[AFS]: Add support for the CB.GetCapabilities operation.

Add support for the CB.GetCapabilities operation with which the fileserver can
ask the client for the following information:

 (1) The list of network interfaces it has available as IPv4 address + netmask
     plus the MTUs.

 (2) The client's UUID.

 (3) The extended capabilities of the client, for which the only current one
     is unified error mapping (abort code interpretation).

To support this, the patch adds the following routines to AFS:

 (1) A function to iterate through all the network interfaces using RTNETLINK
     to extract IPv4 addresses and MTUs.

 (2) A function to iterate through all the network interfaces using RTNETLINK
     to pull out the MAC address of the lowest index interface to use in UUID
     construction.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 473 insertions, 0 deletions

diff --git a/fs/afs/use-rtnetlink.c b/fs/afs/use-rtnetlink.c
new file mode 100644
index 000000000000..82f0daa28970
--- /dev/null
+++ b/fs/afs/use-rtnetlink.c
@@ -0,0 +1,473 @@
+/* RTNETLINK client
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * 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.
+ */
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <linux/if_addr.h>
+#include <linux/if_arp.h>
+#include <linux/inetdevice.h>
+#include <net/netlink.h>
+#include "internal.h"
+
+struct afs_rtm_desc {
+        struct socket           *nlsock;
+        struct afs_interface    *bufs;
+        u8                      *mac;
+        size_t                  nbufs;
+        size_t                  maxbufs;
+        void                    *data;
+        ssize_t                 datalen;
+        size_t                  datamax;
+        int                     msg_seq;
+        unsigned                mac_index;
+        bool                    wantloopback;
+        int (*parse)(struct afs_rtm_desc *, struct nlmsghdr *);
+};
+
+/*
+ * parse an RTM_GETADDR response
+ */
+static int afs_rtm_getaddr_parse(struct afs_rtm_desc *desc,
+                                 struct nlmsghdr *nlhdr)
+{
+        struct afs_interface *this;
+        struct ifaddrmsg *ifa;
+        struct rtattr *rtattr;
+        const char *name;
+        size_t len;
+
+        ifa = (struct ifaddrmsg *) NLMSG_DATA(nlhdr);
+
+        _enter("{ix=%d,af=%d}", ifa->ifa_index, ifa->ifa_family);
+
+        if (ifa->ifa_family != AF_INET) {
+                _leave(" = 0 [family %d]", ifa->ifa_family);
+                return 0;
+        }
+        if (desc->nbufs >= desc->maxbufs) {
+                _leave(" = 0 [max %zu/%zu]", desc->nbufs, desc->maxbufs);
+                return 0;
+        }
+
+        this = &desc->bufs[desc->nbufs];
+
+        this->index = ifa->ifa_index;
+        this->netmask.s_addr = inet_make_mask(ifa->ifa_prefixlen);
+        this->mtu = 0;
+
+        rtattr = NLMSG_DATA(nlhdr) + NLMSG_ALIGN(sizeof(struct ifaddrmsg));
+        len = NLMSG_PAYLOAD(nlhdr, sizeof(struct ifaddrmsg));
+
+        name = "unknown";
+        for (; RTA_OK(rtattr, len); rtattr = RTA_NEXT(rtattr, len)) {
+                switch (rtattr->rta_type) {
+                case IFA_ADDRESS:
+                        memcpy(&this->address, RTA_DATA(rtattr), 4);
+                        break;
+                case IFA_LABEL:
+                        name = RTA_DATA(rtattr);
+                        break;
+                }
+        }
+
+        _debug("%s: "NIPQUAD_FMT"/"NIPQUAD_FMT,
+               name, NIPQUAD(this->address), NIPQUAD(this->netmask));
+
+        desc->nbufs++;
+        _leave(" = 0");
+        return 0;
+}
+
+/*
+ * parse an RTM_GETLINK response for MTUs
+ */
+static int afs_rtm_getlink_if_parse(struct afs_rtm_desc *desc,
+                                    struct nlmsghdr *nlhdr)
+{
+        struct afs_interface *this;
+        struct ifinfomsg *ifi;
+        struct rtattr *rtattr;
+        const char *name;
+        size_t len, loop;
+
+        ifi = (struct ifinfomsg *) NLMSG_DATA(nlhdr);
+
+        _enter("{ix=%d}", ifi->ifi_index);
+
+        for (loop = 0; loop < desc->nbufs; loop++) {
+                this = &desc->bufs[loop];
+                if (this->index == ifi->ifi_index)
+                        goto found;
+        }
+
+        _leave(" = 0 [no match]");
+        return 0;
+
+found:
+        if (ifi->ifi_type == ARPHRD_LOOPBACK && !desc->wantloopback) {
+                _leave(" = 0 [loopback]");
+                return 0;
+        }
+
+        rtattr = NLMSG_DATA(nlhdr) + NLMSG_ALIGN(sizeof(struct ifinfomsg));
+        len = NLMSG_PAYLOAD(nlhdr, sizeof(struct ifinfomsg));
+
+        name = "unknown";
+        for (; RTA_OK(rtattr, len); rtattr = RTA_NEXT(rtattr, len)) {
+                switch (rtattr->rta_type) {
+                case IFLA_MTU:
+                        memcpy(&this->mtu, RTA_DATA(rtattr), 4);
+                        break;
+                case IFLA_IFNAME:
+                        name = RTA_DATA(rtattr);
+                        break;
+                }
+        }
+
+        _debug("%s: "NIPQUAD_FMT"/"NIPQUAD_FMT" mtu %u",
+               name, NIPQUAD(this->address), NIPQUAD(this->netmask),
+               this->mtu);
+
+        _leave(" = 0");
+        return 0;
+}
+
+/*
+ * parse an RTM_GETLINK response for the MAC address belonging to the lowest
+ * non-internal interface
+ */
+static int afs_rtm_getlink_mac_parse(struct afs_rtm_desc *desc,
+                                     struct nlmsghdr *nlhdr)
+{
+        struct ifinfomsg *ifi;
+        struct rtattr *rtattr;
+        const char *name;
+        size_t remain, len;
+        bool set;
+
+        ifi = (struct ifinfomsg *) NLMSG_DATA(nlhdr);
+
+        _enter("{ix=%d}", ifi->ifi_index);
+
+        if (ifi->ifi_index >= desc->mac_index) {
+                _leave(" = 0 [high]");
+                return 0;
+        }
+        if (ifi->ifi_type == ARPHRD_LOOPBACK) {
+                _leave(" = 0 [loopback]");
+                return 0;
+        }
+
+        rtattr = NLMSG_DATA(nlhdr) + NLMSG_ALIGN(sizeof(struct ifinfomsg));
+        remain = NLMSG_PAYLOAD(nlhdr, sizeof(struct ifinfomsg));
+
+        name = "unknown";
+        set = false;
+        for (; RTA_OK(rtattr, remain); rtattr = RTA_NEXT(rtattr, remain)) {
+                switch (rtattr->rta_type) {
+                case IFLA_ADDRESS:
+                        len = RTA_PAYLOAD(rtattr);
+                        memcpy(desc->mac, RTA_DATA(rtattr),
+                               min_t(size_t, len, 6));
+                        desc->mac_index = ifi->ifi_index;
+                        set = true;
+                        break;
+                case IFLA_IFNAME:
+                        name = RTA_DATA(rtattr);
+                        break;
+                }
+        }
+
+        if (set)
+                _debug("%s: %02x:%02x:%02x:%02x:%02x:%02x",
+                       name,
+                       desc->mac[0], desc->mac[1], desc->mac[2],
+                       desc->mac[3], desc->mac[4], desc->mac[5]);
+
+        _leave(" = 0");
+        return 0;
+}
+
+/*
+ * read the rtnetlink response and pass to parsing routine
+ */
+static int afs_read_rtm(struct afs_rtm_desc *desc)
+{
+        struct nlmsghdr *nlhdr, tmphdr;
+        struct msghdr msg;
+        struct kvec iov[1];
+        void *data;
+        bool last = false;
+        int len, ret, remain;
+
+        _enter("");
+
+        do {
+                /* first of all peek to see how big the packet is */
+                memset(&msg, 0, sizeof(msg));
+                iov[0].iov_base = &tmphdr;
+                iov[0].iov_len = sizeof(tmphdr);
+                len = kernel_recvmsg(desc->nlsock, &msg, iov, 1,
+                                     sizeof(tmphdr), MSG_PEEK | MSG_TRUNC);
+                if (len < 0) {
+                        _leave(" = %d [peek]", len);
+                        return len;
+                }
+                if (len == 0)
+                        continue;
+                if (len < sizeof(tmphdr) || len < NLMSG_PAYLOAD(&tmphdr, 0)) {
+                        _leave(" = -EMSGSIZE");
+                        return -EMSGSIZE;
+                }
+
+                if (desc->datamax < len) {
+                        kfree(desc->data);
+                        desc->data = NULL;
+                        data = kmalloc(len, GFP_KERNEL);
+                        if (!data)
+                                return -ENOMEM;
+                        desc->data = data;
+                }
+                desc->datamax = len;
+
+                /* read all the data from this packet */
+                iov[0].iov_base = desc->data;
+                iov[0].iov_len = desc->datamax;
+                desc->datalen = kernel_recvmsg(desc->nlsock, &msg, iov, 1,
+                                               desc->datamax, 0);
+                if (desc->datalen < 0) {
+                        _leave(" = %ld [recv]", desc->datalen);
+                        return desc->datalen;
+                }
+
+                nlhdr = desc->data;
+
+                /* check if the header is valid */
+                if (!NLMSG_OK(nlhdr, desc->datalen) ||
+                    nlhdr->nlmsg_type == NLMSG_ERROR) {
+                        _leave(" = -EIO");
+                        return -EIO;
+                }
+
+                /* see if this is the last message */
+                if (nlhdr->nlmsg_type == NLMSG_DONE ||
+                    !(nlhdr->nlmsg_flags & NLM_F_MULTI))
+                        last = true;
+
+                /* parse the bits we got this time */
+                nlmsg_for_each_msg(nlhdr, desc->data, desc->datalen, remain) {
+                        ret = desc->parse(desc, nlhdr);
+                        if (ret < 0) {
+                                _leave(" = %d [parse]", ret);
+                                return ret;
+                        }
+                }
+
+        } while (!last);
+
+        _leave(" = 0");
+        return 0;
+}
+
+/*
+ * list the interface bound addresses to get the address and netmask
+ */
+static int afs_rtm_getaddr(struct afs_rtm_desc *desc)
+{
+        struct msghdr msg;
+        struct kvec iov[1];
+        int ret;
+
+        struct {
+                struct nlmsghdr nl_msg __attribute__((aligned(NLMSG_ALIGNTO)));
+                struct ifaddrmsg addr_msg __attribute__((aligned(NLMSG_ALIGNTO)));
+        } request;
+
+        _enter("");
+
+        memset(&request, 0, sizeof(request));
+
+        request.nl_msg.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
+        request.nl_msg.nlmsg_type = RTM_GETADDR;
+        request.nl_msg.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
+        request.nl_msg.nlmsg_seq = desc->msg_seq++;
+        request.nl_msg.nlmsg_pid = 0;
+
+        memset(&msg, 0, sizeof(msg));
+        iov[0].iov_base = &request;
+        iov[0].iov_len = sizeof(request);
+
+        ret = kernel_sendmsg(desc->nlsock, &msg, iov, 1, iov[0].iov_len);
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * list the interface link statuses to get the MTUs
+ */
+static int afs_rtm_getlink(struct afs_rtm_desc *desc)
+{
+        struct msghdr msg;
+        struct kvec iov[1];
+        int ret;
+
+        struct {
+                struct nlmsghdr nl_msg __attribute__((aligned(NLMSG_ALIGNTO)));
+                struct ifinfomsg link_msg __attribute__((aligned(NLMSG_ALIGNTO)));
+        } request;
+
+        _enter("");
+
+        memset(&request, 0, sizeof(request));
+
+        request.nl_msg.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
+        request.nl_msg.nlmsg_type = RTM_GETLINK;
+        request.nl_msg.nlmsg_flags = NLM_F_REQUEST | NLM_F_ROOT;
+        request.nl_msg.nlmsg_seq = desc->msg_seq++;
+        request.nl_msg.nlmsg_pid = 0;
+
+        memset(&msg, 0, sizeof(msg));
+        iov[0].iov_base = &request;
+        iov[0].iov_len = sizeof(request);
+
+        ret = kernel_sendmsg(desc->nlsock, &msg, iov, 1, iov[0].iov_len);
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * cull any interface records for which there isn't an MTU value
+ */
+static void afs_cull_interfaces(struct afs_rtm_desc *desc)
+{
+        struct afs_interface *bufs = desc->bufs;
+        size_t nbufs = desc->nbufs;
+        int loop, point = 0;
+
+        _enter("{%zu}", nbufs);
+
+        for (loop = 0; loop < nbufs; loop++) {
+                if (desc->bufs[loop].mtu != 0) {
+                        if (loop != point) {
+                                ASSERTCMP(loop, >, point);
+                                bufs[point] = bufs[loop];
+                        }
+                        point++;
+                }
+        }
+
+        desc->nbufs = point;
+        _leave(" [%zu/%zu]", desc->nbufs, nbufs);
+}
+
+/*
+ * get a list of this system's interface IPv4 addresses, netmasks and MTUs
+ * - returns the number of interface records in the buffer
+ */
+int afs_get_ipv4_interfaces(struct afs_interface *bufs, size_t maxbufs,
+                            bool wantloopback)
+{
+        struct afs_rtm_desc desc;
+        int ret, loop;
+
+        _enter("");
+
+        memset(&desc, 0, sizeof(desc));
+        desc.bufs = bufs;
+        desc.maxbufs = maxbufs;
+        desc.wantloopback = wantloopback;
+
+        ret = sock_create_kern(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE,
+                               &desc.nlsock);
+        if (ret < 0) {
+                _leave(" = %d [sock]", ret);
+                return ret;
+        }
+
+        /* issue RTM_GETADDR */
+        desc.parse = afs_rtm_getaddr_parse;
+        ret = afs_rtm_getaddr(&desc);
+        if (ret < 0)
+                goto error;
+        ret = afs_read_rtm(&desc);
+        if (ret < 0)
+                goto error;
+
+        /* issue RTM_GETLINK */
+        desc.parse = afs_rtm_getlink_if_parse;
+        ret = afs_rtm_getlink(&desc);
+        if (ret < 0)
+                goto error;
+        ret = afs_read_rtm(&desc);
+        if (ret < 0)
+                goto error;
+
+        afs_cull_interfaces(&desc);
+        ret = desc.nbufs;
+
+        for (loop = 0; loop < ret; loop++)
+                _debug("[%d] "NIPQUAD_FMT"/"NIPQUAD_FMT" mtu %u",
+                       bufs[loop].index,
+                       NIPQUAD(bufs[loop].address),
+                       NIPQUAD(bufs[loop].netmask),
+                       bufs[loop].mtu);
+
+error:
+        kfree(desc.data);
+        sock_release(desc.nlsock);
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
+ * get a MAC address from a random ethernet interface that has a real one
+ * - the buffer should be 6 bytes in size
+ */
+int afs_get_MAC_address(u8 mac[6])
+{
+        struct afs_rtm_desc desc;
+        int ret;
+
+        _enter("");
+
+        memset(&desc, 0, sizeof(desc));
+        desc.mac = mac;
+        desc.mac_index = UINT_MAX;
+
+        ret = sock_create_kern(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE,
+                               &desc.nlsock);
+        if (ret < 0) {
+                _leave(" = %d [sock]", ret);
+                return ret;
+        }
+
+        /* issue RTM_GETLINK */
+        desc.parse = afs_rtm_getlink_mac_parse;
+        ret = afs_rtm_getlink(&desc);
+        if (ret < 0)
+                goto error;
+        ret = afs_read_rtm(&desc);
+        if (ret < 0)
+                goto error;
+
+        if (desc.mac_index < UINT_MAX) {
+                /* got a MAC address */
+                _debug("[%d] %02x:%02x:%02x:%02x:%02x:%02x",
+                       desc.mac_index,
+                       mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+        } else {
+                ret = -ENONET;
+        }
+
+error:
+        sock_release(desc.nlsock);
+        _leave(" = %d", ret);
+        return ret;
+}