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