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