1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 1991, 1992 Linus Torvalds
7 * proc root directory handling functions
10 #include <linux/uaccess.h>
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>
32 struct proc_fs_context {
33 struct pid_namespace *pid_ns;
35 enum proc_hidepid hidepid;
37 enum proc_pidonly pidonly;
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),
53 static inline int valid_hidepid(unsigned int value)
55 return (value == HIDEPID_OFF ||
56 value == HIDEPID_NO_ACCESS ||
57 value == HIDEPID_INVISIBLE ||
58 value == HIDEPID_NOT_PTRACEABLE);
61 static int proc_parse_hidepid_param(struct fs_context *fc, struct fs_parameter *param)
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;
68 if (param->type != fs_value_is_string)
69 return invalf(fc, "proc: unexpected type of hidepid value\n");
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;
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;
87 return invalf(fc, "proc: unknown value of hidepid - %s\n", param->string);
92 static int proc_parse_subset_param(struct fs_context *fc, char *value)
94 struct proc_fs_context *ctx = fc->fs_private;
97 char *ptr = strchr(value, ',');
102 if (*value != '\0') {
103 if (!strcmp(value, "pid")) {
104 ctx->pidonly = PROC_PIDONLY_ON;
106 return invalf(fc, "proc: unsupported subset option - %s\n", value);
115 static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param)
117 struct proc_fs_context *ctx = fc->fs_private;
118 struct fs_parse_result result;
121 opt = fs_parse(fc, proc_fs_parameters, param, &result);
127 ctx->gid = result.uint_32;
131 if (proc_parse_hidepid_param(fc, param))
136 if (proc_parse_subset_param(fc, param->string) < 0)
144 ctx->mask |= 1 << opt;
148 static void proc_apply_options(struct proc_fs_info *fs_info,
149 struct fs_context *fc,
150 struct user_namespace *user_ns)
152 struct proc_fs_context *ctx = fc->fs_private;
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;
162 static int proc_fill_super(struct super_block *s, struct fs_context *fc)
164 struct proc_fs_context *ctx = fc->fs_private;
165 struct inode *root_inode;
166 struct proc_fs_info *fs_info;
169 fs_info = kzalloc(sizeof(*fs_info), GFP_KERNEL);
173 fs_info->pid_ns = get_pid_ns(ctx->pid_ns);
174 proc_apply_options(fs_info, fc, current_user_ns());
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;
184 s->s_fs_info = fs_info;
187 * procfs isn't actually a stacking filesystem; however, there is
188 * too much magic going on inside it to permit stacking things on
191 s->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
193 /* procfs dentries and inodes don't require IO to create */
194 s->s_shrink.seeks = 0;
197 root_inode = proc_get_inode(s, &proc_root);
199 pr_err("proc_fill_super: get root inode failed\n");
203 s->s_root = d_make_root(root_inode);
205 pr_err("proc_fill_super: allocate dentry failed\n");
209 ret = proc_setup_self(s);
213 return proc_setup_thread_self(s);
216 static int proc_reconfigure(struct fs_context *fc)
218 struct super_block *sb = fc->root->d_sb;
219 struct proc_fs_info *fs_info = proc_sb_info(sb);
223 proc_apply_options(fs_info, fc, current_user_ns());
227 static int proc_get_tree(struct fs_context *fc)
229 return get_tree_nodev(fc, proc_fill_super);
232 static void proc_fs_context_free(struct fs_context *fc)
234 struct proc_fs_context *ctx = fc->fs_private;
236 put_pid_ns(ctx->pid_ns);
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,
247 static int proc_init_fs_context(struct fs_context *fc)
249 struct proc_fs_context *ctx;
251 ctx = kzalloc(sizeof(struct proc_fs_context), GFP_KERNEL);
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;
263 static void proc_kill_sb(struct super_block *sb)
265 struct proc_fs_info *fs_info = proc_sb_info(sb);
272 dput(fs_info->proc_self);
273 dput(fs_info->proc_thread_self);
276 put_pid_ns(fs_info->pid_ns);
280 static struct file_system_type proc_fs_type = {
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,
288 void __init proc_root_init(void)
290 proc_init_kmemcache();
291 set_proc_pid_nlink();
293 proc_thread_self_init();
294 proc_symlink("mounts", NULL, "self/mounts");
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");
305 proc_mkdir("bus", NULL);
308 register_filesystem(&proc_fs_type);
311 static int proc_root_getattr(struct user_namespace *mnt_userns,
312 const struct path *path, struct kstat *stat,
313 u32 request_mask, unsigned int query_flags)
315 generic_fillattr(&init_user_ns, d_inode(path->dentry), stat);
316 stat->nlink = proc_root.nlink + nr_processes();
320 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
322 if (!proc_pid_lookup(dentry, flags))
325 return proc_lookup(dir, dentry, flags);
328 static int proc_root_readdir(struct file *file, struct dir_context *ctx)
330 if (ctx->pos < FIRST_PROCESS_ENTRY) {
331 int error = proc_readdir(file, ctx);
332 if (unlikely(error <= 0))
334 ctx->pos = FIRST_PROCESS_ENTRY;
337 return proc_pid_readdir(file, ctx);
341 * The root /proc directory is special, as it has the
342 * <pid> directories. Thus we don't use the generic
343 * directory handling functions for that..
345 static const struct file_operations proc_root_operations = {
346 .read = generic_read_dir,
347 .iterate_shared = proc_root_readdir,
348 .llseek = generic_file_llseek,
352 * proc root can do almost nothing..
354 static const struct inode_operations proc_root_inode_operations = {
355 .lookup = proc_root_lookup,
356 .getattr = proc_root_getattr,
360 * This is the root "inode" in the /proc tree..
362 struct proc_dir_entry proc_root = {
363 .low_ino = PROC_ROOT_INO,
365 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
367 .refcnt = REFCOUNT_INIT(1),
368 .proc_iops = &proc_root_inode_operations,
369 .proc_dir_ops = &proc_root_operations,
370 .parent = &proc_root,