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 && !thread_group_leader(task) && 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 u32 tid; 134 u32 fd; 135 }; 136 137 static struct file * 138 task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info) 139 { 140 struct pid_namespace *ns = info->common.ns; 141 u32 curr_tid = info->tid; 142 struct task_struct *curr_task; 143 unsigned int curr_fd = info->fd; 144 145 /* If this function returns a non-NULL file object, 146 * it held a reference to the task/file. 147 * Otherwise, it does not hold any reference. 148 */ 149 again: 150 if (info->task) { 151 curr_task = info->task; 152 curr_fd = info->fd; 153 } else { 154 curr_task = task_seq_get_next(ns, &curr_tid, true); 155 if (!curr_task) { 156 info->task = NULL; 157 info->tid = curr_tid; 158 return NULL; 159 } 160 161 /* set info->task and info->tid */ 162 info->task = curr_task; 163 if (curr_tid == info->tid) { 164 curr_fd = info->fd; 165 } else { 166 info->tid = curr_tid; 167 curr_fd = 0; 168 } 169 } 170 171 rcu_read_lock(); 172 for (;; curr_fd++) { 173 struct file *f; 174 f = task_lookup_next_fd_rcu(curr_task, &curr_fd); 175 if (!f) 176 break; 177 if (!get_file_rcu(f)) 178 continue; 179 180 /* set info->fd */ 181 info->fd = curr_fd; 182 rcu_read_unlock(); 183 return f; 184 } 185 186 /* the current task is done, go to the next task */ 187 rcu_read_unlock(); 188 put_task_struct(curr_task); 189 info->task = NULL; 190 info->fd = 0; 191 curr_tid = ++(info->tid); 192 goto again; 193 } 194 195 static void *task_file_seq_start(struct seq_file *seq, loff_t *pos) 196 { 197 struct bpf_iter_seq_task_file_info *info = seq->private; 198 struct file *file; 199 200 info->task = NULL; 201 file = task_file_seq_get_next(info); 202 if (file && *pos == 0) 203 ++*pos; 204 205 return file; 206 } 207 208 static void *task_file_seq_next(struct seq_file *seq, void *v, loff_t *pos) 209 { 210 struct bpf_iter_seq_task_file_info *info = seq->private; 211 212 ++*pos; 213 ++info->fd; 214 fput((struct file *)v); 215 return task_file_seq_get_next(info); 216 } 217 218 struct bpf_iter__task_file { 219 __bpf_md_ptr(struct bpf_iter_meta *, meta); 220 __bpf_md_ptr(struct task_struct *, task); 221 u32 fd __aligned(8); 222 __bpf_md_ptr(struct file *, file); 223 }; 224 225 DEFINE_BPF_ITER_FUNC(task_file, struct bpf_iter_meta *meta, 226 struct task_struct *task, u32 fd, 227 struct file *file) 228 229 static int __task_file_seq_show(struct seq_file *seq, struct file *file, 230 bool in_stop) 231 { 232 struct bpf_iter_seq_task_file_info *info = seq->private; 233 struct bpf_iter__task_file ctx; 234 struct bpf_iter_meta meta; 235 struct bpf_prog *prog; 236 237 meta.seq = seq; 238 prog = bpf_iter_get_info(&meta, in_stop); 239 if (!prog) 240 return 0; 241 242 ctx.meta = &meta; 243 ctx.task = info->task; 244 ctx.fd = info->fd; 245 ctx.file = file; 246 return bpf_iter_run_prog(prog, &ctx); 247 } 248 249 static int task_file_seq_show(struct seq_file *seq, void *v) 250 { 251 return __task_file_seq_show(seq, v, false); 252 } 253 254 static void task_file_seq_stop(struct seq_file *seq, void *v) 255 { 256 struct bpf_iter_seq_task_file_info *info = seq->private; 257 258 if (!v) { 259 (void)__task_file_seq_show(seq, v, true); 260 } else { 261 fput((struct file *)v); 262 put_task_struct(info->task); 263 info->task = NULL; 264 } 265 } 266 267 static int init_seq_pidns(void *priv_data, struct bpf_iter_aux_info *aux) 268 { 269 struct bpf_iter_seq_task_common *common = priv_data; 270 271 common->ns = get_pid_ns(task_active_pid_ns(current)); 272 return 0; 273 } 274 275 static void fini_seq_pidns(void *priv_data) 276 { 277 struct bpf_iter_seq_task_common *common = priv_data; 278 279 put_pid_ns(common->ns); 280 } 281 282 static const struct seq_operations task_file_seq_ops = { 283 .start = task_file_seq_start, 284 .next = task_file_seq_next, 285 .stop = task_file_seq_stop, 286 .show = task_file_seq_show, 287 }; 288 289 BTF_ID_LIST(btf_task_file_ids) 290 BTF_ID(struct, task_struct) 291 BTF_ID(struct, file) 292 293 static const struct bpf_iter_seq_info task_seq_info = { 294 .seq_ops = &task_seq_ops, 295 .init_seq_private = init_seq_pidns, 296 .fini_seq_private = fini_seq_pidns, 297 .seq_priv_size = sizeof(struct bpf_iter_seq_task_info), 298 }; 299 300 static struct bpf_iter_reg task_reg_info = { 301 .target = "task", 302 .feature = BPF_ITER_RESCHED, 303 .ctx_arg_info_size = 1, 304 .ctx_arg_info = { 305 { offsetof(struct bpf_iter__task, task), 306 PTR_TO_BTF_ID_OR_NULL }, 307 }, 308 .seq_info = &task_seq_info, 309 }; 310 311 static const struct bpf_iter_seq_info task_file_seq_info = { 312 .seq_ops = &task_file_seq_ops, 313 .init_seq_private = init_seq_pidns, 314 .fini_seq_private = fini_seq_pidns, 315 .seq_priv_size = sizeof(struct bpf_iter_seq_task_file_info), 316 }; 317 318 static struct bpf_iter_reg task_file_reg_info = { 319 .target = "task_file", 320 .feature = BPF_ITER_RESCHED, 321 .ctx_arg_info_size = 2, 322 .ctx_arg_info = { 323 { offsetof(struct bpf_iter__task_file, task), 324 PTR_TO_BTF_ID_OR_NULL }, 325 { offsetof(struct bpf_iter__task_file, file), 326 PTR_TO_BTF_ID_OR_NULL }, 327 }, 328 .seq_info = &task_file_seq_info, 329 }; 330 331 static int __init task_iter_init(void) 332 { 333 int ret; 334 335 task_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0]; 336 ret = bpf_iter_reg_target(&task_reg_info); 337 if (ret) 338 return ret; 339 340 task_file_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0]; 341 task_file_reg_info.ctx_arg_info[1].btf_id = btf_task_file_ids[1]; 342 return bpf_iter_reg_target(&task_file_reg_info); 343 } 344 late_initcall(task_iter_init); 345