diff options
Diffstat (limited to 'fs/quota.c')
| -rw-r--r-- | fs/quota.c | 382 |
1 files changed, 382 insertions, 0 deletions
diff --git a/fs/quota.c b/fs/quota.c new file mode 100644 index 000000000000..3f0333a51a23 --- /dev/null +++ b/fs/quota.c @@ -0,0 +1,382 @@ +/* + * 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/kernel.h> +#include <linux/smp_lock.h> +#include <linux/security.h> +#include <linux/syscalls.h> +#include <linux/buffer_head.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_QUOTAOFF: + case Q_SETINFO: + case Q_SETQUOTA: + case Q_GETQUOTA: + /* This is just informative test so we are satisfied without a lock */ + if (!sb_has_quota_enabled(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; + 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) { + 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; +} + +static struct super_block *get_super_to_sync(int type) +{ + struct list_head *head; + int cnt, dirty; + +restart: + spin_lock(&sb_lock); + list_for_each(head, &super_blocks) { + struct super_block *sb = list_entry(head, struct super_block, s_list); + + /* This test just improves performance so it needn't be reliable... */ + for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++) + if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt) + && info_any_dirty(&sb_dqopt(sb)->info[cnt])) + dirty = 1; + if (!dirty) + continue; + sb->s_count++; + spin_unlock(&sb_lock); + down_read(&sb->s_umount); + if (!sb->s_root) { + drop_super(sb); + goto restart; + } + return sb; + } + spin_unlock(&sb_lock); + return NULL; +} + +static void quota_sync_sb(struct super_block *sb, int type) +{ + int cnt; + struct inode *discard[MAXQUOTAS]; + + sb->s_qcop->quota_sync(sb, type); + /* 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. We need i_sem and so we could + * not do it inside dqonoff_sem. Moreover we need to be carefull + * about races with quotaoff() (that is the reason why we have own + * reference to inode). */ + down(&sb_dqopt(sb)->dqonoff_sem); + for (cnt = 0; cnt < MAXQUOTAS; cnt++) { + discard[cnt] = NULL; + if (type != -1 && cnt != type) + continue; + if (!sb_has_quota_enabled(sb, cnt)) + continue; + discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]); + } + up(&sb_dqopt(sb)->dqonoff_sem); + for (cnt = 0; cnt < MAXQUOTAS; cnt++) { + if (discard[cnt]) { + down(&discard[cnt]->i_sem); + truncate_inode_pages(&discard[cnt]->i_data, 0); + up(&discard[cnt]->i_sem); + iput(discard[cnt]); + } + } +} + +void sync_dquots(struct super_block *sb, int type) +{ + if (sb) { + if (sb->s_qcop->quota_sync) + quota_sync_sb(sb, type); + } + else { + while ((sb = get_super_to_sync(type)) != NULL) { + if (sb->s_qcop->quota_sync) + quota_sync_sb(sb, type); + drop_super(sb); + } + } +} + +/* 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; + + if (IS_ERR(pathname = getname(addr))) + return PTR_ERR(pathname); + ret = sb->s_qcop->quota_on(sb, type, id, pathname); + putname(pathname); + return ret; + } + case Q_QUOTAOFF: + return sb->s_qcop->quota_off(sb, type); + + case Q_GETFMT: { + __u32 fmt; + + down_read(&sb_dqopt(sb)->dqptr_sem); + if (!sb_has_quota_enabled(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; + + if ((ret = sb->s_qcop->get_info(sb, type, &info))) + 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; + + if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq))) + 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: + sync_dquots(sb, 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; + + if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq))) + return ret; + if (copy_to_user(addr, &fdq, sizeof(fdq))) + return -EFAULT; + return 0; + } + /* We never reach here unless validity check is broken */ + default: + BUG(); + } + return 0; +} + +/* + * 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. + */ +asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr) +{ + uint cmds, type; + struct super_block *sb = NULL; + struct block_device *bdev; + char *tmp; + int ret; + + cmds = cmd >> SUBCMDSHIFT; + type = cmd & SUBCMDMASK; + + if (cmds != Q_SYNC || special) { + tmp = getname(special); + if (IS_ERR(tmp)) + return PTR_ERR(tmp); + bdev = lookup_bdev(tmp); + putname(tmp); + if (IS_ERR(bdev)) + return PTR_ERR(bdev); + sb = get_super(bdev); + bdput(bdev); + if (!sb) + return -ENODEV; + } + + 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; +} |