From: Borislav Petkov <bp@alien8.de>
To: Alexander Lobakin <alexandr.lobakin@intel.com>
Cc: linux-hardening@vger.kernel.org, x86@kernel.org,
Jesse Brandeburg <jesse.brandeburg@intel.com>,
Kristen Carlson Accardi <kristen@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
Miklos Szeredi <miklos@szeredi.hu>,
Ard Biesheuvel <ardb@kernel.org>, Tony Luck <tony.luck@intel.com>,
Bruce Schlobohm <bruce.schlobohm@intel.com>,
Jessica Yu <jeyu@kernel.org>, kernel test robot <lkp@intel.com>,
Miroslav Benes <mbenes@suse.cz>,
Evgenii Shatokhin <eshatokhin@virtuozzo.com>,
Jonathan Corbet <corbet@lwn.net>,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Nick Desaulniers <ndesaulniers@google.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Arnd Bergmann <arnd@arndb.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Nathan Chancellor <nathan@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Marios Pomonis <pomonis@google.com>,
Sami Tolvanen <samitolvanen@google.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Nicolas Pitre <nico@fluxnic.net>,
linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
linux-arch@vger.kernel.org, live-patching@vger.kernel.org,
llvm@lists.linux.dev
Subject: Re: [PATCH v9 03/15] kallsyms: Hide layout
Date: Wed, 5 Jan 2022 19:46:01 +0100 [thread overview]
Message-ID: <YdXnaYM9P3Grwz/C@zn.tnic> (raw)
In-Reply-To: <20211223002209.1092165-4-alexandr.lobakin@intel.com>
On Thu, Dec 23, 2021 at 01:21:57AM +0100, Alexander Lobakin wrote:
> @@ -687,11 +697,12 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
> iter->name[0] = '\0';
> iter->nameoff = get_symbol_offset(new_pos);
> iter->pos = new_pos;
> - if (new_pos == 0) {
if (!iter->show_layout)
return;
> + if (iter->show_layout && new_pos == 0) {
> iter->pos_arch_end = 0;
> iter->pos_mod_end = 0;
> iter->pos_ftrace_mod_end = 0;
> iter->pos_bpf_end = 0;
> + iter->pos_end = 0;
> }
> }
...
> @@ -838,16 +860,54 @@ static int kallsyms_open(struct inode *inode, struct file *file)
> * using get_symbol_offset for every symbol.
> */
> struct kallsym_iter *iter;
> - iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
> - if (!iter)
> - return -ENOMEM;
> - reset_iter(iter, 0);
> + /*
> + * This fake iter is needed for the cases with unprivileged
> + * access. We need to know the exact number of symbols to
> + * randomize the display layout.
> + */
> + struct kallsym_iter fake;
> + size_t size = sizeof(*iter);
> + loff_t pos;
> +
> + fake.show_layout = true;
> + reset_iter(&fake, 0);
>
> /*
> * Instead of checking this on every s_show() call, cache
> * the result here at open time.
> */
> - iter->show_value = kallsyms_show_value(file->f_cred);
> + fake.show_layout = kallsyms_show_value(file->f_cred);
> + if (fake.show_layout)
> + goto open;
There are those silly labels again:
if (!fake.show_layout) {
for (... )
;
size = ...
}
iter = __seq_open_private(...
> +
> + for (pos = kallsyms_num_syms; update_iter_mod(&fake, pos); pos++)
> + ;
> +
> + size = struct_size(iter, shuffled_pos, fake.pos_end + 1);
> +
> +open:
> + iter = __seq_open_private(file, &kallsyms_op, size);
> + if (!iter)
> + return -ENOMEM;
> +
> + iter->show_layout = fake.show_layout;
> + reset_iter(iter, 0);
> +
> + if (iter->show_layout)
> + return 0;
> +
> + /* Copy the bounds since they were already discovered above */
> + iter->pos_arch_end = fake.pos_arch_end;
> + iter->pos_mod_end = fake.pos_mod_end;
> + iter->pos_ftrace_mod_end = fake.pos_ftrace_mod_end;
> + iter->pos_bpf_end = fake.pos_bpf_end;
> + iter->pos_end = fake.pos_end;
> +
> + for (pos = 0; pos <= iter->pos_end; pos++)
> + iter->shuffled_pos[pos] = pos;
> +
> + shuffle_array(iter->shuffled_pos, iter->pos_end + 1);
> +
> return 0;
> }
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-01-05 18:46 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-23 0:21 [PATCH v9 00/15] Function Granular KASLR Alexander Lobakin
2021-12-23 0:21 ` [PATCH v9 01/15] modpost: fix removing numeric suffixes Alexander Lobakin
2021-12-23 16:19 ` Borislav Petkov
2021-12-27 18:22 ` Alexander Lobakin
2021-12-27 21:26 ` Borislav Petkov
2021-12-28 17:03 ` Alexander Lobakin
2022-01-03 13:07 ` Miroslav Benes
2021-12-23 0:21 ` [PATCH v9 02/15] livepatch: use `-z unique-symbol` if available to nuke pos-based search Alexander Lobakin
2021-12-30 11:10 ` Borislav Petkov
2021-12-30 18:31 ` Fāng-ruì Sòng
2022-01-03 13:55 ` Miroslav Benes
2022-01-03 16:06 ` Alexander Lobakin
2022-01-05 3:24 ` Fāng-ruì Sòng
2022-01-03 16:29 ` Alexander Lobakin
2022-01-03 13:44 ` Miroslav Benes
2021-12-23 0:21 ` [PATCH v9 03/15] kallsyms: Hide layout Alexander Lobakin
2021-12-30 22:36 ` Borislav Petkov
2022-01-03 15:40 ` Alexander Lobakin
2022-01-03 16:59 ` Borislav Petkov
2022-01-05 18:46 ` Borislav Petkov [this message]
2021-12-23 0:21 ` [PATCH v9 04/15] arch: introduce ASM function sections Alexander Lobakin
2022-01-17 21:08 ` Borislav Petkov
2022-01-17 21:38 ` Nicolas Pitre
2022-01-17 21:55 ` Borislav Petkov
2021-12-23 0:21 ` [PATCH v9 05/15] x86: support " Alexander Lobakin
2022-01-21 15:08 ` Borislav Petkov
2022-01-26 14:49 ` Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 06/15] x86: decouple ORC table sorting into a separate file Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 07/15] Makefile: Add build and config option for CONFIG_FG_KASLR Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 08/15] x86/tools: Add relative relocs for randomized functions Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 09/15] x86: Add support for function granular KASLR Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 10/15] FG-KASLR: use a scripted approach to handle .text.* sections Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 11/15] x86/boot: allow FG-KASLR to be selected Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 12/15] module: Reorder functions Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 13/15] module: use a scripted approach for FG-KASLR Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 14/15] Documentation: add documentation " Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 15/15] maintainers: add MAINTAINERS entry " Alexander Lobakin
2021-12-23 15:15 ` [PATCH v9 00/15] Function Granular KASLR Alexander Lobakin
2021-12-23 15:40 ` Peter Zijlstra
2021-12-24 6:38 ` Christoph Hellwig
2021-12-27 18:33 ` Alexander Lobakin
2021-12-30 9:00 ` Christoph Hellwig
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