From: Eric Dumazet <eduma...@google.com>
Two different problems are fixed here :
1) inet_sk_diag_fill() might be called without socket lock held.
icsk->icsk_ca_ops can change under us and module be unloaded.
-> Access to freed memory.
Fix this using rcu_read_lock() to prevent module unload.
2) Some TCP Congestion Control modules provide information
but again this is not safe against icsk->icsk_ca_ops
change and nla_put() errors were ignored. Some sockets
could not get the additional info if skb was almost full.
Fix this by returning a status from get_info() handlers and
using rcu protection as well.
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
include/net/tcp.h | 2 +-
net/ipv4/inet_diag.c | 28 ++++++++++++++++++++++------
net/ipv4/tcp_dctcp.c | 5 +++--
net/ipv4/tcp_illinois.c | 6 +++---
net/ipv4/tcp_vegas.c | 5 +++--
net/ipv4/tcp_vegas.h | 2 +-
net/ipv4/tcp_westwood.c | 6 +++---
7 files changed, 36 insertions(+), 18 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 9598871485ce..051dc5c2802d 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -829,7 +829,7 @@ struct tcp_congestion_ops {
/* hook for packet ack accounting (optional) */
void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
/* get info for inet_diag (optional) */
- void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
+ int (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
char name[TCP_CA_NAME_MAX];
struct module *owner;
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 70e8b3c308ec..bb77ebdae3b3 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -111,6 +111,7 @@ int inet_sk_diag_fill(struct sock *sk, struct
inet_connection_sock *icsk,
const struct nlmsghdr *unlh)
{
const struct inet_sock *inet = inet_sk(sk);
+ const struct tcp_congestion_ops *ca_ops;
const struct inet_diag_handler *handler;
int ext = req->idiag_ext;
struct inet_diag_msg *r;
@@ -208,16 +209,31 @@ int inet_sk_diag_fill(struct sock *sk, struct
inet_connection_sock *icsk,
info = nla_data(attr);
}
- if ((ext & (1 << (INET_DIAG_CONG - 1))) && icsk->icsk_ca_ops)
- if (nla_put_string(skb, INET_DIAG_CONG,
- icsk->icsk_ca_ops->name) < 0)
+ if (ext & (1 << (INET_DIAG_CONG - 1))) {
+ int err = 0;
+
+ rcu_read_lock();
+ ca_ops = READ_ONCE(icsk->icsk_ca_ops);
+ if (ca_ops)
+ err = nla_put_string(skb, INET_DIAG_CONG, ca_ops->name);
+ rcu_read_unlock();
+ if (err < 0)
goto errout;
+ }
handler->idiag_get_info(sk, r, info);
- if (sk->sk_state < TCP_TIME_WAIT &&
- icsk->icsk_ca_ops && icsk->icsk_ca_ops->get_info)
- icsk->icsk_ca_ops->get_info(sk, ext, skb);
+ if (sk->sk_state < TCP_TIME_WAIT) {
+ int err = 0;
+
+ rcu_read_lock();
+ ca_ops = READ_ONCE(icsk->icsk_ca_ops);
+ if (ca_ops && ca_ops->get_info)
+ err = ca_ops->get_info(sk, ext, skb);
+ rcu_read_unlock();
+ if (err < 0)
+ goto errout;
+ }
out:
nlmsg_end(skb, nlh);
diff --git a/net/ipv4/tcp_dctcp.c b/net/ipv4/tcp_dctcp.c
index b504371af742..4376016f7fa5 100644
--- a/net/ipv4/tcp_dctcp.c
+++ b/net/ipv4/tcp_dctcp.c
@@ -277,7 +277,7 @@ static void dctcp_cwnd_event(struct sock *sk, enum
tcp_ca_event ev)
}
}
-static void dctcp_get_info(struct sock *sk, u32 ext, struct sk_buff *skb)
+static int dctcp_get_info(struct sock *sk, u32 ext, struct sk_buff *skb)
{
const struct dctcp *ca = inet_csk_ca(sk);
@@ -297,8 +297,9 @@ static void dctcp_get_info(struct sock *sk, u32 ext, struct
sk_buff *skb)
info.dctcp_ab_tot = ca->acked_bytes_total;
}
- nla_put(skb, INET_DIAG_DCTCPINFO, sizeof(info), &info);
+ return nla_put(skb, INET_DIAG_DCTCPINFO, sizeof(info), &info);
}
+ return 0;
}
static struct tcp_congestion_ops dctcp __read_mostly = {
diff --git a/net/ipv4/tcp_illinois.c b/net/ipv4/tcp_illinois.c
index 1d5a30a90adf..67476f085e48 100644
--- a/net/ipv4/tcp_illinois.c
+++ b/net/ipv4/tcp_illinois.c
@@ -300,8 +300,7 @@ static u32 tcp_illinois_ssthresh(struct sock *sk)
}
/* Extract info for Tcp socket info provided via netlink. */
-static void tcp_illinois_info(struct sock *sk, u32 ext,
- struct sk_buff *skb)
+static int tcp_illinois_info(struct sock *sk, u32 ext, struct sk_buff *skb)
{
const struct illinois *ca = inet_csk_ca(sk);
@@ -318,8 +317,9 @@ static void tcp_illinois_info(struct sock *sk, u32 ext,
do_div(t, info.tcpv_rttcnt);
info.tcpv_rtt = t;
}
- nla_put(skb, INET_DIAG_VEGASINFO, sizeof(info), &info);
+ return nla_put(skb, INET_DIAG_VEGASINFO, sizeof(info), &info);
}
+ return 0;
}
static struct tcp_congestion_ops tcp_illinois __read_mostly = {
diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c
index a6afde666ab1..c71a1b8f7bde 100644
--- a/net/ipv4/tcp_vegas.c
+++ b/net/ipv4/tcp_vegas.c
@@ -286,7 +286,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack,
u32 acked)
}
/* Extract info for Tcp socket info provided via netlink. */
-void tcp_vegas_get_info(struct sock *sk, u32 ext, struct sk_buff *skb)
+int tcp_vegas_get_info(struct sock *sk, u32 ext, struct sk_buff *skb)
{
const struct vegas *ca = inet_csk_ca(sk);
if (ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
@@ -297,8 +297,9 @@ void tcp_vegas_get_info(struct sock *sk, u32 ext, struct
sk_buff *skb)
.tcpv_minrtt = ca->minRTT,
};
- nla_put(skb, INET_DIAG_VEGASINFO, sizeof(info), &info);
+ return nla_put(skb, INET_DIAG_VEGASINFO, sizeof(info), &info);
}
+ return 0;
}
EXPORT_SYMBOL_GPL(tcp_vegas_get_info);
diff --git a/net/ipv4/tcp_vegas.h b/net/ipv4/tcp_vegas.h
index 0531b99d8637..e8a6b33cc61d 100644
--- a/net/ipv4/tcp_vegas.h
+++ b/net/ipv4/tcp_vegas.h
@@ -19,6 +19,6 @@ void tcp_vegas_init(struct sock *sk);
void tcp_vegas_state(struct sock *sk, u8 ca_state);
void tcp_vegas_pkts_acked(struct sock *sk, u32 cnt, s32 rtt_us);
void tcp_vegas_cwnd_event(struct sock *sk, enum tcp_ca_event event);
-void tcp_vegas_get_info(struct sock *sk, u32 ext, struct sk_buff *skb);
+int tcp_vegas_get_info(struct sock *sk, u32 ext, struct sk_buff *skb);
#endif /* __TCP_VEGAS_H */
diff --git a/net/ipv4/tcp_westwood.c b/net/ipv4/tcp_westwood.c
index bb63fba47d47..b3c57cceb990 100644
--- a/net/ipv4/tcp_westwood.c
+++ b/net/ipv4/tcp_westwood.c
@@ -256,8 +256,7 @@ static void tcp_westwood_event(struct sock *sk, enum
tcp_ca_event event)
}
/* Extract info for Tcp socket info provided via netlink. */
-static void tcp_westwood_info(struct sock *sk, u32 ext,
- struct sk_buff *skb)
+static int tcp_westwood_info(struct sock *sk, u32 ext, struct sk_buff *skb)
{
const struct westwood *ca = inet_csk_ca(sk);
@@ -268,8 +267,9 @@ static void tcp_westwood_info(struct sock *sk, u32 ext,
.tcpv_minrtt = jiffies_to_usecs(ca->rtt_min),
};
- nla_put(skb, INET_DIAG_VEGASINFO, sizeof(info), &info);
+ return nla_put(skb, INET_DIAG_VEGASINFO, sizeof(info), &info);
}
+ return 0;
}
static struct tcp_congestion_ops tcp_westwood __read_mostly = {
--
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