Subject: [PATCH bpf-next 1/3] bpf: preserve command of the process that loaded the program

From: Stanislav Fomichev <[email-masked]>
Date: Fri, 11 Oct 2019 09:21:22 -0700

Even though we have the pointer to user_struct and can recover
uid of the user who has created the program, it usually contains
0 (root) which is not very informative. Let's store the comm of the
calling process and export it via bpf_prog_info. This should help
answer the question "which process loaded this particular program".

Signed-off-by: Stanislav Fomichev <[email-masked]>
---
 include/linux/bpf.h      | 1 +
 include/uapi/linux/bpf.h | 2 ++
 kernel/bpf/syscall.c     | 4 ++++
 3 files changed, 7 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 5b9d22338606..b03ea396afe5 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -421,6 +421,7 @@ struct bpf_prog_aux {
 		struct work_struct work;
 		struct rcu_head	rcu;
 	};
+	char created_by_comm[BPF_CREATED_COMM_LEN];
 };
 
 struct bpf_array {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index a65c3b0c6935..4e883ecbba1e 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -326,6 +326,7 @@ enum bpf_attach_type {
 #define BPF_F_NUMA_NODE		(1U << 2)
 
 #define BPF_OBJ_NAME_LEN 16U
+#define BPF_CREATED_COMM_LEN	16U
 
 /* Flags for accessing BPF object from syscall side. */
 #define BPF_F_RDONLY		(1U << 3)
@@ -3252,6 +3253,7 @@ struct bpf_prog_info {
 	__aligned_u64 prog_tags;
 	__u64 run_time_ns;
 	__u64 run_cnt;
+	char created_by_comm[BPF_CREATED_COMM_LEN];
 } __attribute__((aligned(8)));
 
 struct bpf_map_info {
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 82eabd4e38ad..51c125292eaf 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1735,6 +1735,8 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
 	bpf_prog_kallsyms_add(prog);
 	perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_LOAD, 0);
 
+	get_task_comm(prog->aux->created_by_comm, current);
+
 	err = bpf_prog_new_fd(prog);
 	if (err < 0)
 		bpf_prog_put(prog);
@@ -2337,6 +2339,8 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
 
 	memcpy(info.tag, prog->tag, sizeof(prog->tag));
 	memcpy(info.name, prog->aux->name, sizeof(prog->aux->name));
+	memcpy(info.created_by_comm, prog->aux->created_by_comm,
+	       sizeof(prog->aux->created_by_comm));
 
 	ulen = info.nr_map_ids;
 	info.nr_map_ids = prog->aux->used_map_cnt;
-- 
2.23.0.700.g56cf767bdb-goog