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 34 task = bpf_get_current_task_btf(); 35 if (task->pid != target_pid) 36 return 0; 37 38 /* simulate bpf_get_current_cgroup_id() helper */ 39 bpf_rcu_read_lock(); 40 cgroup_id = task->cgroups->dfl_cgrp->kn->id; 41 bpf_rcu_read_unlock(); 42 return 0; 43 } 44 45 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") 46 int task_succ(void *ctx) 47 { 48 struct task_struct *task, *real_parent; 49 long init_val = 2; 50 long *ptr; 51 52 task = bpf_get_current_task_btf(); 53 if (task->pid != target_pid) 54 return 0; 55 56 bpf_rcu_read_lock(); 57 /* region including helper using rcu ptr real_parent */ 58 real_parent = task->real_parent; 59 ptr = bpf_task_storage_get(&map_a, real_parent, &init_val, 60 BPF_LOCAL_STORAGE_GET_F_CREATE); 61 if (!ptr) 62 goto out; 63 ptr = bpf_task_storage_get(&map_a, real_parent, 0, 0); 64 if (!ptr) 65 goto out; 66 task_storage_val = *ptr; 67 out: 68 bpf_rcu_read_unlock(); 69 return 0; 70 } 71 72 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep") 73 int no_lock(void *ctx) 74 { 75 struct task_struct *task, *real_parent; 76 77 /* no bpf_rcu_read_lock(), old code still works */ 78 task = bpf_get_current_task_btf(); 79 real_parent = task->real_parent; 80 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0); 81 return 0; 82 } 83 84 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep") 85 int two_regions(void *ctx) 86 { 87 struct task_struct *task, *real_parent; 88 89 /* two regions */ 90 task = bpf_get_current_task_btf(); 91 bpf_rcu_read_lock(); 92 bpf_rcu_read_unlock(); 93 bpf_rcu_read_lock(); 94 real_parent = task->real_parent; 95 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0); 96 bpf_rcu_read_unlock(); 97 return 0; 98 } 99 100 SEC("?fentry/" SYS_PREFIX "sys_getpgid") 101 int non_sleepable_1(void *ctx) 102 { 103 struct task_struct *task, *real_parent; 104 105 task = bpf_get_current_task_btf(); 106 bpf_rcu_read_lock(); 107 real_parent = task->real_parent; 108 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0); 109 bpf_rcu_read_unlock(); 110 return 0; 111 } 112 113 SEC("?fentry/" SYS_PREFIX "sys_getpgid") 114 int non_sleepable_2(void *ctx) 115 { 116 struct task_struct *task, *real_parent; 117 118 bpf_rcu_read_lock(); 119 task = bpf_get_current_task_btf(); 120 bpf_rcu_read_unlock(); 121 122 bpf_rcu_read_lock(); 123 real_parent = task->real_parent; 124 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0); 125 bpf_rcu_read_unlock(); 126 return 0; 127 } 128 129 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep") 130 int task_acquire(void *ctx) 131 { 132 struct task_struct *task, *real_parent; 133 134 task = bpf_get_current_task_btf(); 135 bpf_rcu_read_lock(); 136 real_parent = task->real_parent; 137 /* acquire a reference which can be used outside rcu read lock region */ 138 real_parent = bpf_task_acquire(real_parent); 139 bpf_rcu_read_unlock(); 140 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0); 141 bpf_task_release(real_parent); 142 return 0; 143 } 144 145 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") 146 int miss_lock(void *ctx) 147 { 148 struct task_struct *task; 149 struct css_set *cgroups; 150 struct cgroup *dfl_cgrp; 151 152 /* missing bpf_rcu_read_lock() */ 153 task = bpf_get_current_task_btf(); 154 bpf_rcu_read_lock(); 155 (void)bpf_task_storage_get(&map_a, task, 0, 0); 156 bpf_rcu_read_unlock(); 157 bpf_rcu_read_unlock(); 158 return 0; 159 } 160 161 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") 162 int miss_unlock(void *ctx) 163 { 164 struct task_struct *task; 165 struct css_set *cgroups; 166 struct cgroup *dfl_cgrp; 167 168 /* missing bpf_rcu_read_unlock() */ 169 task = bpf_get_current_task_btf(); 170 bpf_rcu_read_lock(); 171 (void)bpf_task_storage_get(&map_a, task, 0, 0); 172 return 0; 173 } 174 175 SEC("?fentry/" SYS_PREFIX "sys_getpgid") 176 int non_sleepable_rcu_mismatch(void *ctx) 177 { 178 struct task_struct *task, *real_parent; 179 180 task = bpf_get_current_task_btf(); 181 /* non-sleepable: missing bpf_rcu_read_unlock() in one path */ 182 bpf_rcu_read_lock(); 183 real_parent = task->real_parent; 184 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0); 185 if (real_parent) 186 bpf_rcu_read_unlock(); 187 return 0; 188 } 189 190 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") 191 int inproper_sleepable_helper(void *ctx) 192 { 193 struct task_struct *task, *real_parent; 194 struct pt_regs *regs; 195 __u32 value = 0; 196 void *ptr; 197 198 task = bpf_get_current_task_btf(); 199 /* sleepable helper in rcu read lock region */ 200 bpf_rcu_read_lock(); 201 real_parent = task->real_parent; 202 regs = (struct pt_regs *)bpf_task_pt_regs(real_parent); 203 if (!regs) { 204 bpf_rcu_read_unlock(); 205 return 0; 206 } 207 208 ptr = (void *)PT_REGS_IP(regs); 209 (void)bpf_copy_from_user_task(&value, sizeof(uint32_t), ptr, task, 0); 210 user_data = value; 211 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0); 212 bpf_rcu_read_unlock(); 213 return 0; 214 } 215 216 SEC("?lsm.s/bpf") 217 int BPF_PROG(inproper_sleepable_kfunc, int cmd, union bpf_attr *attr, unsigned int size) 218 { 219 struct bpf_key *bkey; 220 221 /* sleepable kfunc in rcu read lock region */ 222 bpf_rcu_read_lock(); 223 bkey = bpf_lookup_user_key(key_serial, flags); 224 bpf_rcu_read_unlock(); 225 if (!bkey) 226 return -1; 227 bpf_key_put(bkey); 228 229 return 0; 230 } 231 232 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep") 233 int nested_rcu_region(void *ctx) 234 { 235 struct task_struct *task, *real_parent; 236 237 /* nested rcu read lock regions */ 238 task = bpf_get_current_task_btf(); 239 bpf_rcu_read_lock(); 240 bpf_rcu_read_lock(); 241 real_parent = task->real_parent; 242 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0); 243 bpf_rcu_read_unlock(); 244 bpf_rcu_read_unlock(); 245 return 0; 246 } 247 248 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") 249 int task_untrusted_non_rcuptr(void *ctx) 250 { 251 struct task_struct *task, *last_wakee; 252 253 task = bpf_get_current_task_btf(); 254 bpf_rcu_read_lock(); 255 /* the pointer last_wakee marked as untrusted */ 256 last_wakee = task->real_parent->last_wakee; 257 (void)bpf_task_storage_get(&map_a, last_wakee, 0, 0); 258 bpf_rcu_read_unlock(); 259 return 0; 260 } 261 262 SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") 263 int task_untrusted_rcuptr(void *ctx) 264 { 265 struct task_struct *task, *real_parent; 266 267 task = bpf_get_current_task_btf(); 268 bpf_rcu_read_lock(); 269 real_parent = task->real_parent; 270 bpf_rcu_read_unlock(); 271 /* helper use of rcu ptr outside the rcu read lock region */ 272 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0); 273 return 0; 274 } 275 276 SEC("?fentry.s/" SYS_PREFIX "sys_nanosleep") 277 int cross_rcu_region(void *ctx) 278 { 279 struct task_struct *task, *real_parent; 280 281 /* rcu ptr define/use in different regions */ 282 task = bpf_get_current_task_btf(); 283 bpf_rcu_read_lock(); 284 real_parent = task->real_parent; 285 bpf_rcu_read_unlock(); 286 bpf_rcu_read_lock(); 287 (void)bpf_task_storage_get(&map_a, real_parent, 0, 0); 288 bpf_rcu_read_unlock(); 289 return 0; 290 } 291