v4.19.13 snapshot.
diff --git a/net/ax25/ax25_uid.c b/net/ax25/ax25_uid.c
new file mode 100644
index 0000000..99d02e3
--- /dev/null
+++ b/net/ax25/ax25_uid.c
@@ -0,0 +1,207 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
+ */
+
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <net/ax25.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <linux/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/notifier.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/stat.h>
+#include <linux/sysctl.h>
+#include <linux/export.h>
+#include <net/ip.h>
+#include <net/arp.h>
+
+/*
+ * Callsign/UID mapper. This is in kernel space for security on multi-amateur machines.
+ */
+
+static HLIST_HEAD(ax25_uid_list);
+static DEFINE_RWLOCK(ax25_uid_lock);
+
+int ax25_uid_policy;
+
+EXPORT_SYMBOL(ax25_uid_policy);
+
+ax25_uid_assoc *ax25_findbyuid(kuid_t uid)
+{
+ ax25_uid_assoc *ax25_uid, *res = NULL;
+
+ read_lock(&ax25_uid_lock);
+ ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
+ if (uid_eq(ax25_uid->uid, uid)) {
+ ax25_uid_hold(ax25_uid);
+ res = ax25_uid;
+ break;
+ }
+ }
+ read_unlock(&ax25_uid_lock);
+
+ return res;
+}
+
+EXPORT_SYMBOL(ax25_findbyuid);
+
+int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
+{
+ ax25_uid_assoc *ax25_uid;
+ ax25_uid_assoc *user;
+ unsigned long res;
+
+ switch (cmd) {
+ case SIOCAX25GETUID:
+ res = -ENOENT;
+ read_lock(&ax25_uid_lock);
+ ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
+ if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0) {
+ res = from_kuid_munged(current_user_ns(), ax25_uid->uid);
+ break;
+ }
+ }
+ read_unlock(&ax25_uid_lock);
+
+ return res;
+
+ case SIOCAX25ADDUID:
+ {
+ kuid_t sax25_kuid;
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+ sax25_kuid = make_kuid(current_user_ns(), sax->sax25_uid);
+ if (!uid_valid(sax25_kuid))
+ return -EINVAL;
+ user = ax25_findbyuid(sax25_kuid);
+ if (user) {
+ ax25_uid_put(user);
+ return -EEXIST;
+ }
+ if (sax->sax25_uid == 0)
+ return -EINVAL;
+ if ((ax25_uid = kmalloc(sizeof(*ax25_uid), GFP_KERNEL)) == NULL)
+ return -ENOMEM;
+
+ refcount_set(&ax25_uid->refcount, 1);
+ ax25_uid->uid = sax25_kuid;
+ ax25_uid->call = sax->sax25_call;
+
+ write_lock(&ax25_uid_lock);
+ hlist_add_head(&ax25_uid->uid_node, &ax25_uid_list);
+ write_unlock(&ax25_uid_lock);
+
+ return 0;
+ }
+ case SIOCAX25DELUID:
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+
+ ax25_uid = NULL;
+ write_lock(&ax25_uid_lock);
+ ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
+ if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0)
+ break;
+ }
+ if (ax25_uid == NULL) {
+ write_unlock(&ax25_uid_lock);
+ return -ENOENT;
+ }
+ hlist_del_init(&ax25_uid->uid_node);
+ ax25_uid_put(ax25_uid);
+ write_unlock(&ax25_uid_lock);
+
+ return 0;
+
+ default:
+ return -EINVAL;
+ }
+
+ return -EINVAL; /*NOTREACHED */
+}
+
+#ifdef CONFIG_PROC_FS
+
+static void *ax25_uid_seq_start(struct seq_file *seq, loff_t *pos)
+ __acquires(ax25_uid_lock)
+{
+ read_lock(&ax25_uid_lock);
+ return seq_hlist_start_head(&ax25_uid_list, *pos);
+}
+
+static void *ax25_uid_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+ return seq_hlist_next(v, &ax25_uid_list, pos);
+}
+
+static void ax25_uid_seq_stop(struct seq_file *seq, void *v)
+ __releases(ax25_uid_lock)
+{
+ read_unlock(&ax25_uid_lock);
+}
+
+static int ax25_uid_seq_show(struct seq_file *seq, void *v)
+{
+ char buf[11];
+
+ if (v == SEQ_START_TOKEN)
+ seq_printf(seq, "Policy: %d\n", ax25_uid_policy);
+ else {
+ struct ax25_uid_assoc *pt;
+
+ pt = hlist_entry(v, struct ax25_uid_assoc, uid_node);
+ seq_printf(seq, "%6d %s\n",
+ from_kuid_munged(seq_user_ns(seq), pt->uid),
+ ax2asc(buf, &pt->call));
+ }
+ return 0;
+}
+
+const struct seq_operations ax25_uid_seqops = {
+ .start = ax25_uid_seq_start,
+ .next = ax25_uid_seq_next,
+ .stop = ax25_uid_seq_stop,
+ .show = ax25_uid_seq_show,
+};
+#endif
+
+/*
+ * Free all memory associated with UID/Callsign structures.
+ */
+void __exit ax25_uid_free(void)
+{
+ ax25_uid_assoc *ax25_uid;
+
+ write_lock(&ax25_uid_lock);
+again:
+ ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
+ hlist_del_init(&ax25_uid->uid_node);
+ ax25_uid_put(ax25_uid);
+ goto again;
+ }
+ write_unlock(&ax25_uid_lock);
+}