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Date: Wed, 25 Apr 2012 16:35:53 +0400
From: Pavel Emelyanov <xemul@...allels.com>
To: David Miller <davem@...emloft.net>,
Linux Netdev List <netdev@...r.kernel.org>
Subject: [PATCH] tcp repair: Fix unaligned access when repairing options
Don't pick __u8/__u16 values directly from raw pointers, but instead use
an array of structures of code:value pairs. This is OK, since the buffer
we take options from is not an skb memory, but a user-to-kernel one.
For those options which don't require any value now, require this to be
zero (for potential future extension of this API).
Signed-off-by: Pavel Emelyanov <xemul@...allels.com>
---
include/linux/tcp.h | 5 ++++
net/ipv4/tcp.c | 60 +++++++++++++++++---------------------------------
2 files changed, 26 insertions(+), 39 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 9865936..d0401d9 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -111,6 +111,11 @@ enum {
#define TCP_QUEUE_SEQ 21
#define TCP_REPAIR_OPTIONS 22
+struct tcp_repair_opt {
+ __u8 opt_code;
+ __u16 opt_val;
+};
+
enum {
TCP_NO_QUEUE,
TCP_RECV_QUEUE,
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index de6a238..9670af3 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2283,60 +2283,40 @@ static inline int tcp_can_repair_sock(struct sock *sk)
((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_ESTABLISHED));
}
-static int tcp_repair_options_est(struct tcp_sock *tp, char __user *optbuf, unsigned int len)
+static int tcp_repair_options_est(struct tcp_sock *tp,
+ struct tcp_repair_opt __user *optbuf, unsigned int len)
{
- /*
- * Options are stored in CODE:VALUE form where CODE is 8bit and VALUE
- * fits the respective TCPOLEN_ size
- */
+ struct tcp_repair_opt opt;
- while (len > 0) {
- u8 opcode;
-
- if (get_user(opcode, optbuf))
+ while (len >= sizeof(opt)) {
+ if (copy_from_user(&opt, optbuf, sizeof(opt)))
return -EFAULT;
optbuf++;
- len--;
-
- switch (opcode) {
- case TCPOPT_MSS: {
- u16 in_mss;
+ len -= sizeof(opt);
- if (len < sizeof(in_mss))
- return -ENODATA;
- if (get_user(in_mss, optbuf))
- return -EFAULT;
-
- tp->rx_opt.mss_clamp = in_mss;
-
- optbuf += sizeof(in_mss);
- len -= sizeof(in_mss);
+ switch (opt.opt_code) {
+ case TCPOPT_MSS:
+ tp->rx_opt.mss_clamp = opt.opt_val;
break;
- }
- case TCPOPT_WINDOW: {
- u8 wscale;
-
- if (len < sizeof(wscale))
- return -ENODATA;
- if (get_user(wscale, optbuf))
- return -EFAULT;
-
- if (wscale > 14)
+ case TCPOPT_WINDOW:
+ if (opt.opt_val > 14)
return -EFBIG;
- tp->rx_opt.snd_wscale = wscale;
-
- optbuf += sizeof(wscale);
- len -= sizeof(wscale);
+ tp->rx_opt.snd_wscale = opt.opt_val;
break;
- }
case TCPOPT_SACK_PERM:
+ if (opt.opt_val != 0)
+ return -EINVAL;
+
tp->rx_opt.sack_ok |= TCP_SACK_SEEN;
if (sysctl_tcp_fack)
tcp_enable_fack(tp);
break;
case TCPOPT_TIMESTAMP:
+ if (opt.opt_val != 0)
+ return -EINVAL;
+
tp->rx_opt.tstamp_ok = 1;
break;
}
@@ -2557,7 +2537,9 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
if (!tp->repair)
err = -EINVAL;
else if (sk->sk_state == TCP_ESTABLISHED)
- err = tcp_repair_options_est(tp, optval, optlen);
+ err = tcp_repair_options_est(tp,
+ (struct tcp_repair_opt __user *)optval,
+ optlen);
else
err = -EPERM;
break;
--
1.5.5.6
--
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