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