#include <linux/cred.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/quotaops.h> #include <linux/sched.h> #include <linux/slab.h> #include <net/netlink.h> #include <net/genetlink.h> static const struct genl_multicast_group quota_mcgrps[] = { { .name = "events", }, }; /* Netlink family structure for quota */ static struct genl_family quota_genl_family __ro_after_init = { .module = THIS_MODULE, .hdrsize = 0, .name = "VFS_DQUOT", .version = 1, .maxattr = QUOTA_NL_A_MAX, .mcgrps = quota_mcgrps, .n_mcgrps = ARRAY_SIZE(quota_mcgrps), }; /** * quota_send_warning - Send warning to userspace about exceeded quota * @qid: The kernel internal quota identifier. * @dev: The device on which the fs is mounted (sb->s_dev) * @warntype: The type of the warning: QUOTA_NL_... * * This can be used by filesystems (including those which don't use * dquot) to send a message to userspace relating to quota limits. * */ void quota_send_warning(struct kqid qid, dev_t dev, const char warntype) { static atomic_t seq; struct sk_buff *skb; void *msg_head; int ret; int msg_size = 4 * nla_total_size(sizeof(u32)) + 2 * nla_total_size_64bit(sizeof(u64)); /* We have to allocate using GFP_NOFS as we are called from a * filesystem performing write and thus further recursion into * the fs to free some data could cause deadlocks. */ skb = genlmsg_new(msg_size, GFP_NOFS); if (!skb) { printk(KERN_ERR "VFS: Not enough memory to send quota warning.\n"); return; } msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq), "a_genl_family, 0, QUOTA_NL_C_WARNING); if (!msg_head) { printk(KERN_ERR "VFS: Cannot store netlink header in quota warning.\n"); goto err_out; } ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, qid.type); if (ret) goto attr_err_out; ret = nla_put_u64_64bit(skb, QUOTA_NL_A_EXCESS_ID, from_kqid_munged(&init_user_ns, qid), QUOTA_NL_A_PAD); if (ret) goto attr_err_out; ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype); if (ret) goto attr_err_out; ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR, MAJOR(dev)); if (ret) goto attr_err_out; ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR, MINOR(dev)); if (ret) goto attr_err_out; ret = nla_put_u64_64bit(skb, QUOTA_NL_A_CAUSED_ID, from_kuid_munged(&init_user_ns, current_uid()), QUOTA_NL_A_PAD); if (ret) goto attr_err_out; genlmsg_end(skb, msg_head); genlmsg_multicast("a_genl_family, skb, 0, 0, GFP_NOFS); return; attr_err_out: printk(KERN_ERR "VFS: Not enough space to compose quota message!\n"); err_out: kfree_skb(skb); } EXPORT_SYMBOL(quota_send_warning); static int __init quota_init(void) { if (genl_register_family("a_genl_family) != 0) printk(KERN_ERR "VFS: Failed to create quota netlink interface.\n"); return 0; }; fs_initcall(quota_init);