From: Christoph Hellwig <hch@lst.de>
To: "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/3] net: add a CMSG_USER_DATA macro
Date: Mon, 11 May 2020 13:59:11 +0200 [thread overview]
Message-ID: <20200511115913.1420836-2-hch@lst.de> (raw)
In-Reply-To: <20200511115913.1420836-1-hch@lst.de>
Add a variant of CMSG_DATA that operates on user pointer to avoid
sparse warnings about casting to/from user pointers. Also fix up
CMSG_DATA to rely on the gcc extension that allows void pointer
arithmetics to cut down on the amount of casts.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
include/linux/socket.h | 5 ++++-
net/core/scm.c | 4 ++--
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 54338fac45cb7..4cc64d611cf49 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -94,7 +94,10 @@ struct cmsghdr {
#define CMSG_ALIGN(len) ( ((len)+sizeof(long)-1) & ~(sizeof(long)-1) )
-#define CMSG_DATA(cmsg) ((void *)((char *)(cmsg) + sizeof(struct cmsghdr)))
+#define CMSG_DATA(cmsg) \
+ ((void *)(cmsg) + sizeof(struct cmsghdr))
+#define CMSG_USER_DATA(cmsg) \
+ ((void __user *)(cmsg) + sizeof(struct cmsghdr))
#define CMSG_SPACE(len) (sizeof(struct cmsghdr) + CMSG_ALIGN(len))
#define CMSG_LEN(len) (sizeof(struct cmsghdr) + (len))
diff --git a/net/core/scm.c b/net/core/scm.c
index dc6fed1f221c4..abfdc85a64c1b 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -236,7 +236,7 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
err = -EFAULT;
if (copy_to_user(cm, &cmhdr, sizeof cmhdr))
goto out;
- if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr)))
+ if (copy_to_user(CMSG_USER_DATA(cm), data, cmlen - sizeof(*cm)))
goto out;
cmlen = CMSG_SPACE(len);
if (msg->msg_controllen < cmlen)
@@ -300,7 +300,7 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
if (fdnum < fdmax)
fdmax = fdnum;
- for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
+ for (i=0, cmfptr =(int __user *)CMSG_USER_DATA(cm); i<fdmax;
i++, cmfptr++)
{
struct socket *sock;
--
2.26.2
next prev parent reply other threads:[~2020-05-11 11:59 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-11 11:59 improve msg_control kernel vs user pointer handling Christoph Hellwig
2020-05-11 11:59 ` Christoph Hellwig [this message]
2020-05-12 8:28 ` [PATCH 1/3] net: add a CMSG_USER_DATA macro Sergei Shtylyov
2020-05-13 6:03 ` Christoph Hellwig
2020-05-11 11:59 ` [PATCH 2/3] net/scm: cleanup scm_detach_fds Christoph Hellwig
2020-05-13 9:29 ` Ido Schimmel
2020-05-13 9:49 ` Christoph Hellwig
2020-05-13 9:58 ` Ido Schimmel
2020-05-13 10:10 ` Christoph Hellwig
2020-05-13 10:17 ` Christoph Hellwig
2020-05-13 10:31 ` Ido Schimmel
2020-05-11 11:59 ` [PATCH 3/3] net: cleanly handle kernel vs user buffers for ->msg_control Christoph Hellwig
2020-05-13 15:41 ` Eric Dumazet
2020-05-13 16:09 ` Christoph Hellwig
2020-05-13 16:18 ` Eric Dumazet
2020-05-13 16:58 ` Christoph Hellwig
2020-05-12 0:00 ` improve msg_control kernel vs user pointer handling David Miller
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