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