1 files changed, 531 insertions, 0 deletions

diff --git a/fs/afs/addr_prefs.c b/fs/afs/addr_prefs.c
new file mode 100644
index 0000000000..a189ff8a50
--- /dev/null
+++ b/fs/afs/addr_prefs.c
@@ -0,0 +1,531 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Address preferences management
+ *
+ * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": addr_prefs: " fmt
+#include <linux/slab.h>
+#include <linux/ctype.h>
+#include <linux/inet.h>
+#include <linux/seq_file.h>
+#include <keys/rxrpc-type.h>
+#include "internal.h"
+
+static inline struct afs_net *afs_seq2net_single(struct seq_file *m)
+{
+	return afs_net(seq_file_single_net(m));
+}
+
+/*
+ * Split a NUL-terminated string up to the first newline around spaces.  The
+ * source string will be modified to have NUL-terminations inserted.
+ */
+static int afs_split_string(char **pbuf, char *strv[], unsigned int maxstrv)
+{
+	unsigned int count = 0;
+	char *p = *pbuf;
+
+	maxstrv--; /* Allow for terminal NULL */
+	for (;;) {
+		/* Skip over spaces */
+		while (isspace(*p)) {
+			if (*p == '\n') {
+				p++;
+				break;
+			}
+			p++;
+		}
+		if (!*p)
+			break;
+
+		/* Mark start of word */
+		if (count >= maxstrv) {
+			pr_warn("Too many elements in string\n");
+			return -EINVAL;
+		}
+		strv[count++] = p;
+
+		/* Skip over word */
+		while (!isspace(*p))
+			p++;
+		if (!*p)
+			break;
+
+		/* Mark end of word */
+		if (*p == '\n') {
+			*p++ = 0;
+			break;
+		}
+		*p++ = 0;
+	}
+
+	*pbuf = p;
+	strv[count] = NULL;
+	return count;
+}
+
+/*
+ * Parse an address with an optional subnet mask.
+ */
+static int afs_parse_address(char *p, struct afs_addr_preference *pref)
+{
+	const char *stop;
+	unsigned long mask, tmp;
+	char *end = p + strlen(p);
+	bool bracket = false;
+
+	if (*p == '[') {
+		p++;
+		bracket = true;
+	}
+
+#if 0
+	if (*p == '[') {
+		p++;
+		q = memchr(p, ']', end - p);
+		if (!q) {
+			pr_warn("Can't find closing ']'\n");
+			return -EINVAL;
+		}
+	} else {
+		for (q = p; q < end; q++)
+			if (*q == '/')
+				break;
+	}
+#endif
+
+	if (in4_pton(p, end - p, (u8 *)&pref->ipv4_addr, -1, &stop)) {
+		pref->family = AF_INET;
+		mask = 32;
+	} else if (in6_pton(p, end - p, (u8 *)&pref->ipv6_addr, -1, &stop)) {
+		pref->family = AF_INET6;
+		mask = 128;
+	} else {
+		pr_warn("Can't determine address family\n");
+		return -EINVAL;
+	}
+
+	p = (char *)stop;
+	if (bracket) {
+		if (*p != ']') {
+			pr_warn("Can't find closing ']'\n");
+			return -EINVAL;
+		}
+		p++;
+	}
+
+	if (*p == '/') {
+		p++;
+		tmp = simple_strtoul(p, &p, 10);
+		if (tmp > mask) {
+			pr_warn("Subnet mask too large\n");
+			return -EINVAL;
+		}
+		if (tmp == 0) {
+			pr_warn("Subnet mask too small\n");
+			return -EINVAL;
+		}
+		mask = tmp;
+	}
+
+	if (*p) {
+		pr_warn("Invalid address\n");
+		return -EINVAL;
+	}
+
+	pref->subnet_mask = mask;
+	return 0;
+}
+
+enum cmp_ret {
+	CONTINUE_SEARCH,
+	INSERT_HERE,
+	EXACT_MATCH,
+	SUBNET_MATCH,
+};
+
+/*
+ * See if a candidate address matches a listed address.
+ */
+static enum cmp_ret afs_cmp_address_pref(const struct afs_addr_preference *a,
+					 const struct afs_addr_preference *b)
+{
+	int subnet = min(a->subnet_mask, b->subnet_mask);
+	const __be32 *pa, *pb;
+	u32 mask, na, nb;
+	int diff;
+
+	if (a->family != b->family)
+		return INSERT_HERE;
+
+	switch (a->family) {
+	case AF_INET6:
+		pa = a->ipv6_addr.s6_addr32;
+		pb = b->ipv6_addr.s6_addr32;
+		break;
+	case AF_INET:
+		pa = &a->ipv4_addr.s_addr;
+		pb = &b->ipv4_addr.s_addr;
+		break;
+	}
+
+	while (subnet > 32) {
+		diff = ntohl(*pa++) - ntohl(*pb++);
+		if (diff < 0)
+			return INSERT_HERE; /* a<b */
+		if (diff > 0)
+			return CONTINUE_SEARCH; /* a>b */
+		subnet -= 32;
+	}
+
+	if (subnet == 0)
+		return EXACT_MATCH;
+
+	mask = 0xffffffffU << (32 - subnet);
+	na = ntohl(*pa);
+	nb = ntohl(*pb);
+	diff = (na & mask) - (nb & mask);
+	//kdebug("diff %08x %08x %08x %d", na, nb, mask, diff);
+	if (diff < 0)
+		return INSERT_HERE; /* a<b */
+	if (diff > 0)
+		return CONTINUE_SEARCH; /* a>b */
+	if (a->subnet_mask == b->subnet_mask)
+		return EXACT_MATCH;
+	if (a->subnet_mask > b->subnet_mask)
+		return SUBNET_MATCH; /* a binds tighter than b */
+	return CONTINUE_SEARCH; /* b binds tighter than a */
+}
+
+/*
+ * Insert an address preference.
+ */
+static int afs_insert_address_pref(struct afs_addr_preference_list **_preflist,
+				   struct afs_addr_preference *pref,
+				   int index)
+{
+	struct afs_addr_preference_list *preflist = *_preflist, *old = preflist;
+	size_t size, max_prefs;
+
+	_enter("{%u/%u/%u},%u", preflist->ipv6_off, preflist->nr, preflist->max_prefs, index);
+
+	if (preflist->nr == 255)
+		return -ENOSPC;
+	if (preflist->nr >= preflist->max_prefs) {
+		max_prefs = preflist->max_prefs + 1;
+		size = struct_size(preflist, prefs, max_prefs);
+		size = roundup_pow_of_two(size);
+		max_prefs = min_t(size_t, (size - sizeof(*preflist)) / sizeof(*pref), 255);
+		preflist = kmalloc(size, GFP_KERNEL);
+		if (!preflist)
+			return -ENOMEM;
+		*preflist = **_preflist;
+		preflist->max_prefs = max_prefs;
+		*_preflist = preflist;
+
+		if (index < preflist->nr)
+			memcpy(preflist->prefs + index + 1, old->prefs + index,
+			       sizeof(*pref) * (preflist->nr - index));
+		if (index > 0)
+			memcpy(preflist->prefs, old->prefs, sizeof(*pref) * index);
+	} else {
+		if (index < preflist->nr)
+			memmove(preflist->prefs + index + 1, preflist->prefs + index,
+			       sizeof(*pref) * (preflist->nr - index));
+	}
+
+	preflist->prefs[index] = *pref;
+	preflist->nr++;
+	if (pref->family == AF_INET)
+		preflist->ipv6_off++;
+	return 0;
+}
+
+/*
+ * Add an address preference.
+ *	echo "add <proto> <IP>[/<mask>] <prior>" >/proc/fs/afs/addr_prefs
+ */
+static int afs_add_address_pref(struct afs_net *net, struct afs_addr_preference_list **_preflist,
+				int argc, char **argv)
+{
+	struct afs_addr_preference_list *preflist = *_preflist;
+	struct afs_addr_preference pref;
+	enum cmp_ret cmp;
+	int ret, i, stop;
+
+	if (argc != 3) {
+		pr_warn("Wrong number of params\n");
+		return -EINVAL;
+	}
+
+	if (strcmp(argv[0], "udp") != 0) {
+		pr_warn("Unsupported protocol\n");
+		return -EINVAL;
+	}
+
+	ret = afs_parse_address(argv[1], &pref);
+	if (ret < 0)
+		return ret;
+
+	ret = kstrtou16(argv[2], 10, &pref.prio);
+	if (ret < 0) {
+		pr_warn("Invalid priority\n");
+		return ret;
+	}
+
+	if (pref.family == AF_INET) {
+		i = 0;
+		stop = preflist->ipv6_off;
+	} else {
+		i = preflist->ipv6_off;
+		stop = preflist->nr;
+	}
+
+	for (; i < stop; i++) {
+		cmp = afs_cmp_address_pref(&pref, &preflist->prefs[i]);
+		switch (cmp) {
+		case CONTINUE_SEARCH:
+			continue;
+		case INSERT_HERE:
+		case SUBNET_MATCH:
+			return afs_insert_address_pref(_preflist, &pref, i);
+		case EXACT_MATCH:
+			preflist->prefs[i].prio = pref.prio;
+			return 0;
+		}
+	}
+
+	return afs_insert_address_pref(_preflist, &pref, i);
+}
+
+/*
+ * Delete an address preference.
+ */
+static int afs_delete_address_pref(struct afs_addr_preference_list **_preflist,
+				   int index)
+{
+	struct afs_addr_preference_list *preflist = *_preflist;
+
+	_enter("{%u/%u/%u},%u", preflist->ipv6_off, preflist->nr, preflist->max_prefs, index);
+
+	if (preflist->nr == 0)
+		return -ENOENT;
+
+	if (index < preflist->nr - 1)
+		memmove(preflist->prefs + index, preflist->prefs + index + 1,
+			sizeof(preflist->prefs[0]) * (preflist->nr - index - 1));
+
+	if (index < preflist->ipv6_off)
+		preflist->ipv6_off--;
+	preflist->nr--;
+	return 0;
+}
+
+/*
+ * Delete an address preference.
+ *	echo "del <proto> <IP>[/<mask>]" >/proc/fs/afs/addr_prefs
+ */
+static int afs_del_address_pref(struct afs_net *net, struct afs_addr_preference_list **_preflist,
+				int argc, char **argv)
+{
+	struct afs_addr_preference_list *preflist = *_preflist;
+	struct afs_addr_preference pref;
+	enum cmp_ret cmp;
+	int ret, i, stop;
+
+	if (argc != 2) {
+		pr_warn("Wrong number of params\n");
+		return -EINVAL;
+	}
+
+	if (strcmp(argv[0], "udp") != 0) {
+		pr_warn("Unsupported protocol\n");
+		return -EINVAL;
+	}
+
+	ret = afs_parse_address(argv[1], &pref);
+	if (ret < 0)
+		return ret;
+
+	if (pref.family == AF_INET) {
+		i = 0;
+		stop = preflist->ipv6_off;
+	} else {
+		i = preflist->ipv6_off;
+		stop = preflist->nr;
+	}
+
+	for (; i < stop; i++) {
+		cmp = afs_cmp_address_pref(&pref, &preflist->prefs[i]);
+		switch (cmp) {
+		case CONTINUE_SEARCH:
+			continue;
+		case INSERT_HERE:
+		case SUBNET_MATCH:
+			return 0;
+		case EXACT_MATCH:
+			return afs_delete_address_pref(_preflist, i);
+		}
+	}
+
+	return -ENOANO;
+}
+
+/*
+ * Handle writes to /proc/fs/afs/addr_prefs
+ */
+int afs_proc_addr_prefs_write(struct file *file, char *buf, size_t size)
+{
+	struct afs_addr_preference_list *preflist, *old;
+	struct seq_file *m = file->private_data;
+	struct afs_net *net = afs_seq2net_single(m);
+	size_t psize;
+	char *argv[5];
+	int ret, argc, max_prefs;
+
+	inode_lock(file_inode(file));
+
+	/* Allocate a candidate new list and initialise it from the old. */
+	old = rcu_dereference_protected(net->address_prefs,
+					lockdep_is_held(&file_inode(file)->i_rwsem));
+
+	if (old)
+		max_prefs = old->nr + 1;
+	else
+		max_prefs = 1;
+
+	psize = struct_size(old, prefs, max_prefs);
+	psize = roundup_pow_of_two(psize);
+	max_prefs = min_t(size_t, (psize - sizeof(*old)) / sizeof(old->prefs[0]), 255);
+
+	ret = -ENOMEM;
+	preflist = kmalloc(struct_size(preflist, prefs, max_prefs), GFP_KERNEL);
+	if (!preflist)
+		goto done;
+
+	if (old)
+		memcpy(preflist, old, struct_size(preflist, prefs, old->nr));
+	else
+		memset(preflist, 0, sizeof(*preflist));
+	preflist->max_prefs = max_prefs;
+
+	do {
+		argc = afs_split_string(&buf, argv, ARRAY_SIZE(argv));
+		if (argc < 0)
+			return argc;
+		if (argc < 2)
+			goto inval;
+
+		if (strcmp(argv[0], "add") == 0)
+			ret = afs_add_address_pref(net, &preflist, argc - 1, argv + 1);
+		else if (strcmp(argv[0], "del") == 0)
+			ret = afs_del_address_pref(net, &preflist, argc - 1, argv + 1);
+		else
+			goto inval;
+		if (ret < 0)
+			goto done;
+	} while (*buf);
+
+	preflist->version++;
+	rcu_assign_pointer(net->address_prefs, preflist);
+	/* Store prefs before version */
+	smp_store_release(&net->address_pref_version, preflist->version);
+	kfree_rcu(old, rcu);
+	preflist = NULL;
+	ret = 0;
+
+done:
+	kfree(preflist);
+	inode_unlock(file_inode(file));
+	_leave(" = %d", ret);
+	return ret;
+
+inval:
+	pr_warn("Invalid Command\n");
+	ret = -EINVAL;
+	goto done;
+}
+
+/*
+ * Mark the priorities on an address list if the address preferences table has
+ * changed.  The caller must hold the RCU read lock.
+ */
+void afs_get_address_preferences_rcu(struct afs_net *net, struct afs_addr_list *alist)
+{
+	const struct afs_addr_preference_list *preflist =
+		rcu_dereference(net->address_prefs);
+	const struct sockaddr_in6 *sin6;
+	const struct sockaddr_in *sin;
+	const struct sockaddr *sa;
+	struct afs_addr_preference test;
+	enum cmp_ret cmp;
+	int i, j;
+
+	if (!preflist || !preflist->nr || !alist->nr_addrs ||
+	    smp_load_acquire(&alist->addr_pref_version) == preflist->version)
+		return;
+
+	test.family = AF_INET;
+	test.subnet_mask = 32;
+	test.prio = 0;
+	for (i = 0; i < alist->nr_ipv4; i++) {
+		sa = rxrpc_kernel_remote_addr(alist->addrs[i].peer);
+		sin = (const struct sockaddr_in *)sa;
+		test.ipv4_addr = sin->sin_addr;
+		for (j = 0; j < preflist->ipv6_off; j++) {
+			cmp = afs_cmp_address_pref(&test, &preflist->prefs[j]);
+			switch (cmp) {
+			case CONTINUE_SEARCH:
+				continue;
+			case INSERT_HERE:
+				break;
+			case EXACT_MATCH:
+			case SUBNET_MATCH:
+				WRITE_ONCE(alist->addrs[i].prio, preflist->prefs[j].prio);
+				break;
+			}
+		}
+	}
+
+	test.family = AF_INET6;
+	test.subnet_mask = 128;
+	test.prio = 0;
+	for (; i < alist->nr_addrs; i++) {
+		sa = rxrpc_kernel_remote_addr(alist->addrs[i].peer);
+		sin6 = (const struct sockaddr_in6 *)sa;
+		test.ipv6_addr = sin6->sin6_addr;
+		for (j = preflist->ipv6_off; j < preflist->nr; j++) {
+			cmp = afs_cmp_address_pref(&test, &preflist->prefs[j]);
+			switch (cmp) {
+			case CONTINUE_SEARCH:
+				continue;
+			case INSERT_HERE:
+				break;
+			case EXACT_MATCH:
+			case SUBNET_MATCH:
+				WRITE_ONCE(alist->addrs[i].prio, preflist->prefs[j].prio);
+				break;
+			}
+		}
+	}
+
+	smp_store_release(&alist->addr_pref_version, preflist->version);
+}
+
+/*
+ * Mark the priorities on an address list if the address preferences table has
+ * changed.  Avoid taking the RCU read lock if we can.
+ */
+void afs_get_address_preferences(struct afs_net *net, struct afs_addr_list *alist)
+{
+	if (!net->address_prefs ||
+	    /* Load version before prefs */
+	    smp_load_acquire(&net->address_pref_version) == alist->addr_pref_version)
+		return;
+
+	rcu_read_lock();
+	afs_get_address_preferences_rcu(net, alist);
+	rcu_read_unlock();
+}