Awesome! We probably need to delete more lines. Not sure a good way
to feed this sort of change back to upstreams though, as they *do* need
this with OpenSSL.
On 2014/05/30 18:15, Edd Barrett wrote:
> On Thu, May 22, 2014 at 12:07:33AM +0100, Zé Loff wrote:
> >
> > I know, that subject's line is too long, but I didn't manage to phrase
> > that in a shorter form. On the upside, it pretty much tells the whole
> > story: elinks is creating a file on ~ whose name is the contents of
> > ~/elinks/elinks.conf.
>
> I can reproduce this, although it is not always in ~. Rather in ${CWD}.
>
> This is actually a use after free (and maybe a security issue) introduced by
> us when we were fixing RAND_egd() fallout. If we look at the patch to
> init_ssl():
>
> ---8<---
> $OpenBSD: patch-src_network_ssl_ssl_c,v 1.1 2014/04/19 17:59:38 sthen Exp $
> --- src/network/ssl/ssl.c.orig Sat Apr 19 18:44:13 2014
> +++ src/network/ssl/ssl.c Sat Apr 19 18:45:12 2014
> @@ -49,11 +49,8 @@ init_openssl(struct module *module)
> * cannot initialize the PRNG and so every attempt to use SSL fails.
> * It's actually an OpenSSL FAQ, and according to them, it's up to the
> * application coders to seed the RNG. -- William Yodlowsky */
> - if (RAND_egd(RAND_file_name(f_randfile, sizeof(f_randfile))) < 0) {
> - /* Not an EGD, so read and write to it */
> - if (RAND_load_file(f_randfile, -1))
> - RAND_write_file(f_randfile);
> - }
> + if (RAND_load_file(f_randfile, -1))
> + RAND_write_file(f_randfile);
>
> SSLeay_add_ssl_algorithms();
> context = SSL_CTX_new(SSLv23_client_method());
> ---8<---
>
> The removed RAND_egd check is side effecting! The nested call to
> RAND_file_name() is populating f_randfile with the path to the RNG device
> node. Without it, we end up using the uninitialised f_randfile buffer, which
> happens to contain the the contents of your config file.
>
> So, we end up passing the contents of a file named the same as the contents
> of your elinks config file to RAND_{load,write}_file(). Looking at he
> implementation of RAND_load_file(), the path is not even used by that call?!
> The call to RAND_write_file() is then putting some junk in the file... Whut?
>
> FWIW, the below patch fixes stops elinks from creating that weird file, but
> I am not confident the RNG is correctly seeded by elinks.
>
> Someone who understands OpenSSL should comment.
>
> ---8<---
> Index: Makefile
> ===================================================================
> RCS file: /home/edd/cvsync/ports/www/elinks/Makefile,v
> retrieving revision 1.32
> diff -u -p -r1.32 Makefile
> --- Makefile 10 Oct 2013 20:10:51 -0000 1.32
> +++ Makefile 30 May 2014 16:23:51 -0000
> @@ -2,7 +2,7 @@
>
> COMMENT= full-featured text WWW browser
> DISTNAME= elinks-0.11.7
> -REVISION= 7
> +REVISION= 8
> CATEGORIES= www
> MASTER_SITES= http://elinks.cz/download/
>
> Index: patches/patch-src_network_ssl_ssl_c
> ===================================================================
> RCS file:
> /home/edd/cvsync/ports/www/elinks/patches/patch-src_network_ssl_ssl_c,v
> retrieving revision 1.1
> diff -u -p -r1.1 patch-src_network_ssl_ssl_c
> --- patches/patch-src_network_ssl_ssl_c 19 Apr 2014 17:59:38 -0000
> 1.1
> +++ patches/patch-src_network_ssl_ssl_c 30 May 2014 16:18:08 -0000
> @@ -1,7 +1,14 @@
> $OpenBSD: patch-src_network_ssl_ssl_c,v 1.1 2014/04/19 17:59:38 sthen Exp $
> ---- src/network/ssl/ssl.c.orig Sat Apr 19 18:44:13 2014
> -+++ src/network/ssl/ssl.c Sat Apr 19 18:45:12 2014
> -@@ -49,11 +49,8 @@ init_openssl(struct module *module)
> +--- src/network/ssl/ssl.c.orig Sat Aug 22 12:15:08 2009
> ++++ src/network/ssl/ssl.c Fri May 30 17:17:48 2014
> +@@ -45,15 +45,15 @@ init_openssl(struct module *module)
> + {
> + unsigned char f_randfile[PATH_MAX];
> +
> ++ if (RAND_file_name(f_randfile, sizeof(f_randfile)) == NULL)
> ++ return S_SSL_ERROR;
> ++
> + /* In a nutshell, on OS's without a /dev/urandom, the OpenSSL library
> * cannot initialize the PRNG and so every attempt to use SSL fails.
> * It's actually an OpenSSL FAQ, and according to them, it's up to the
> * application coders to seed the RNG. -- William Yodlowsky */
> ---8<---
>
> --
> Best Regards
> Edd Barrett
>
> http://www.theunixzoo.co.uk
