[PATCH] socket: move compat timeout handling into sock.c

From: Arnd Bergmann
Date: Tue Jan 08 2019 - 15:10:34 EST


This is a cleanup to prepare for the addition of 64-bit time_t
in O_SNDTIMEO/O_RCVTIMEO. The existing compat handler seems
unnecessarily complex and error-prone, moving it all into the
main setsockopt()/getsockopt() implementation requires half
as much code and is easier to extend.

32-bit user space can now use old_timeval32 on both 32-bit
and 64-bit machines, while 64-bit code can use
__old_kernel_timeval.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
net/compat.c | 66 +------------------------------------------------
net/core/sock.c | 65 +++++++++++++++++++++++++++++++-----------------
2 files changed, 44 insertions(+), 87 deletions(-)

diff --git a/net/compat.c b/net/compat.c
index 959d1c51826d..ce8f6e8cdcd2 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -348,28 +348,6 @@ static int do_set_attach_filter(struct socket *sock, int level, int optname,
sizeof(struct sock_fprog));
}

-static int do_set_sock_timeout(struct socket *sock, int level,
- int optname, char __user *optval, unsigned int optlen)
-{
- struct compat_timeval __user *up = (struct compat_timeval __user *)optval;
- struct timeval ktime;
- mm_segment_t old_fs;
- int err;
-
- if (optlen < sizeof(*up))
- return -EINVAL;
- if (!access_ok(up, sizeof(*up)) ||
- __get_user(ktime.tv_sec, &up->tv_sec) ||
- __get_user(ktime.tv_usec, &up->tv_usec))
- return -EFAULT;
- old_fs = get_fs();
- set_fs(KERNEL_DS);
- err = sock_setsockopt(sock, level, optname, (char *)&ktime, sizeof(ktime));
- set_fs(old_fs);
-
- return err;
-}
-
static int compat_sock_setsockopt(struct socket *sock, int level, int optname,
char __user *optval, unsigned int optlen)
{
@@ -377,10 +355,6 @@ static int compat_sock_setsockopt(struct socket *sock, int level, int optname,
optname == SO_ATTACH_REUSEPORT_CBPF)
return do_set_attach_filter(sock, level, optname,
optval, optlen);
- if (!COMPAT_USE_64BIT_TIME &&
- (optname == SO_RCVTIMEO || optname == SO_SNDTIMEO))
- return do_set_sock_timeout(sock, level, optname, optval, optlen);
-
return sock_setsockopt(sock, level, optname, optval, optlen);
}

@@ -417,44 +391,6 @@ COMPAT_SYSCALL_DEFINE5(setsockopt, int, fd, int, level, int, optname,
return __compat_sys_setsockopt(fd, level, optname, optval, optlen);
}

-static int do_get_sock_timeout(struct socket *sock, int level, int optname,
- char __user *optval, int __user *optlen)
-{
- struct compat_timeval __user *up;
- struct timeval ktime;
- mm_segment_t old_fs;
- int len, err;
-
- up = (struct compat_timeval __user *) optval;
- if (get_user(len, optlen))
- return -EFAULT;
- if (len < sizeof(*up))
- return -EINVAL;
- len = sizeof(ktime);
- old_fs = get_fs();
- set_fs(KERNEL_DS);
- err = sock_getsockopt(sock, level, optname, (char *) &ktime, &len);
- set_fs(old_fs);
-
- if (!err) {
- if (put_user(sizeof(*up), optlen) ||
- !access_ok(up, sizeof(*up)) ||
- __put_user(ktime.tv_sec, &up->tv_sec) ||
- __put_user(ktime.tv_usec, &up->tv_usec))
- err = -EFAULT;
- }
- return err;
-}
-
-static int compat_sock_getsockopt(struct socket *sock, int level, int optname,
- char __user *optval, int __user *optlen)
-{
- if (!COMPAT_USE_64BIT_TIME &&
- (optname == SO_RCVTIMEO || optname == SO_SNDTIMEO))
- return do_get_sock_timeout(sock, level, optname, optval, optlen);
- return sock_getsockopt(sock, level, optname, optval, optlen);
-}
-
int compat_sock_get_timestamp(struct sock *sk, struct timeval __user *userstamp)
{
struct compat_timeval __user *ctv;
@@ -527,7 +463,7 @@ static int __compat_sys_getsockopt(int fd, int level, int optname,
}

if (level == SOL_SOCKET)
- err = compat_sock_getsockopt(sock, level,
+ err = sock_getsockopt(sock, level,
optname, optval, optlen);
else if (sock->ops->compat_getsockopt)
err = sock->ops->compat_getsockopt(sock, level,
diff --git a/net/core/sock.c b/net/core/sock.c
index 6aa2e7e0b4fb..e50b9a2abc92 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -335,14 +335,48 @@ int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
}
EXPORT_SYMBOL(__sk_backlog_rcv);

+static int sock_get_timeout(long timeo, void *optval)
+{
+ struct __kernel_old_timeval tv;
+
+ if (timeo == MAX_SCHEDULE_TIMEOUT) {
+ tv.tv_sec = 0;
+ tv.tv_usec = 0;
+ } else {
+ tv.tv_sec = timeo / HZ;
+ tv.tv_usec = ((timeo % HZ) * USEC_PER_SEC) / HZ;
+ }
+
+ if (in_compat_syscall() && !COMPAT_USE_64BIT_TIME) {
+ struct old_timeval32 tv32 = { tv.tv_sec, tv.tv_usec };
+ *(struct old_timeval32 *)optval = tv32;
+ return sizeof(tv32);
+ }
+
+ *(struct __kernel_old_timeval *)optval = tv;
+ return sizeof(tv);
+}
+
static int sock_set_timeout(long *timeo_p, char __user *optval, int optlen)
{
- struct timeval tv;
+ struct __kernel_old_timeval tv;

- if (optlen < sizeof(tv))
- return -EINVAL;
- if (copy_from_user(&tv, optval, sizeof(tv)))
- return -EFAULT;
+ if (in_compat_syscall() && !COMPAT_USE_64BIT_TIME) {
+ struct old_timeval32 tv32;
+
+ if (optlen < sizeof(tv32))
+ return -EINVAL;
+
+ if (copy_from_user(&tv, optval, sizeof(tv)))
+ return -EFAULT;
+ tv.tv_sec = tv32.tv_sec;
+ tv.tv_usec = tv32.tv_usec;
+ } else {
+ if (optlen < sizeof(tv))
+ return -EINVAL;
+ if (copy_from_user(&tv, optval, sizeof(tv)))
+ return -EFAULT;
+ }
if (tv.tv_usec < 0 || tv.tv_usec >= USEC_PER_SEC)
return -EDOM;

@@ -1099,7 +1133,8 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
int val;
u64 val64;
struct linger ling;
- struct timeval tm;
+ struct old_timeval32 tm32;
+ struct __kernel_old_timeval tm;
struct sock_txtime txtime;
} v;

@@ -1200,25 +1235,11 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
break;

case SO_RCVTIMEO:
- lv = sizeof(struct timeval);
- if (sk->sk_rcvtimeo == MAX_SCHEDULE_TIMEOUT) {
- v.tm.tv_sec = 0;
- v.tm.tv_usec = 0;
- } else {
- v.tm.tv_sec = sk->sk_rcvtimeo / HZ;
- v.tm.tv_usec = ((sk->sk_rcvtimeo % HZ) * USEC_PER_SEC) / HZ;
- }
+ lv = sock_get_timeout(sk->sk_rcvtimeo, optval);
break;

case SO_SNDTIMEO:
- lv = sizeof(struct timeval);
- if (sk->sk_sndtimeo == MAX_SCHEDULE_TIMEOUT) {
- v.tm.tv_sec = 0;
- v.tm.tv_usec = 0;
- } else {
- v.tm.tv_sec = sk->sk_sndtimeo / HZ;
- v.tm.tv_usec = ((sk->sk_sndtimeo % HZ) * USEC_PER_SEC) / HZ;
- }
+ lv = sock_get_timeout(sk->sk_sndtimeo, optval);
break;

case SO_RCVLOWAT:
--
2.20.0