUCT_OPS:
- default:
break;
+ case BPF_MAP_TYPE_UNSPEC:
+ default:
+ return -EOPNOTSUPP;
}
if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
- LIBBPF_OPTS(bpf_map_create_opts, opts);
-
/* TODO: probe for device, once libbpf has a function to create
* map-in-map for offload
*/
if (ifindex)
- return false;
+ goto cleanup;
fd_inner = bpf_map_create(BPF_MAP_TYPE_HASH, NULL,
sizeof(__u32), sizeof(__u32), 1, NULL);
if (fd_inner < 0)
- return false;
+ goto cleanup;
opts.inner_map_fd = fd_inner;
- fd = bpf_map_create(map_type, NULL, sizeof(__u32), sizeof(__u32), 1, &opts);
- close(fd_inner);
- } else {
- LIBBPF_OPTS(bpf_map_create_opts, opts);
-
- /* Note: No other restriction on map type probes for offload */
- opts.map_flags = map_flags;
- opts.map_ifindex = ifindex;
- if (btf_fd >= 0) {
- opts.btf_fd = btf_fd;
- opts.btf_key_type_id = btf_key_type_id;
- opts.btf_value_type_id = btf_value_type_id;
- }
+ }
- fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts);
+ if (btf_fd >= 0) {
+ opts.btf_fd = btf_fd;
+ opts.btf_key_type_id = btf_key_type_id;
+ opts.btf_value_type_id = btf_value_type_id;
}
+
+ fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts);
+ err = -errno;
+
+cleanup:
if (fd >= 0)
close(fd);
+ if (fd_inner >= 0)
+ close(fd_inner);
if (btf_fd >= 0)
close(btf_fd);
- return fd >= 0;
+ if (exp_err)
+ return fd < 0 && err == exp_err ? 1 : 0;
+ else
+ return fd >= 0 ? 1 : 0;
+}
+
+int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts)
+{
+ int ret;
+
+ if (opts)
+ return libbpf_err(-EINVAL);
+
+ ret = probe_map_create(map_type, 0);
+ return libbpf_err(ret);
+}
+
+bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
+{
+ return probe_map_create(map_type, ifindex) == 1;
+}
+
+int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id,
+ const void *opts)
+{
+ struct bpf_insn insns[] = {
+ BPF_EMIT_CALL((__u32)helper_id),
+ BPF_EXIT_INSN(),
+ };
+ const size_t insn_cnt = ARRAY_SIZE(insns);
+ char buf[4096];
+ int ret;
+
+ if (opts)
+ return libbpf_err(-EINVAL);
+
+ /* we can't successfully load all prog types to check for BPF helper
+ * support, so bail out with -EOPNOTSUPP error
+ */
+ switch (prog_type) {
+ case BPF_PROG_TYPE_TRACING:
+ case BPF_PROG_TYPE_EXT:
+ case BPF_PROG_TYPE_LSM:
+ case BPF_PROG_TYPE_STRUCT_OPS:
+ return -EOPNOTSUPP;
+ default:
+ break;
+ }
+
+ buf[0] = '\0';
+ ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf), 0);
+ if (ret < 0)
+ return libbpf_err(ret);
+
+ /* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id)
+ * at all, it will emit something like "invalid func unknown#181".
+ * If BPF verifier recognizes BPF helper but it's not supported for
+ * given BPF program type, it will emit "unknown func bpf_sys_bpf#166".
+ * In both cases, provided combination of BPF program type and BPF
+ * helper is not supported by the kernel.
+ * In all other cases, probe_prog_load() above will either succeed (e.g.,
+ * because BPF helper happens to accept no input arguments or it
+ * accepts one input argument and initial PTR_TO_CTX is fine for
+ * that), or we'll get some more specific BPF verifier error about
+ * some unsatisfied conditions.
+ */
+ if (ret == 0 && (strstr(buf, "invalid func ") || strstr(buf, "unknown func ")))
+ return 0;
+ return 1; /* assume supported */
}
bool bpf_probe_helper(enum bpf_func_id id, enum bpf_prog_type prog_type,
@@ -318,8 +454,7 @@ bool bpf_probe_helper(enum bpf_func_id id, enum bpf_prog_type prog_type,
char buf[4096] = {};
bool res;
- probe_load(prog_type, insns, ARRAY_SIZE(insns), buf, sizeof(buf),
- ifindex);
+ probe_prog_load(prog_type, insns, ARRAY_SIZE(insns), buf, sizeof(buf), ifindex);
res = !grep(buf, "invalid func ") && !grep(buf, "unknown func ");
if (ifindex) {
@@ -351,8 +486,8 @@ bool bpf_probe_large_insn_limit(__u32 ifindex)
insns[BPF_MAXINSNS] = BPF_EXIT_INSN();
errno = 0;
- probe_load(BPF_PROG_TYPE_SCHED_CLS, insns, ARRAY_SIZE(insns), NULL, 0,
- ifindex);
+ probe_prog_load(BPF_PROG_TYPE_SCHED_CLS, insns, ARRAY_SIZE(insns), NULL, 0,
+ ifindex);
return errno != E2BIG && errno != EINVAL;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-19 14:08:10 +0000