From: Kees Cook <keescook@chromium.org> To: "kernel-hardening@lists.openwall.com" <kernel-hardening@lists.openwall.com> Cc: Kees Cook <keescook@chromium.org>, Hannes Frederic Sowa <hannes@stressinduktion.org>, "Signed-off-by : David S . Miller" <davem@davemloft.net>, Laura Abbott <labbott@redhat.com>, "x86@kernel.org" <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v2 06/20] randstruct: Whitelist UNIXCB cast Date: Fri, 26 May 2017 13:20:13 -0700 [thread overview] Message-ID: <CAGXu5jJZRF4YfZxKTOsW1D2snOJyfsUqBi+51Nda=aD1a+JeWQ@mail.gmail.com> (raw) In-Reply-To: <1495829844-69341-7-git-send-email-keescook@chromium.org> On Fri, May 26, 2017 at 1:17 PM, Kees Cook <keescook@chromium.org> wrote: > This is another false positive in bad cast detection: > > net/unix/af_unix.c: In function ‘unix_skb_scm_eq’: > net/unix/af_unix.c:1621:31: note: found mismatched rhs struct pointer types: ‘struct unix_skb_parms’ and ‘char’ > > const struct unix_skb_parms *u = &UNIXCB(skb); > ^ > > UNIXCB is: > > #define UNIXCB(skb) (*(struct unix_skb_parms *)&((skb)->cb)) > > And ->cb is: > > char cb[48] __aligned(8); > > This is a rather crazy cast, but appears to be safe in the face of > randomization, so whitelist it in the plugin. > > Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> > Cc: Signed-off-by: David S. Miller <davem@davemloft.net> Argh, paste-o. I was adding git history folks here to Cc, pardon the glitch. This should be Cc: and absolutely not a S-o-B from Dave. -Kees > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > scripts/gcc-plugins/randomize_layout_plugin.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c > index e126ac7874af..bf110915a5aa 100644 > --- a/scripts/gcc-plugins/randomize_layout_plugin.c > +++ b/scripts/gcc-plugins/randomize_layout_plugin.c > @@ -43,6 +43,8 @@ struct whitelist_entry { > }; > > static const struct whitelist_entry whitelist[] = { > + /* unix_skb_parms via UNIXCB() buffer */ > + { "net/unix/af_unix.c", "unix_skb_parms", "char" }, > /* walk struct security_hook_heads as an array of struct list_head */ > { "security/security.c", "list_head", "security_hook_heads" }, > { } > -- > 2.7.4 > -- Kees Cook Pixel Security
WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org> To: "kernel-hardening@lists.openwall.com" <kernel-hardening@lists.openwall.com> Cc: Kees Cook <keescook@chromium.org>, Hannes Frederic Sowa <hannes@stressinduktion.org>, "Signed-off-by : David S . Miller" <davem@davemloft.net>, Laura Abbott <labbott@redhat.com>, "x86@kernel.org" <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org> Subject: [kernel-hardening] Re: [PATCH v2 06/20] randstruct: Whitelist UNIXCB cast Date: Fri, 26 May 2017 13:20:13 -0700 [thread overview] Message-ID: <CAGXu5jJZRF4YfZxKTOsW1D2snOJyfsUqBi+51Nda=aD1a+JeWQ@mail.gmail.com> (raw) In-Reply-To: <1495829844-69341-7-git-send-email-keescook@chromium.org> On Fri, May 26, 2017 at 1:17 PM, Kees Cook <keescook@chromium.org> wrote: > This is another false positive in bad cast detection: > > net/unix/af_unix.c: In function ‘unix_skb_scm_eq’: > net/unix/af_unix.c:1621:31: note: found mismatched rhs struct pointer types: ‘struct unix_skb_parms’ and ‘char’ > > const struct unix_skb_parms *u = &UNIXCB(skb); > ^ > > UNIXCB is: > > #define UNIXCB(skb) (*(struct unix_skb_parms *)&((skb)->cb)) > > And ->cb is: > > char cb[48] __aligned(8); > > This is a rather crazy cast, but appears to be safe in the face of > randomization, so whitelist it in the plugin. > > Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> > Cc: Signed-off-by: David S. Miller <davem@davemloft.net> Argh, paste-o. I was adding git history folks here to Cc, pardon the glitch. This should be Cc: and absolutely not a S-o-B from Dave. -Kees > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > scripts/gcc-plugins/randomize_layout_plugin.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c > index e126ac7874af..bf110915a5aa 100644 > --- a/scripts/gcc-plugins/randomize_layout_plugin.c > +++ b/scripts/gcc-plugins/randomize_layout_plugin.c > @@ -43,6 +43,8 @@ struct whitelist_entry { > }; > > static const struct whitelist_entry whitelist[] = { > + /* unix_skb_parms via UNIXCB() buffer */ > + { "net/unix/af_unix.c", "unix_skb_parms", "char" }, > /* walk struct security_hook_heads as an array of struct list_head */ > { "security/security.c", "list_head", "security_hook_heads" }, > { } > -- > 2.7.4 > -- Kees Cook Pixel Security
next prev parent reply other threads:[~2017-05-27 1:13 UTC|newest] Thread overview: 116+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-05-26 20:17 [PATCH v2 00/20] Introduce struct layout randomization plugin Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 01/20] NFS: Avoid cross-structure casting Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-28 7:53 ` Christoph Hellwig 2017-05-28 7:53 ` [kernel-hardening] " Christoph Hellwig 2017-05-28 16:55 ` Kees Cook 2017-05-28 16:55 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 02/20] gcc-plugins: Detail c-common.h location for GCC 4.6 Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 03/20] compiler: Add __designated_init annotation Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 04/20] gcc-plugins: Add the randstruct plugin Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-06-29 22:08 ` Arnd Bergmann 2017-06-29 22:08 ` [kernel-hardening] " Arnd Bergmann 2017-06-29 22:53 ` Kees Cook 2017-06-29 22:53 ` [kernel-hardening] " Kees Cook 2017-06-30 0:04 ` Kees Cook 2017-06-30 0:04 ` [kernel-hardening] " Kees Cook 2017-06-30 7:35 ` Arnd Bergmann 2017-06-30 7:35 ` [kernel-hardening] " Arnd Bergmann 2017-06-30 7:55 ` Ard Biesheuvel 2017-06-30 7:55 ` [kernel-hardening] " Ard Biesheuvel 2017-06-30 8:27 ` Arnd Bergmann 2017-06-30 8:27 ` [kernel-hardening] " Arnd Bergmann 2017-06-30 14:41 ` Kees Cook 2017-06-30 14:41 ` [kernel-hardening] " Kees Cook 2017-06-30 15:22 ` Arnd Bergmann 2017-06-30 15:22 ` [kernel-hardening] " Arnd Bergmann 2017-05-26 20:17 ` [PATCH v2 05/20] randstruct: Whitelist struct security_hook_heads cast Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-27 8:41 ` Christoph Hellwig 2017-05-27 8:41 ` [kernel-hardening] " Christoph Hellwig 2017-05-27 20:09 ` Kees Cook 2017-05-27 20:09 ` [kernel-hardening] " Kees Cook 2017-05-27 20:09 ` Kees Cook 2017-05-27 22:04 ` Tetsuo Handa 2017-05-27 22:04 ` [kernel-hardening] " Tetsuo Handa 2017-05-27 22:04 ` Tetsuo Handa 2017-05-28 0:43 ` [kernel-hardening] " Kees Cook 2017-05-28 0:43 ` Kees Cook 2017-05-28 0:43 ` Kees Cook 2017-05-30 10:34 ` James Morris 2017-05-30 10:34 ` [kernel-hardening] " James Morris 2017-05-30 10:34 ` James Morris 2017-05-26 20:17 ` [PATCH v2 06/20] randstruct: Whitelist UNIXCB cast Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:20 ` Kees Cook [this message] 2017-05-26 20:20 ` [kernel-hardening] " Kees Cook 2017-05-28 7:56 ` Christoph Hellwig 2017-05-28 7:56 ` [kernel-hardening] " Christoph Hellwig 2017-05-26 20:17 ` [PATCH v2 07/20] randstruct: Whitelist big_key path struct overloading Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-28 8:12 ` Christoph Hellwig 2017-05-28 8:12 ` [kernel-hardening] " Christoph Hellwig 2017-05-28 16:59 ` Kees Cook 2017-05-28 16:59 ` [kernel-hardening] " Kees Cook 2017-06-19 19:24 ` Kees Cook 2017-06-19 19:24 ` [kernel-hardening] " Kees Cook 2017-09-07 7:20 ` Christoph Hellwig 2017-09-07 7:20 ` [kernel-hardening] " Christoph Hellwig 2017-09-07 22:55 ` Kees Cook 2017-09-07 22:55 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 08/20] randstruct: Whitelist NIU struct page overloading Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-28 8:15 ` Christoph Hellwig 2017-05-28 8:15 ` [kernel-hardening] " Christoph Hellwig 2017-05-28 17:35 ` Kees Cook 2017-05-28 17:35 ` [kernel-hardening] " Kees Cook 2017-05-28 17:35 ` Kees Cook 2017-05-28 17:37 ` Kees Cook 2017-05-28 17:37 ` [kernel-hardening] " Kees Cook 2017-05-28 17:37 ` Kees Cook 2017-05-26 20:17 ` [PATCH v2 09/20] randstruct: Mark various structs for randomization Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 10/20] randstruct: opt-out externally exposed function pointer structs Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 11/20] randstruct: Disable randomization of ACPICA structs Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-27 8:42 ` Christoph Hellwig 2017-05-27 8:42 ` [kernel-hardening] " Christoph Hellwig 2017-05-27 20:03 ` Kees Cook 2017-05-27 20:03 ` [kernel-hardening] " Kees Cook 2017-05-28 4:55 ` Christoph Hellwig 2017-05-28 4:55 ` [kernel-hardening] " Christoph Hellwig 2017-05-26 20:17 ` [PATCH v2 12/20] sgi-xp: Use designated initializers Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-27 8:44 ` Christoph Hellwig 2017-05-27 8:44 ` [kernel-hardening] " Christoph Hellwig 2017-05-26 20:17 ` [PATCH v2 13/20] drm/amdgpu: " Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 14/20] drm/amd/powerplay: " Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-27 8:47 ` Christoph Hellwig 2017-05-27 8:47 ` [kernel-hardening] " Christoph Hellwig 2017-05-27 20:10 ` Kees Cook 2017-05-27 20:10 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 15/20] mtk-vcodec: " Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 16/20] ntfs: Use ERR_CAST() to avoid cross-structure cast Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 17/20] ocfs2: " Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 18/20] randstruct: Enable function pointer struct detection Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 19/20] [RFC] task_struct: Allow randomized layout Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-26 20:23 ` Linus Torvalds 2017-05-26 20:23 ` [kernel-hardening] " Linus Torvalds 2017-05-26 20:32 ` Kees Cook 2017-05-26 20:32 ` [kernel-hardening] " Kees Cook 2017-05-26 20:17 ` [PATCH v2 20/20] ACPICA: Use designated initializers Kees Cook 2017-05-26 20:17 ` [kernel-hardening] " Kees Cook 2017-05-28 7:45 ` Christoph Hellwig 2017-05-28 7:45 ` [kernel-hardening] " Christoph Hellwig
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