1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun #include <linux/cred.h>
3*4882a593Smuzhiyun #include <linux/init.h>
4*4882a593Smuzhiyun #include <linux/kernel.h>
5*4882a593Smuzhiyun #include <linux/quotaops.h>
6*4882a593Smuzhiyun #include <linux/sched.h>
7*4882a593Smuzhiyun #include <linux/slab.h>
8*4882a593Smuzhiyun #include <net/netlink.h>
9*4882a593Smuzhiyun #include <net/genetlink.h>
10*4882a593Smuzhiyun
11*4882a593Smuzhiyun static const struct genl_multicast_group quota_mcgrps[] = {
12*4882a593Smuzhiyun { .name = "events", },
13*4882a593Smuzhiyun };
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun /* Netlink family structure for quota */
16*4882a593Smuzhiyun static struct genl_family quota_genl_family __ro_after_init = {
17*4882a593Smuzhiyun .module = THIS_MODULE,
18*4882a593Smuzhiyun .hdrsize = 0,
19*4882a593Smuzhiyun .name = "VFS_DQUOT",
20*4882a593Smuzhiyun .version = 1,
21*4882a593Smuzhiyun .maxattr = QUOTA_NL_A_MAX,
22*4882a593Smuzhiyun .mcgrps = quota_mcgrps,
23*4882a593Smuzhiyun .n_mcgrps = ARRAY_SIZE(quota_mcgrps),
24*4882a593Smuzhiyun };
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun /**
27*4882a593Smuzhiyun * quota_send_warning - Send warning to userspace about exceeded quota
28*4882a593Smuzhiyun * @qid: The kernel internal quota identifier.
29*4882a593Smuzhiyun * @dev: The device on which the fs is mounted (sb->s_dev)
30*4882a593Smuzhiyun * @warntype: The type of the warning: QUOTA_NL_...
31*4882a593Smuzhiyun *
32*4882a593Smuzhiyun * This can be used by filesystems (including those which don't use
33*4882a593Smuzhiyun * dquot) to send a message to userspace relating to quota limits.
34*4882a593Smuzhiyun *
35*4882a593Smuzhiyun */
36*4882a593Smuzhiyun
quota_send_warning(struct kqid qid,dev_t dev,const char warntype)37*4882a593Smuzhiyun void quota_send_warning(struct kqid qid, dev_t dev,
38*4882a593Smuzhiyun const char warntype)
39*4882a593Smuzhiyun {
40*4882a593Smuzhiyun static atomic_t seq;
41*4882a593Smuzhiyun struct sk_buff *skb;
42*4882a593Smuzhiyun void *msg_head;
43*4882a593Smuzhiyun int ret;
44*4882a593Smuzhiyun int msg_size = 4 * nla_total_size(sizeof(u32)) +
45*4882a593Smuzhiyun 2 * nla_total_size_64bit(sizeof(u64));
46*4882a593Smuzhiyun
47*4882a593Smuzhiyun /* We have to allocate using GFP_NOFS as we are called from a
48*4882a593Smuzhiyun * filesystem performing write and thus further recursion into
49*4882a593Smuzhiyun * the fs to free some data could cause deadlocks. */
50*4882a593Smuzhiyun skb = genlmsg_new(msg_size, GFP_NOFS);
51*4882a593Smuzhiyun if (!skb) {
52*4882a593Smuzhiyun printk(KERN_ERR
53*4882a593Smuzhiyun "VFS: Not enough memory to send quota warning.\n");
54*4882a593Smuzhiyun return;
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq),
57*4882a593Smuzhiyun "a_genl_family, 0, QUOTA_NL_C_WARNING);
58*4882a593Smuzhiyun if (!msg_head) {
59*4882a593Smuzhiyun printk(KERN_ERR
60*4882a593Smuzhiyun "VFS: Cannot store netlink header in quota warning.\n");
61*4882a593Smuzhiyun goto err_out;
62*4882a593Smuzhiyun }
63*4882a593Smuzhiyun ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, qid.type);
64*4882a593Smuzhiyun if (ret)
65*4882a593Smuzhiyun goto attr_err_out;
66*4882a593Smuzhiyun ret = nla_put_u64_64bit(skb, QUOTA_NL_A_EXCESS_ID,
67*4882a593Smuzhiyun from_kqid_munged(&init_user_ns, qid),
68*4882a593Smuzhiyun QUOTA_NL_A_PAD);
69*4882a593Smuzhiyun if (ret)
70*4882a593Smuzhiyun goto attr_err_out;
71*4882a593Smuzhiyun ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
72*4882a593Smuzhiyun if (ret)
73*4882a593Smuzhiyun goto attr_err_out;
74*4882a593Smuzhiyun ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev));
75*4882a593Smuzhiyun if (ret)
76*4882a593Smuzhiyun goto attr_err_out;
77*4882a593Smuzhiyun ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev));
78*4882a593Smuzhiyun if (ret)
79*4882a593Smuzhiyun goto attr_err_out;
80*4882a593Smuzhiyun ret = nla_put_u64_64bit(skb, QUOTA_NL_A_CAUSED_ID,
81*4882a593Smuzhiyun from_kuid_munged(&init_user_ns, current_uid()),
82*4882a593Smuzhiyun QUOTA_NL_A_PAD);
83*4882a593Smuzhiyun if (ret)
84*4882a593Smuzhiyun goto attr_err_out;
85*4882a593Smuzhiyun genlmsg_end(skb, msg_head);
86*4882a593Smuzhiyun
87*4882a593Smuzhiyun genlmsg_multicast("a_genl_family, skb, 0, 0, GFP_NOFS);
88*4882a593Smuzhiyun return;
89*4882a593Smuzhiyun attr_err_out:
90*4882a593Smuzhiyun printk(KERN_ERR "VFS: Not enough space to compose quota message!\n");
91*4882a593Smuzhiyun err_out:
92*4882a593Smuzhiyun kfree_skb(skb);
93*4882a593Smuzhiyun }
94*4882a593Smuzhiyun EXPORT_SYMBOL(quota_send_warning);
95*4882a593Smuzhiyun
quota_init(void)96*4882a593Smuzhiyun static int __init quota_init(void)
97*4882a593Smuzhiyun {
98*4882a593Smuzhiyun if (genl_register_family("a_genl_family) != 0)
99*4882a593Smuzhiyun printk(KERN_ERR
100*4882a593Smuzhiyun "VFS: Failed to create quota netlink interface.\n");
101*4882a593Smuzhiyun return 0;
102*4882a593Smuzhiyun };
103*4882a593Smuzhiyun fs_initcall(quota_init);
104