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Date: Sun, 26 Nov 2023 01:56:16 +0530
From: Siddh Raman Pant <code@...dh.me>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] nfc: Extract nfc_dev access from nfc_alloc_send_skb() into the callers
The only reason why nfc_dev was accessed inside nfc_alloc_send_skb() is
for getting the headroom and tailroom values.
This can cause UAF to be reported from nfc_alloc_send_skb(), but the
callers are responsible for managing the device access, and thus the
UAF being reported, as the callers (like nfc_llcp_send_ui_frame()) may
repeatedly call this function, and this function will repeatedly try
to get the same headroom and tailroom values.
Thus, put the nfc_dev access responsibility on the callers and accept
the headroom and tailroom values directly.
Signed-off-by: Siddh Raman Pant <code@...dh.me>
---
include/net/nfc/nfc.h | 6 +++---
net/nfc/core.c | 14 +++++++-------
net/nfc/llcp_commands.c | 20 ++++++++++++++------
net/nfc/rawsock.c | 8 ++++++--
4 files changed, 30 insertions(+), 18 deletions(-)
diff --git a/include/net/nfc/nfc.h b/include/net/nfc/nfc.h
index 5dee575fbe86..efe20a9a8499 100644
--- a/include/net/nfc/nfc.h
+++ b/include/net/nfc/nfc.h
@@ -260,9 +260,9 @@ static inline const char *nfc_device_name(const struct nfc_dev *dev)
return dev_name(&dev->dev);
}
-struct sk_buff *nfc_alloc_send_skb(struct nfc_dev *dev, struct sock *sk,
- unsigned int flags, unsigned int size,
- unsigned int *err);
+struct sk_buff *nfc_alloc_send_skb(struct sock *sk, unsigned int flags,
+ unsigned int size, int headroom,
+ int tailroom, unsigned int *err);
struct sk_buff *nfc_alloc_recv_skb(unsigned int size, gfp_t gfp);
int nfc_set_remote_general_bytes(struct nfc_dev *dev,
diff --git a/net/nfc/core.c b/net/nfc/core.c
index eb2c0959e5b6..1f7d20971f6f 100644
--- a/net/nfc/core.c
+++ b/net/nfc/core.c
@@ -705,25 +705,25 @@ EXPORT_SYMBOL(nfc_tm_deactivated);
/**
* nfc_alloc_send_skb - allocate a skb for data exchange responses
*
- * @dev: device sending the response
* @sk: socket sending the response
* @flags: MSG_DONTWAIT flag
* @size: size to allocate
+ * @headroom: Extra headroom, in addition to size
+ * @tailroom: Extra tailroom, in addition to size
* @err: pointer to memory to store the error code
*/
-struct sk_buff *nfc_alloc_send_skb(struct nfc_dev *dev, struct sock *sk,
- unsigned int flags, unsigned int size,
- unsigned int *err)
+struct sk_buff *nfc_alloc_send_skb(struct sock *sk, unsigned int flags,
+ unsigned int size, int headroom,
+ int tailroom, unsigned int *err)
{
struct sk_buff *skb;
unsigned int total_size;
- total_size = size +
- dev->tx_headroom + dev->tx_tailroom + NFC_HEADER_SIZE;
+ total_size = size + headroom + tailroom + NFC_HEADER_SIZE;
skb = sock_alloc_send_skb(sk, total_size, flags & MSG_DONTWAIT, err);
if (skb)
- skb_reserve(skb, dev->tx_headroom + NFC_HEADER_SIZE);
+ skb_reserve(skb, headroom + NFC_HEADER_SIZE);
return skb;
}
diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c
index e2680a3bef79..39c7c59bbf66 100644
--- a/net/nfc/llcp_commands.c
+++ b/net/nfc/llcp_commands.c
@@ -314,13 +314,17 @@ static struct sk_buff *llcp_allocate_pdu(struct nfc_llcp_sock *sock,
u8 cmd, u16 size)
{
struct sk_buff *skb;
- int err;
+ int err, headroom, tailroom;
if (sock->ssap == 0)
return NULL;
- skb = nfc_alloc_send_skb(sock->dev, &sock->sk, MSG_DONTWAIT,
- size + LLCP_HEADER_SIZE, &err);
+ headroom = sock->dev->tx_headroom;
+ tailroom = sock->dev->tx_tailroom;
+
+ skb = nfc_alloc_send_skb(&sock->sk, MSG_DONTWAIT,
+ size + LLCP_HEADER_SIZE, headroom, tailroom,
+ &err);
if (skb == NULL) {
pr_err("Could not allocate PDU\n");
return NULL;
@@ -734,7 +738,7 @@ int nfc_llcp_send_ui_frame(struct nfc_llcp_sock *sock, u8 ssap, u8 dsap,
size_t frag_len = 0, remaining_len;
u8 *msg_ptr, *msg_data;
u16 remote_miu;
- int err;
+ int err, headroom, tailroom;
pr_debug("Send UI frame len %zd\n", len);
@@ -751,6 +755,9 @@ int nfc_llcp_send_ui_frame(struct nfc_llcp_sock *sock, u8 ssap, u8 dsap,
return -EFAULT;
}
+ headroom = sock->dev->tx_headroom;
+ tailroom = sock->dev->tx_tailroom;
+
remaining_len = len;
msg_ptr = msg_data;
@@ -763,8 +770,9 @@ int nfc_llcp_send_ui_frame(struct nfc_llcp_sock *sock, u8 ssap, u8 dsap,
pr_debug("Fragment %zd bytes remaining %zd",
frag_len, remaining_len);
- pdu = nfc_alloc_send_skb(sock->dev, &sock->sk, 0,
- frag_len + LLCP_HEADER_SIZE, &err);
+ pdu = nfc_alloc_send_skb(&sock->sk, 0,
+ frag_len + LLCP_HEADER_SIZE,
+ headroom, tailroom, &err);
if (pdu == NULL) {
pr_err("Could not allocate PDU (error=%d)\n", err);
len -= remaining_len;
diff --git a/net/nfc/rawsock.c b/net/nfc/rawsock.c
index 5125392bb68e..fab1facb7105 100644
--- a/net/nfc/rawsock.c
+++ b/net/nfc/rawsock.c
@@ -207,7 +207,7 @@ static int rawsock_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
struct sock *sk = sock->sk;
struct nfc_dev *dev = nfc_rawsock(sk)->dev;
struct sk_buff *skb;
- int rc;
+ int rc, headroom, tailroom;
pr_debug("sock=%p sk=%p len=%zu\n", sock, sk, len);
@@ -217,7 +217,11 @@ static int rawsock_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
if (sock->state != SS_CONNECTED)
return -ENOTCONN;
- skb = nfc_alloc_send_skb(dev, sk, msg->msg_flags, len, &rc);
+ headroom = dev->tx_headroom;
+ tailroom = dev->tx_tailroom;
+
+ skb = nfc_alloc_send_skb(sk, msg->msg_flags, len, headroom, tailroom,
+ &rc);
if (skb == NULL)
return rc;
--
2.42.0
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