tools/testing/selftests/bpf/progs/rcu_read_lock.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2022 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_tracing_net.h"
   8 #include "bpf_misc.h"
   9
  10 char _license[] SEC("license") = "GPL";
  11
  12 struct {
  13         __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
  14         __uint(map_flags, BPF_F_NO_PREALLOC);
  15         __type(key, int);
  16         __type(value, long);
  17 } map_a SEC(".maps");
  18
  19 __u32 user_data, key_serial, target_pid;
  20 __u64 flags, task_storage_val, cgroup_id;
  21
  22 struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;
  23 void bpf_key_put(struct bpf_key *key) __ksym;
  24 void bpf_rcu_read_lock(void) __ksym;
  25 void bpf_rcu_read_unlock(void) __ksym;
  26 struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
  27 void bpf_task_release(struct task_struct *p) __ksym;
  28
  29 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
  30 int get_cgroup_id(void *ctx)
  31 {
  32         struct task_struct *task;
  33         struct css_set *cgroups;
  34
  35         task = bpf_get_current_task_btf();
  36         if (task->pid != target_pid)
  37                 return 0;
  38
  39         /* simulate bpf_get_current_cgroup_id() helper */
  40         bpf_rcu_read_lock();
  41         cgroups = task->cgroups;
  42         if (!cgroups)
  43                 goto unlock;
  44         cgroup_id = cgroups->dfl_cgrp->kn->id;
  45 unlock:
  46         bpf_rcu_read_unlock();
  47         return 0;
  48 }
  49
  50 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
  51 int task_succ(void *ctx)
  52 {
  53         struct task_struct *task, *real_parent;
  54         long init_val = 2;
  55         long *ptr;
  56
  57         task = bpf_get_current_task_btf();
  58         if (task->pid != target_pid)
  59                 return 0;
  60
  61         bpf_rcu_read_lock();
  62         /* region including helper using rcu ptr real_parent */
  63         real_parent = task->real_parent;
  64         if (!real_parent)
  65                 goto out;
  66         ptr = bpf_task_storage_get(&map_a, real_parent, &init_val,
  67                                    BPF_LOCAL_STORAGE_GET_F_CREATE);
  68         if (!ptr)
  69                 goto out;
  70         ptr = bpf_task_storage_get(&map_a, real_parent, 0, 0);
  71         if (!ptr)
  72                 goto out;
  73         task_storage_val = *ptr;
  74 out:
  75         bpf_rcu_read_unlock();
  76         return 0;
  77 }
  78
  79 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
  80 int no_lock(void *ctx)
  81 {
  82         struct task_struct *task, *real_parent;
  83
  84         /* old style ptr_to_btf_id is not allowed in sleepable */
  85         task = bpf_get_current_task_btf();
  86         real_parent = task->real_parent;
  87         (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
  88         return 0;
  89 }
  90
  91 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
  92 int two_regions(void *ctx)
  93 {
  94         struct task_struct *task, *real_parent;
  95
  96         /* two regions */
  97         task = bpf_get_current_task_btf();
  98         bpf_rcu_read_lock();
  99         bpf_rcu_read_unlock();
 100         bpf_rcu_read_lock();
 101         real_parent = task->real_parent;
 102         if (!real_parent)
 103                 goto out;
 104         (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
 105 out:
 106         bpf_rcu_read_unlock();
 107         return 0;
 108 }
 109
 110 SEC("?fentry/" SYS_PREFIX "sys_getpgid")
 111 int non_sleepable_1(void *ctx)
 112 {
 113         struct task_struct *task, *real_parent;
 114
 115         task = bpf_get_current_task_btf();
 116         bpf_rcu_read_lock();
 117         real_parent = task->real_parent;
 118         if (!real_parent)
 119                 goto out;
 120         (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
 121 out:
 122         bpf_rcu_read_unlock();
 123         return 0;
 124 }
 125
 126 SEC("?fentry/" SYS_PREFIX "sys_getpgid")
 127 int non_sleepable_2(void *ctx)
 128 {
 129         struct task_struct *task, *real_parent;
 130
 131         bpf_rcu_read_lock();
 132         task = bpf_get_current_task_btf();
 133         bpf_rcu_read_unlock();
 134
 135         bpf_rcu_read_lock();
 136         real_parent = task->real_parent;
 137         if (!real_parent)
 138                 goto out;
 139         (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
 140 out:
 141         bpf_rcu_read_unlock();
 142         return 0;
 143 }
 144
 145 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
 146 int task_acquire(void *ctx)
 147 {
 148         struct task_struct *task, *real_parent, *gparent;
 149
 150         task = bpf_get_current_task_btf();
 151         bpf_rcu_read_lock();
 152         real_parent = task->real_parent;
 153         if (!real_parent)
 154                 goto out;
 155
 156         /* rcu_ptr->rcu_field */
 157         gparent = real_parent->real_parent;
 158         if (!gparent)
 159                 goto out;
 160
 161         /* acquire a reference which can be used outside rcu read lock region */
 162         gparent = bpf_task_acquire(gparent);
 163         if (!gparent)
 164                 goto out;
 165
 166         (void)bpf_task_storage_get(&map_a, gparent, 0, 0);
 167         bpf_task_release(gparent);
 168 out:
 169         bpf_rcu_read_unlock();
 170         return 0;
 171 }
 172
 173 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
 174 int miss_lock(void *ctx)
 175 {
 176         struct task_struct *task;
 177
 178         /* missing bpf_rcu_read_lock() */
 179         task = bpf_get_current_task_btf();
 180         bpf_rcu_read_lock();
 181         (void)bpf_task_storage_get(&map_a, task, 0, 0);
 182         bpf_rcu_read_unlock();
 183         bpf_rcu_read_unlock();
 184         return 0;
 185 }
 186
 187 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
 188 int miss_unlock(void *ctx)
 189 {
 190         struct task_struct *task;
 191
 192         /* missing bpf_rcu_read_unlock() */
 193         task = bpf_get_current_task_btf();
 194         bpf_rcu_read_lock();
 195         (void)bpf_task_storage_get(&map_a, task, 0, 0);
 196         return 0;
 197 }
 198
 199 SEC("?fentry/" SYS_PREFIX "sys_getpgid")
 200 int non_sleepable_rcu_mismatch(void *ctx)
 201 {
 202         struct task_struct *task, *real_parent;
 203
 204         task = bpf_get_current_task_btf();
 205         /* non-sleepable: missing bpf_rcu_read_unlock() in one path */
 206         bpf_rcu_read_lock();
 207         real_parent = task->real_parent;
 208         if (!real_parent)
 209                 goto out;
 210         (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
 211         if (real_parent)
 212                 bpf_rcu_read_unlock();
 213 out:
 214         return 0;
 215 }
 216
 217 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
 218 int inproper_sleepable_helper(void *ctx)
 219 {
 220         struct task_struct *task, *real_parent;
 221         struct pt_regs *regs;
 222         __u32 value = 0;
 223         void *ptr;
 224
 225         task = bpf_get_current_task_btf();
 226         /* sleepable helper in rcu read lock region */
 227         bpf_rcu_read_lock();
 228         real_parent = task->real_parent;
 229         if (!real_parent)
 230                 goto out;
 231         regs = (struct pt_regs *)bpf_task_pt_regs(real_parent);
 232         if (!regs)
 233                 goto out;
 234
 235         ptr = (void *)PT_REGS_IP(regs);
 236         (void)bpf_copy_from_user_task(&value, sizeof(uint32_t), ptr, task, 0);
 237         user_data = value;
 238         (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
 239 out:
 240         bpf_rcu_read_unlock();
 241         return 0;
 242 }
 243
 244 SEC("?lsm.s/bpf")
 245 int BPF_PROG(inproper_sleepable_kfunc, int cmd, union bpf_attr *attr, unsigned int size)
 246 {
 247         struct bpf_key *bkey;
 248
 249         /* sleepable kfunc in rcu read lock region */
 250         bpf_rcu_read_lock();
 251         bkey = bpf_lookup_user_key(key_serial, flags);
 252         bpf_rcu_read_unlock();
 253         if (!bkey)
 254                 return -1;
 255         bpf_key_put(bkey);
 256
 257         return 0;
 258 }
 259
 260 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
 261 int nested_rcu_region(void *ctx)
 262 {
 263         struct task_struct *task, *real_parent;
 264
 265         /* nested rcu read lock regions */
 266         task = bpf_get_current_task_btf();
 267         bpf_rcu_read_lock();
 268         bpf_rcu_read_lock();
 269         real_parent = task->real_parent;
 270         if (!real_parent)
 271                 goto out;
 272         (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
 273 out:
 274         bpf_rcu_read_unlock();
 275         bpf_rcu_read_unlock();
 276         return 0;
 277 }
 278
 279 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
 280 int task_trusted_non_rcuptr(void *ctx)
 281 {
 282         struct task_struct *task, *group_leader;
 283
 284         task = bpf_get_current_task_btf();
 285         bpf_rcu_read_lock();
 286         /* the pointer group_leader is explicitly marked as trusted */
 287         group_leader = task->real_parent->group_leader;
 288         (void)bpf_task_storage_get(&map_a, group_leader, 0, 0);
 289         bpf_rcu_read_unlock();
 290         return 0;
 291 }
 292
 293 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
 294 int task_untrusted_rcuptr(void *ctx)
 295 {
 296         struct task_struct *task, *real_parent;
 297
 298         task = bpf_get_current_task_btf();
 299         bpf_rcu_read_lock();
 300         real_parent = task->real_parent;
 301         bpf_rcu_read_unlock();
 302         /* helper use of rcu ptr outside the rcu read lock region */
 303         (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
 304         return 0;
 305 }
 306
 307 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep")
 308 int cross_rcu_region(void *ctx)
 309 {
 310         struct task_struct *task, *real_parent;
 311
 312         /* rcu ptr define/use in different regions */
 313         task = bpf_get_current_task_btf();
 314         bpf_rcu_read_lock();
 315         real_parent = task->real_parent;
 316         bpf_rcu_read_unlock();
 317         bpf_rcu_read_lock();
 318         (void)bpf_task_storage_get(&map_a, real_parent, 0, 0);
 319         bpf_rcu_read_unlock();
 320         return 0;
 321 }