In multi-threaded applications bpf_get_current_comm is returning per-thread
names, this helper will return comm from real_parent.
This makes a difference for some Java applications, where get_current_comm is
returning per-thread names, but get_current_pcomm will return "java".
Signed-off-by: Carlos Neira <cneirabustos@xxxxxxxxx>
---
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 15 ++++-
kernel/bpf/core.c | 1 +
kernel/bpf/helpers.c | 28 +++++++++
kernel/trace/bpf_trace.c | 2 +
tools/include/uapi/linux/bpf.h | 15 ++++-
.../selftests/bpf/prog_tests/current_pcomm.c | 57 +++++++++++++++++++
.../selftests/bpf/progs/test_current_pcomm.c | 17 ++++++
8 files changed, 134 insertions(+), 2 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/current_pcomm.c
create mode 100644 tools/testing/selftests/bpf/progs/test_current_pcomm.c
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 81f38e2fda78..93b0c197fd75 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1754,6 +1754,7 @@ extern const struct bpf_func_proto bpf_skc_to_tcp_sock_proto;
extern const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto;
extern const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto;
extern const struct bpf_func_proto bpf_skc_to_udp6_sock_proto;
+extern const struct bpf_func_proto bpf_get_current_pcomm_proto;
const struct bpf_func_proto *bpf_tracing_func_proto(
enum bpf_func_id func_id, const struct bpf_prog *prog);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 544b89a64918..200a2309e5e1 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3509,6 +3509,18 @@ union bpf_attr {
*
* **-EPERM** This helper cannot be used under the
* current sock_ops->op.
+ *
+ * long bpf_get_current_pcomm(void *buf, u32 size_of_buf)
+ * Description
+ * Copy the **comm** attribute of the real_parent current task
+ * into *buf* of *size_of_buf*. The **comm** attribute contains
+ * the name of the executable (excluding the path) for real_parent
+ * of current task.
+ * The *size_of_buf* must be strictly positive. On success, the
+ * helper makes sure that the *buf* is NUL-terminated. On failure,
+ * it is filled with zeroes.
+ * Return
+ * 0 on success, or a negative error in case of failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3655,7 +3667,8 @@ union bpf_attr {
FN(get_task_stack), \
FN(load_hdr_opt), \
FN(store_hdr_opt), \
- FN(reserve_hdr_opt),
+ FN(reserve_hdr_opt), \
+ FN(get_current_pcomm), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ed0b3578867c..fd346c2ff6f6 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2208,6 +2208,7 @@ const struct bpf_func_proto bpf_get_current_cgroup_id_proto __weak;
const struct bpf_func_proto bpf_get_current_ancestor_cgroup_id_proto __weak;
const struct bpf_func_proto bpf_get_local_storage_proto __weak;
const struct bpf_func_proto bpf_get_ns_current_pid_tgid_proto __weak;
+const struct bpf_func_proto bpf_get_current_pcomm_proto __weak;
const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)
{
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index be43ab3e619f..9fb663945e0b 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -575,6 +575,34 @@ const struct bpf_func_proto bpf_get_ns_current_pid_tgid_proto = {
.arg4_type = ARG_CONST_SIZE,
};
+BPF_CALL_2(bpf_get_current_pcomm, char *, buf, u32, size)
+{
+ struct task_struct *task = current;
+
+ if (unlikely(!task))
+ goto err_clear;
+
+ strncpy(buf, task->real_parent->comm, size);
+
+ /* Verifier guarantees that size > 0. For task->comm exceeding
+ * size, guarantee that buf is %NUL-terminated. Unconditionally
+ * done here to save the size test.
+ */
+ buf[size - 1] = 0;
+ return 0;
+err_clear:
+ memset(buf, 0, size);
+ return -EINVAL;
+}
+
+const struct bpf_func_proto bpf_get_current_pcomm_proto = {
+ .func = bpf_get_current_pcomm,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_UNINIT_MEM,
+ .arg2_type = ARG_CONST_SIZE,
+};
+
static const struct bpf_func_proto bpf_get_raw_smp_processor_id_proto = {
.func = bpf_get_raw_cpu_id,
.gpl_only = false,
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index a8d4f253ed77..7cfeb58c729a 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1182,6 +1182,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_jiffies64_proto;
case BPF_FUNC_get_task_stack:
return &bpf_get_task_stack_proto;
+ case BPF_FUNC_get_current_pcomm:
+ return &bpf_get_current_pcomm_proto;
default:
return NULL;
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 544b89a64918..200a2309e5e1 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3509,6 +3509,18 @@ union bpf_attr {
*
* **-EPERM** This helper cannot be used under the
* current sock_ops->op.
+ *
+ * long bpf_get_current_pcomm(void *buf, u32 size_of_buf)
+ * Description
+ * Copy the **comm** attribute of the real_parent current task
+ * into *buf* of *size_of_buf*. The **comm** attribute contains
+ * the name of the executable (excluding the path) for real_parent
+ * of current task.
+ * The *size_of_buf* must be strictly positive. On success, the
+ * helper makes sure that the *buf* is NUL-terminated. On failure,
+ * it is filled with zeroes.
+ * Return
+ * 0 on success, or a negative error in case of failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3655,7 +3667,8 @@ union bpf_attr {
FN(get_task_stack), \
FN(load_hdr_opt), \
FN(store_hdr_opt), \
- FN(reserve_hdr_opt),
+ FN(reserve_hdr_opt), \
+ FN(get_current_pcomm), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/tools/testing/selftests/bpf/prog_tests/current_pcomm.c b/tools/testing/selftests/bpf/prog_tests/current_pcomm.c
new file mode 100644
index 000000000000..23b708e1c417
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/current_pcomm.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Carlos Neira cneirabustos@xxxxxxxxx */
+
+#define _GNU_SOURCE
+#include <test_progs.h>
+#include "test_current_pcomm.skel.h"
+#include <sys/types.h>
+#include <unistd.h>
+#include <string.h>
+#include <pthread.h>
+
+void *current_pcomm(void *args)
+{
+ struct test_current_pcomm__bss *bss;
+ struct test_current_pcomm *skel;
+ int err, duration = 0;
+
+ skel = test_current_pcomm__open_and_load();
+ if (CHECK(!skel, "skel_open_load", "failed to load skeleton"))
+ goto cleanup;
+
+ bss = skel->bss;
+
+ err = test_current_pcomm__attach(skel);
+ if (CHECK(err, "skel_attach", "skeleton attach failed %d", err))
+ goto cleanup;
+
+ /* trigger tracepoint */
+ usleep(10);
+ err = memcmp(bss->comm, "current_pcomm2", 14);
+ if (CHECK(!err, "pcomm ", "bss->comm: %s\n", bss->comm))
+ goto cleanup;
+cleanup:
+ test_current_pcomm__destroy(skel);
+ return NULL;
+}
+
+int test_current_pcomm(void)
+{
+ int err = 0, duration = 0;
+ pthread_t tid;
+
+ err = pthread_create(&tid, NULL, ¤t_pcomm, NULL);
+ if (CHECK(err, "thread", "thread creation failed %d", err))
+ return EXIT_FAILURE;
+ err = pthread_setname_np(tid, "current_pcomm2");
+ if (CHECK(err, "thread naming", "thread naming failed %d", err))
+ return EXIT_FAILURE;
+
+ usleep(5);
+
+ err = pthread_join(tid, NULL);
+ if (CHECK(err, "thread join", "thread join failed %d", err))
+ return EXIT_FAILURE;
+
+ return EXIT_SUCCESS;
+}
diff --git a/tools/testing/selftests/bpf/progs/test_current_pcomm.c b/tools/testing/selftests/bpf/progs/test_current_pcomm.c
new file mode 100644
index 000000000000..27dab17ccdd4
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_current_pcomm.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Carlos Neira cneirabustos@xxxxxxxxx */
+
+#include <linux/bpf.h>
+#include <stdint.h>
+#include <bpf/bpf_helpers.h>
+
+char comm[16] = {0};
+
+SEC("raw_tracepoint/sys_enter")
+int current_pcomm(const void *ctx)
+{
+ bpf_get_current_pcomm(comm, sizeof(comm));
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.20.1
