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 { 141 struct pid_namespace *ns = info->common.ns; 142 u32 curr_tid = info->tid, max_fds; 143 struct files_struct *curr_files; 144 struct task_struct *curr_task; 145 int curr_fd = info->fd; 146 147 /* If this function returns a non-NULL file object, 148 * it held a reference to the task/files_struct/file. 149 * Otherwise, it does not hold any reference. 150 */ 151 again: 152 if (info->task) { 153 curr_task = info->task; 154 curr_files = info->files; 155 curr_fd = info->fd; 156 } else { 157 curr_task = task_seq_get_next(ns, &curr_tid, true); 158 if (!curr_task) { 159 info->task = NULL; 160 info->files = NULL; 161 info->tid = curr_tid; 162 return NULL; 163 } 164 165 curr_files = get_files_struct(curr_task); 166 if (!curr_files) { 167 put_task_struct(curr_task); 168 curr_tid = curr_tid + 1; 169 info->fd = 0; 170 goto again; 171 } 172 173 info->files = curr_files; 174 info->task = curr_task; 175 if (curr_tid == info->tid) { 176 curr_fd = info->fd; 177 } else { 178 info->tid = curr_tid; 179 curr_fd = 0; 180 } 181 } 182 183 rcu_read_lock(); 184 max_fds = files_fdtable(curr_files)->max_fds; 185 for (; curr_fd < max_fds; curr_fd++) { 186 struct file *f; 187 188 f = fcheck_files(curr_files, curr_fd); 189 if (!f) 190 continue; 191 if (!get_file_rcu(f)) 192 continue; 193 194 /* set info->fd */ 195 info->fd = curr_fd; 196 rcu_read_unlock(); 197 return f; 198 } 199 200 /* the current task is done, go to the next task */ 201 rcu_read_unlock(); 202 put_files_struct(curr_files); 203 put_task_struct(curr_task); 204 info->task = NULL; 205 info->files = NULL; 206 info->fd = 0; 207 curr_tid = ++(info->tid); 208 goto again; 209 } 210 211 static void *task_file_seq_start(struct seq_file *seq, loff_t *pos) 212 { 213 struct bpf_iter_seq_task_file_info *info = seq->private; 214 struct file *file; 215 216 info->task = NULL; 217 info->files = NULL; 218 file = task_file_seq_get_next(info); 219 if (file && *pos == 0) 220 ++*pos; 221 222 return file; 223 } 224 225 static void *task_file_seq_next(struct seq_file *seq, void *v, loff_t *pos) 226 { 227 struct bpf_iter_seq_task_file_info *info = seq->private; 228 229 ++*pos; 230 ++info->fd; 231 fput((struct file *)v); 232 return task_file_seq_get_next(info); 233 } 234 235 struct bpf_iter__task_file { 236 __bpf_md_ptr(struct bpf_iter_meta *, meta); 237 __bpf_md_ptr(struct task_struct *, task); 238 u32 fd __aligned(8); 239 __bpf_md_ptr(struct file *, file); 240 }; 241 242 DEFINE_BPF_ITER_FUNC(task_file, struct bpf_iter_meta *meta, 243 struct task_struct *task, u32 fd, 244 struct file *file) 245 246 static int __task_file_seq_show(struct seq_file *seq, struct file *file, 247 bool in_stop) 248 { 249 struct bpf_iter_seq_task_file_info *info = seq->private; 250 struct bpf_iter__task_file ctx; 251 struct bpf_iter_meta meta; 252 struct bpf_prog *prog; 253 254 meta.seq = seq; 255 prog = bpf_iter_get_info(&meta, in_stop); 256 if (!prog) 257 return 0; 258 259 ctx.meta = &meta; 260 ctx.task = info->task; 261 ctx.fd = info->fd; 262 ctx.file = file; 263 return bpf_iter_run_prog(prog, &ctx); 264 } 265 266 static int task_file_seq_show(struct seq_file *seq, void *v) 267 { 268 return __task_file_seq_show(seq, v, false); 269 } 270 271 static void task_file_seq_stop(struct seq_file *seq, void *v) 272 { 273 struct bpf_iter_seq_task_file_info *info = seq->private; 274 275 if (!v) { 276 (void)__task_file_seq_show(seq, v, true); 277 } else { 278 fput((struct file *)v); 279 put_files_struct(info->files); 280 put_task_struct(info->task); 281 info->files = NULL; 282 info->task = NULL; 283 } 284 } 285 286 static int init_seq_pidns(void *priv_data, struct bpf_iter_aux_info *aux) 287 { 288 struct bpf_iter_seq_task_common *common = priv_data; 289 290 common->ns = get_pid_ns(task_active_pid_ns(current)); 291 return 0; 292 } 293 294 static void fini_seq_pidns(void *priv_data) 295 { 296 struct bpf_iter_seq_task_common *common = priv_data; 297 298 put_pid_ns(common->ns); 299 } 300 301 static const struct seq_operations task_file_seq_ops = { 302 .start = task_file_seq_start, 303 .next = task_file_seq_next, 304 .stop = task_file_seq_stop, 305 .show = task_file_seq_show, 306 }; 307 308 BTF_ID_LIST(btf_task_file_ids) 309 BTF_ID(struct, task_struct) 310 BTF_ID(struct, file) 311 312 static const struct bpf_iter_seq_info task_seq_info = { 313 .seq_ops = &task_seq_ops, 314 .init_seq_private = init_seq_pidns, 315 .fini_seq_private = fini_seq_pidns, 316 .seq_priv_size = sizeof(struct bpf_iter_seq_task_info), 317 }; 318 319 static struct bpf_iter_reg task_reg_info = { 320 .target = "task", 321 .feature = BPF_ITER_RESCHED, 322 .ctx_arg_info_size = 1, 323 .ctx_arg_info = { 324 { offsetof(struct bpf_iter__task, task), 325 PTR_TO_BTF_ID_OR_NULL }, 326 }, 327 .seq_info = &task_seq_info, 328 }; 329 330 static const struct bpf_iter_seq_info task_file_seq_info = { 331 .seq_ops = &task_file_seq_ops, 332 .init_seq_private = init_seq_pidns, 333 .fini_seq_private = fini_seq_pidns, 334 .seq_priv_size = sizeof(struct bpf_iter_seq_task_file_info), 335 }; 336 337 static struct bpf_iter_reg task_file_reg_info = { 338 .target = "task_file", 339 .feature = BPF_ITER_RESCHED, 340 .ctx_arg_info_size = 2, 341 .ctx_arg_info = { 342 { offsetof(struct bpf_iter__task_file, task), 343 PTR_TO_BTF_ID_OR_NULL }, 344 { offsetof(struct bpf_iter__task_file, file), 345 PTR_TO_BTF_ID_OR_NULL }, 346 }, 347 .seq_info = &task_file_seq_info, 348 }; 349 350 static int __init task_iter_init(void) 351 { 352 int ret; 353 354 task_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0]; 355 ret = bpf_iter_reg_target(&task_reg_info); 356 if (ret) 357 return ret; 358 359 task_file_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0]; 360 task_file_reg_info.ctx_arg_info[1].btf_id = btf_task_file_ids[1]; 361 return bpf_iter_reg_target(&task_file_reg_info); 362 } 363 late_initcall(task_iter_init); 364