netdev - [PATCH 05/18] net/xfrm: Parse userspi_info{,

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Message-Id: <20180726023144.31066-6-dima@arista.com>
Date:   Thu, 26 Jul 2018 03:31:31 +0100
From:   Dmitry Safonov <dima@...sta.com>
To:     linux-kernel@...r.kernel.org
Cc:     Dmitry Safonov <dima@...sta.com>,
        "David S. Miller" <davem@...emloft.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Dmitry Safonov <0x7f454c46@...il.com>, netdev@...r.kernel.org
Subject: [PATCH 05/18] net/xfrm: Parse userspi_info{,_packed} depending on syscall

Struct xfrm_userspi_info differs in size between 64-bit/32-bit UAPI
because of (possible) padding of xfrm_usersa_info:

          32-bit                                   64-bit
----------------------------------------------------------------------
sizeof(xfrm_userspi_info) = 228     |  sizeof(xfrm_userspi_info) = 232
xfrm_userspi_info::info = 0         |  xfrm_userspi_info::info = 0
xfrm_userspi_info::min = 220        |  xfrm_userspi_info::min = 224
xfrm_userspi_info::max = 224        |  xfrm_userspi_info::max = 228

xfrm_alloc_userspi() can handle both UAPI by checking the type of
send() syscall used by userspace with XFRM_MSG_ALLOCSPI.

Cc: "David S. Miller" <davem@...emloft.net>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Steffen Klassert <steffen.klassert@...unet.com>
Cc: netdev@...r.kernel.org
Signed-off-by: Dmitry Safonov <dima@...sta.com>
---
 net/xfrm/xfrm_user.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index b382cdd3bef6..bf2ca93edaf5 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -61,6 +61,12 @@ struct xfrm_userpolicy_info_packed {
 	__u8				share;
 } __packed;
 
+struct xfrm_userspi_info_packed {
+	struct xfrm_usersa_info_packed	info;
+	__u32				min;
+	__u32				max;
+} __packed;
+
 static int verify_one_alg(struct nlattr **attrs, enum xfrm_attr_type_t type)
 {
 	struct nlattr *rt = attrs[type];
@@ -1279,11 +1285,21 @@ static int xfrm_alloc_userspi(struct sk_buff *skb, struct nlmsghdr *nlh,
 	xfrm_address_t *daddr;
 	int family;
 	int err;
-	u32 mark;
+	u32 mark, spi_min, spi_max;
 	struct xfrm_mark m;
 
 	p = nlmsg_data(nlh);
-	err = verify_spi_info(p->info.id.proto, p->min, p->max);
+	if (in_compat_syscall()) {
+		struct xfrm_userspi_info_packed *_p = nlmsg_data(nlh);
+
+		spi_min = _p->min;
+		spi_max = _p->max;
+	} else {
+		spi_min = p->min;
+		spi_max = p->max;
+	}
+
+	err = verify_spi_info(p->info.id.proto, spi_min, spi_max);
 	if (err)
 		goto out_noput;
 
@@ -1310,7 +1326,7 @@ static int xfrm_alloc_userspi(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (x == NULL)
 		goto out_noput;
 
-	err = xfrm_alloc_spi(x, p->min, p->max);
+	err = xfrm_alloc_spi(x, spi_min, spi_max);
 	if (err)
 		goto out;
 
-- 
2.13.6