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net: Fix security_socket_sendmsg() bypass problem.

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The sendmmsg() introduced by commit 228e548e "net: Add sendmmsg socket system
call" is capable of sending to multiple different destination addresses.

SMACK is using destination's address for checking sendmsg() permission.
However, security_socket_sendmsg() is called for only once even if multiple
different destination addresses are passed to sendmmsg().

Therefore, we need to call security_socket_sendmsg() for each destination
address rather than only the first destination address.

Since calling security_socket_sendmsg() every time when only single destination
address was passed to sendmmsg() is a waste of time, omit calling
security_socket_sendmsg() unless destination address of previous datagram and
that of current datagram differs.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Anton Blanchard <anton@samba.org>
Cc: stable <stable@kernel.org> [3.0+]
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tetsuo Handa 2011-08-04 14:07:40 +00:00 committed by David S. Miller
parent 98382f419f
commit c71d8ebe7a
1 changed files with 34 additions and 9 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

43
net/socket.c
View file

@ -1871,8 +1871,14 @@ SYSCALL_DEFINE2(shutdown, int, fd, int, how)
#define COMPAT_NAMELEN(msg) COMPAT_MSG(msg, msg_namelen) #define COMPAT_NAMELEN(msg) COMPAT_MSG(msg, msg_namelen)
#define COMPAT_FLAGS(msg) COMPAT_MSG(msg, msg_flags) #define COMPAT_FLAGS(msg) COMPAT_MSG(msg, msg_flags)
struct used_address {
struct sockaddr_storage name;
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 flags, int nosec) struct msghdr *msg_sys, unsigned flags,
struct used_address *used_address)
{ {
struct compat_msghdr __user *msg_compat = struct compat_msghdr __user *msg_compat =
(struct compat_msghdr __user *)msg; (struct compat_msghdr __user *)msg;
@ -1953,8 +1959,28 @@ static int __sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
if (sock->file->f_flags & O_NONBLOCK) if (sock->file->f_flags & O_NONBLOCK)
msg_sys->msg_flags |= MSG_DONTWAIT; msg_sys->msg_flags |= MSG_DONTWAIT;
err = (nosec ? sock_sendmsg_nosec : sock_sendmsg)(sock, msg_sys, /*
total_len); * If this is sendmmsg() and current destination address is same as
* previously succeeded address, omit asking LSM's decision.
* used_address->name_len is initialized to UINT_MAX so that the first
* destination address never matches.
*/
if (used_address && used_address->name_len == msg_sys->msg_namelen &&
!memcmp(&used_address->name, msg->msg_name,
used_address->name_len)) {
err = sock_sendmsg_nosec(sock, msg_sys, total_len);
goto out_freectl;
}
err = sock_sendmsg(sock, msg_sys, total_len);
/*
* If this is sendmmsg() and sending to current destination address was
* successful, remember it.
*/
if (used_address && err >= 0) {
used_address->name_len = msg_sys->msg_namelen;
memcpy(&used_address->name, msg->msg_name,
used_address->name_len);
}
out_freectl: out_freectl:
if (ctl_buf != ctl) if (ctl_buf != ctl)
@ -1979,7 +2005,7 @@ SYSCALL_DEFINE3(sendmsg, int, fd, struct msghdr __user *, msg, unsigned, flags)
if (!sock) if (!sock)
goto out; goto out;
err = __sys_sendmsg(sock, msg, &msg_sys, flags, 0); err = __sys_sendmsg(sock, msg, &msg_sys, flags, NULL);
fput_light(sock->file, fput_needed); fput_light(sock->file, fput_needed);
out: out:
@ -1998,6 +2024,7 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
struct mmsghdr __user *entry; struct mmsghdr __user *entry;
struct compat_mmsghdr __user *compat_entry; struct compat_mmsghdr __user *compat_entry;
struct msghdr msg_sys; struct msghdr msg_sys;
struct used_address used_address;
if (vlen > UIO_MAXIOV) if (vlen > UIO_MAXIOV)
vlen = UIO_MAXIOV; vlen = UIO_MAXIOV;
@ -2008,24 +2035,22 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
if (!sock) if (!sock)
return err; return err;
used_address.name_len = UINT_MAX;
entry = mmsg; entry = mmsg;
compat_entry = (struct compat_mmsghdr __user *)mmsg; compat_entry = (struct compat_mmsghdr __user *)mmsg;
err = 0; err = 0;
while (datagrams < vlen) { while (datagrams < vlen) {
/*
* No need to ask LSM for more than the first datagram.
*/
if (MSG_CMSG_COMPAT & flags) { if (MSG_CMSG_COMPAT & flags) {
err = __sys_sendmsg(sock, (struct msghdr __user *)compat_entry, err = __sys_sendmsg(sock, (struct msghdr __user *)compat_entry,
&msg_sys, flags, datagrams); &msg_sys, flags, &used_address);
if (err < 0) if (err < 0)
break; break;
err = __put_user(err, &compat_entry->msg_len); err = __put_user(err, &compat_entry->msg_len);
++compat_entry; ++compat_entry;
} else { } else {
err = __sys_sendmsg(sock, (struct msghdr __user *)entry, err = __sys_sendmsg(sock, (struct msghdr __user *)entry,
&msg_sys, flags, datagrams); &msg_sys, flags, &used_address);
if (err < 0) if (err < 0)
break; break;
err = put_user(err, &entry->msg_len); err = put_user(err, &entry->msg_len);