From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752732AbdJAAHY (ORCPT ); Sat, 30 Sep 2017 20:07:24 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:52073 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752427AbdJAAHS (ORCPT ); Sat, 30 Sep 2017 20:07:18 -0400 X-ME-Sender: X-Sasl-enc: fM07hdMPWPb+IHQBYeQuGJZ8TLiJQBwWXfxfdVZsrfAz 1506816437 From: "Tobin C. Harding" To: Greg KH , Petr Mladek , Joe Perches , Ian Campbell , Sergey Senozhatsky Cc: "Tobin C. Harding" , kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon , Steven Rostedt , William Roberts , Chris Fries , Dave Weinstein Subject: [kernel-hardening] [RFC V2 3/6] lib: vsprintf: physical address kernel pointer filtering options Date: Sun, 1 Oct 2017 11:06:47 +1100 Message-Id: <1506816410-10230-4-git-send-email-me@tobin.cc> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1506816410-10230-1-git-send-email-me@tobin.cc> References: <1506816410-10230-1-git-send-email-me@tobin.cc> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add the kptr_restrict setting of 4 which results in %pa and %p[rR] values being cleansed. Address types printed with %pa are replaced by zeros. Resources printed with %p[rR] have the starting address replaced by zeros, resource size is still shown. Signed-off-by: Tobin C. Harding --- Documentation/sysctl/kernel.txt | 5 +++++ kernel/sysctl.c | 3 +-- lib/vsprintf.c | 31 +++++++++++++++++++++++++++++-- 3 files changed, 35 insertions(+), 4 deletions(-) diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index 7ee183af..b6d45bc 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -398,6 +398,11 @@ When kptr_restrict is set to (3), kernel pointers printed using %p and %pK will be replaced with 0's regardless of privileges, however kernel pointers printed using %pP will continue to be printed. +When kptr_restrict is set to (4), kernel pointers printed with +%p, %pK, %pa, and %p[rR] will be replaced with 0's regardless of +privileges. Kernel pointers printed using %pP will continue to be +printed. + ============================================================== l2cr: (PPC only) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 37ba637..f777b32 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -129,7 +129,6 @@ static unsigned long one_ul = 1; static int one_hundred = 100; static int one_thousand = 1000; #ifdef CONFIG_PRINTK -static int three = 3; static int ten_thousand = 10000; #endif #ifdef CONFIG_PERF_EVENTS @@ -852,7 +851,7 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = proc_dointvec_minmax_sysadmin, .extra1 = &zero, - .extra2 = &three, + .extra2 = &four, }, #endif { diff --git a/lib/vsprintf.c b/lib/vsprintf.c index e6eace0..0271223 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -406,6 +406,22 @@ static inline int kptr_restrict_cleanse_kernel_pointers(void) return kptr_restrict >= 3; } +/* + * return non-zero if we should cleanse pointers for %pa* specifiers. + */ +static inline int kptr_restrict_cleanse_addresses(void) +{ + return kptr_restrict >= 4; +} + +/* + * return non-zero if we should cleanse pointers for %p[rR] specifiers. + */ +static inline int kptr_restrict_cleanse_resources(void) +{ + return kptr_restrict >= 4; +} + static noinline_for_stack char *number(char *buf, char *end, unsigned long long num, struct printf_spec spec) @@ -758,6 +774,7 @@ char *resource_string(char *buf, char *end, struct resource *res, char *p = sym, *pend = sym + sizeof(sym); int decode = (fmt[0] == 'R') ? 1 : 0; + int cleanse = kptr_restrict_cleanse_resources(); const struct printf_spec *specp; *p++ = '['; @@ -785,10 +802,11 @@ char *resource_string(char *buf, char *end, struct resource *res, p = string(p, pend, "size ", str_spec); p = number(p, pend, resource_size(res), *specp); } else { - p = number(p, pend, res->start, *specp); + p = number(p, pend, cleanse ? 0UL : res->start, *specp); if (res->start != res->end) { *p++ = '-'; - p = number(p, pend, res->end, *specp); + p = number(p, pend, cleanse ? + res->end - res->start : res->end, *specp); } } if (decode) { @@ -1391,6 +1409,9 @@ char *address_val(char *buf, char *end, const void *addr, const char *fmt) break; } + if (kptr_restrict_cleanse_addresses()) + num = 0UL; + return special_hex_number(buf, end, num, size); } @@ -1714,6 +1735,12 @@ char *device_node_string(char *buf, char *end, struct device_node *dn, * pointer to the real address. * * Note: That for kptr_restrict set to 3, %p and %pK have the same meaning. + * + * Note: That for kptr_restrict set to 4, %pa will null out the physical + * address. + * + * Note: That for kptr_restrict set to 4, %p[rR] will null out the memory + * address. */ static noinline_for_stack char *pointer(const char *fmt, char *buf, char *end, void *ptr, -- 2.7.4