1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 /* Copyright (c) 2020 Facebook */
3 #include <vmlinux.h>
4 #include <bpf/bpf_helpers.h>
5 #include <bpf/bpf_core_read.h>
6 #include <bpf/bpf_tracing.h>
7 #include "pid_iter.h"
8
9 /* keep in sync with the definition in main.h */
10 enum bpf_obj_type {
11 BPF_OBJ_UNKNOWN,
12 BPF_OBJ_PROG,
13 BPF_OBJ_MAP,
14 BPF_OBJ_LINK,
15 BPF_OBJ_BTF,
16 };
17
18 extern const void bpf_link_fops __ksym;
19 extern const void bpf_map_fops __ksym;
20 extern const void bpf_prog_fops __ksym;
21 extern const void btf_fops __ksym;
22
23 const volatile enum bpf_obj_type obj_type = BPF_OBJ_UNKNOWN;
24
get_obj_id(void * ent,enum bpf_obj_type type)25 static __always_inline __u32 get_obj_id(void *ent, enum bpf_obj_type type)
26 {
27 switch (type) {
28 case BPF_OBJ_PROG:
29 return BPF_CORE_READ((struct bpf_prog *)ent, aux, id);
30 case BPF_OBJ_MAP:
31 return BPF_CORE_READ((struct bpf_map *)ent, id);
32 case BPF_OBJ_BTF:
33 return BPF_CORE_READ((struct btf *)ent, id);
34 case BPF_OBJ_LINK:
35 return BPF_CORE_READ((struct bpf_link *)ent, id);
36 default:
37 return 0;
38 }
39 }
40
41 /* could be used only with BPF_LINK_TYPE_PERF_EVENT links */
get_bpf_cookie(struct bpf_link * link)42 static __u64 get_bpf_cookie(struct bpf_link *link)
43 {
44 struct bpf_perf_link *perf_link;
45 struct perf_event *event;
46
47 perf_link = container_of(link, struct bpf_perf_link, link);
48 event = BPF_CORE_READ(perf_link, perf_file, private_data);
49 return BPF_CORE_READ(event, bpf_cookie);
50 }
51
52 SEC("iter/task_file")
iter(struct bpf_iter__task_file * ctx)53 int iter(struct bpf_iter__task_file *ctx)
54 {
55 struct file *file = ctx->file;
56 struct task_struct *task = ctx->task;
57 struct pid_iter_entry e;
58 const void *fops;
59
60 if (!file || !task)
61 return 0;
62
63 switch (obj_type) {
64 case BPF_OBJ_PROG:
65 fops = &bpf_prog_fops;
66 break;
67 case BPF_OBJ_MAP:
68 fops = &bpf_map_fops;
69 break;
70 case BPF_OBJ_BTF:
71 fops = &btf_fops;
72 break;
73 case BPF_OBJ_LINK:
74 fops = &bpf_link_fops;
75 break;
76 default:
77 return 0;
78 }
79
80 if (file->f_op != fops)
81 return 0;
82
83 __builtin_memset(&e, 0, sizeof(e));
84 e.pid = task->tgid;
85 e.id = get_obj_id(file->private_data, obj_type);
86
87 if (obj_type == BPF_OBJ_LINK) {
88 struct bpf_link *link = (struct bpf_link *) file->private_data;
89
90 if (BPF_CORE_READ(link, type) == BPF_LINK_TYPE_PERF_EVENT) {
91 e.has_bpf_cookie = true;
92 e.bpf_cookie = get_bpf_cookie(link);
93 }
94 }
95
96 bpf_probe_read_kernel_str(&e.comm, sizeof(e.comm),
97 task->group_leader->comm);
98 bpf_seq_write(ctx->meta->seq, &e, sizeof(e));
99
100 return 0;
101 }
102
103 char LICENSE[] SEC("license") = "Dual BSD/GPL";
104