ethtool: Compat handling for struct ethtool_rxnfc

This structure was accidentally defined such that its layout can
differ between 32-bit and 64-bit processes.  Add compat structure
definitions and an ioctl wrapper function.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: stable@kernel.org [2.6.30+]
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 141 insertions, 7 deletions

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index aac3e2eeb4fd..b297f288f6eb 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -13,6 +13,9 @@
 #ifndef _LINUX_ETHTOOL_H
 #define _LINUX_ETHTOOL_H
 
+#ifdef __KERNEL__
+#include <linux/compat.h>
+#endif
 #include <linux/types.h>
 #include <linux/if_ether.h>
 
@@ -450,6 +453,37 @@ struct ethtool_rxnfc {
         __u32                           rule_locs[0];
 };
 
+#ifdef __KERNEL__
+#ifdef CONFIG_COMPAT
+
+struct compat_ethtool_rx_flow_spec {
+        u32             flow_type;
+        union {
+                struct ethtool_tcpip4_spec              tcp_ip4_spec;
+                struct ethtool_tcpip4_spec              udp_ip4_spec;
+                struct ethtool_tcpip4_spec              sctp_ip4_spec;
+                struct ethtool_ah_espip4_spec           ah_ip4_spec;
+                struct ethtool_ah_espip4_spec           esp_ip4_spec;
+                struct ethtool_usrip4_spec              usr_ip4_spec;
+                struct ethhdr                           ether_spec;
+                u8                                      hdata[72];
+        } h_u, m_u;
+        compat_u64      ring_cookie;
+        u32             location;
+};
+
+struct compat_ethtool_rxnfc {
+        u32                             cmd;
+        u32                             flow_type;
+        compat_u64                      data;
+        struct compat_ethtool_rx_flow_spec fs;
+        u32                             rule_cnt;
+        u32                             rule_locs[0];
+};
+
+#endif /* CONFIG_COMPAT */
+#endif /* __KERNEL__ */
+
 /**
  * struct ethtool_rxfh_indir - command to get or set RX flow hash indirection
  * @cmd: Specific command number - %ETHTOOL_GRXFHINDIR or %ETHTOOL_SRXFHINDIR
diff --git a/net/socket.c b/net/socket.c
index 937d0fcf74bc..5212447c86e7 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2588,23 +2588,123 @@ static int dev_ifconf(struct net *net, struct compat_ifconf __user *uifc32)
 
 static int ethtool_ioctl(struct net *net, struct compat_ifreq __user *ifr32)
 {
+        struct compat_ethtool_rxnfc __user *compat_rxnfc;
+        bool convert_in = false, convert_out = false;
+        size_t buf_size = ALIGN(sizeof(struct ifreq), 8);
+        struct ethtool_rxnfc __user *rxnfc;
         struct ifreq __user *ifr;
+        u32 rule_cnt = 0, actual_rule_cnt;
+        u32 ethcmd;
         u32 data;
-        void __user *datap;
+        int ret;
+
+        if (get_user(data, &ifr32->ifr_ifru.ifru_data))
+                return -EFAULT;
 
-        ifr = compat_alloc_user_space(sizeof(*ifr));
+        compat_rxnfc = compat_ptr(data);
 
-        if (copy_in_user(&ifr->ifr_name, &ifr32->ifr_name, IFNAMSIZ))
+        if (get_user(ethcmd, &compat_rxnfc->cmd))
                 return -EFAULT;
 
-        if (get_user(data, &ifr32->ifr_ifru.ifru_data))
+        /* Most ethtool structures are defined without padding.
+         * Unfortunately struct ethtool_rxnfc is an exception.
+         */
+        switch (ethcmd) {
+        default:
+                break;
+        case ETHTOOL_GRXCLSRLALL:
+                /* Buffer size is variable */
+                if (get_user(rule_cnt, &compat_rxnfc->rule_cnt))
+                        return -EFAULT;
+                if (rule_cnt > KMALLOC_MAX_SIZE / sizeof(u32))
+                        return -ENOMEM;
+                buf_size += rule_cnt * sizeof(u32);
+                /* fall through */
+        case ETHTOOL_GRXRINGS:
+        case ETHTOOL_GRXCLSRLCNT:
+        case ETHTOOL_GRXCLSRULE:
+                convert_out = true;
+                /* fall through */
+        case ETHTOOL_SRXCLSRLDEL:
+        case ETHTOOL_SRXCLSRLINS:
+                buf_size += sizeof(struct ethtool_rxnfc);
+                convert_in = true;
+                break;
+        }
+
+        ifr = compat_alloc_user_space(buf_size);
+        rxnfc = (void *)ifr + ALIGN(sizeof(struct ifreq), 8);
+
+        if (copy_in_user(&ifr->ifr_name, &ifr32->ifr_name, IFNAMSIZ))
                 return -EFAULT;
 
-        datap = compat_ptr(data);
-        if (put_user(datap, &ifr->ifr_ifru.ifru_data))
+        if (put_user(convert_in ? rxnfc : compat_ptr(data),
+                     &ifr->ifr_ifru.ifru_data))
                 return -EFAULT;
 
-        return dev_ioctl(net, SIOCETHTOOL, ifr);
+        if (convert_in) {
+                /* We expect there to be holes between fs.m_u and
+                 * fs.ring_cookie and at the end of fs, but nowhere else.
+                 */
+                BUILD_BUG_ON(offsetof(struct compat_ethtool_rxnfc, fs.m_u) +
+                             sizeof(compat_rxnfc->fs.m_u) !=
+                             offsetof(struct ethtool_rxnfc, fs.m_u) +
+                             sizeof(rxnfc->fs.m_u));
+                BUILD_BUG_ON(
+                        offsetof(struct compat_ethtool_rxnfc, fs.location) -
+                        offsetof(struct compat_ethtool_rxnfc, fs.ring_cookie) !=
+                        offsetof(struct ethtool_rxnfc, fs.location) -
+                        offsetof(struct ethtool_rxnfc, fs.ring_cookie));
+
+                if (copy_in_user(rxnfc, compat_rxnfc,
+                                 (void *)(&rxnfc->fs.m_u + 1) -
+                                 (void *)rxnfc) ||
+                    copy_in_user(&rxnfc->fs.ring_cookie,
+                                 &compat_rxnfc->fs.ring_cookie,
+                                 (void *)(&rxnfc->fs.location + 1) -
+                                 (void *)&rxnfc->fs.ring_cookie) ||
+                    copy_in_user(&rxnfc->rule_cnt, &compat_rxnfc->rule_cnt,
+                                 sizeof(rxnfc->rule_cnt)))
+                        return -EFAULT;
+        }
+
+        ret = dev_ioctl(net, SIOCETHTOOL, ifr);
+        if (ret)
+                return ret;
+
+        if (convert_out) {
+                if (copy_in_user(compat_rxnfc, rxnfc,
+                                 (const void *)(&rxnfc->fs.m_u + 1) -
+                                 (const void *)rxnfc) ||
+                    copy_in_user(&compat_rxnfc->fs.ring_cookie,
+                                 &rxnfc->fs.ring_cookie,
+                                 (const void *)(&rxnfc->fs.location + 1) -
+                                 (const void *)&rxnfc->fs.ring_cookie) ||
+                    copy_in_user(&compat_rxnfc->rule_cnt, &rxnfc->rule_cnt,
+                                 sizeof(rxnfc->rule_cnt)))
+                        return -EFAULT;
+
+                if (ethcmd == ETHTOOL_GRXCLSRLALL) {
+                        /* As an optimisation, we only copy the actual
+                         * number of rules that the underlying
+                         * function returned.  Since Mallory might
+                         * change the rule count in user memory, we
+                         * check that it is less than the rule count
+                         * originally given (as the user buffer size),
+                         * which has been range-checked.
+                         */
+                        if (get_user(actual_rule_cnt, &rxnfc->rule_cnt))
+                                return -EFAULT;
+                        if (actual_rule_cnt < rule_cnt)
+                                rule_cnt = actual_rule_cnt;
+                        if (copy_in_user(&compat_rxnfc->rule_locs[0],
+                                         &rxnfc->rule_locs[0],
+                                         rule_cnt * sizeof(u32)))
+                                return -EFAULT;
+                }
+        }
+
+        return 0;
 }
 
 static int compat_siocwandev(struct net *net, struct compat_ifreq __user *uifr32)