[PATCH] remove mount option parsing from procfs

From: Rene Scharfe
Date: Thu Feb 17 2005 - 16:33:42 EST


OK, my previous patches on the subject were _so_ bad that noone even
bothered to flame me. Here's an attempt to fix this. :]

This patch removes the mount options of the proc filesystem. They don't
have any effect since 2.4.something.

Explanation: Only proc_fill_super() calls parse_options, notably
proc_remount() does not. And proc_fill_super() is only called at the
very first mount which in turn is the one caused by kern_mount() in
fs/proc/root.c and that passes a NULL pointer as mount options
string. It is called only once because proc is a filesystem with a
single super_block (i.e. it uses get_sb_single()).

Since noone seems to miss the uid and gid options so far I suggest to
simply remove them. Their function can be easily performed in
userspace. E.g. this (if it worked like intended):

# mount -t proc -o uid=procuser,gid=procgrp proc /proc

can be done like so, probably in some init script:

# mount -t proc proc /proc && chown procuser:procgrp /proc

But I don't see why anyone would want to do that in the first place.

Comments?

Rene


--- linux-2.6.11-rc4/fs/proc/inode.c~ 2005-02-05 03:21:58.000000000 +0100
+++ linux-2.6.11-rc4/fs/proc/inode.c 2005-02-11 05:33:47.000000000 +0100
@@ -14,7 +14,6 @@
#include <linux/limits.h>
#include <linux/init.h>
#include <linux/module.h>
-#include <linux/parser.h>
#include <linux/smp_lock.h>

#include <asm/system.h>
@@ -143,51 +142,6 @@ static struct super_operations proc_sops
.remount_fs = proc_remount,
};

-enum {
- Opt_uid, Opt_gid, Opt_err
-};
-
-static match_table_t tokens = {
- {Opt_uid, "uid=%u"},
- {Opt_gid, "gid=%u"},
- {Opt_err, NULL}
-};
-
-static int parse_options(char *options,uid_t *uid,gid_t *gid)
-{
- char *p;
- int option;
-
- *uid = current->uid;
- *gid = current->gid;
- if (!options)
- return 1;
-
- while ((p = strsep(&options, ",")) != NULL) {
- substring_t args[MAX_OPT_ARGS];
- int token;
- if (!*p)
- continue;
-
- token = match_token(p, tokens, args);
- switch (token) {
- case Opt_uid:
- if (match_int(args, &option))
- return 0;
- *uid = option;
- break;
- case Opt_gid:
- if (match_int(args, &option))
- return 0;
- *gid = option;
- break;
- default:
- return 0;
- }
- }
- return 1;
-}
-
struct inode *proc_get_inode(struct super_block *sb, unsigned int ino,
struct proc_dir_entry *de)
{
@@ -249,10 +203,11 @@ int proc_fill_super(struct super_block *
* Fixup the root inode's nlink value
*/
root_inode->i_nlink += nr_processes();
+ root_inode->i_uid = 0;
+ root_inode->i_gid = 0;
s->s_root = d_alloc_root(root_inode);
if (!s->s_root)
goto out_no_root;
- parse_options(data, &root_inode->i_uid, &root_inode->i_gid);
return 0;

out_no_root:
-
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