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1// SPDX-License-Identifier: GPL-2.02#include <linux/cred.h>3#include <linux/init.h>4#include <linux/kernel.h>5#include <linux/quotaops.h>6#include <linux/sched.h>7#include <linux/slab.h>8#include <net/netlink.h>9#include <net/genetlink.h>10 11static const struct genl_multicast_group quota_mcgrps[] = {12 { .name = "events", },13};14 15/* Netlink family structure for quota */16static struct genl_family quota_genl_family __ro_after_init = {17 .module = THIS_MODULE,18 .hdrsize = 0,19 .name = "VFS_DQUOT",20 .version = 1,21 .maxattr = QUOTA_NL_A_MAX,22 .mcgrps = quota_mcgrps,23 .n_mcgrps = ARRAY_SIZE(quota_mcgrps),24};25 26/**27 * quota_send_warning - Send warning to userspace about exceeded quota28 * @qid: The kernel internal quota identifier.29 * @dev: The device on which the fs is mounted (sb->s_dev)30 * @warntype: The type of the warning: QUOTA_NL_...31 *32 * This can be used by filesystems (including those which don't use33 * dquot) to send a message to userspace relating to quota limits.34 *35 */36 37void quota_send_warning(struct kqid qid, dev_t dev,38 const char warntype)39{40 static atomic_t seq;41 struct sk_buff *skb;42 void *msg_head;43 int ret;44 int msg_size = 4 * nla_total_size(sizeof(u32)) +45 2 * nla_total_size_64bit(sizeof(u64));46 47 /* We have to allocate using GFP_NOFS as we are called from a48 * filesystem performing write and thus further recursion into49 * the fs to free some data could cause deadlocks. */50 skb = genlmsg_new(msg_size, GFP_NOFS);51 if (!skb) {52 printk(KERN_ERR53 "VFS: Not enough memory to send quota warning.\n");54 return;55 }56 msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq),57 "a_genl_family, 0, QUOTA_NL_C_WARNING);58 if (!msg_head) {59 printk(KERN_ERR60 "VFS: Cannot store netlink header in quota warning.\n");61 goto err_out;62 }63 ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, qid.type);64 if (ret)65 goto attr_err_out;66 ret = nla_put_u64_64bit(skb, QUOTA_NL_A_EXCESS_ID,67 from_kqid_munged(&init_user_ns, qid),68 QUOTA_NL_A_PAD);69 if (ret)70 goto attr_err_out;71 ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);72 if (ret)73 goto attr_err_out;74 ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev));75 if (ret)76 goto attr_err_out;77 ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));78 if (ret)79 goto attr_err_out;80 ret = nla_put_u64_64bit(skb, QUOTA_NL_A_CAUSED_ID,81 from_kuid_munged(&init_user_ns, current_uid()),82 QUOTA_NL_A_PAD);83 if (ret)84 goto attr_err_out;85 genlmsg_end(skb, msg_head);86 87 genlmsg_multicast("a_genl_family, skb, 0, 0, GFP_NOFS);88 return;89attr_err_out:90 printk(KERN_ERR "VFS: Not enough space to compose quota message!\n");91err_out:92 kfree_skb(skb);93}94EXPORT_SYMBOL(quota_send_warning);95 96static int __init quota_init(void)97{98 if (genl_register_family("a_genl_family) != 0)99 printk(KERN_ERR100 "VFS: Failed to create quota netlink interface.\n");101 return 0;102};103fs_initcall(quota_init);104