1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
  3
  4#include <vmlinux.h>
  5#include <bpf/bpf_helpers.h>
  6#include <bpf/bpf_tracing.h>
  7#include <bpf/bpf_core_read.h>
  8#include "bpf_misc.h"
  9#include "xdp_metadata.h"
 10#include "bpf_kfuncs.h"
 11
 12extern struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym __weak;
 13extern void bpf_task_release(struct task_struct *p) __ksym __weak;
 14
 15__weak int subprog_trusted_task_nullable(struct task_struct *task __arg_trusted __arg_nullable)
 16{
 17	if (!task)
 18		return 0;
 19	return task->pid + task->tgid;
 20}
 21
 22__weak int subprog_trusted_task_nullable_extra_layer(struct task_struct *task __arg_trusted __arg_nullable)
 23{
 24	return subprog_trusted_task_nullable(task) + subprog_trusted_task_nullable(NULL);
 25}
 26
 27SEC("?tp_btf/task_newtask")
 28__success __log_level(2)
 29__msg("Validating subprog_trusted_task_nullable() func#1...")
 30__msg(": R1=trusted_ptr_or_null_task_struct(")
 31int trusted_task_arg_nullable(void *ctx)
 32{
 33	struct task_struct *t1 = bpf_get_current_task_btf();
 34	struct task_struct *t2 = bpf_task_acquire(t1);
 35	int res = 0;
 36
 37	/* known NULL */
 38	res += subprog_trusted_task_nullable(NULL);
 39
 40	/* known non-NULL */
 41	res += subprog_trusted_task_nullable(t1);
 42	res += subprog_trusted_task_nullable_extra_layer(t1);
 43
 44	/* unknown if NULL or not */
 45	res += subprog_trusted_task_nullable(t2);
 46	res += subprog_trusted_task_nullable_extra_layer(t2);
 47
 48	if (t2) {
 49		/* known non-NULL after explicit NULL check, just in case */
 50		res += subprog_trusted_task_nullable(t2);
 51		res += subprog_trusted_task_nullable_extra_layer(t2);
 52
 53		bpf_task_release(t2);
 54	}
 55
 56	return res;
 57}
 58
 59__weak int subprog_trusted_task_nonnull(struct task_struct *task __arg_trusted)
 60{
 61	return task->pid + task->tgid;
 62}
 63
 64SEC("?kprobe")
 65__failure __log_level(2)
 66__msg("R1 type=scalar expected=ptr_, trusted_ptr_, rcu_ptr_")
 67__msg("Caller passes invalid args into func#1 ('subprog_trusted_task_nonnull')")
 68int trusted_task_arg_nonnull_fail1(void *ctx)
 69{
 70	return subprog_trusted_task_nonnull(NULL);
 71}
 72
 73SEC("?tp_btf/task_newtask")
 74__failure __log_level(2)
 75__msg("R1 type=ptr_or_null_ expected=ptr_, trusted_ptr_, rcu_ptr_")
 76__msg("Caller passes invalid args into func#1 ('subprog_trusted_task_nonnull')")
 77int trusted_task_arg_nonnull_fail2(void *ctx)
 78{
 79	struct task_struct *t = bpf_get_current_task_btf();
 80	struct task_struct *nullable;
 81	int res;
 82
 83	nullable = bpf_task_acquire(t);
 84
 85	 /* should fail, PTR_TO_BTF_ID_OR_NULL */
 86	res = subprog_trusted_task_nonnull(nullable);
 87
 88	if (nullable)
 89		bpf_task_release(nullable);
 90
 91	return res;
 92}
 93
 94SEC("?kprobe")
 95__success __log_level(2)
 96__msg("Validating subprog_trusted_task_nonnull() func#1...")
 97__msg(": R1=trusted_ptr_task_struct(")
 98int trusted_task_arg_nonnull(void *ctx)
 99{
100	struct task_struct *t = bpf_get_current_task_btf();
101
102	return subprog_trusted_task_nonnull(t);
103}
104
105struct task_struct___local {} __attribute__((preserve_access_index));
106
107__weak int subprog_nullable_task_flavor(
108	struct task_struct___local *task __arg_trusted __arg_nullable)
109{
110	char buf[16];
111
112	if (!task)
113		return 0;
114
115	return bpf_copy_from_user_task(&buf, sizeof(buf), NULL, (void *)task, 0);
116}
117
118SEC("?uprobe.s")
119__success __log_level(2)
120__msg("Validating subprog_nullable_task_flavor() func#1...")
121__msg(": R1=trusted_ptr_or_null_task_struct(")
122int flavor_ptr_nullable(void *ctx)
123{
124	struct task_struct___local *t = (void *)bpf_get_current_task_btf();
125
126	return subprog_nullable_task_flavor(t);
127}
128
129__weak int subprog_nonnull_task_flavor(struct task_struct___local *task __arg_trusted)
130{
131	char buf[16];
132
133	return bpf_copy_from_user_task(&buf, sizeof(buf), NULL, (void *)task, 0);
134}
135
136SEC("?uprobe.s")
137__success __log_level(2)
138__msg("Validating subprog_nonnull_task_flavor() func#1...")
139__msg(": R1=trusted_ptr_task_struct(")
140int flavor_ptr_nonnull(void *ctx)
141{
142	struct task_struct *t = bpf_get_current_task_btf();
143
144	return subprog_nonnull_task_flavor((void *)t);
145}
146
147__weak int subprog_trusted_destroy(struct task_struct *task __arg_trusted)
148{
149	bpf_task_release(task); /* should be rejected */
150
151	return 0;
152}
153
154SEC("?tp_btf/task_newtask")
155__failure __log_level(2)
156__msg("release kernel function bpf_task_release expects refcounted PTR_TO_BTF_ID")
157int BPF_PROG(trusted_destroy_fail, struct task_struct *task, u64 clone_flags)
158{
159	return subprog_trusted_destroy(task);
160}
161
162__weak int subprog_trusted_acq_rel(struct task_struct *task __arg_trusted)
163{
164	struct task_struct *owned;
165
166	owned = bpf_task_acquire(task);
167	if (!owned)
168		return 0;
169
170	bpf_task_release(owned); /* this one is OK, we acquired it locally */
171
172	return 0;
173}
174
175SEC("?tp_btf/task_newtask")
176__success __log_level(2)
177int BPF_PROG(trusted_acq_rel, struct task_struct *task, u64 clone_flags)
178{
179	return subprog_trusted_acq_rel(task);
180}
181
182char _license[] SEC("license") = "GPL";