| |
| #include <linux/cred.h> |
| #include <linux/init.h> |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/quotaops.h> |
| #include <linux/sched.h> |
| #include <linux/slab.h> |
| #include <net/netlink.h> |
| #include <net/genetlink.h> |
| |
| /* Netlink family structure for quota */ |
| static struct genl_family quota_genl_family = { |
| /* |
| * Needed due to multicast group ID abuse - old code assumed |
| * the family ID was also a valid multicast group ID (which |
| * isn't true) and userspace might thus rely on it. Assign a |
| * static ID for this group to make dealing with that easier. |
| */ |
| .id = GENL_ID_VFS_DQUOT, |
| .hdrsize = 0, |
| .name = "VFS_DQUOT", |
| .version = 1, |
| .maxattr = QUOTA_NL_A_MAX, |
| }; |
| |
| static struct genl_multicast_group quota_mcgrp = { |
| .name = "events", |
| }; |
| |
| /** |
| * 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(struct kqid qid, 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), |
| "a_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, qid.type); |
| if (ret) |
| goto attr_err_out; |
| ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, |
| from_kqid_munged(&init_user_ns, qid)); |
| 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, |
| from_kuid_munged(&init_user_ns, current_uid())); |
| if (ret) |
| goto attr_err_out; |
| genlmsg_end(skb, msg_head); |
| |
| genlmsg_multicast("a_genl_family, skb, 0, quota_mcgrp.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("a_genl_family) != 0) |
| printk(KERN_ERR |
| "VFS: Failed to create quota netlink interface.\n"); |
| if (genl_register_mc_group("a_genl_family, "a_mcgrp)) |
| printk(KERN_ERR |
| "VFS: Failed to register quota mcast group.\n"); |
| return 0; |
| }; |
| |
| module_init(quota_init); |