Re: [PATCH] diskquota: 32bit quota tools on 64bit architectures

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 18 Jun 2007 12:21:47 +0400
Vasily Tarasov <vtaras@openvz.org> wrote:

> From: Vasily Tarasov <vtaras@openvz.org>
> 
> This patch should be applied after Arnd Bergmann's patch,
> that intoduces new compat types: 
> http://lkml.org/lkml/2007/6/15/98
> 
> OpenVZ Linux kernel team has discovered the problem 
> with 32bit quota tools working on 64bit architectures.
> In 2.6.10 kernel sys32_quotactl() function was replaced by sys_quotactl() with
> the comment "sys_quotactl seems to be 32/64bit clean, enable it for 32bit"
> However this isn't right. Look at if_dqblk structure:
> 
> struct if_dqblk {
>         __u64 dqb_bhardlimit;
>         __u64 dqb_bsoftlimit;
>         __u64 dqb_curspace;
>         __u64 dqb_ihardlimit;
>         __u64 dqb_isoftlimit;
>         __u64 dqb_curinodes;
>         __u64 dqb_btime;
>         __u64 dqb_itime;
>         __u32 dqb_valid;
> };
> 
> For 32 bit quota tools sizeof(if_dqblk) == 0x44.
> But for 64 bit kernel its size is 0x48, 'cause of alignment!
> Thus we got a problem. Attached patch reintroduce sys32_quotactl() function,
> that handles this and related situations.
> 
> Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
> 
> ---
> 
> In OpenVZ technology 32 bit Virtual Environments over 
> 64 bit OS are common, hence we have customers, that complains on this bad quota
> behaviour: 
> 
> # /usr/bin/quota
> quota: error while getting quota from /dev/sda1 for 0: Success
> 
> The reason is caused above.

Only x86_64 and ia64 are fixed.  Would it be correct to assume that the
other CONFIG_COMPAT architectures also need to be fixed?


> --- linux-2.6.22-rc4-fixed/arch/x86_64/ia32/ia32entry.S.orig	2007-06-14 15:55:24.000000000 +0400
> +++ linux-2.6.22-rc4-fixed/arch/x86_64/ia32/ia32entry.S	2007-06-14 16:22:52.000000000 +0400
> @@ -526,7 +526,7 @@ ia32_sys_call_table:
>  	.quad sys_init_module
>  	.quad sys_delete_module
>  	.quad quiet_ni_syscall		/* 130  get_kernel_syms */
> -	.quad sys_quotactl
> +	.quad sys32_quotactl
>  	.quad sys_getpgid
>  	.quad sys_fchdir
>  	.quad quiet_ni_syscall	/* bdflush */
> --- linux-2.6.22-rc4-fixed/arch/ia64/ia32/ia32_entry.S.orig	2007-06-14 15:55:24.000000000 +0400
> +++ linux-2.6.22-rc4-fixed/arch/ia64/ia32/ia32_entry.S	2007-06-14 16:22:52.000000000 +0400
> @@ -304,7 +304,7 @@ ia32_syscall_table:
>  	data8 sys_ni_syscall	/* init_module */
>  	data8 sys_ni_syscall	/* delete_module */
>  	data8 sys_ni_syscall	/* get_kernel_syms */  /* 130 */
> -	data8 sys_quotactl
> +	data8 sys32_quotactl
>  	data8 sys_getpgid
>  	data8 sys_fchdir
>  	data8 sys_ni_syscall	/* sys_bdflush */
> --- linux-2.6.22-rc4-fixed/fs/quota.c.orig	2007-06-14 15:55:26.000000000 +0400
> +++ linux-2.6.22-rc4-fixed/fs/quota.c	2007-06-18 12:00:56.000000000 +0400
> @@ -10,12 +10,14 @@
>  #include <linux/slab.h>
>  #include <asm/current.h>
>  #include <asm/uaccess.h>
> +#include <asm/compat.h>
>  #include <linux/kernel.h>
>  #include <linux/security.h>
>  #include <linux/syscalls.h>
>  #include <linux/buffer_head.h>
>  #include <linux/capability.h>
>  #include <linux/quotaops.h>
> +#include <linux/types.h>
>  
>  /* Check validity of generic quotactl commands */
>  static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
> @@ -384,3 +386,119 @@ asmlinkage long sys_quotactl(unsigned in
>  
>  	return ret;
>  }
> +
> +#if defined(CONFIG_X86_64) || defined(CONFIG_IA64)
> +/*
> + * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
> + * and is necessary due to alignment problems.
> + */
> +struct compat_if_dqblk {
> +	compat_u64 dqb_bhardlimit;
> +	compat_u64 dqb_bsoftlimit;
> +	compat_u64 dqb_curspace;
> +	compat_u64 dqb_ihardlimit;
> +	compat_u64 dqb_isoftlimit;
> +	compat_u64 dqb_curinodes;
> +	compat_u64 dqb_btime;
> +	compat_u64 dqb_itime;
> +	compat_uint_t dqb_valid;
> +};
> +
> +/* XFS structures */
> +struct compat_fs_qfilestat {
> +	compat_u64 dqb_bhardlimit;
> +	compat_u64 qfs_nblks;
> +	compat_uint_t qfs_nextents;
> +};
> +
> +struct compat_fs_quota_stat {
> +	__s8		qs_version;
> +	__u16		qs_flags;
> +	__s8		qs_pad;
> +	struct compat_fs_qfilestat	qs_uquota;
> +	struct compat_fs_qfilestat	qs_gquota;
> +	compat_uint_t	qs_incoredqs;
> +	compat_int_t	qs_btimelimit;
> +	compat_int_t	qs_itimelimit;
> +	compat_int_t	qs_rtbtimelimit;
> +	__u16		qs_bwarnlimit;
> +	__u16		qs_iwarnlimit;
> +};
> +
> +asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
> +						qid_t id, void __user *addr)
> +{
> +	unsigned int cmds;
> +	struct if_dqblk __user *dqblk;
> +	struct compat_if_dqblk __user *compat_dqblk;
> +	struct fs_quota_stat __user *fsqstat;
> +	struct compat_fs_quota_stat __user *compat_fsqstat;
> +	compat_uint_t data;
> +	u16 xdata;
> +	long ret;
> +
> +	cmds = cmd >> SUBCMDSHIFT;
> +
> +	switch (cmds) {
> +	case Q_GETQUOTA:
> +		dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
> +		compat_dqblk = addr;
> +		ret = sys_quotactl(cmd, special, id, dqblk);
> +		if (ret)
> +			break;
> +		if (copy_in_user(compat_dqblk, dqblk, sizeof(*compat_dqblk)) ||
> +			get_user(data, &dqblk->dqb_valid) ||
> +			put_user(data, &compat_dqblk->dqb_valid))
> +			ret = -EFAULT;
> +		break;
> +	case Q_SETQUOTA:
> +		dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
> +		compat_dqblk = addr;
> +		ret = -EFAULT;
> +		if (copy_in_user(dqblk, compat_dqblk, sizeof(*compat_dqblk)) ||
> +			get_user(data, &compat_dqblk->dqb_valid) ||
> +			put_user(data, &dqblk->dqb_valid))
> +			break;
> +		ret = sys_quotactl(cmd, special, id, dqblk);
> +		break;
> +	case Q_XGETQSTAT:
> +		fsqstat = compat_alloc_user_space(sizeof(struct fs_quota_stat));
> +		compat_fsqstat = addr;
> +		ret = sys_quotactl(cmd, special, id, fsqstat);
> +		if (ret)
> +			break;
> +		ret = -EFAULT;
> +		/* Copying qs_version, qs_flags, qs_pad */
> +		if (copy_in_user(compat_fsqstat, fsqstat,
> +			offsetof(struct compat_fs_quota_stat, qs_uquota)))
> +			break;
> +		/* Copying qs_uquota */
> +		if (copy_in_user(&compat_fsqstat->qs_uquota,
> +			&fsqstat->qs_uquota,
> +			sizeof(compat_fsqstat->qs_uquota)) ||
> +			get_user(data, &fsqstat->qs_uquota.qfs_nextents) ||
> +			put_user(data, &compat_fsqstat->qs_uquota.qfs_nextents))
> +			break;
> +		/* Copying qs_gquota */
> +		if (copy_in_user(&compat_fsqstat->qs_gquota,
> +			&fsqstat->qs_gquota,
> +			sizeof(compat_fsqstat->qs_gquota)) ||
> +			get_user(data, &fsqstat->qs_gquota.qfs_nextents) ||
> +			put_user(data, &compat_fsqstat->qs_gquota.qfs_nextents))
> +			break;
> +		/* Copying the rest */
> +		if (copy_in_user(&compat_fsqstat->qs_incoredqs,
> +			&fsqstat->qs_incoredqs,
> +			sizeof(struct compat_fs_quota_stat) -
> +			offsetof(struct compat_fs_quota_stat, qs_incoredqs)) ||
> +			get_user(xdata, &fsqstat->qs_iwarnlimit) ||
> +			put_user(xdata, &compat_fsqstat->qs_iwarnlimit))
> +			break;
> +		ret = 0;
> +		break;
> +	default:
> +		ret = sys_quotactl(cmd, special, id, addr);
> +	}
> +	return ret;
> +}
> +#endif