Line data Source code
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 0 : value == HIDEPID_NO_ACCESS ||
54 0 : value == HIDEPID_INVISIBLE ||
55 0 : value == HIDEPID_NOT_PTRACEABLE);
56 : }
57 :
58 0 : static int proc_parse_hidepid_param(struct fs_context *fc, struct fs_parameter *param)
59 : {
60 0 : struct proc_fs_context *ctx = fc->fs_private;
61 0 : struct fs_parameter_spec hidepid_u32_spec = fsparam_u32("hidepid", Opt_hidepid);
62 : struct fs_parse_result result;
63 0 : int base = (unsigned long)hidepid_u32_spec.data;
64 :
65 0 : if (param->type != fs_value_is_string)
66 0 : return invalf(fc, "proc: unexpected type of hidepid value\n");
67 :
68 0 : if (!kstrtouint(param->string, base, &result.uint_32)) {
69 0 : if (!valid_hidepid(result.uint_32))
70 0 : return invalf(fc, "proc: unknown value of hidepid - %s\n", param->string);
71 0 : ctx->hidepid = result.uint_32;
72 : return 0;
73 : }
74 :
75 0 : if (!strcmp(param->string, "off"))
76 0 : ctx->hidepid = HIDEPID_OFF;
77 0 : else if (!strcmp(param->string, "noaccess"))
78 0 : ctx->hidepid = HIDEPID_NO_ACCESS;
79 0 : else if (!strcmp(param->string, "invisible"))
80 0 : ctx->hidepid = HIDEPID_INVISIBLE;
81 0 : else if (!strcmp(param->string, "ptraceable"))
82 0 : ctx->hidepid = HIDEPID_NOT_PTRACEABLE;
83 : else
84 0 : return invalf(fc, "proc: unknown value of hidepid - %s\n", param->string);
85 :
86 : return 0;
87 : }
88 :
89 0 : static int proc_parse_subset_param(struct fs_context *fc, char *value)
90 : {
91 0 : struct proc_fs_context *ctx = fc->fs_private;
92 :
93 0 : while (value) {
94 0 : char *ptr = strchr(value, ',');
95 :
96 0 : if (ptr != NULL)
97 0 : *ptr++ = '\0';
98 :
99 0 : if (*value != '\0') {
100 0 : if (!strcmp(value, "pid")) {
101 0 : ctx->pidonly = PROC_PIDONLY_ON;
102 : } else {
103 0 : return invalf(fc, "proc: unsupported subset option - %s\n", value);
104 : }
105 : }
106 : value = ptr;
107 : }
108 :
109 : return 0;
110 : }
111 :
112 1 : static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param)
113 : {
114 1 : struct proc_fs_context *ctx = fc->fs_private;
115 : struct fs_parse_result result;
116 : int opt;
117 :
118 1 : opt = fs_parse(fc, proc_fs_parameters, param, &result);
119 1 : if (opt < 0)
120 : return opt;
121 :
122 0 : switch (opt) {
123 : case Opt_gid:
124 0 : ctx->gid = result.uint_32;
125 0 : break;
126 :
127 : case Opt_hidepid:
128 0 : if (proc_parse_hidepid_param(fc, param))
129 : return -EINVAL;
130 : break;
131 :
132 : case Opt_subset:
133 0 : if (proc_parse_subset_param(fc, param->string) < 0)
134 : return -EINVAL;
135 : break;
136 :
137 : default:
138 : return -EINVAL;
139 : }
140 :
141 0 : ctx->mask |= 1 << opt;
142 0 : 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 1 : struct proc_fs_context *ctx = fc->fs_private;
150 :
151 1 : if (ctx->mask & (1 << Opt_gid))
152 0 : fs_info->pid_gid = make_kgid(user_ns, ctx->gid);
153 1 : if (ctx->mask & (1 << Opt_hidepid))
154 0 : fs_info->hide_pid = ctx->hidepid;
155 1 : if (ctx->mask & (1 << Opt_subset))
156 0 : fs_info->pidonly = ctx->pidonly;
157 : }
158 :
159 1 : static int proc_fill_super(struct super_block *s, struct fs_context *fc)
160 : {
161 1 : 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 1 : fs_info = kzalloc(sizeof(*fs_info), GFP_KERNEL);
167 1 : if (!fs_info)
168 : return -ENOMEM;
169 :
170 2 : fs_info->pid_ns = get_pid_ns(ctx->pid_ns);
171 2 : proc_apply_options(fs_info, fc, current_user_ns());
172 :
173 : /* User space would break if executables or devices appear on proc */
174 1 : s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV;
175 1 : s->s_flags |= SB_NODIRATIME | SB_NOSUID | SB_NOEXEC;
176 1 : s->s_blocksize = 1024;
177 1 : s->s_blocksize_bits = 10;
178 1 : s->s_magic = PROC_SUPER_MAGIC;
179 1 : s->s_op = &proc_sops;
180 1 : s->s_time_gran = 1;
181 1 : 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 1 : s->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
189 :
190 : /* procfs dentries and inodes don't require IO to create */
191 1 : s->s_shrink.seeks = 0;
192 :
193 1 : pde_get(&proc_root);
194 1 : root_inode = proc_get_inode(s, &proc_root);
195 1 : if (!root_inode) {
196 0 : pr_err("proc_fill_super: get root inode failed\n");
197 0 : return -ENOMEM;
198 : }
199 :
200 1 : s->s_root = d_make_root(root_inode);
201 1 : if (!s->s_root) {
202 0 : pr_err("proc_fill_super: allocate dentry failed\n");
203 0 : return -ENOMEM;
204 : }
205 :
206 1 : ret = proc_setup_self(s);
207 1 : if (ret) {
208 : return ret;
209 : }
210 1 : return proc_setup_thread_self(s);
211 : }
212 :
213 0 : static int proc_reconfigure(struct fs_context *fc)
214 : {
215 0 : struct super_block *sb = fc->root->d_sb;
216 0 : struct proc_fs_info *fs_info = proc_sb_info(sb);
217 :
218 0 : sync_filesystem(sb);
219 :
220 0 : proc_apply_options(fs_info, fc, current_user_ns());
221 0 : return 0;
222 : }
223 :
224 1 : static int proc_get_tree(struct fs_context *fc)
225 : {
226 1 : return get_tree_nodev(fc, proc_fill_super);
227 : }
228 :
229 1 : static void proc_fs_context_free(struct fs_context *fc)
230 : {
231 1 : struct proc_fs_context *ctx = fc->fs_private;
232 :
233 1 : put_pid_ns(ctx->pid_ns);
234 1 : kfree(ctx);
235 1 : }
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 1 : static int proc_init_fs_context(struct fs_context *fc)
245 : {
246 : struct proc_fs_context *ctx;
247 :
248 1 : ctx = kzalloc(sizeof(struct proc_fs_context), GFP_KERNEL);
249 1 : if (!ctx)
250 : return -ENOMEM;
251 :
252 2 : ctx->pid_ns = get_pid_ns(task_active_pid_ns(current));
253 1 : put_user_ns(fc->user_ns);
254 1 : fc->user_ns = get_user_ns(ctx->pid_ns->user_ns);
255 1 : fc->fs_private = ctx;
256 1 : fc->ops = &proc_fs_context_ops;
257 1 : return 0;
258 : }
259 :
260 0 : static void proc_kill_sb(struct super_block *sb)
261 : {
262 0 : struct proc_fs_info *fs_info = proc_sb_info(sb);
263 :
264 0 : if (!fs_info) {
265 0 : kill_anon_super(sb);
266 0 : return;
267 : }
268 :
269 0 : dput(fs_info->proc_self);
270 0 : dput(fs_info->proc_thread_self);
271 :
272 0 : kill_anon_super(sb);
273 0 : put_pid_ns(fs_info->pid_ns);
274 0 : 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 1 : void __init proc_root_init(void)
286 : {
287 1 : proc_init_kmemcache();
288 1 : set_proc_pid_nlink();
289 1 : proc_self_init();
290 1 : proc_thread_self_init();
291 1 : proc_symlink("mounts", NULL, "self/mounts");
292 :
293 : proc_net_init();
294 1 : proc_mkdir("fs", NULL);
295 1 : proc_mkdir("driver", NULL);
296 1 : 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 1 : proc_tty_init();
302 1 : proc_mkdir("bus", NULL);
303 1 : 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 1 : register_filesystem(&proc_fs_type);
311 1 : }
312 :
313 0 : 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 0 : generic_fillattr(&nop_mnt_idmap, d_inode(path->dentry), stat);
318 0 : stat->nlink = proc_root.nlink + nr_processes();
319 0 : return 0;
320 : }
321 :
322 0 : static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
323 : {
324 0 : if (!proc_pid_lookup(dentry, flags))
325 : return NULL;
326 :
327 0 : return proc_lookup(dir, dentry, flags);
328 : }
329 :
330 0 : static int proc_root_readdir(struct file *file, struct dir_context *ctx)
331 : {
332 0 : if (ctx->pos < FIRST_PROCESS_ENTRY) {
333 0 : int error = proc_readdir(file, ctx);
334 0 : if (unlikely(error <= 0))
335 : return error;
336 0 : ctx->pos = FIRST_PROCESS_ENTRY;
337 : }
338 :
339 0 : return proc_pid_readdir(file, ctx);
340 : }
341 :
342 : /*
343 : * The root /proc directory is special, as it has the
344 : * <pid> directories. Thus we don't use the generic
345 : * directory handling functions for that..
346 : */
347 : static const struct file_operations proc_root_operations = {
348 : .read = generic_read_dir,
349 : .iterate_shared = proc_root_readdir,
350 : .llseek = generic_file_llseek,
351 : };
352 :
353 : /*
354 : * proc root can do almost nothing..
355 : */
356 : static const struct inode_operations proc_root_inode_operations = {
357 : .lookup = proc_root_lookup,
358 : .getattr = proc_root_getattr,
359 : };
360 :
361 : /*
362 : * This is the root "inode" in the /proc tree..
363 : */
364 : struct proc_dir_entry proc_root = {
365 : .low_ino = PROC_ROOT_INO,
366 : .namelen = 5,
367 : .mode = S_IFDIR | S_IRUGO | S_IXUGO,
368 : .nlink = 2,
369 : .refcnt = REFCOUNT_INIT(1),
370 : .proc_iops = &proc_root_inode_operations,
371 : .proc_dir_ops = &proc_root_operations,
372 : .parent = &proc_root,
373 : .subdir = RB_ROOT,
374 : .name = "/proc",
375 : };
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