1 files changed, 71 insertions, 7 deletions

diff --git a/fs/proc/root.c b/fs/proc/root.c
index 9a8a2b77b874..46a15d8a29ca 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -18,6 +18,7 @@
 #include <linux/bitops.h>
 #include <linux/mount.h>
 #include <linux/pid_namespace.h>
+#include <linux/parser.h>
 
 #include "internal.h"
 
@@ -36,6 +37,63 @@ static int proc_set_super(struct super_block *sb, void *data)
 	return err;
 }
 
+enum {
+	Opt_gid, Opt_hidepid, Opt_err,
+};
+
+static const match_table_t tokens = {
+	{Opt_hidepid, "hidepid=%u"},
+	{Opt_gid, "gid=%u"},
+	{Opt_err, NULL},
+};
+
+static int proc_parse_options(char *options, struct pid_namespace *pid)
+{
+	char *p;
+	substring_t args[MAX_OPT_ARGS];
+	int option;
+
+	if (!options)
+		return 1;
+
+	while ((p = strsep(&options, ",")) != NULL) {
+		int token;
+		if (!*p)
+			continue;
+
+		args[0].to = args[0].from = 0;
+		token = match_token(p, tokens, args);
+		switch (token) {
+		case Opt_gid:
+			if (match_int(&args[0], &option))
+				return 0;
+			pid->pid_gid = option;
+			break;
+		case Opt_hidepid:
+			if (match_int(&args[0], &option))
+				return 0;
+			if (option < 0 || option > 2) {
+				pr_err("proc: hidepid value must be between 0 and 2.\n");
+				return 0;
+			}
+			pid->hide_pid = option;
+			break;
+		default:
+			pr_err("proc: unrecognized mount option \"%s\" "
+			       "or missing value\n", p);
+			return 0;
+		}
+	}
+
+	return 1;
+}
+
+int proc_remount(struct super_block *sb, int *flags, char *data)
+{
+	struct pid_namespace *pid = sb->s_fs_info;
+	return !proc_parse_options(data, pid);
+}
+
 static struct dentry *proc_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
@@ -43,11 +101,15 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
 	struct super_block *sb;
 	struct pid_namespace *ns;
 	struct proc_inode *ei;
+	char *options;
 
-	if (flags & MS_KERNMOUNT)
+	if (flags & MS_KERNMOUNT) {
 		ns = (struct pid_namespace *)data;
-	else
+		options = NULL;
+	} else {
 		ns = current->nsproxy->pid_ns;
+		options = data;
+	}
 
 	sb = sget(fs_type, proc_test_super, proc_set_super, ns);
 	if (IS_ERR(sb))
@@ -55,6 +117,10 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
 
 	if (!sb->s_root) {
 		sb->s_flags = flags;
+		if (!proc_parse_options(options, ns)) {
+			deactivate_locked_super(sb);
+			return ERR_PTR(-EINVAL);
+		}
 		err = proc_fill_super(sb);
 		if (err) {
 			deactivate_locked_super(sb);
@@ -91,20 +157,18 @@ static struct file_system_type proc_fs_type = {
 
 void __init proc_root_init(void)
 {
-	struct vfsmount *mnt;
 	int err;
 
 	proc_init_inodecache();
 	err = register_filesystem(&proc_fs_type);
 	if (err)
 		return;
-	mnt = kern_mount_data(&proc_fs_type, &init_pid_ns);
-	if (IS_ERR(mnt)) {
+	err = pid_ns_prepare_proc(&init_pid_ns);
+	if (err) {
 		unregister_filesystem(&proc_fs_type);
 		return;
 	}
 
-	init_pid_ns.proc_mnt = mnt;
 	proc_symlink("mounts", NULL, "self/mounts");
 
 	proc_net_init();
@@ -209,5 +273,5 @@ int pid_ns_prepare_proc(struct pid_namespace *ns)
 
 void pid_ns_release_proc(struct pid_namespace *ns)
 {
-	mntput(ns->proc_mnt);
+	kern_unmount(ns->proc_mnt);
 }