cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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netlink.c (2886B)

      1// SPDX-License-Identifier: GPL-2.0
      2#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 quota
     28 * @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 use
     33 * 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 a
     48	 * filesystem performing write and thus further recursion into
     49	 * the fs to free some data could cause deadlocks. */
     50	skb = genlmsg_new(msg_size, GFP_NOFS);
     51	if (!skb) {
     52		printk(KERN_ERR
     53		  "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			&quota_genl_family, 0, QUOTA_NL_C_WARNING);
     58	if (!msg_head) {
     59		printk(KERN_ERR
     60		  "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(&quota_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(&quota_genl_family) != 0)
     99		printk(KERN_ERR
    100		       "VFS: Failed to create quota netlink interface.\n");
    101	return 0;
    102};
    103fs_initcall(quota_init);