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2023-12-11 072de836f53be56a70cecf70b43ae43b7ce17376 
 kernel/fs/proc/root.c
....@@ -19,150 +19,270 @@
1919 #include <linux/module.h>
2020 #include <linux/bitops.h>
2121 #include <linux/user_namespace.h>
22
+#include <linux/fs_context.h>
2223 #include <linux/mount.h>
2324 #include <linux/pid_namespace.h>
24
-#include <linux/parser.h>
25
+#include <linux/fs_parser.h>
2526 #include <linux/cred.h>
27
+#include <linux/magic.h>
28
+#include <linux/slab.h>
2629 
2730 #include "internal.h"
2831 
29
-static int proc_test_super(struct super_block *sb, void *data)
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)
3054 {
31
-	return sb->s_fs_info == data;
55
+	return (value == HIDEPID_OFF ||
56
+		value == HIDEPID_NO_ACCESS ||
57
+		value == HIDEPID_INVISIBLE ||
58
+		value == HIDEPID_NOT_PTRACEABLE);
3259 }
3360 
34
-static int proc_set_super(struct super_block *sb, void *data)
61
+static int proc_parse_hidepid_param(struct fs_context *fc, struct fs_parameter *param)
3562 {
36
-	int err = set_anon_super(sb, NULL);
37
-	if (!err) {
38
-		struct pid_namespace *ns = (struct pid_namespace *)data;
39
-		sb->s_fs_info = get_pid_ns(ns);
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;
4076 	}
41
-	return err;
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;
4290 }
4391 
44
-enum {
45
-	Opt_gid, Opt_hidepid, Opt_err,
46
-};
47
-
48
-static const match_table_t tokens = {
49
-	{Opt_hidepid, "hidepid=%u"},
50
-	{Opt_gid, "gid=%u"},
51
-	{Opt_err, NULL},
52
-};
53
-
54
-static int proc_parse_options(char *options, struct pid_namespace *pid)
92
+static int proc_parse_subset_param(struct fs_context *fc, char *value)
5593 {
56
-	char *p;
57
-	substring_t args[MAX_OPT_ARGS];
58
-	int option;
94
+	struct proc_fs_context *ctx = fc->fs_private;
5995 
60
-	if (!options)
61
-		return 1;
96
+	while (value) {
97
+		char *ptr = strchr(value, ',');
6298 
63
-	while ((p = strsep(&options, ",")) != NULL) {
64
-		int token;
65
-		if (!*p)
66
-			continue;
99
+		if (ptr != NULL)
100
+			*ptr++ = '\0';
67101 
68
-		args[0].to = args[0].from = NULL;
69
-		token = match_token(p, tokens, args);
70
-		switch (token) {
71
-		case Opt_gid:
72
-			if (match_int(&args[0], &option))
73
-				return 0;
74
-			pid->pid_gid = make_kgid(current_user_ns(), option);
75
-			break;
76
-		case Opt_hidepid:
77
-			if (match_int(&args[0], &option))
78
-				return 0;
79
-			if (option < HIDEPID_OFF ||
80
-			    option > HIDEPID_INVISIBLE) {
81
-				pr_err("proc: hidepid value must be between 0 and 2.\n");
82
-				return 0;
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);
83107 			}
84
-			pid->hide_pid = option;
85
-			break;
86
-		default:
87
-			pr_err("proc: unrecognized mount option \"%s\" "
88
-			       "or missing value\n", p);
89
-			return 0;
90108 		}
109
+		value = ptr;
91110 	}
92111 
93
-	return 1;
112
+	return 0;
94113 }
95114 
96
-int proc_remount(struct super_block *sb, int *flags, char *data)
115
+static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param)
97116 {
98
-	struct pid_namespace *pid = sb->s_fs_info;
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);
99220 
100221 	sync_filesystem(sb);
101
-	return !proc_parse_options(data, pid);
222
+
223
+	proc_apply_options(fs_info, fc, current_user_ns());
224
+	return 0;
102225 }
103226 
104
-static struct dentry *proc_mount(struct file_system_type *fs_type,
105
-	int flags, const char *dev_name, void *data)
227
+static int proc_get_tree(struct fs_context *fc)
106228 {
107
-	int err;
108
-	struct super_block *sb;
109
-	struct pid_namespace *ns;
110
-	char *options;
229
+	return get_tree_nodev(fc, proc_fill_super);
230
+}
111231 
112
-	if (flags & SB_KERNMOUNT) {
113
-		ns = (struct pid_namespace *)data;
114
-		options = NULL;
115
-	} else {
116
-		ns = task_active_pid_ns(current);
117
-		options = data;
232
+static void proc_fs_context_free(struct fs_context *fc)
233
+{
234
+	struct proc_fs_context *ctx = fc->fs_private;
118235 
119
-		/* Does the mounter have privilege over the pid namespace? */
120
-		if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
121
-			return ERR_PTR(-EPERM);
122
-	}
236
+	put_pid_ns(ctx->pid_ns);
237
+	kfree(ctx);
238
+}
123239 
124
-	sb = sget(fs_type, proc_test_super, proc_set_super, flags, ns);
125
-	if (IS_ERR(sb))
126
-		return ERR_CAST(sb);
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
+};
127246 
128
-	if (!proc_parse_options(options, ns)) {
129
-		deactivate_locked_super(sb);
130
-		return ERR_PTR(-EINVAL);
131
-	}
247
+static int proc_init_fs_context(struct fs_context *fc)
248
+{
249
+	struct proc_fs_context *ctx;
132250 
133
-	if (!sb->s_root) {
134
-		err = proc_fill_super(sb);
135
-		if (err) {
136
-			deactivate_locked_super(sb);
137
-			return ERR_PTR(err);
138
-		}
251
+	ctx = kzalloc(sizeof(struct proc_fs_context), GFP_KERNEL);
252
+	if (!ctx)
253
+		return -ENOMEM;
139254 
140
-		sb->s_flags |= MS_ACTIVE;
141
-		/* User space would break if executables appear on proc */
142
-		sb->s_iflags |= SB_I_NOEXEC;
143
-	}
144
-
145
-	return dget(sb->s_root);
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;
146261 }
147262 
148263 static void proc_kill_sb(struct super_block *sb)
149264 {
150
-	struct pid_namespace *ns;
265
+	struct proc_fs_info *fs_info = proc_sb_info(sb);
151266 
152
-	ns = (struct pid_namespace *)sb->s_fs_info;
153
-	if (ns->proc_self)
154
-		dput(ns->proc_self);
155
-	if (ns->proc_thread_self)
156
-		dput(ns->proc_thread_self);
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
+
157275 	kill_anon_super(sb);
158
-	put_pid_ns(ns);
276
+	put_pid_ns(fs_info->pid_ns);
277
+	kfree(fs_info);
159278 }
160279 
161280 static struct file_system_type proc_fs_type = {
162
-	.name		= "proc",
163
-	.mount		= proc_mount,
164
-	.kill_sb	= proc_kill_sb,
165
-	.fs_flags	= FS_USERNS_MOUNT,
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,
166286 };
167287 
168288 void __init proc_root_init(void)
....@@ -174,7 +294,6 @@
174294 	proc_symlink("mounts", NULL, "self/mounts");
175295 
176296 	proc_net_init();
177
-	proc_uid_init();
178297 	proc_mkdir("fs", NULL);
179298 	proc_mkdir("driver", NULL);
180299 	proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */
....@@ -199,9 +318,9 @@
199318 
200319 static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
201320 {
202
-	if (!proc_pid_lookup(dir, dentry, flags))
321
+	if (!proc_pid_lookup(dentry, flags))
203322 		return NULL;
204
-	
323
+
205324 	return proc_lookup(dir, dentry, flags);
206325 }
207326 
....@@ -246,25 +365,8 @@
246365 	.nlink		= 2, 
247366 	.refcnt		= REFCOUNT_INIT(1),
248367 	.proc_iops	= &proc_root_inode_operations, 
249
-	.proc_fops	= &proc_root_operations,
368
+	.proc_dir_ops	= &proc_root_operations,
250369 	.parent		= &proc_root,
251370 	.subdir		= RB_ROOT,
252371 	.name		= "/proc",
253372 };
254
-
255
-int pid_ns_prepare_proc(struct pid_namespace *ns)
256
-{
257
-	struct vfsmount *mnt;
258
-
259
-	mnt = kern_mount_data(&proc_fs_type, ns);
260
-	if (IS_ERR(mnt))
261
-		return PTR_ERR(mnt);
262
-
263
-	ns->proc_mnt = mnt;
264
-	return 0;
265
-}
266
-
267
-void pid_ns_release_proc(struct pid_namespace *ns)
268
-{
269
-	kern_unmount(ns->proc_mnt);
270
-}