--- /dev/null
+// 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;
+}
goto done;
}
+/*
+ * Display the list of addr_prefs known to the namespace.
+ */
+static int afs_proc_addr_prefs_show(struct seq_file *m, void *v)
+{
+ struct afs_addr_preference_list *preflist;
+ struct afs_addr_preference *pref;
+ struct afs_net *net = afs_seq2net_single(m);
+ union {
+ struct sockaddr_in sin;
+ struct sockaddr_in6 sin6;
+ } addr;
+ unsigned int i;
+ char buf[44]; /* Maximum ipv6 + max subnet is 43 */
+
+ rcu_read_lock();
+ preflist = rcu_dereference(net->address_prefs);
+
+ if (!preflist) {
+ seq_puts(m, "NO PREFS\n");
+ return 0;
+ }
+
+ seq_printf(m, "PROT SUBNET PRIOR (v=%u n=%u/%u/%u)\n",
+ preflist->version, preflist->ipv6_off, preflist->nr, preflist->max_prefs);
+
+ memset(&addr, 0, sizeof(addr));
+
+ for (i = 0; i < preflist->nr; i++) {
+ pref = &preflist->prefs[i];
+
+ addr.sin.sin_family = pref->family;
+ if (pref->family == AF_INET) {
+ memcpy(&addr.sin.sin_addr, &pref->ipv4_addr,
+ sizeof(addr.sin.sin_addr));
+ snprintf(buf, sizeof(buf), "%pISc/%u", &addr.sin, pref->subnet_mask);
+ seq_printf(m, "UDP %-43.43s %5u\n", buf, pref->prio);
+ } else {
+ memcpy(&addr.sin6.sin6_addr, &pref->ipv6_addr,
+ sizeof(addr.sin6.sin6_addr));
+ snprintf(buf, sizeof(buf), "%pISc/%u", &addr.sin6, pref->subnet_mask);
+ seq_printf(m, "UDP %-43.43s %5u\n", buf, pref->prio);
+ }
+ }
+
+ rcu_read_lock();
+ return 0;
+}
+
/*
* Display the name of the current workstation cell.
*/
&afs_proc_sysname_ops,
afs_proc_sysname_write,
sizeof(struct seq_net_private),
- NULL))
+ NULL) ||
+ !proc_create_net_single_write("addr_prefs", 0644, p,
+ afs_proc_addr_prefs_show,
+ afs_proc_addr_prefs_write,
+ NULL))
goto error_tree;
net->proc_afs = p;
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