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* [PATCH] scm: remove use CMSG{_COMPAT}_ALIGN(sizeof(struct {compat_}cmsghdr))
@ 2017-01-03 12:42 yuan linyu
  2017-01-04 18:24 ` David Miller
  0 siblings, 1 reply; 3+ messages in thread
From: yuan linyu @ 2017-01-03 12:42 UTC (permalink / raw)
  To: netdev; +Cc: David S . Miller, yuan linyu

From: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>

sizeof(struct cmsghdr) and sizeof(struct compat_cmsghdr) already aligned.
remove use CMSG_ALIGN(sizeof(struct cmsghdr)) and
CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)) keep code consistent.

Signed-off-by: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
---
 include/linux/socket.h |  6 +++---
 net/compat.c           | 14 ++++++--------
 net/core/scm.c         |  2 +-
 net/ipv4/ip_sockglue.c |  2 +-
 net/rxrpc/sendmsg.c    |  2 +-
 5 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/include/linux/socket.h b/include/linux/socket.h
index b5cc5a6..c064380 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -92,9 +92,9 @@ struct cmsghdr {
 
 #define CMSG_ALIGN(len) ( ((len)+sizeof(long)-1) & ~(sizeof(long)-1) )
 
-#define CMSG_DATA(cmsg)	((void *)((char *)(cmsg) + CMSG_ALIGN(sizeof(struct cmsghdr))))
-#define CMSG_SPACE(len) (CMSG_ALIGN(sizeof(struct cmsghdr)) + CMSG_ALIGN(len))
-#define CMSG_LEN(len) (CMSG_ALIGN(sizeof(struct cmsghdr)) + (len))
+#define CMSG_DATA(cmsg)	((void *)((char *)(cmsg) + sizeof(struct cmsghdr)))
+#define CMSG_SPACE(len) (sizeof(struct cmsghdr) + CMSG_ALIGN(len))
+#define CMSG_LEN(len) (sizeof(struct cmsghdr) + (len))
 
 #define __CMSG_FIRSTHDR(ctl,len) ((len) >= sizeof(struct cmsghdr) ? \
 				  (struct cmsghdr *)(ctl) : \
diff --git a/net/compat.c b/net/compat.c
index 96c544b..4e27dd1 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -90,11 +90,11 @@ int get_compat_msghdr(struct msghdr *kmsg,
 #define CMSG_COMPAT_ALIGN(len)	ALIGN((len), sizeof(s32))
 
 #define CMSG_COMPAT_DATA(cmsg)				\
-	((void __user *)((char __user *)(cmsg) + CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr))))
+	((void __user *)((char __user *)(cmsg) + sizeof(struct compat_cmsghdr)))
 #define CMSG_COMPAT_SPACE(len)				\
-	(CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)) + CMSG_COMPAT_ALIGN(len))
+	(sizeof(struct compat_cmsghdr) + CMSG_COMPAT_ALIGN(len))
 #define CMSG_COMPAT_LEN(len)				\
-	(CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)) + (len))
+	(sizeof(struct compat_cmsghdr) + (len))
 
 #define CMSG_COMPAT_FIRSTHDR(msg)			\
 	(((msg)->msg_controllen) >= sizeof(struct compat_cmsghdr) ?	\
@@ -141,8 +141,7 @@ int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg, struct sock *sk,
 		if (!CMSG_COMPAT_OK(ucmlen, ucmsg, kmsg))
 			return -EINVAL;
 
-		tmp = ((ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg))) +
-		       CMSG_ALIGN(sizeof(struct cmsghdr)));
+		tmp = ((ucmlen - sizeof(*ucmsg)) + sizeof(struct cmsghdr));
 		tmp = CMSG_ALIGN(tmp);
 		kcmlen += tmp;
 		ucmsg = cmsg_compat_nxthdr(kmsg, ucmsg, ucmlen);
@@ -168,8 +167,7 @@ int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg, struct sock *sk,
 			goto Efault;
 		if (!CMSG_COMPAT_OK(ucmlen, ucmsg, kmsg))
 			goto Einval;
-		tmp = ((ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg))) +
-		       CMSG_ALIGN(sizeof(struct cmsghdr)));
+		tmp = ((ucmlen - sizeof(*ucmsg)) + sizeof(struct cmsghdr));
 		if ((char *)kcmsg_base + kcmlen - (char *)kcmsg < CMSG_ALIGN(tmp))
 			goto Einval;
 		kcmsg->cmsg_len = tmp;
@@ -178,7 +176,7 @@ int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg, struct sock *sk,
 		    __get_user(kcmsg->cmsg_type, &ucmsg->cmsg_type) ||
 		    copy_from_user(CMSG_DATA(kcmsg),
 				   CMSG_COMPAT_DATA(ucmsg),
-				   (ucmlen - CMSG_COMPAT_ALIGN(sizeof(*ucmsg)))))
+				   (ucmlen - sizeof(*ucmsg))))
 			goto Efault;
 
 		/* Advance. */
diff --git a/net/core/scm.c b/net/core/scm.c
index d882043..b6d8368 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -71,7 +71,7 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
 	struct file **fpp;
 	int i, num;
 
-	num = (cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr)))/sizeof(int);
+	num = (cmsg->cmsg_len - sizeof(struct cmsghdr))/sizeof(int);
 
 	if (num <= 0)
 		return 0;
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 53ae0c6..c77e65e 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -272,7 +272,7 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc,
 			continue;
 		switch (cmsg->cmsg_type) {
 		case IP_RETOPTS:
-			err = cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr));
+			err = cmsg->cmsg_len - sizeof(struct cmsghdr);
 
 			/* Our caller is responsible for freeing ipc->opt */
 			err = ip_options_get(net, &ipc->opt, CMSG_DATA(cmsg),
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index b214a4d..0a6ef21 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -376,7 +376,7 @@ static int rxrpc_sendmsg_cmsg(struct msghdr *msg,
 		if (!CMSG_OK(msg, cmsg))
 			return -EINVAL;
 
-		len = cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr));
+		len = cmsg->cmsg_len - sizeof(struct cmsghdr);
 		_debug("CMSG %d, %d, %d",
 		       cmsg->cmsg_level, cmsg->cmsg_type, len);
 
-- 
2.7.4

^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] scm: remove use CMSG{_COMPAT}_ALIGN(sizeof(struct {compat_}cmsghdr))
  2017-01-03 12:42 [PATCH] scm: remove use CMSG{_COMPAT}_ALIGN(sizeof(struct {compat_}cmsghdr)) yuan linyu
@ 2017-01-04 18:24 ` David Miller
  2017-01-04 23:45   ` YUAN Linyu
  0 siblings, 1 reply; 3+ messages in thread
From: David Miller @ 2017-01-04 18:24 UTC (permalink / raw)
  To: cugyly; +Cc: netdev, Linyu.Yuan

From: yuan linyu <cugyly@163.com>
Date: Tue,  3 Jan 2017 20:42:17 +0800

> From: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
> 
> sizeof(struct cmsghdr) and sizeof(struct compat_cmsghdr) already aligned.
> remove use CMSG_ALIGN(sizeof(struct cmsghdr)) and
> CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)) keep code consistent.
> 
> Signed-off-by: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>

Applied, and I added the following commit which will make sure our
analysis is accurate.

====================
[PATCH] net: Assert at build time the assumptions we make about the CMSG header.

It must always be the case that CMSG_ALIGN(sizeof(hdr)) == sizeof(hdr).

Otherwise there are missing adjustments in the various calculations
that parse and build these things.

Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/compat.c | 3 +++
 net/socket.c | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/net/compat.c b/net/compat.c
index 4e27dd1..ba3ac72 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -130,6 +130,9 @@ int cmsghdr_from_user_compat_to_kern(struct msghdr *kmsg, struct sock *sk,
 	__kernel_size_t kcmlen, tmp;
 	int err = -EFAULT;
 
+	BUILD_BUG_ON(sizeof(struct compat_cmsghdr) !=
+		     CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)));
+
 	kcmlen = 0;
 	kcmsg_base = kcmsg = (struct cmsghdr *)stackbuf;
 	ucmsg = CMSG_COMPAT_FIRSTHDR(kmsg);
diff --git a/net/socket.c b/net/socket.c
index 8487bf1..5f3b5a2 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1948,6 +1948,8 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg,
 		ctl_buf = msg_sys->msg_control;
 		ctl_len = msg_sys->msg_controllen;
 	} else if (ctl_len) {
+		BUILD_BUG_ON(sizeof(struct cmsghdr) !=
+			     CMSG_ALIGN(sizeof(struct cmsghdr)));
 		if (ctl_len > sizeof(ctl)) {
 			ctl_buf = sock_kmalloc(sock->sk, ctl_len, GFP_KERNEL);
 			if (ctl_buf == NULL)
-- 
2.4.11

^ permalink raw reply related	[flat|nested] 3+ messages in thread
* RE: [PATCH] scm: remove use CMSG{_COMPAT}_ALIGN(sizeof(struct {compat_}cmsghdr))
  2017-01-04 18:24 ` David Miller
@ 2017-01-04 23:45   ` YUAN Linyu
  0 siblings, 0 replies; 3+ messages in thread
From: YUAN Linyu @ 2017-01-04 23:45 UTC (permalink / raw)
  To: David Miller, cugyly; +Cc: netdev

Thanks

> -----Original Message-----
> From: David Miller [mailto:davem@davemloft.net]
> Sent: Thursday, January 05, 2017 2:25 AM
> To: cugyly@163.com
> Cc: netdev@vger.kernel.org; YUAN Linyu
> Subject: Re: [PATCH] scm: remove use CMSG{_COMPAT}_ALIGN(sizeof(struct
> {compat_}cmsghdr))
> 
> From: yuan linyu <cugyly@163.com>
> Date: Tue,  3 Jan 2017 20:42:17 +0800
> 
> > From: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
> >
> > sizeof(struct cmsghdr) and sizeof(struct compat_cmsghdr) already aligned.
> > remove use CMSG_ALIGN(sizeof(struct cmsghdr)) and
> > CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)) keep code
> consistent.
> >
> > Signed-off-by: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn>
> 
> Applied, and I added the following commit which will make sure our
> analysis is accurate.
> 
> ====================
> [PATCH] net: Assert at build time the assumptions we make about the CMSG
> header.
> 
> It must always be the case that CMSG_ALIGN(sizeof(hdr)) == sizeof(hdr).
> 
> Otherwise there are missing adjustments in the various calculations
> that parse and build these things.
> 
> Signed-off-by: David S. Miller <davem@davemloft.net>
> ---
>  net/compat.c | 3 +++
>  net/socket.c | 2 ++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/net/compat.c b/net/compat.c
> index 4e27dd1..ba3ac72 100644
> --- a/net/compat.c
> +++ b/net/compat.c
> @@ -130,6 +130,9 @@ int cmsghdr_from_user_compat_to_kern(struct
> msghdr *kmsg, struct sock *sk,
>  	__kernel_size_t kcmlen, tmp;
>  	int err = -EFAULT;
> 
> +	BUILD_BUG_ON(sizeof(struct compat_cmsghdr) !=
> +		     CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)));
> +
>  	kcmlen = 0;
>  	kcmsg_base = kcmsg = (struct cmsghdr *)stackbuf;
>  	ucmsg = CMSG_COMPAT_FIRSTHDR(kmsg);
> diff --git a/net/socket.c b/net/socket.c
> index 8487bf1..5f3b5a2 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -1948,6 +1948,8 @@ static int ___sys_sendmsg(struct socket *sock,
> struct user_msghdr __user *msg,
>  		ctl_buf = msg_sys->msg_control;
>  		ctl_len = msg_sys->msg_controllen;
>  	} else if (ctl_len) {
> +		BUILD_BUG_ON(sizeof(struct cmsghdr) !=
> +			     CMSG_ALIGN(sizeof(struct cmsghdr)));
>  		if (ctl_len > sizeof(ctl)) {
>  			ctl_buf = sock_kmalloc(sock->sk, ctl_len, GFP_KERNEL);
>  			if (ctl_buf == NULL)
> --
> 2.4.11

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-01-04 23:45 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2017-01-03 12:42 [PATCH] scm: remove use CMSG{_COMPAT}_ALIGN(sizeof(struct {compat_}cmsghdr)) yuan linyu
2017-01-04 18:24 ` David Miller
2017-01-04 23:45   ` YUAN Linyu

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