[32/33] sctp: add sctp_sock_get_primary_addr
diff mbox series

Message ID 20200513062649.2100053-33-hch@lst.de
State New
Headers show
Series
  • [01/33] net: add sock_set_reuseaddr
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Commit Message

Christoph Hellwig May 13, 2020, 6:26 a.m. UTC
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@lst.de>
---
 fs/dlm/lowcomms.c       | 11 +++-----
 include/net/sctp/sctp.h |  1 +
 net/sctp/socket.c       | 57 +++++++++++++++++++++++++----------------
 3 files changed, 39 insertions(+), 30 deletions(-)

Comments

Marcelo Ricardo Leitner May 13, 2020, 6:03 p.m. UTC | #1
On Wed, May 13, 2020 at 08:26:47AM +0200, Christoph Hellwig wrote:
> Add a helper to directly get the SCTP_PRIMARY_ADDR sockopt from kernel
> space without going through a fake uaccess.

Same comment as on the other dlm/sctp patch.

> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  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
>
David Laight May 14, 2020, 9:51 a.m. UTC | #2
From: Marcelo Ricardo Leitner
> Sent: 13 May 2020 19:03
> 
> On Wed, May 13, 2020 at 08:26:47AM +0200, Christoph Hellwig wrote:
> > Add a helper to directly get the SCTP_PRIMARY_ADDR sockopt from kernel
> > space without going through a fake uaccess.
> 
> Same comment as on the other dlm/sctp patch.

Wouldn't it be best to write sctp_[gs]etsockotp() that
use a kernel buffer and then implement the user-space
calls using a wrapper that does the copies to an on-stack
(or malloced if big) buffer.

That will also simplify the code be removing all the copies
and -EFAULT returns.
Only the size checks will be needed and the code can assume
the buffer is at least the size of the on-stack buffer.

Our SCTP code uses SO_REUSADDR, SCTP_EVENTS, SCTP_NODELAY,
SCTP_STATUS, SCTP_INITMSG, IPV6_ONLY, SCTP_SOCKOPT_BINDX_ADD
and SO_LINGER.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
David Laight May 14, 2020, 12:30 p.m. UTC | #3
From: David Laight
> Sent: 14 May 2020 10:51
> From: Marcelo Ricardo Leitner
> > Sent: 13 May 2020 19:03
> >
> > On Wed, May 13, 2020 at 08:26:47AM +0200, Christoph Hellwig wrote:
> > > Add a helper to directly get the SCTP_PRIMARY_ADDR sockopt from kernel
> > > space without going through a fake uaccess.
> >
> > Same comment as on the other dlm/sctp patch.
> 
> Wouldn't it be best to write sctp_[gs]etsockotp() that
> use a kernel buffer and then implement the user-space
> calls using a wrapper that does the copies to an on-stack
> (or malloced if big) buffer.

Actually looking at __sys_setsockopt() it calls
BPF_CGROUP_RUN_PROG_SETSOCKOPT() which (by the look of it)
can copy the user buffer into malloc()ed memory and
cause set_fs(KERNEL_DS) be called.

The only way to get rid of that set_fs() is to always
have the buffer in kernel memory when the underlying
setsockopt() code is called.

The comment above __sys_[sg]etsockopt() about not knowing
the length is just wrong.
It probably applied to getsockopt() in the dim and distant
past before it was made read-update.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
David Laight May 14, 2020, 1:27 p.m. UTC | #4
From: David Laight
> Sent: 14 May 2020 13:30
> Subject: RE: [PATCH 32/33] sctp: add sctp_sock_get_primary_addr
> 
> From: David Laight
> > Sent: 14 May 2020 10:51
> > From: Marcelo Ricardo Leitner
> > > Sent: 13 May 2020 19:03
> > >
> > > On Wed, May 13, 2020 at 08:26:47AM +0200, Christoph Hellwig wrote:
> > > > Add a helper to directly get the SCTP_PRIMARY_ADDR sockopt from kernel
> > > > space without going through a fake uaccess.
> > >
> > > Same comment as on the other dlm/sctp patch.
> >
> > Wouldn't it be best to write sctp_[gs]etsockotp() that
> > use a kernel buffer and then implement the user-space
> > calls using a wrapper that does the copies to an on-stack
> > (or malloced if big) buffer.
> 
> Actually looking at __sys_setsockopt() it calls
> BPF_CGROUP_RUN_PROG_SETSOCKOPT() which (by the look of it)
> can copy the user buffer into malloc()ed memory and
> cause set_fs(KERNEL_DS) be called.
> 
> The only way to get rid of that set_fs() is to always
> have the buffer in kernel memory when the underlying
> setsockopt() code is called.

And having started to try coding __sys_setsockopt()
and then found the compat code I suspect that would
be a whole lot more sane if the buffer was in kernel
and it knew that at least (say) 64 bytes were allocated.

The whole compat_alloc_user_space() 'crap' could probably go.

Actually it looks like an application can avoid whatever
checks BPF_CGROUP_RUN_PROG_SETSOCKOPT() is trying to do
by using the 32bit compat ioctls.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

Patch
diff mbox series

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;
 }