1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/proc/root.c 4 * 5 * Copyright (C) 1991, 1992 Linus Torvalds 6 * 7 * proc root directory handling functions 8 */ 9 #include <linux/errno.h> 10 #include <linux/time.h> 11 #include <linux/proc_fs.h> 12 #include <linux/stat.h> 13 #include <linux/init.h> 14 #include <linux/sched.h> 15 #include <linux/sched/stat.h> 16 #include <linux/module.h> 17 #include <linux/bitops.h> 18 #include <linux/user_namespace.h> 19 #include <linux/fs_context.h> 20 #include <linux/mount.h> 21 #include <linux/pid_namespace.h> 22 #include <linux/fs_parser.h> 23 #include <linux/cred.h> 24 #include <linux/magic.h> 25 #include <linux/slab.h> 26 27 #include "internal.h" 28 29 struct proc_fs_context { 30 struct pid_namespace *pid_ns; 31 unsigned int mask; 32 enum proc_hidepid hidepid; 33 int gid; 34 enum proc_pidonly pidonly; 35 }; 36 37 enum proc_param { 38 Opt_gid, 39 Opt_hidepid, 40 Opt_subset, 41 }; 42 43 static const struct fs_parameter_spec proc_fs_parameters[] = { 44 fsparam_u32("gid", Opt_gid), 45 fsparam_string("hidepid", Opt_hidepid), 46 fsparam_string("subset", Opt_subset), 47 {} 48 }; 49 50 static inline int valid_hidepid(unsigned int value) 51 { 52 return (value == HIDEPID_OFF || 53 value == HIDEPID_NO_ACCESS || 54 value == HIDEPID_INVISIBLE || 55 value == HIDEPID_NOT_PTRACEABLE); 56 } 57 58 static int proc_parse_hidepid_param(struct fs_context *fc, struct fs_parameter *param) 59 { 60 struct proc_fs_context *ctx = fc->fs_private; 61 struct fs_parameter_spec hidepid_u32_spec = fsparam_u32("hidepid", Opt_hidepid); 62 struct fs_parse_result result; 63 int base = (unsigned long)hidepid_u32_spec.data; 64 65 if (param->type != fs_value_is_string) 66 return invalf(fc, "proc: unexpected type of hidepid value\n"); 67 68 if (!kstrtouint(param->string, base, &result.uint_32)) { 69 if (!valid_hidepid(result.uint_32)) 70 return invalf(fc, "proc: unknown value of hidepid - %s\n", param->string); 71 ctx->hidepid = result.uint_32; 72 return 0; 73 } 74 75 if (!strcmp(param->string, "off")) 76 ctx->hidepid = HIDEPID_OFF; 77 else if (!strcmp(param->string, "noaccess")) 78 ctx->hidepid = HIDEPID_NO_ACCESS; 79 else if (!strcmp(param->string, "invisible")) 80 ctx->hidepid = HIDEPID_INVISIBLE; 81 else if (!strcmp(param->string, "ptraceable")) 82 ctx->hidepid = HIDEPID_NOT_PTRACEABLE; 83 else 84 return invalf(fc, "proc: unknown value of hidepid - %s\n", param->string); 85 86 return 0; 87 } 88 89 static int proc_parse_subset_param(struct fs_context *fc, char *value) 90 { 91 struct proc_fs_context *ctx = fc->fs_private; 92 93 while (value) { 94 char *ptr = strchr(value, ','); 95 96 if (ptr != NULL) 97 *ptr++ = '\0'; 98 99 if (*value != '\0') { 100 if (!strcmp(value, "pid")) { 101 ctx->pidonly = PROC_PIDONLY_ON; 102 } else { 103 return invalf(fc, "proc: unsupported subset option - %s\n", value); 104 } 105 } 106 value = ptr; 107 } 108 109 return 0; 110 } 111 112 static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) 113 { 114 struct proc_fs_context *ctx = fc->fs_private; 115 struct fs_parse_result result; 116 int opt; 117 118 opt = fs_parse(fc, proc_fs_parameters, param, &result); 119 if (opt < 0) 120 return opt; 121 122 switch (opt) { 123 case Opt_gid: 124 ctx->gid = result.uint_32; 125 break; 126 127 case Opt_hidepid: 128 if (proc_parse_hidepid_param(fc, param)) 129 return -EINVAL; 130 break; 131 132 case Opt_subset: 133 if (proc_parse_subset_param(fc, param->string) < 0) 134 return -EINVAL; 135 break; 136 137 default: 138 return -EINVAL; 139 } 140 141 ctx->mask |= 1 << opt; 142 return 0; 143 } 144 145 static void proc_apply_options(struct proc_fs_info *fs_info, 146 struct fs_context *fc, 147 struct user_namespace *user_ns) 148 { 149 struct proc_fs_context *ctx = fc->fs_private; 150 151 if (ctx->mask & (1 << Opt_gid)) 152 fs_info->pid_gid = make_kgid(user_ns, ctx->gid); 153 if (ctx->mask & (1 << Opt_hidepid)) 154 fs_info->hide_pid = ctx->hidepid; 155 if (ctx->mask & (1 << Opt_subset)) 156 fs_info->pidonly = ctx->pidonly; 157 } 158 159 static int proc_fill_super(struct super_block *s, struct fs_context *fc) 160 { 161 struct proc_fs_context *ctx = fc->fs_private; 162 struct inode *root_inode; 163 struct proc_fs_info *fs_info; 164 int ret; 165 166 fs_info = kzalloc(sizeof(*fs_info), GFP_KERNEL); 167 if (!fs_info) 168 return -ENOMEM; 169 170 fs_info->pid_ns = get_pid_ns(ctx->pid_ns); 171 proc_apply_options(fs_info, fc, current_user_ns()); 172 173 /* User space would break if executables or devices appear on proc */ 174 s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV; 175 s->s_flags |= SB_NODIRATIME | SB_NOSUID | SB_NOEXEC; 176 s->s_blocksize = 1024; 177 s->s_blocksize_bits = 10; 178 s->s_magic = PROC_SUPER_MAGIC; 179 s->s_op = &proc_sops; 180 s->s_time_gran = 1; 181 s->s_fs_info = fs_info; 182 183 /* 184 * procfs isn't actually a stacking filesystem; however, there is 185 * too much magic going on inside it to permit stacking things on 186 * top of it 187 */ 188 s->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH; 189 190 /* procfs dentries and inodes don't require IO to create */ 191 s->s_shrink.seeks = 0; 192 193 pde_get(&proc_root); 194 root_inode = proc_get_inode(s, &proc_root); 195 if (!root_inode) { 196 pr_err("proc_fill_super: get root inode failed\n"); 197 return -ENOMEM; 198 } 199 200 s->s_root = d_make_root(root_inode); 201 if (!s->s_root) { 202 pr_err("proc_fill_super: allocate dentry failed\n"); 203 return -ENOMEM; 204 } 205 206 ret = proc_setup_self(s); 207 if (ret) { 208 return ret; 209 } 210 return proc_setup_thread_self(s); 211 } 212 213 static int proc_reconfigure(struct fs_context *fc) 214 { 215 struct super_block *sb = fc->root->d_sb; 216 struct proc_fs_info *fs_info = proc_sb_info(sb); 217 218 sync_filesystem(sb); 219 220 proc_apply_options(fs_info, fc, current_user_ns()); 221 return 0; 222 } 223 224 static int proc_get_tree(struct fs_context *fc) 225 { 226 return get_tree_nodev(fc, proc_fill_super); 227 } 228 229 static void proc_fs_context_free(struct fs_context *fc) 230 { 231 struct proc_fs_context *ctx = fc->fs_private; 232 233 put_pid_ns(ctx->pid_ns); 234 kfree(ctx); 235 } 236 237 static const struct fs_context_operations proc_fs_context_ops = { 238 .free = proc_fs_context_free, 239 .parse_param = proc_parse_param, 240 .get_tree = proc_get_tree, 241 .reconfigure = proc_reconfigure, 242 }; 243 244 static int proc_init_fs_context(struct fs_context *fc) 245 { 246 struct proc_fs_context *ctx; 247 248 ctx = kzalloc(sizeof(struct proc_fs_context), GFP_KERNEL); 249 if (!ctx) 250 return -ENOMEM; 251 252 ctx->pid_ns = get_pid_ns(task_active_pid_ns(current)); 253 put_user_ns(fc->user_ns); 254 fc->user_ns = get_user_ns(ctx->pid_ns->user_ns); 255 fc->fs_private = ctx; 256 fc->ops = &proc_fs_context_ops; 257 return 0; 258 } 259 260 static void proc_kill_sb(struct super_block *sb) 261 { 262 struct proc_fs_info *fs_info = proc_sb_info(sb); 263 264 if (!fs_info) { 265 kill_anon_super(sb); 266 return; 267 } 268 269 dput(fs_info->proc_self); 270 dput(fs_info->proc_thread_self); 271 272 kill_anon_super(sb); 273 put_pid_ns(fs_info->pid_ns); 274 kfree(fs_info); 275 } 276 277 static struct file_system_type proc_fs_type = { 278 .name = "proc", 279 .init_fs_context = proc_init_fs_context, 280 .parameters = proc_fs_parameters, 281 .kill_sb = proc_kill_sb, 282 .fs_flags = FS_USERNS_MOUNT | FS_DISALLOW_NOTIFY_PERM, 283 }; 284 285 void __init proc_root_init(void) 286 { 287 proc_init_kmemcache(); 288 set_proc_pid_nlink(); 289 proc_self_init(); 290 proc_thread_self_init(); 291 proc_symlink("mounts", NULL, "self/mounts"); 292 293 proc_net_init(); 294 proc_mkdir("fs", NULL); 295 proc_mkdir("driver", NULL); 296 proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */ 297 #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE) 298 /* just give it a mountpoint */ 299 proc_create_mount_point("openprom"); 300 #endif 301 proc_tty_init(); 302 proc_mkdir("bus", NULL); 303 proc_sys_init(); 304 305 /* 306 * Last things last. It is not like userspace processes eager 307 * to open /proc files exist at this point but register last 308 * anyway. 309 */ 310 register_filesystem(&proc_fs_type); 311 } 312 313 static int proc_root_getattr(struct mnt_idmap *idmap, 314 const struct path *path, struct kstat *stat, 315 u32 request_mask, unsigned int query_flags) 316 { 317 generic_fillattr(&nop_mnt_idmap, request_mask, d_inode(path->dentry), 318 stat); 319 stat->nlink = proc_root.nlink + nr_processes(); 320 return 0; 321 } 322 323 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags) 324 { 325 if (!proc_pid_lookup(dentry, flags)) 326 return NULL; 327 328 return proc_lookup(dir, dentry, flags); 329 } 330 331 static int proc_root_readdir(struct file *file, struct dir_context *ctx) 332 { 333 if (ctx->pos < FIRST_PROCESS_ENTRY) { 334 int error = proc_readdir(file, ctx); 335 if (unlikely(error <= 0)) 336 return error; 337 ctx->pos = FIRST_PROCESS_ENTRY; 338 } 339 340 return proc_pid_readdir(file, ctx); 341 } 342 343 /* 344 * The root /proc directory is special, as it has the 345 * <pid> directories. Thus we don't use the generic 346 * directory handling functions for that.. 347 */ 348 static const struct file_operations proc_root_operations = { 349 .read = generic_read_dir, 350 .iterate_shared = proc_root_readdir, 351 .llseek = generic_file_llseek, 352 }; 353 354 /* 355 * proc root can do almost nothing.. 356 */ 357 static const struct inode_operations proc_root_inode_operations = { 358 .lookup = proc_root_lookup, 359 .getattr = proc_root_getattr, 360 }; 361 362 /* 363 * This is the root "inode" in the /proc tree.. 364 */ 365 struct proc_dir_entry proc_root = { 366 .low_ino = PROC_ROOT_INO, 367 .namelen = 5, 368 .mode = S_IFDIR | S_IRUGO | S_IXUGO, 369 .nlink = 2, 370 .refcnt = REFCOUNT_INIT(1), 371 .proc_iops = &proc_root_inode_operations, 372 .proc_dir_ops = &proc_root_operations, 373 .parent = &proc_root, 374 .subdir = RB_ROOT, 375 .name = "/proc", 376 }; 377