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