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Message-ID: <20230217182454.2432057-1-edumazet@google.com>
Date: Fri, 17 Feb 2023 18:24:54 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>,
Kees Cook <keescook@...omium.org>
Subject: [PATCH net-next] scm: add user copy checks to put_cmsg()
This is a followup of commit 2558b8039d05 ("net: use a bounce
buffer for copying skb->mark")
x86 and powerpc define user_access_begin, meaning
that they are not able to perform user copy checks
when using user_write_access_begin() / unsafe_copy_to_user()
and friends [1]
Instead of waiting bugs to trigger on other arches,
add a check_object_size() in put_cmsg() to make sure
that new code tested on x86 with CONFIG_HARDENED_USERCOPY=y
will perform more security checks.
[1] We can not generically call check_object_size() from
unsafe_copy_to_user() because UACCESS is enabled at this point.
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Kees Cook <keescook@...omium.org>
---
net/core/scm.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/core/scm.c b/net/core/scm.c
index 5c356f0dee30c3edaa57b49176cce021d5248cd7..acb7d776fa6ec29cdd9ae7d3a9970384c887ac75 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -229,6 +229,8 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data)
if (msg->msg_control_is_user) {
struct cmsghdr __user *cm = msg->msg_control_user;
+ check_object_size(data, cmlen - sizeof(*cm), true);
+
if (!user_write_access_begin(cm, cmlen))
goto efault;
--
2.39.2.637.g21b0678d19-goog
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