Re: CVS commit: src/sys/kern

[Tom Ivar Helbekkmo <tih%hamartun.priv.no@localhost>]

Christos Zoulas <christos%netbsd.org@localhost> writes:

> Log Message:
> make sure that we have enough space, don't require the exact size
> (Tom Ivar Helbekkmo)

Oops.  That wasn't enough.  If we're going to allow the caller of
getsockopt(2) to supply an oversized buffer for receiving the option
data, we need to keep track of both the size of the allocated kmem
buffer, so we can free it afterwards, and the actual size of the data
written into it, so we can return that to the caller.

As far as I can tell, there's nothing for it but to expand the sockopt
struct, adding either a field for the alloc'ed size, or one for the
actual size of what's being returned to the caller.  I went for the
latter, because it's the simplest change to make.

Here's what I'm running with at the moment:

Index: sys/sys/socketvar.h
===================================================================
RCS file: /cvsroot/src/sys/sys/socketvar.h,v
retrieving revision 1.145
diff -u -u -r1.145 socketvar.h
--- sys/sys/socketvar.h	6 Jul 2017 17:08:57 -0000	1.145
+++ sys/sys/socketvar.h	3 Jan 2018 10:53:17 -0000
@@ -224,6 +224,7 @@
 	int		sopt_level;		/* option level */
 	int		sopt_name;		/* option name */
 	size_t		sopt_size;		/* data length */
+	size_t		sopt_retsize;		/* returned data length */
 	void *		sopt_data;		/* data pointer */
 	uint8_t		sopt_buf[sizeof(int)];	/* internal storage */
 };
Index: sys/kern/uipc_socket.c
===================================================================
RCS file: /cvsroot/src/sys/kern/uipc_socket.c,v
retrieving revision 1.258
diff -u -u -r1.258 uipc_socket.c
--- sys/kern/uipc_socket.c	1 Jan 2018 00:45:12 -0000	1.258
+++ sys/kern/uipc_socket.c	3 Jan 2018 10:53:23 -0000
@@ -2113,6 +2113,8 @@
 		return EINVAL;
 	
 	memcpy(sopt->sopt_data, buf, len);
+	sopt->sopt_retsize = len;
+
 	return 0;
 }
 
@@ -2176,6 +2178,7 @@
 	
 	m_copydata(m, 0, len, sopt->sopt_data);
 	m_freem(m);
+	sopt->sopt_retsize = len;
 
 	return 0;
 }
Index: sys/kern/uipc_syscalls.c
===================================================================
RCS file: /cvsroot/src/sys/kern/uipc_syscalls.c,v
retrieving revision 1.189
diff -u -u -r1.189 uipc_syscalls.c
--- sys/kern/uipc_syscalls.c	31 Dec 2017 19:39:57 -0000	1.189
+++ sys/kern/uipc_syscalls.c	3 Jan 2018 10:53:24 -0000
@@ -1249,7 +1249,7 @@
 		goto out;
 
 	if (valsize > 0) {
-		len = min(valsize, sopt.sopt_size);
+		len = min(valsize, sopt.sopt_retsize);
 		error = copyout(sopt.sopt_data, SCARG(uap, val), len);
 		if (error)
 			goto out;
Index: share/man/man9/sockopt.9
===================================================================
RCS file: /cvsroot/src/share/man/man9/sockopt.9,v
retrieving revision 1.10
diff -u -u -r1.10 sockopt.9
--- share/man/man9/sockopt.9	16 Jan 2017 12:54:25 -0000	1.10
+++ share/man/man9/sockopt.9	3 Jan 2018 10:53:33 -0000
@@ -57,6 +57,7 @@
 	int		sopt_level;		/* option level */
 	int		sopt_name;		/* option name */
 	size_t		sopt_size;		/* data length */
+	size_t		sopt_retsize;		/* returned data length */
 	void *		sopt_data;		/* data pointer */
 	uint8_t		sopt_buf[sizeof(int)];	/* internal storage */
 };
@@ -133,7 +134,7 @@
 which will not fail.
 .It Fn sockopt_setint "sopt" "value"
 Common case of set sockopt integer value.
-The sockpt structure must contain an int sized data field or be previously
+The sockopt structure must contain an int sized data field or be previously
 unset, in which case the data pointer will be set to the internal storage.
 .El
 .Sh CODE REFERENCES


-tih
-- 
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