net: Unbreak compat_sys_{send,recv}msg

I broke them in this commit:

    commit 1be374a0518a288147c6a7398792583200a67261
    Author: Andy Lutomirski <luto@amacapital.net>
    Date:   Wed May 22 14:07:44 2013 -0700

        net: Block MSG_CMSG_COMPAT in send(m)msg and recv(m)msg

This patch adds __sys_sendmsg and __sys_sendmsg as common helpers that accept
MSG_CMSG_COMPAT and blocks MSG_CMSG_COMPAT at the syscall entrypoints.  It
also reverts some unnecessary checks in sys_socketcall.

Apparently I was suffering from underscore blindness the first time around.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Tested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 33bf2df..b10ce4b 100644 (file)
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -320,6 +320,9 @@ extern int put_cmsg(struct msghdr*, int level, int type, int len, void *data);
 
 struct timespec;
 
+/* The __sys_...msg variants allow MSG_CMSG_COMPAT */
+extern long __sys_recvmsg(int fd, struct msghdr __user *msg, unsigned flags);
+extern long __sys_sendmsg(int fd, struct msghdr __user *msg, unsigned flags);
 extern int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
                          unsigned int flags, struct timespec *timeout);
 extern int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg,

diff --git a/net/compat.c b/net/compat.c
index 79ae884..f0a1ba6 100644 (file)
--- a/net/compat.c
+++ b/net/compat.c
@@ -734,19 +734,25 @@ static unsigned char nas[21] = {
 
 asmlinkage long compat_sys_sendmsg(int fd, struct compat_msghdr __user *msg, unsigned int flags)
 {
-       return sys_sendmsg(fd, (struct msghdr __user *)msg, flags | MSG_CMSG_COMPAT);
+       if (flags & MSG_CMSG_COMPAT)
+               return -EINVAL;
+       return __sys_sendmsg(fd, (struct msghdr __user *)msg, flags | MSG_CMSG_COMPAT);
 }
 
 asmlinkage long compat_sys_sendmmsg(int fd, struct compat_mmsghdr __user *mmsg,
                                    unsigned int vlen, unsigned int flags)
 {
+       if (flags & MSG_CMSG_COMPAT)
+               return -EINVAL;
        return __sys_sendmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,
                              flags | MSG_CMSG_COMPAT);
 }
 
 asmlinkage long compat_sys_recvmsg(int fd, struct compat_msghdr __user *msg, unsigned int flags)
 {
-       return sys_recvmsg(fd, (struct msghdr __user *)msg, flags | MSG_CMSG_COMPAT);
+       if (flags & MSG_CMSG_COMPAT)
+               return -EINVAL;
+       return __sys_recvmsg(fd, (struct msghdr __user *)msg, flags | MSG_CMSG_COMPAT);
 }
 
 asmlinkage long compat_sys_recv(int fd, void __user *buf, size_t len, unsigned int flags)
@@ -768,6 +774,9 @@ asmlinkage long compat_sys_recvmmsg(int fd, struct compat_mmsghdr __user *mmsg,
        int datagrams;
        struct timespec ktspec;
 
+       if (flags & MSG_CMSG_COMPAT)
+               return -EINVAL;
+
        if (COMPAT_USE_64BIT_TIME)
                return __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,
                                      flags | MSG_CMSG_COMPAT,

diff --git a/net/socket.c b/net/socket.c
index 9ff6366..4ca1526 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1956,7 +1956,7 @@ struct used_address {
        unsigned int name_len;
 };
 
-static int __sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
+static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
                         struct msghdr *msg_sys, unsigned int flags,
                         struct used_address *used_address)
 {
@@ -2071,26 +2071,30 @@ out:
  *     BSD sendmsg interface
  */
 
-SYSCALL_DEFINE3(sendmsg, int, fd, struct msghdr __user *, msg, unsigned int, flags)
+long __sys_sendmsg(int fd, struct msghdr __user *msg, unsigned flags)
 {
        int fput_needed, err;
        struct msghdr msg_sys;
        struct socket *sock;
 
-       if (flags & MSG_CMSG_COMPAT)
-               return -EINVAL;
-
        sock = sockfd_lookup_light(fd, &err, &fput_needed);
        if (!sock)
                goto out;
 
-       err = __sys_sendmsg(sock, msg, &msg_sys, flags, NULL);
+       err = ___sys_sendmsg(sock, msg, &msg_sys, flags, NULL);
 
        fput_light(sock->file, fput_needed);
 out:
        return err;
 }
 
+SYSCALL_DEFINE3(sendmsg, int, fd, struct msghdr __user *, msg, unsigned int, flags)
+{
+       if (flags & MSG_CMSG_COMPAT)
+               return -EINVAL;
+       return __sys_sendmsg(fd, msg, flags);
+}
+
 /*
  *     Linux sendmmsg interface
  */
@@ -2121,15 +2125,16 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
 
        while (datagrams < vlen) {
                if (MSG_CMSG_COMPAT & flags) {
-                       err = __sys_sendmsg(sock, (struct msghdr __user *)compat_entry,
-                                           &msg_sys, flags, &used_address);
+                       err = ___sys_sendmsg(sock, (struct msghdr __user *)compat_entry,
+                                            &msg_sys, flags, &used_address);
                        if (err < 0)
                                break;
                        err = __put_user(err, &compat_entry->msg_len);
                        ++compat_entry;
                } else {
-                       err = __sys_sendmsg(sock, (struct msghdr __user *)entry,
-                                           &msg_sys, flags, &used_address);
+                       err = ___sys_sendmsg(sock,
+                                            (struct msghdr __user *)entry,
+                                            &msg_sys, flags, &used_address);
                        if (err < 0)
                                break;
                        err = put_user(err, &entry->msg_len);
@@ -2158,7 +2163,7 @@ SYSCALL_DEFINE4(sendmmsg, int, fd, struct mmsghdr __user *, mmsg,
        return __sys_sendmmsg(fd, mmsg, vlen, flags);
 }
 
-static int __sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
+static int ___sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
                         struct msghdr *msg_sys, unsigned int flags, int nosec)
 {
        struct compat_msghdr __user *msg_compat =
@@ -2250,27 +2255,31 @@ out:
  *     BSD recvmsg interface
  */
 
-SYSCALL_DEFINE3(recvmsg, int, fd, struct msghdr __user *, msg,
-               unsigned int, flags)
+long __sys_recvmsg(int fd, struct msghdr __user *msg, unsigned flags)
 {
        int fput_needed, err;
        struct msghdr msg_sys;
        struct socket *sock;
 
-       if (flags & MSG_CMSG_COMPAT)
-               return -EINVAL;
-
        sock = sockfd_lookup_light(fd, &err, &fput_needed);
        if (!sock)
                goto out;
 
-       err = __sys_recvmsg(sock, msg, &msg_sys, flags, 0);
+       err = ___sys_recvmsg(sock, msg, &msg_sys, flags, 0);
 
        fput_light(sock->file, fput_needed);
 out:
        return err;
 }
 
+SYSCALL_DEFINE3(recvmsg, int, fd, struct msghdr __user *, msg,
+               unsigned int, flags)
+{
+       if (flags & MSG_CMSG_COMPAT)
+               return -EINVAL;
+       return __sys_recvmsg(fd, msg, flags);
+}
+
 /*
  *     Linux recvmmsg interface
  */
@@ -2308,17 +2317,18 @@ int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
                 * No need to ask LSM for more than the first datagram.
                 */
                if (MSG_CMSG_COMPAT & flags) {
-                       err = __sys_recvmsg(sock, (struct msghdr __user *)compat_entry,
-                                           &msg_sys, flags & ~MSG_WAITFORONE,
-                                           datagrams);
+                       err = ___sys_recvmsg(sock, (struct msghdr __user *)compat_entry,
+                                            &msg_sys, flags & ~MSG_WAITFORONE,
+                                            datagrams);
                        if (err < 0)
                                break;
                        err = __put_user(err, &compat_entry->msg_len);
                        ++compat_entry;
                } else {
-                       err = __sys_recvmsg(sock, (struct msghdr __user *)entry,
-                                           &msg_sys, flags & ~MSG_WAITFORONE,
-                                           datagrams);
+                       err = ___sys_recvmsg(sock,
+                                            (struct msghdr __user *)entry,
+                                            &msg_sys, flags & ~MSG_WAITFORONE,
+                                            datagrams);
                        if (err < 0)
                                break;
                        err = put_user(err, &entry->msg_len);
@@ -2505,31 +2515,15 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args)
                                   (int __user *)a[4]);
                break;
        case SYS_SENDMSG:
-               if (a[2] & MSG_CMSG_COMPAT) {
-                       err = -EINVAL;
-                       break;
-               }
                err = sys_sendmsg(a0, (struct msghdr __user *)a1, a[2]);
                break;
        case SYS_SENDMMSG:
-               if (a[3] & MSG_CMSG_COMPAT) {
-                       err = -EINVAL;
-                       break;
-               }
                err = sys_sendmmsg(a0, (struct mmsghdr __user *)a1, a[2], a[3]);
                break;
        case SYS_RECVMSG:
-               if (a[2] & MSG_CMSG_COMPAT) {
-                       err = -EINVAL;
-                       break;
-               }
                err = sys_recvmsg(a0, (struct msghdr __user *)a1, a[2]);
                break;
        case SYS_RECVMMSG:
-               if (a[3] & MSG_CMSG_COMPAT) {
-                       err = -EINVAL;
-                       break;
-               }
                err = sys_recvmmsg(a0, (struct mmsghdr __user *)a1, a[2], a[3],
                                   (struct timespec __user *)a[4]);
                break;