inet: add RCU protection to inet->opt
We lack proper synchronization to manipulate inet->opt ip_options
Problem is ip_make_skb() calls ip_setup_cork() and
ip_setup_cork() possibly makes a copy of ipc->opt (struct ip_options),
without any protection against another thread manipulating inet->opt.
Another thread can change inet->opt pointer and free old one under us.
Use RCU to protect inet->opt (changed to inet->inet_opt).
Instead of handling atomic refcounts, just copy ip_options when
necessary, to avoid cache line dirtying.
We cant insert an rcu_head in struct ip_options since its included in
skb->cb[], so this patch is large because I had to introduce a new
ip_options_rcu structure.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index a0af7ea..2b3c23c 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1857,6 +1857,11 @@
return CIPSO_V4_HDR_LEN + ret_val;
}
+static void opt_kfree_rcu(struct rcu_head *head)
+{
+ kfree(container_of(head, struct ip_options_rcu, rcu));
+}
+
/**
* cipso_v4_sock_setattr - Add a CIPSO option to a socket
* @sk: the socket
@@ -1879,7 +1884,7 @@
unsigned char *buf = NULL;
u32 buf_len;
u32 opt_len;
- struct ip_options *opt = NULL;
+ struct ip_options_rcu *old, *opt = NULL;
struct inet_sock *sk_inet;
struct inet_connection_sock *sk_conn;
@@ -1915,22 +1920,25 @@
ret_val = -ENOMEM;
goto socket_setattr_failure;
}
- memcpy(opt->__data, buf, buf_len);
- opt->optlen = opt_len;
- opt->cipso = sizeof(struct iphdr);
+ memcpy(opt->opt.__data, buf, buf_len);
+ opt->opt.optlen = opt_len;
+ opt->opt.cipso = sizeof(struct iphdr);
kfree(buf);
buf = NULL;
sk_inet = inet_sk(sk);
+
+ old = rcu_dereference_protected(sk_inet->inet_opt, sock_owned_by_user(sk));
if (sk_inet->is_icsk) {
sk_conn = inet_csk(sk);
- if (sk_inet->opt)
- sk_conn->icsk_ext_hdr_len -= sk_inet->opt->optlen;
- sk_conn->icsk_ext_hdr_len += opt->optlen;
+ if (old)
+ sk_conn->icsk_ext_hdr_len -= old->opt.optlen;
+ sk_conn->icsk_ext_hdr_len += opt->opt.optlen;
sk_conn->icsk_sync_mss(sk, sk_conn->icsk_pmtu_cookie);
}
- opt = xchg(&sk_inet->opt, opt);
- kfree(opt);
+ rcu_assign_pointer(sk_inet->inet_opt, opt);
+ if (old)
+ call_rcu(&old->rcu, opt_kfree_rcu);
return 0;
@@ -1960,7 +1968,7 @@
unsigned char *buf = NULL;
u32 buf_len;
u32 opt_len;
- struct ip_options *opt = NULL;
+ struct ip_options_rcu *opt = NULL;
struct inet_request_sock *req_inet;
/* We allocate the maximum CIPSO option size here so we are probably
@@ -1988,15 +1996,16 @@
ret_val = -ENOMEM;
goto req_setattr_failure;
}
- memcpy(opt->__data, buf, buf_len);
- opt->optlen = opt_len;
- opt->cipso = sizeof(struct iphdr);
+ memcpy(opt->opt.__data, buf, buf_len);
+ opt->opt.optlen = opt_len;
+ opt->opt.cipso = sizeof(struct iphdr);
kfree(buf);
buf = NULL;
req_inet = inet_rsk(req);
opt = xchg(&req_inet->opt, opt);
- kfree(opt);
+ if (opt)
+ call_rcu(&opt->rcu, opt_kfree_rcu);
return 0;
@@ -2016,34 +2025,34 @@
* values on failure.
*
*/
-static int cipso_v4_delopt(struct ip_options **opt_ptr)
+static int cipso_v4_delopt(struct ip_options_rcu **opt_ptr)
{
int hdr_delta = 0;
- struct ip_options *opt = *opt_ptr;
+ struct ip_options_rcu *opt = *opt_ptr;
- if (opt->srr || opt->rr || opt->ts || opt->router_alert) {
+ if (opt->opt.srr || opt->opt.rr || opt->opt.ts || opt->opt.router_alert) {
u8 cipso_len;
u8 cipso_off;
unsigned char *cipso_ptr;
int iter;
int optlen_new;
- cipso_off = opt->cipso - sizeof(struct iphdr);
- cipso_ptr = &opt->__data[cipso_off];
+ cipso_off = opt->opt.cipso - sizeof(struct iphdr);
+ cipso_ptr = &opt->opt.__data[cipso_off];
cipso_len = cipso_ptr[1];
- if (opt->srr > opt->cipso)
- opt->srr -= cipso_len;
- if (opt->rr > opt->cipso)
- opt->rr -= cipso_len;
- if (opt->ts > opt->cipso)
- opt->ts -= cipso_len;
- if (opt->router_alert > opt->cipso)
- opt->router_alert -= cipso_len;
- opt->cipso = 0;
+ if (opt->opt.srr > opt->opt.cipso)
+ opt->opt.srr -= cipso_len;
+ if (opt->opt.rr > opt->opt.cipso)
+ opt->opt.rr -= cipso_len;
+ if (opt->opt.ts > opt->opt.cipso)
+ opt->opt.ts -= cipso_len;
+ if (opt->opt.router_alert > opt->opt.cipso)
+ opt->opt.router_alert -= cipso_len;
+ opt->opt.cipso = 0;
memmove(cipso_ptr, cipso_ptr + cipso_len,
- opt->optlen - cipso_off - cipso_len);
+ opt->opt.optlen - cipso_off - cipso_len);
/* determining the new total option length is tricky because of
* the padding necessary, the only thing i can think to do at
@@ -2052,21 +2061,21 @@
* from there we can determine the new total option length */
iter = 0;
optlen_new = 0;
- while (iter < opt->optlen)
- if (opt->__data[iter] != IPOPT_NOP) {
- iter += opt->__data[iter + 1];
+ while (iter < opt->opt.optlen)
+ if (opt->opt.__data[iter] != IPOPT_NOP) {
+ iter += opt->opt.__data[iter + 1];
optlen_new = iter;
} else
iter++;
- hdr_delta = opt->optlen;
- opt->optlen = (optlen_new + 3) & ~3;
- hdr_delta -= opt->optlen;
+ hdr_delta = opt->opt.optlen;
+ opt->opt.optlen = (optlen_new + 3) & ~3;
+ hdr_delta -= opt->opt.optlen;
} else {
/* only the cipso option was present on the socket so we can
* remove the entire option struct */
*opt_ptr = NULL;
- hdr_delta = opt->optlen;
- kfree(opt);
+ hdr_delta = opt->opt.optlen;
+ call_rcu(&opt->rcu, opt_kfree_rcu);
}
return hdr_delta;
@@ -2083,15 +2092,15 @@
void cipso_v4_sock_delattr(struct sock *sk)
{
int hdr_delta;
- struct ip_options *opt;
+ struct ip_options_rcu *opt;
struct inet_sock *sk_inet;
sk_inet = inet_sk(sk);
- opt = sk_inet->opt;
- if (opt == NULL || opt->cipso == 0)
+ opt = rcu_dereference_protected(sk_inet->inet_opt, 1);
+ if (opt == NULL || opt->opt.cipso == 0)
return;
- hdr_delta = cipso_v4_delopt(&sk_inet->opt);
+ hdr_delta = cipso_v4_delopt(&sk_inet->inet_opt);
if (sk_inet->is_icsk && hdr_delta > 0) {
struct inet_connection_sock *sk_conn = inet_csk(sk);
sk_conn->icsk_ext_hdr_len -= hdr_delta;
@@ -2109,12 +2118,12 @@
*/
void cipso_v4_req_delattr(struct request_sock *req)
{
- struct ip_options *opt;
+ struct ip_options_rcu *opt;
struct inet_request_sock *req_inet;
req_inet = inet_rsk(req);
opt = req_inet->opt;
- if (opt == NULL || opt->cipso == 0)
+ if (opt == NULL || opt->opt.cipso == 0)
return;
cipso_v4_delopt(&req_inet->opt);
@@ -2184,14 +2193,18 @@
*/
int cipso_v4_sock_getattr(struct sock *sk, struct netlbl_lsm_secattr *secattr)
{
- struct ip_options *opt;
+ struct ip_options_rcu *opt;
+ int res = -ENOMSG;
- opt = inet_sk(sk)->opt;
- if (opt == NULL || opt->cipso == 0)
- return -ENOMSG;
-
- return cipso_v4_getattr(opt->__data + opt->cipso - sizeof(struct iphdr),
- secattr);
+ rcu_read_lock();
+ opt = rcu_dereference(inet_sk(sk)->inet_opt);
+ if (opt && opt->opt.cipso)
+ res = cipso_v4_getattr(opt->opt.__data +
+ opt->opt.cipso -
+ sizeof(struct iphdr),
+ secattr);
+ rcu_read_unlock();
+ return res;
}
/**