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 = { 16 /* 17 * Needed due to multicast group ID abuse - old code assumed 18 * the family ID was also a valid multicast group ID (which 19 * isn't true) and userspace might thus rely on it. Assign a 20 * static ID for this group to make dealing with that easier. 21 */ 22 .id = GENL_ID_VFS_DQUOT, 23 .hdrsize = 0, 24 .name = "VFS_DQUOT", 25 .version = 1, 26 .maxattr = QUOTA_NL_A_MAX, 27 .mcgrps = quota_mcgrps, 28 .n_mcgrps = ARRAY_SIZE(quota_mcgrps), 29 }; 30 31 /** 32 * quota_send_warning - Send warning to userspace about exceeded quota 33 * @qid: The kernel internal quota identifier. 34 * @dev: The device on which the fs is mounted (sb->s_dev) 35 * @warntype: The type of the warning: QUOTA_NL_... 36 * 37 * This can be used by filesystems (including those which don't use 38 * dquot) to send a message to userspace relating to quota limits. 39 * 40 */ 41 42 void quota_send_warning(struct kqid qid, dev_t dev, 43 const char warntype) 44 { 45 static atomic_t seq; 46 struct sk_buff *skb; 47 void *msg_head; 48 int ret; 49 int msg_size = 4 * nla_total_size(sizeof(u32)) + 50 2 * nla_total_size_64bit(sizeof(u64)); 51 52 /* We have to allocate using GFP_NOFS as we are called from a 53 * filesystem performing write and thus further recursion into 54 * the fs to free some data could cause deadlocks. */ 55 skb = genlmsg_new(msg_size, GFP_NOFS); 56 if (!skb) { 57 printk(KERN_ERR 58 "VFS: Not enough memory to send quota warning.\n"); 59 return; 60 } 61 msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq), 62 "a_genl_family, 0, QUOTA_NL_C_WARNING); 63 if (!msg_head) { 64 printk(KERN_ERR 65 "VFS: Cannot store netlink header in quota warning.\n"); 66 goto err_out; 67 } 68 ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, qid.type); 69 if (ret) 70 goto attr_err_out; 71 ret = nla_put_u64_64bit(skb, QUOTA_NL_A_EXCESS_ID, 72 from_kqid_munged(&init_user_ns, qid), 73 QUOTA_NL_A_PAD); 74 if (ret) 75 goto attr_err_out; 76 ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype); 77 if (ret) 78 goto attr_err_out; 79 ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev)); 80 if (ret) 81 goto attr_err_out; 82 ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev)); 83 if (ret) 84 goto attr_err_out; 85 ret = nla_put_u64_64bit(skb, QUOTA_NL_A_CAUSED_ID, 86 from_kuid_munged(&init_user_ns, current_uid()), 87 QUOTA_NL_A_PAD); 88 if (ret) 89 goto attr_err_out; 90 genlmsg_end(skb, msg_head); 91 92 genlmsg_multicast("a_genl_family, skb, 0, 0, GFP_NOFS); 93 return; 94 attr_err_out: 95 printk(KERN_ERR "VFS: Not enough space to compose quota message!\n"); 96 err_out: 97 kfree_skb(skb); 98 } 99 EXPORT_SYMBOL(quota_send_warning); 100 101 static int __init quota_init(void) 102 { 103 if (genl_register_family("a_genl_family) != 0) 104 printk(KERN_ERR 105 "VFS: Failed to create quota netlink interface.\n"); 106 return 0; 107 }; 108 fs_initcall(quota_init); 109