[PATCH 32/33] sctp: add sctp_sock_get_primary_addr

From: Christoph Hellwig
Date: Wed May 13 2020 - 02:30:13 EST


Add a helper to directly get the SCTP_PRIMARY_ADDR sockopt from kernel
space without going through a fake uaccess.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/dlm/lowcomms.c | 11 +++-----
include/net/sctp/sctp.h | 1 +
net/sctp/socket.c | 57 +++++++++++++++++++++++++----------------
3 files changed, 39 insertions(+), 30 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 6fa45365666a8..46d2d71b62c57 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -855,10 +855,9 @@ static int tcp_accept_from_sock(struct connection *con)
static int sctp_accept_from_sock(struct connection *con)
{
/* Check that the new node is in the lockspace */
- struct sctp_prim prim;
+ struct sctp_prim prim = { };
int nodeid;
- int prim_len, ret;
- int addr_len;
+ int addr_len, ret;
struct connection *newcon;
struct connection *addcon;
struct socket *newsock;
@@ -876,11 +875,7 @@ static int sctp_accept_from_sock(struct connection *con)
if (ret < 0)
goto accept_err;

- memset(&prim, 0, sizeof(struct sctp_prim));
- prim_len = sizeof(struct sctp_prim);
-
- ret = kernel_getsockopt(newsock, IPPROTO_SCTP, SCTP_PRIMARY_ADDR,
- (char *)&prim, &prim_len);
+ ret = sctp_sock_get_primary_addr(con->sock->sk, &prim);
if (ret < 0) {
log_print("getsockopt/sctp_primary_addr failed: %d", ret);
goto accept_err;
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index b505fa082f254..c98b1d14db853 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -618,5 +618,6 @@ static inline bool sctp_newsk_ready(const struct sock *sk)
int sctp_setsockopt_bindx(struct sock *sk, struct sockaddr *kaddrs,
int addrs_size, int op);
void sctp_sock_set_nodelay(struct sock *sk, bool val);
+int sctp_sock_get_primary_addr(struct sock *sk, struct sctp_prim *prim);

#endif /* __net_sctp_h__ */
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 64c395f7a86d5..39bf8090dbe1e 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -6411,6 +6411,35 @@ static int sctp_getsockopt_local_addrs(struct sock *sk, int len,
return err;
}

+static int __sctp_sock_get_primary_addr(struct sock *sk, struct sctp_prim *prim)
+{
+ struct sctp_association *asoc;
+
+ asoc = sctp_id2assoc(sk, prim->ssp_assoc_id);
+ if (!asoc)
+ return -EINVAL;
+ if (!asoc->peer.primary_path)
+ return -ENOTCONN;
+
+ memcpy(&prim->ssp_addr, &asoc->peer.primary_path->ipaddr,
+ asoc->peer.primary_path->af_specific->sockaddr_len);
+
+ sctp_get_pf_specific(sk->sk_family)->addr_to_user(sctp_sk(sk),
+ (union sctp_addr *)&prim->ssp_addr);
+ return 0;
+}
+
+int sctp_sock_get_primary_addr(struct sock *sk, struct sctp_prim *prim)
+{
+ int ret;
+
+ lock_sock(sk);
+ ret = __sctp_sock_get_primary_addr(sk, prim);
+ release_sock(sk);
+ return ret;
+}
+EXPORT_SYMBOL(sctp_sock_get_primary_addr);
+
/* 7.1.10 Set Primary Address (SCTP_PRIMARY_ADDR)
*
* Requests that the local SCTP stack use the enclosed peer address as
@@ -6421,35 +6450,19 @@ static int sctp_getsockopt_primary_addr(struct sock *sk, int len,
char __user *optval, int __user *optlen)
{
struct sctp_prim prim;
- struct sctp_association *asoc;
- struct sctp_sock *sp = sctp_sk(sk);
+ int ret;

if (len < sizeof(struct sctp_prim))
return -EINVAL;
-
- len = sizeof(struct sctp_prim);
-
- if (copy_from_user(&prim, optval, len))
+ if (copy_from_user(&prim, optval, sizeof(struct sctp_prim)))
return -EFAULT;

- asoc = sctp_id2assoc(sk, prim.ssp_assoc_id);
- if (!asoc)
- return -EINVAL;
-
- if (!asoc->peer.primary_path)
- return -ENOTCONN;
-
- memcpy(&prim.ssp_addr, &asoc->peer.primary_path->ipaddr,
- asoc->peer.primary_path->af_specific->sockaddr_len);
-
- sctp_get_pf_specific(sk->sk_family)->addr_to_user(sp,
- (union sctp_addr *)&prim.ssp_addr);
+ ret = __sctp_sock_get_primary_addr(sk, &prim);
+ if (ret)
+ return ret;

- if (put_user(len, optlen))
+ if (put_user(len, optlen) || copy_to_user(optval, &prim, len))
return -EFAULT;
- if (copy_to_user(optval, &prim, len))
- return -EFAULT;
-
return 0;
}

--
2.26.2