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-rw-r--r--fs/quota/netlink.c103
1 files changed, 103 insertions, 0 deletions
diff --git a/fs/quota/netlink.c b/fs/quota/netlink.c
new file mode 100644
index 000000000..95acdae39
--- /dev/null
+++ b/fs/quota/netlink.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0
+#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),
+ &quota_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(&quota_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(&quota_genl_family) != 0)
+ printk(KERN_ERR
+ "VFS: Failed to create quota netlink interface.\n");
+ return 0;
+};
+fs_initcall(quota_init);