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linux/fs/quota/quota.c
Steven Whitehouse 86e931a35e VFS: Export dquot_send_warning 
Sending a message to userspace in a generic format to warn
of events (e.g. quota exceeded) in the quota subsystem is
a generically useful feature. This patch makes some minor
changes to the send_message function from dquot.c renaming
it quota_send_message, moving it to quota.c and exporting it
for use by filesystems which do not use the dquot code.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2009-12-03 11:53:02 +00:00

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/*
* Quota code necessary even when VFS quota support is not compiled
* into the kernel. The interesting stuff is over in dquot.c, here
* we have symbols for initial quotactl(2) handling, the sysctl(2)
* variables, etc - things needed even when quota support disabled.
*/
#include <linux/fs.h>
#include <linux/namei.h>
#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>
#include <net/netlink.h>
#include <net/genetlink.h>
/* Check validity of generic quotactl commands */
static int generic_quotactl_valid(struct super_block *sb, int type, int cmd,
qid_t id)
{
if (type >= MAXQUOTAS)
return -EINVAL;
if (!sb && cmd != Q_SYNC)
return -ENODEV;
/* Is operation supported? */
if (sb && !sb->s_qcop)
return -ENOSYS;
switch (cmd) {
case Q_GETFMT:
break;
case Q_QUOTAON:
if (!sb->s_qcop->quota_on)
return -ENOSYS;
break;
case Q_QUOTAOFF:
if (!sb->s_qcop->quota_off)
return -ENOSYS;
break;
case Q_SETINFO:
if (!sb->s_qcop->set_info)
return -ENOSYS;
break;
case Q_GETINFO:
if (!sb->s_qcop->get_info)
return -ENOSYS;
break;
case Q_SETQUOTA:
if (!sb->s_qcop->set_dqblk)
return -ENOSYS;
break;
case Q_GETQUOTA:
if (!sb->s_qcop->get_dqblk)
return -ENOSYS;
break;
case Q_SYNC:
if (sb && !sb->s_qcop->quota_sync)
return -ENOSYS;
break;
default:
return -EINVAL;
}
/* Is quota turned on for commands which need it? */
switch (cmd) {
case Q_GETFMT:
case Q_GETINFO:
case Q_SETINFO:
case Q_SETQUOTA:
case Q_GETQUOTA:
/* This is just an informative test so we are satisfied
* without the lock */
if (!sb_has_quota_active(sb, type))
return -ESRCH;
}
/* Check privileges */
if (cmd == Q_GETQUOTA) {
if (((type == USRQUOTA && current_euid() != id) ||
(type == GRPQUOTA && !in_egroup_p(id))) &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
}
else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
return 0;
}
/* Check validity of XFS Quota Manager commands */
static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd,
qid_t id)
{
if (type >= XQM_MAXQUOTAS)
return -EINVAL;
if (!sb)
return -ENODEV;
if (!sb->s_qcop)
return -ENOSYS;
switch (cmd) {
case Q_XQUOTAON:
case Q_XQUOTAOFF:
case Q_XQUOTARM:
if (!sb->s_qcop->set_xstate)
return -ENOSYS;
break;
case Q_XGETQSTAT:
if (!sb->s_qcop->get_xstate)
return -ENOSYS;
break;
case Q_XSETQLIM:
if (!sb->s_qcop->set_xquota)
return -ENOSYS;
break;
case Q_XGETQUOTA:
if (!sb->s_qcop->get_xquota)
return -ENOSYS;
break;
case Q_XQUOTASYNC:
if (!sb->s_qcop->quota_sync)
return -ENOSYS;
break;
default:
return -EINVAL;
}
/* Check privileges */
if (cmd == Q_XGETQUOTA) {
if (((type == XQM_USRQUOTA && current_euid() != id) ||
(type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
} else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
}
return 0;
}
static int check_quotactl_valid(struct super_block *sb, int type, int cmd,
qid_t id)
{
int error;
if (XQM_COMMAND(cmd))
error = xqm_quotactl_valid(sb, type, cmd, id);
else
error = generic_quotactl_valid(sb, type, cmd, id);
if (!error)
error = security_quotactl(cmd, type, id, sb);
return error;
}
#ifdef CONFIG_QUOTA
void sync_quota_sb(struct super_block *sb, int type)
{
int cnt;
if (!sb->s_qcop->quota_sync)
return;
sb->s_qcop->quota_sync(sb, type);
if (sb_dqopt(sb)->flags & DQUOT_QUOTA_SYS_FILE)
return;
/* This is not very clever (and fast) but currently I don't know about
* any other simple way of getting quota data to disk and we must get
* them there for userspace to be visible... */
if (sb->s_op->sync_fs)
sb->s_op->sync_fs(sb, 1);
sync_blockdev(sb->s_bdev);
/*
* Now when everything is written we can discard the pagecache so
* that userspace sees the changes.
*/
mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (type != -1 && cnt != type)
continue;
if (!sb_has_quota_active(sb, cnt))
continue;
mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex,
I_MUTEX_QUOTA);
truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0);
mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex);
}
mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
}
#endif
static void sync_dquots(int type)
{
struct super_block *sb;
int cnt;
spin_lock(&sb_lock);
restart:
list_for_each_entry(sb, &super_blocks, s_list) {
/* This test just improves performance so it needn't be
* reliable... */
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (type != -1 && type != cnt)
continue;
if (!sb_has_quota_active(sb, cnt))
continue;
if (!info_dirty(&sb_dqopt(sb)->info[cnt]) &&
list_empty(&sb_dqopt(sb)->info[cnt].dqi_dirty_list))
continue;
break;
}
if (cnt == MAXQUOTAS)
continue;
sb->s_count++;
spin_unlock(&sb_lock);
down_read(&sb->s_umount);
if (sb->s_root)
sync_quota_sb(sb, type);
up_read(&sb->s_umount);
spin_lock(&sb_lock);
if (__put_super_and_need_restart(sb))
goto restart;
}
spin_unlock(&sb_lock);
}
/* Copy parameters and call proper function */
static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
void __user *addr)
{
int ret;
switch (cmd) {
case Q_QUOTAON: {
char *pathname;
pathname = getname(addr);
if (IS_ERR(pathname))
return PTR_ERR(pathname);
ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
putname(pathname);
return ret;
}
case Q_QUOTAOFF:
return sb->s_qcop->quota_off(sb, type, 0);
case Q_GETFMT: {
__u32 fmt;
down_read(&sb_dqopt(sb)->dqptr_sem);
if (!sb_has_quota_active(sb, type)) {
up_read(&sb_dqopt(sb)->dqptr_sem);
return -ESRCH;
}
fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
up_read(&sb_dqopt(sb)->dqptr_sem);
if (copy_to_user(addr, &fmt, sizeof(fmt)))
return -EFAULT;
return 0;
}
case Q_GETINFO: {
struct if_dqinfo info;
ret = sb->s_qcop->get_info(sb, type, &info);
if (ret)
return ret;
if (copy_to_user(addr, &info, sizeof(info)))
return -EFAULT;
return 0;
}
case Q_SETINFO: {
struct if_dqinfo info;
if (copy_from_user(&info, addr, sizeof(info)))
return -EFAULT;
return sb->s_qcop->set_info(sb, type, &info);
}
case Q_GETQUOTA: {
struct if_dqblk idq;
ret = sb->s_qcop->get_dqblk(sb, type, id, &idq);
if (ret)
return ret;
if (copy_to_user(addr, &idq, sizeof(idq)))
return -EFAULT;
return 0;
}
case Q_SETQUOTA: {
struct if_dqblk idq;
if (copy_from_user(&idq, addr, sizeof(idq)))
return -EFAULT;
return sb->s_qcop->set_dqblk(sb, type, id, &idq);
}
case Q_SYNC:
if (sb)
sync_quota_sb(sb, type);
else
sync_dquots(type);
return 0;
case Q_XQUOTAON:
case Q_XQUOTAOFF:
case Q_XQUOTARM: {
__u32 flags;
if (copy_from_user(&flags, addr, sizeof(flags)))
return -EFAULT;
return sb->s_qcop->set_xstate(sb, flags, cmd);
}
case Q_XGETQSTAT: {
struct fs_quota_stat fqs;
if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
return ret;
if (copy_to_user(addr, &fqs, sizeof(fqs)))
return -EFAULT;
return 0;
}
case Q_XSETQLIM: {
struct fs_disk_quota fdq;
if (copy_from_user(&fdq, addr, sizeof(fdq)))
return -EFAULT;
return sb->s_qcop->set_xquota(sb, type, id, &fdq);
}
case Q_XGETQUOTA: {
struct fs_disk_quota fdq;
ret = sb->s_qcop->get_xquota(sb, type, id, &fdq);
if (ret)
return ret;
if (copy_to_user(addr, &fdq, sizeof(fdq)))
return -EFAULT;
return 0;
}
case Q_XQUOTASYNC:
return sb->s_qcop->quota_sync(sb, type);
/* We never reach here unless validity check is broken */
default:
BUG();
}
return 0;
}
/*
* look up a superblock on which quota ops will be performed
* - use the name of a block device to find the superblock thereon
*/
static struct super_block *quotactl_block(const char __user *special)
{
#ifdef CONFIG_BLOCK
struct block_device *bdev;
struct super_block *sb;
char *tmp = getname(special);
if (IS_ERR(tmp))
return ERR_CAST(tmp);
bdev = lookup_bdev(tmp);
putname(tmp);
if (IS_ERR(bdev))
return ERR_CAST(bdev);
sb = get_super(bdev);
bdput(bdev);
if (!sb)
return ERR_PTR(-ENODEV);
return sb;
#else
return ERR_PTR(-ENODEV);
#endif
}
/*
* This is the system call interface. This communicates with
* the user-level programs. Currently this only supports diskquota
* calls. Maybe we need to add the process quotas etc. in the future,
* but we probably should use rlimits for that.
*/
SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
qid_t, id, void __user *, addr)
{
uint cmds, type;
struct super_block *sb = NULL;
int ret;
cmds = cmd >> SUBCMDSHIFT;
type = cmd & SUBCMDMASK;
if (cmds != Q_SYNC || special) {
sb = quotactl_block(special);
if (IS_ERR(sb))
return PTR_ERR(sb);
}
ret = check_quotactl_valid(sb, type, cmds, id);
if (ret >= 0)
ret = do_quotactl(sb, type, cmds, id, addr);
if (sb)
drop_super(sb);
return ret;
}
#if defined(CONFIG_COMPAT_FOR_U64_ALIGNMENT)
/*
* 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
#ifdef CONFIG_QUOTA_NETLINK_INTERFACE
/* Netlink family structure for quota */
static struct genl_family quota_genl_family = {
.id = GENL_ID_GENERATE,
.hdrsize = 0,
.name = "VFS_DQUOT",
.version = 1,
.maxattr = QUOTA_NL_A_MAX,
};
/**
* quota_send_warning - Send warning to userspace about exceeded quota
* @type: The quota type: USRQQUOTA, GRPQUOTA,...
* @id: The user or group id of the quota that was exceeded
* @dev: The device on which the fs is mounted (sb->s_dev)
* @warntype: The type of the warning: QUOTA_NL_...
*
* This can be used by filesystems (including those which don't use
* dquot) to send a message to userspace relating to quota limits.
*
*/
void quota_send_warning(short type, unsigned int id, dev_t dev,
const char warntype)
{
static atomic_t seq;
struct sk_buff *skb;
void *msg_head;
int ret;
int msg_size = 4 * nla_total_size(sizeof(u32)) +
2 * nla_total_size(sizeof(u64));
/* We have to allocate using GFP_NOFS as we are called from a
* filesystem performing write and thus further recursion into
* the fs to free some data could cause deadlocks. */
skb = genlmsg_new(msg_size, GFP_NOFS);
if (!skb) {
printk(KERN_ERR
"VFS: Not enough memory to send quota warning.\n");
return;
}
msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq),
&quota_genl_family, 0, QUOTA_NL_C_WARNING);
if (!msg_head) {
printk(KERN_ERR
"VFS: Cannot store netlink header in quota warning.\n");
goto err_out;
}
ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, type);
if (ret)
goto attr_err_out;
ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, id);
if (ret)
goto attr_err_out;
ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
if (ret)
goto attr_err_out;
ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev));
if (ret)
goto attr_err_out;
ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));
if (ret)
goto attr_err_out;
ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current_uid());
if (ret)
goto attr_err_out;
genlmsg_end(skb, msg_head);
genlmsg_multicast(skb, 0, quota_genl_family.id, GFP_NOFS);
return;
attr_err_out:
printk(KERN_ERR "VFS: Not enough space to compose quota message!\n");
err_out:
kfree_skb(skb);
}
EXPORT_SYMBOL(quota_send_warning);
static int __init quota_init(void)
{
if (genl_register_family(&quota_genl_family) != 0)
printk(KERN_ERR
"VFS: Failed to create quota netlink interface.\n");
return 0;
};
module_init(quota_init);
#endif
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