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net: Unbreak compat_sys_{send,recv}msg
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I broke them in this commit:

    commit 1be374a
    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>
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Andy Lutomirski authored and David S. Miller committed Jun 6, 2013
1 parent 4d3797d commit a7526eb
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Showing 3 changed files with 47 additions and 41 deletions.
3 changes: 3 additions & 0 deletions include/linux/socket.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down
13 changes: 11 additions & 2 deletions net/compat.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand All @@ -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,
Expand Down
72 changes: 33 additions & 39 deletions net/socket.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
{
Expand Down Expand Up @@ -2071,26 +2071,30 @@ static int __sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
* 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
*/
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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 =
Expand Down Expand Up @@ -2250,27 +2255,31 @@ static int __sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
* 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
*/
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
Expand Down

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