diskquota: 32bit quota tools on 64bit architectures

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.

[michal.k.k.piotrowski@gmail.com: build fix]
[akpm@linux-foundation.org: Make it link with CONFIG_QUOTA=n]
Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Jan Kara <jack@ucw.cz>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 121 insertions, 2 deletions

diff --git a/arch/ia64/ia32/ia32_entry.S b/arch/ia64/ia32/ia32_entry.S
index 99b665e2b1d5..06efd1f9b800 100644
--- a/arch/ia64/ia32/ia32_entry.S
+++ b/arch/ia64/ia32/ia32_entry.S
@@ -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 */
diff --git a/arch/x86_64/ia32/ia32entry.S b/arch/x86_64/ia32/ia32entry.S
index 47565c3345d2..782dea819438 100644
--- a/arch/x86_64/ia32/ia32entry.S
+++ b/arch/x86_64/ia32/ia32entry.S
@@ -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 */
diff --git a/fs/quota.c b/fs/quota.c
index 9f237d6182c9..e6577ac15a6c 100644
--- a/fs/quota.c
+++ b/fs/quota.c
@@ -10,12 +10,14 @@
 #include <linux/slab.h>
 #include <asm/current.h>
 #include <asm/uaccess.h>
+#include <linux/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 int cmd, const char __user *special, qid_t
 
         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
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 7e11e2c98bf9..b0ec498a18d9 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -14,6 +14,7 @@ asmlinkage long sys_ni_syscall(void)
 
 cond_syscall(sys_nfsservctl);
 cond_syscall(sys_quotactl);
+cond_syscall(sys32_quotactl);
 cond_syscall(sys_acct);
 cond_syscall(sys_lookup_dcookie);
 cond_syscall(sys_swapon);