1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | /* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ |
3 | |
4 | #ifndef _TASK_KFUNC_COMMON_H |
5 | #define _TASK_KFUNC_COMMON_H |
6 | |
7 | #include <errno.h> |
8 | #include <vmlinux.h> |
9 | #include <bpf/bpf_helpers.h> |
10 | #include <bpf/bpf_tracing.h> |
11 | |
12 | struct __tasks_kfunc_map_value { |
13 | struct task_struct __kptr * task; |
14 | }; |
15 | |
16 | struct hash_map { |
17 | __uint(type, BPF_MAP_TYPE_HASH); |
18 | __type(key, int); |
19 | __type(value, struct __tasks_kfunc_map_value); |
20 | __uint(max_entries, 1); |
21 | } __tasks_kfunc_map SEC(".maps" ); |
22 | |
23 | struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym; |
24 | void bpf_task_release(struct task_struct *p) __ksym; |
25 | struct task_struct *bpf_task_from_pid(s32 pid) __ksym; |
26 | void bpf_rcu_read_lock(void) __ksym; |
27 | void bpf_rcu_read_unlock(void) __ksym; |
28 | |
29 | static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p) |
30 | { |
31 | s32 pid; |
32 | long status; |
33 | |
34 | status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid); |
35 | if (status) |
36 | return NULL; |
37 | |
38 | return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); |
39 | } |
40 | |
41 | static inline int tasks_kfunc_map_insert(struct task_struct *p) |
42 | { |
43 | struct __tasks_kfunc_map_value local, *v; |
44 | long status; |
45 | struct task_struct *acquired, *old; |
46 | s32 pid; |
47 | |
48 | status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid); |
49 | if (status) |
50 | return status; |
51 | |
52 | local.task = NULL; |
53 | status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST); |
54 | if (status) |
55 | return status; |
56 | |
57 | v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); |
58 | if (!v) { |
59 | bpf_map_delete_elem(&__tasks_kfunc_map, &pid); |
60 | return -ENOENT; |
61 | } |
62 | |
63 | acquired = bpf_task_acquire(p); |
64 | if (!acquired) |
65 | return -ENOENT; |
66 | |
67 | old = bpf_kptr_xchg(&v->task, acquired); |
68 | if (old) { |
69 | bpf_task_release(old); |
70 | return -EEXIST; |
71 | } |
72 | |
73 | return 0; |
74 | } |
75 | |
76 | #endif /* _TASK_KFUNC_COMMON_H */ |
77 | |