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_ref * 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 struct task_struct *bpf_task_kptr_get(struct task_struct **pp) __ksym; 25 void bpf_task_release(struct task_struct *p) __ksym; 26 27 static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p) 28 { 29 s32 pid; 30 long status; 31 32 status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid); 33 if (status) 34 return NULL; 35 36 return bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); 37 } 38 39 static inline int tasks_kfunc_map_insert(struct task_struct *p) 40 { 41 struct __tasks_kfunc_map_value local, *v; 42 long status; 43 struct task_struct *acquired, *old; 44 s32 pid; 45 46 status = bpf_probe_read_kernel(&pid, sizeof(pid), &p->pid); 47 if (status) 48 return status; 49 50 local.task = NULL; 51 status = bpf_map_update_elem(&__tasks_kfunc_map, &pid, &local, BPF_NOEXIST); 52 if (status) 53 return status; 54 55 v = bpf_map_lookup_elem(&__tasks_kfunc_map, &pid); 56 if (!v) { 57 bpf_map_delete_elem(&__tasks_kfunc_map, &pid); 58 return -ENOENT; 59 } 60 61 acquired = bpf_task_acquire(p); 62 old = bpf_kptr_xchg(&v->task, acquired); 63 if (old) { 64 bpf_task_release(old); 65 return -EEXIST; 66 } 67 68 return 0; 69 } 70 71 #endif /* _TASK_KFUNC_COMMON_H */ 72