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Message-ID: <20170506040720.GD32707@kroah.com>
Date: Fri, 5 May 2017 21:07:20 -0700
From: Greg KH <gregkh@...uxfoundation.org>
To: kernel-hardening@...ts.openwall.com, Petr Mladek <pmladek@...e.com>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc: linux-kernel@...r.kernel.org, Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Steven Rostedt <rostedt@...dmis.org>,
William Roberts <william.c.roberts@...el.com>,
Chris Fries <cfries@...gle.com>, Dave Weinstein <olorin@...gle.com>
Subject: [RFC 3/6] lib: vsprintf: physical address kernel pointer filtering
options
From: Dave Weinstein <olorin@...gle.com>
Add the kptr_restrict setting of 4 which results in %pa and
%p[rR] values being replaced by zeros.
Cc: William Roberts <william.c.roberts@...el.com>
Cc: Chris Fries <cfries@...gle.com>
Signed-off-by: Dave Weinstein <olorin@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
Documentation/sysctl/kernel.txt | 8 +++++++-
kernel/sysctl.c | 3 +--
lib/vsprintf.c | 33 ++++++++++++++++++++++++++++++---
3 files changed, 38 insertions(+), 6 deletions(-)
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index c9f5da409868..df069ec42e4a 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -393,7 +393,13 @@ When kptr_restrict is set to (2), kernel pointers printed using
%pK will be replaced with 0's regardless of privileges.
When kptr_restrict is set to (3), kernel pointers printed using
-%p and %pK will be replaced with 0's regardless of privileges.
+%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.
==============================================================
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 1bfdd262c66a..acf7e6cb00b4 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
@@ -831,7 +830,7 @@ 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 f4e11dade1ab..75a49795fcae 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -405,6 +405,22 @@ static inline int kptr_restrict_always_cleanse_pointers(void)
return kptr_restrict >= 3;
}
+/*
+ * Always cleanse physical addresses (%pa* specifiers)
+ */
+static inline int kptr_restrict_cleanse_addresses(void)
+{
+ return kptr_restrict >= 4;
+}
+
+/*
+ * Always cleanse resource addresses (%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)
@@ -757,6 +773,7 @@ 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++ = '[';
@@ -784,10 +801,11 @@ 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) {
@@ -1390,7 +1408,9 @@ char *address_val(char *buf, char *end, const void *addr, const char *fmt)
break;
}
- return special_hex_number(buf, end, num, size);
+ return special_hex_number(buf, end,
+ kptr_restrict_cleanse_addresses() ? 0UL : num,
+ size);
}
static noinline_for_stack
@@ -1581,6 +1601,12 @@ char *flags_string(char *buf, char *end, void *flags_ptr, const char *fmt)
*
* 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,
@@ -1738,6 +1764,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
}
case 2: /* restrict only %pK */
case 3: /* restrict all non-extensioned %p and %pK */
+ case 4: /* restrict all non-extensioned %p, %pK, %pa*, %p[rR] */
default:
ptr = NULL;
break;
--
2.12.2
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