1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Copyright (c) 2020 Facebook */ 3 4 #include <linux/init.h> 5 #include <linux/namei.h> 6 #include <linux/pid_namespace.h> 7 #include <linux/fs.h> 8 #include <linux/fdtable.h> 9 #include <linux/filter.h> 10 #include <linux/btf_ids.h> 11 12 struct bpf_iter_seq_task_common { 13 struct pid_namespace *ns; 14 }; 15 16 struct bpf_iter_seq_task_info { 17 /* The first field must be struct bpf_iter_seq_task_common. 18 * this is assumed by {init, fini}_seq_pidns() callback functions. 19 */ 20 struct bpf_iter_seq_task_common common; 21 u32 tid; 22 }; 23 24 static struct task_struct *task_seq_get_next(struct pid_namespace *ns, 25 u32 *tid, 26 bool skip_if_dup_files) 27 { 28 struct task_struct *task = NULL; 29 struct pid *pid; 30 31 rcu_read_lock(); 32 retry: 33 pid = find_ge_pid(*tid, ns); 34 if (pid) { 35 *tid = pid_nr_ns(pid, ns); 36 task = get_pid_task(pid, PIDTYPE_PID); 37 if (!task) { 38 ++*tid; 39 goto retry; 40 } else if (skip_if_dup_files && task->tgid != task->pid && 41 task->files == task->group_leader->files) { 42 put_task_struct(task); 43 task = NULL; 44 ++*tid; 45 goto retry; 46 } 47 } 48 rcu_read_unlock(); 49 50 return task; 51 } 52 53 static void *task_seq_start(struct seq_file *seq, loff_t *pos) 54 { 55 struct bpf_iter_seq_task_info *info = seq->private; 56 struct task_struct *task; 57 58 task = task_seq_get_next(info->common.ns, &info->tid, false); 59 if (!task) 60 return NULL; 61 62 if (*pos == 0) 63 ++*pos; 64 return task; 65 } 66 67 static void *task_seq_next(struct seq_file *seq, void *v, loff_t *pos) 68 { 69 struct bpf_iter_seq_task_info *info = seq->private; 70 struct task_struct *task; 71 72 ++*pos; 73 ++info->tid; 74 put_task_struct((struct task_struct *)v); 75 task = task_seq_get_next(info->common.ns, &info->tid, false); 76 if (!task) 77 return NULL; 78 79 return task; 80 } 81 82 struct bpf_iter__task { 83 __bpf_md_ptr(struct bpf_iter_meta *, meta); 84 __bpf_md_ptr(struct task_struct *, task); 85 }; 86 87 DEFINE_BPF_ITER_FUNC(task, struct bpf_iter_meta *meta, struct task_struct *task) 88 89 static int __task_seq_show(struct seq_file *seq, struct task_struct *task, 90 bool in_stop) 91 { 92 struct bpf_iter_meta meta; 93 struct bpf_iter__task ctx; 94 struct bpf_prog *prog; 95 96 meta.seq = seq; 97 prog = bpf_iter_get_info(&meta, in_stop); 98 if (!prog) 99 return 0; 100 101 meta.seq = seq; 102 ctx.meta = &meta; 103 ctx.task = task; 104 return bpf_iter_run_prog(prog, &ctx); 105 } 106 107 static int task_seq_show(struct seq_file *seq, void *v) 108 { 109 return __task_seq_show(seq, v, false); 110 } 111 112 static void task_seq_stop(struct seq_file *seq, void *v) 113 { 114 if (!v) 115 (void)__task_seq_show(seq, v, true); 116 else 117 put_task_struct((struct task_struct *)v); 118 } 119 120 static const struct seq_operations task_seq_ops = { 121 .start = task_seq_start, 122 .next = task_seq_next, 123 .stop = task_seq_stop, 124 .show = task_seq_show, 125 }; 126 127 struct bpf_iter_seq_task_file_info { 128 /* The first field must be struct bpf_iter_seq_task_common. 129 * this is assumed by {init, fini}_seq_pidns() callback functions. 130 */ 131 struct bpf_iter_seq_task_common common; 132 struct task_struct *task; 133 struct files_struct *files; 134 u32 tid; 135 u32 fd; 136 }; 137 138 static struct file * 139 task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info, 140 struct task_struct **task, struct files_struct **fstruct) 141 { 142 struct pid_namespace *ns = info->common.ns; 143 u32 curr_tid = info->tid, max_fds; 144 struct files_struct *curr_files; 145 struct task_struct *curr_task; 146 int curr_fd = info->fd; 147 148 /* If this function returns a non-NULL file object, 149 * it held a reference to the task/files_struct/file. 150 * Otherwise, it does not hold any reference. 151 */ 152 again: 153 if (*task) { 154 curr_task = *task; 155 curr_files = *fstruct; 156 curr_fd = info->fd; 157 } else { 158 curr_task = task_seq_get_next(ns, &curr_tid, true); 159 if (!curr_task) 160 return NULL; 161 162 curr_files = get_files_struct(curr_task); 163 if (!curr_files) { 164 put_task_struct(curr_task); 165 curr_tid = ++(info->tid); 166 info->fd = 0; 167 goto again; 168 } 169 170 /* set *fstruct, *task and info->tid */ 171 *fstruct = curr_files; 172 *task = curr_task; 173 if (curr_tid == info->tid) { 174 curr_fd = info->fd; 175 } else { 176 info->tid = curr_tid; 177 curr_fd = 0; 178 } 179 } 180 181 rcu_read_lock(); 182 max_fds = files_fdtable(curr_files)->max_fds; 183 for (; curr_fd < max_fds; curr_fd++) { 184 struct file *f; 185 186 f = fcheck_files(curr_files, curr_fd); 187 if (!f) 188 continue; 189 if (!get_file_rcu(f)) 190 continue; 191 192 /* set info->fd */ 193 info->fd = curr_fd; 194 rcu_read_unlock(); 195 return f; 196 } 197 198 /* the current task is done, go to the next task */ 199 rcu_read_unlock(); 200 put_files_struct(curr_files); 201 put_task_struct(curr_task); 202 *task = NULL; 203 *fstruct = NULL; 204 info->fd = 0; 205 curr_tid = ++(info->tid); 206 goto again; 207 } 208 209 static void *task_file_seq_start(struct seq_file *seq, loff_t *pos) 210 { 211 struct bpf_iter_seq_task_file_info *info = seq->private; 212 struct files_struct *files = NULL; 213 struct task_struct *task = NULL; 214 struct file *file; 215 216 file = task_file_seq_get_next(info, &task, &files); 217 if (!file) { 218 info->files = NULL; 219 info->task = NULL; 220 return NULL; 221 } 222 223 if (*pos == 0) 224 ++*pos; 225 info->task = task; 226 info->files = files; 227 228 return file; 229 } 230 231 static void *task_file_seq_next(struct seq_file *seq, void *v, loff_t *pos) 232 { 233 struct bpf_iter_seq_task_file_info *info = seq->private; 234 struct files_struct *files = info->files; 235 struct task_struct *task = info->task; 236 struct file *file; 237 238 ++*pos; 239 ++info->fd; 240 fput((struct file *)v); 241 file = task_file_seq_get_next(info, &task, &files); 242 if (!file) { 243 info->files = NULL; 244 info->task = NULL; 245 return NULL; 246 } 247 248 info->task = task; 249 info->files = files; 250 251 return file; 252 } 253 254 struct bpf_iter__task_file { 255 __bpf_md_ptr(struct bpf_iter_meta *, meta); 256 __bpf_md_ptr(struct task_struct *, task); 257 u32 fd __aligned(8); 258 __bpf_md_ptr(struct file *, file); 259 }; 260 261 DEFINE_BPF_ITER_FUNC(task_file, struct bpf_iter_meta *meta, 262 struct task_struct *task, u32 fd, 263 struct file *file) 264 265 static int __task_file_seq_show(struct seq_file *seq, struct file *file, 266 bool in_stop) 267 { 268 struct bpf_iter_seq_task_file_info *info = seq->private; 269 struct bpf_iter__task_file ctx; 270 struct bpf_iter_meta meta; 271 struct bpf_prog *prog; 272 273 meta.seq = seq; 274 prog = bpf_iter_get_info(&meta, in_stop); 275 if (!prog) 276 return 0; 277 278 ctx.meta = &meta; 279 ctx.task = info->task; 280 ctx.fd = info->fd; 281 ctx.file = file; 282 return bpf_iter_run_prog(prog, &ctx); 283 } 284 285 static int task_file_seq_show(struct seq_file *seq, void *v) 286 { 287 return __task_file_seq_show(seq, v, false); 288 } 289 290 static void task_file_seq_stop(struct seq_file *seq, void *v) 291 { 292 struct bpf_iter_seq_task_file_info *info = seq->private; 293 294 if (!v) { 295 (void)__task_file_seq_show(seq, v, true); 296 } else { 297 fput((struct file *)v); 298 put_files_struct(info->files); 299 put_task_struct(info->task); 300 info->files = NULL; 301 info->task = NULL; 302 } 303 } 304 305 static int init_seq_pidns(void *priv_data, struct bpf_iter_aux_info *aux) 306 { 307 struct bpf_iter_seq_task_common *common = priv_data; 308 309 common->ns = get_pid_ns(task_active_pid_ns(current)); 310 return 0; 311 } 312 313 static void fini_seq_pidns(void *priv_data) 314 { 315 struct bpf_iter_seq_task_common *common = priv_data; 316 317 put_pid_ns(common->ns); 318 } 319 320 static const struct seq_operations task_file_seq_ops = { 321 .start = task_file_seq_start, 322 .next = task_file_seq_next, 323 .stop = task_file_seq_stop, 324 .show = task_file_seq_show, 325 }; 326 327 BTF_ID_LIST(btf_task_file_ids) 328 BTF_ID(struct, task_struct) 329 BTF_ID(struct, file) 330 331 static const struct bpf_iter_seq_info task_seq_info = { 332 .seq_ops = &task_seq_ops, 333 .init_seq_private = init_seq_pidns, 334 .fini_seq_private = fini_seq_pidns, 335 .seq_priv_size = sizeof(struct bpf_iter_seq_task_info), 336 }; 337 338 static struct bpf_iter_reg task_reg_info = { 339 .target = "task", 340 .ctx_arg_info_size = 1, 341 .ctx_arg_info = { 342 { offsetof(struct bpf_iter__task, task), 343 PTR_TO_BTF_ID_OR_NULL }, 344 }, 345 .seq_info = &task_seq_info, 346 }; 347 348 static const struct bpf_iter_seq_info task_file_seq_info = { 349 .seq_ops = &task_file_seq_ops, 350 .init_seq_private = init_seq_pidns, 351 .fini_seq_private = fini_seq_pidns, 352 .seq_priv_size = sizeof(struct bpf_iter_seq_task_file_info), 353 }; 354 355 static struct bpf_iter_reg task_file_reg_info = { 356 .target = "task_file", 357 .ctx_arg_info_size = 2, 358 .ctx_arg_info = { 359 { offsetof(struct bpf_iter__task_file, task), 360 PTR_TO_BTF_ID_OR_NULL }, 361 { offsetof(struct bpf_iter__task_file, file), 362 PTR_TO_BTF_ID_OR_NULL }, 363 }, 364 .seq_info = &task_file_seq_info, 365 }; 366 367 static int __init task_iter_init(void) 368 { 369 int ret; 370 371 task_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0]; 372 ret = bpf_iter_reg_target(&task_reg_info); 373 if (ret) 374 return ret; 375 376 task_file_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0]; 377 task_file_reg_info.ctx_arg_info[1].btf_id = btf_task_file_ids[1]; 378 return bpf_iter_reg_target(&task_file_reg_info); 379 } 380 late_initcall(task_iter_init); 381