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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/mount.h> | |
23 | #include <linux/pid_namespace.h> | |
24 | #include <linux/parser.h> | |
25 | #include <linux/cred.h> | |
26 | ||
27 | #include "internal.h" | |
28 | ||
29 | enum { | |
30 | Opt_gid, Opt_hidepid, Opt_err, | |
31 | }; | |
32 | ||
33 | static const match_table_t tokens = { | |
34 | {Opt_hidepid, "hidepid=%u"}, | |
35 | {Opt_gid, "gid=%u"}, | |
36 | {Opt_err, NULL}, | |
37 | }; | |
38 | ||
39 | int proc_parse_options(char *options, struct pid_namespace *pid) | |
40 | { | |
41 | char *p; | |
42 | substring_t args[MAX_OPT_ARGS]; | |
43 | int option; | |
44 | ||
45 | if (!options) | |
46 | return 1; | |
47 | ||
48 | while ((p = strsep(&options, ",")) != NULL) { | |
49 | int token; | |
50 | if (!*p) | |
51 | continue; | |
52 | ||
53 | args[0].to = args[0].from = NULL; | |
54 | token = match_token(p, tokens, args); | |
55 | switch (token) { | |
56 | case Opt_gid: | |
57 | if (match_int(&args[0], &option)) | |
58 | return 0; | |
59 | pid->pid_gid = make_kgid(current_user_ns(), option); | |
60 | break; | |
61 | case Opt_hidepid: | |
62 | if (match_int(&args[0], &option)) | |
63 | return 0; | |
64 | if (option < HIDEPID_OFF || | |
65 | option > HIDEPID_INVISIBLE) { | |
66 | pr_err("proc: hidepid value must be between 0 and 2.\n"); | |
67 | return 0; | |
68 | } | |
69 | pid->hide_pid = option; | |
70 | break; | |
71 | default: | |
72 | pr_err("proc: unrecognized mount option \"%s\" " | |
73 | "or missing value\n", p); | |
74 | return 0; | |
75 | } | |
76 | } | |
77 | ||
78 | return 1; | |
79 | } | |
80 | ||
81 | int proc_remount(struct super_block *sb, int *flags, char *data) | |
82 | { | |
83 | struct pid_namespace *pid = sb->s_fs_info; | |
84 | ||
85 | sync_filesystem(sb); | |
86 | return !proc_parse_options(data, pid); | |
87 | } | |
88 | ||
89 | static struct dentry *proc_mount(struct file_system_type *fs_type, | |
90 | int flags, const char *dev_name, void *data) | |
91 | { | |
92 | struct pid_namespace *ns; | |
93 | ||
94 | if (flags & SB_KERNMOUNT) { | |
95 | ns = data; | |
96 | data = NULL; | |
97 | } else { | |
98 | ns = task_active_pid_ns(current); | |
99 | } | |
100 | ||
101 | return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super); | |
102 | } | |
103 | ||
104 | static void proc_kill_sb(struct super_block *sb) | |
105 | { | |
106 | struct pid_namespace *ns; | |
107 | ||
108 | ns = (struct pid_namespace *)sb->s_fs_info; | |
109 | if (ns->proc_self) | |
110 | dput(ns->proc_self); | |
111 | if (ns->proc_thread_self) | |
112 | dput(ns->proc_thread_self); | |
113 | kill_anon_super(sb); | |
114 | put_pid_ns(ns); | |
115 | } | |
116 | ||
117 | static struct file_system_type proc_fs_type = { | |
118 | .name = "proc", | |
119 | .mount = proc_mount, | |
120 | .kill_sb = proc_kill_sb, | |
121 | .fs_flags = FS_USERNS_MOUNT, | |
122 | }; | |
123 | ||
124 | void __init proc_root_init(void) | |
125 | { | |
126 | int err; | |
127 | ||
128 | proc_init_inodecache(); | |
129 | set_proc_pid_nlink(); | |
130 | err = register_filesystem(&proc_fs_type); | |
131 | if (err) | |
132 | return; | |
133 | ||
134 | proc_self_init(); | |
135 | proc_thread_self_init(); | |
136 | proc_symlink("mounts", NULL, "self/mounts"); | |
137 | ||
138 | proc_net_init(); | |
139 | ||
140 | #ifdef CONFIG_SYSVIPC | |
141 | proc_mkdir("sysvipc", NULL); | |
142 | #endif | |
143 | proc_mkdir("fs", NULL); | |
144 | proc_mkdir("driver", NULL); | |
145 | proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */ | |
146 | #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE) | |
147 | /* just give it a mountpoint */ | |
148 | proc_create_mount_point("openprom"); | |
149 | #endif | |
150 | proc_tty_init(); | |
151 | proc_mkdir("bus", NULL); | |
152 | proc_sys_init(); | |
153 | } | |
154 | ||
155 | static int proc_root_getattr(const struct path *path, struct kstat *stat, | |
156 | u32 request_mask, unsigned int query_flags) | |
157 | { | |
158 | generic_fillattr(d_inode(path->dentry), stat); | |
159 | stat->nlink = proc_root.nlink + nr_processes(); | |
160 | return 0; | |
161 | } | |
162 | ||
163 | static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags) | |
164 | { | |
165 | if (!proc_pid_lookup(dir, dentry, flags)) | |
166 | return NULL; | |
167 | ||
168 | return proc_lookup(dir, dentry, flags); | |
169 | } | |
170 | ||
171 | static int proc_root_readdir(struct file *file, struct dir_context *ctx) | |
172 | { | |
173 | if (ctx->pos < FIRST_PROCESS_ENTRY) { | |
174 | int error = proc_readdir(file, ctx); | |
175 | if (unlikely(error <= 0)) | |
176 | return error; | |
177 | ctx->pos = FIRST_PROCESS_ENTRY; | |
178 | } | |
179 | ||
180 | return proc_pid_readdir(file, ctx); | |
181 | } | |
182 | ||
183 | /* | |
184 | * The root /proc directory is special, as it has the | |
185 | * <pid> directories. Thus we don't use the generic | |
186 | * directory handling functions for that.. | |
187 | */ | |
188 | static const struct file_operations proc_root_operations = { | |
189 | .read = generic_read_dir, | |
190 | .iterate_shared = proc_root_readdir, | |
191 | .llseek = generic_file_llseek, | |
192 | }; | |
193 | ||
194 | /* | |
195 | * proc root can do almost nothing.. | |
196 | */ | |
197 | static const struct inode_operations proc_root_inode_operations = { | |
198 | .lookup = proc_root_lookup, | |
199 | .getattr = proc_root_getattr, | |
200 | }; | |
201 | ||
202 | /* | |
203 | * This is the root "inode" in the /proc tree.. | |
204 | */ | |
205 | struct proc_dir_entry proc_root = { | |
206 | .low_ino = PROC_ROOT_INO, | |
207 | .namelen = 5, | |
208 | .mode = S_IFDIR | S_IRUGO | S_IXUGO, | |
209 | .nlink = 2, | |
210 | .count = ATOMIC_INIT(1), | |
211 | .proc_iops = &proc_root_inode_operations, | |
212 | .proc_fops = &proc_root_operations, | |
213 | .parent = &proc_root, | |
214 | .subdir = RB_ROOT_CACHED, | |
215 | .name = "/proc", | |
216 | }; | |
217 | ||
218 | int pid_ns_prepare_proc(struct pid_namespace *ns) | |
219 | { | |
220 | struct vfsmount *mnt; | |
221 | ||
222 | mnt = kern_mount_data(&proc_fs_type, ns); | |
223 | if (IS_ERR(mnt)) | |
224 | return PTR_ERR(mnt); | |
225 | ||
226 | ns->proc_mnt = mnt; | |
227 | return 0; | |
228 | } | |
229 | ||
230 | void pid_ns_release_proc(struct pid_namespace *ns) | |
231 | { | |
232 | kern_unmount(ns->proc_mnt); | |
233 | } |