Commit 66f592e2 authored by David Howells's avatar David Howells Committed by Al Viro
Browse files

proc: Add fs_context support to procfs 



Add fs_context support to procfs.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 60a3c3a5

fs/proc/inode.c

+0 −1
Original line number Diff line number Diff line
@@ -127,7 +127,6 @@ const struct super_operations proc_sops = { 
	.drop_inode	= generic_delete_inode,

	.evict_inode	= proc_evict_inode,

	.statfs		= simple_statfs,

	.remount_fs	= proc_remount,

	.show_options	= proc_show_options,

};

fs/proc/internal.h

+0 −1
Original line number Diff line number Diff line
@@ -270,7 +270,6 @@ static inline void proc_tty_init(void) {} 
extern struct proc_dir_entry proc_root;



extern void proc_self_init(void);

extern int proc_remount(struct super_block *, int *, char *);



/*

 * task_[no]mmu.c

fs/proc/root.c

+129 −66
Original line number Diff line number Diff line
@@ -19,74 +19,89 @@ 
#include <linux/module.h>

#include <linux/bitops.h>

#include <linux/user_namespace.h>

#include <linux/fs_context.h>

#include <linux/mount.h>

#include <linux/pid_namespace.h>

#include <linux/parser.h>

#include <linux/fs_parser.h>

#include <linux/cred.h>

#include <linux/magic.h>

#include <linux/slab.h>



#include "internal.h"



enum {

	Opt_gid, Opt_hidepid, Opt_err,

struct proc_fs_context {

	struct pid_namespace	*pid_ns;

	unsigned int		mask;

	int			hidepid;

	int			gid;

};



static const match_table_t tokens = {

	{Opt_hidepid, "hidepid=%u"},

	{Opt_gid, "gid=%u"},

	{Opt_err, NULL},

enum proc_param {

	Opt_gid,

	Opt_hidepid,

};



static int proc_parse_options(char *options, struct pid_namespace *pid)

{

	char *p;

	substring_t args[MAX_OPT_ARGS];

	int option;

static const struct fs_parameter_spec proc_param_specs[] = {

	fsparam_u32("gid",	Opt_gid),

	fsparam_u32("hidepid",	Opt_hidepid),

	{}

};



static const struct fs_parameter_description proc_fs_parameters = {

	.name		= "proc",

	.specs		= proc_param_specs,

};



	if (!options)

		return 1;

static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param)

{

	struct proc_fs_context *ctx = fc->fs_private;

	struct fs_parse_result result;

	int opt;



	while ((p = strsep(&options, ",")) != NULL) {

		int token;

		if (!*p)

			continue;

	opt = fs_parse(fc, &proc_fs_parameters, param, &result);

	if (opt < 0)

		return opt;



		args[0].to = args[0].from = NULL;

		token = match_token(p, tokens, args);

		switch (token) {

	switch (opt) {

	case Opt_gid:

			if (match_int(&args[0], &option))

				return 0;

			pid->pid_gid = make_kgid(current_user_ns(), option);

		ctx->gid = result.uint_32;

		break;



	case Opt_hidepid:

			if (match_int(&args[0], &option))

				return 0;

			if (option < HIDEPID_OFF ||

			    option > HIDEPID_INVISIBLE) {

				pr_err("proc: hidepid value must be between 0 and 2.\n");

				return 0;

			}

			pid->hide_pid = option;

		ctx->hidepid = result.uint_32;

		if (ctx->hidepid < HIDEPID_OFF ||

		    ctx->hidepid > HIDEPID_INVISIBLE)

			return invalf(fc, "proc: hidepid value must be between 0 and 2.\n");

		break;



	default:

			pr_err("proc: unrecognized mount option \"%s\" "

			       "or missing value\n", p);

			return 0;

		return -EINVAL;

	}



	ctx->mask |= 1 << opt;

	return 0;

}



	return 1;

static void proc_apply_options(struct super_block *s,

			       struct fs_context *fc,

			       struct pid_namespace *pid_ns,

			       struct user_namespace *user_ns)

{

	struct proc_fs_context *ctx = fc->fs_private;



	if (ctx->mask & (1 << Opt_gid))

		pid_ns->pid_gid = make_kgid(user_ns, ctx->gid);

	if (ctx->mask & (1 << Opt_hidepid))

		pid_ns->hide_pid = ctx->hidepid;

}



static int proc_fill_super(struct super_block *s, void *data, int silent)

static int proc_fill_super(struct super_block *s, struct fs_context *fc)

{

	struct pid_namespace *ns = get_pid_ns(s->s_fs_info);

	struct pid_namespace *pid_ns = get_pid_ns(s->s_fs_info);

	struct inode *root_inode;

	int ret;



	if (!proc_parse_options(data, ns))

		return -EINVAL;

	proc_apply_options(s, fc, pid_ns, current_user_ns());



	/* User space would break if executables or devices appear on proc */

	s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV;
@@ -127,27 +142,55 @@ static int proc_fill_super(struct super_block *s, void *data, int silent) 
	return proc_setup_thread_self(s);

}



int proc_remount(struct super_block *sb, int *flags, char *data)

static int proc_reconfigure(struct fs_context *fc)

{

	struct super_block *sb = fc->root->d_sb;

	struct pid_namespace *pid = sb->s_fs_info;



	sync_filesystem(sb);

	return !proc_parse_options(data, pid);



	proc_apply_options(sb, fc, pid, current_user_ns());

	return 0;

}



static struct dentry *proc_mount(struct file_system_type *fs_type,

	int flags, const char *dev_name, void *data)

static int proc_get_tree(struct fs_context *fc)

{

	struct pid_namespace *ns;

	struct proc_fs_context *ctx = fc->fs_private;



	if (flags & SB_KERNMOUNT) {

		ns = data;

		data = NULL;

	} else {

		ns = task_active_pid_ns(current);

	put_user_ns(fc->user_ns);

	fc->user_ns = get_user_ns(ctx->pid_ns->user_ns);

	fc->s_fs_info = ctx->pid_ns;

	return vfs_get_super(fc, vfs_get_keyed_super, proc_fill_super);

}



	return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);

static void proc_fs_context_free(struct fs_context *fc)

{

	struct proc_fs_context *ctx = fc->fs_private;



	if (ctx->pid_ns)

		put_pid_ns(ctx->pid_ns);

	kfree(ctx);

}



static const struct fs_context_operations proc_fs_context_ops = {

	.free		= proc_fs_context_free,

	.parse_param	= proc_parse_param,

	.get_tree	= proc_get_tree,

	.reconfigure	= proc_reconfigure,

};



static int proc_init_fs_context(struct fs_context *fc)

{

	struct proc_fs_context *ctx;



	ctx = kzalloc(sizeof(struct proc_fs_context), GFP_KERNEL);

	if (!ctx)

		return -ENOMEM;



	ctx->pid_ns = get_pid_ns(task_active_pid_ns(current));

	fc->fs_private = ctx;

	fc->ops = &proc_fs_context_ops;

	return 0;

}



static void proc_kill_sb(struct super_block *sb)
@@ -165,7 +208,8 @@ static void proc_kill_sb(struct super_block *sb) 


static struct file_system_type proc_fs_type = {

	.name			= "proc",

	.mount		= proc_mount,

	.init_fs_context	= proc_init_fs_context,

	.parameters		= &proc_fs_parameters,

	.kill_sb		= proc_kill_sb,

	.fs_flags		= FS_USERNS_MOUNT,

};
@@ -258,9 +302,28 @@ struct proc_dir_entry proc_root = { 


int pid_ns_prepare_proc(struct pid_namespace *ns)

{

	struct proc_fs_context *ctx;

	struct fs_context *fc;

	struct vfsmount *mnt;



	mnt = kern_mount_data(&proc_fs_type, ns);

	fc = fs_context_for_mount(&proc_fs_type, SB_KERNMOUNT);

	if (IS_ERR(fc))

		return PTR_ERR(fc);



	if (fc->user_ns != ns->user_ns) {

		put_user_ns(fc->user_ns);

		fc->user_ns = get_user_ns(ns->user_ns);

	}



	ctx = fc->fs_private;

	if (ctx->pid_ns != ns) {

		put_pid_ns(ctx->pid_ns);

		get_pid_ns(ns);

		ctx->pid_ns = ns;

	}



	mnt = fc_mount(fc);

	put_fs_context(fc);

	if (IS_ERR(mnt))

		return PTR_ERR(mnt);