From: Kristen Carlson Accardi <kristen@linux.intel.com>
To: keescook@chromium.org, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Cc: arjan@linux.intel.com, linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com,
Kristen Carlson Accardi <kristen@linux.intel.com>
Subject: [PATCH v2 3/9] x86/boot: Allow a "silent" kaslr random byte fetch
Date: Thu, 21 May 2020 09:56:34 -0700 [thread overview]
Message-ID: <20200521165641.15940-4-kristen@linux.intel.com> (raw)
In-Reply-To: <20200521165641.15940-1-kristen@linux.intel.com>
From: Kees Cook <keescook@chromium.org>
Under earlyprintk, each RNG call produces a debug report line. When
shuffling hundreds of functions, this is not useful information (each
line is identical and tells us nothing new). Instead, allow for a NULL
"purpose" to suppress the debug reporting.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
---
arch/x86/lib/kaslr.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/arch/x86/lib/kaslr.c b/arch/x86/lib/kaslr.c
index a53665116458..2b3eb8c948a3 100644
--- a/arch/x86/lib/kaslr.c
+++ b/arch/x86/lib/kaslr.c
@@ -56,11 +56,14 @@ unsigned long kaslr_get_random_long(const char *purpose)
unsigned long raw, random = get_boot_seed();
bool use_i8254 = true;
- debug_putstr(purpose);
- debug_putstr(" KASLR using");
+ if (purpose) {
+ debug_putstr(purpose);
+ debug_putstr(" KASLR using");
+ }
if (has_cpuflag(X86_FEATURE_RDRAND)) {
- debug_putstr(" RDRAND");
+ if (purpose)
+ debug_putstr(" RDRAND");
if (rdrand_long(&raw)) {
random ^= raw;
use_i8254 = false;
@@ -68,7 +71,8 @@ unsigned long kaslr_get_random_long(const char *purpose)
}
if (has_cpuflag(X86_FEATURE_TSC)) {
- debug_putstr(" RDTSC");
+ if (purpose)
+ debug_putstr(" RDTSC");
raw = rdtsc();
random ^= raw;
@@ -76,7 +80,8 @@ unsigned long kaslr_get_random_long(const char *purpose)
}
if (use_i8254) {
- debug_putstr(" i8254");
+ if (purpose)
+ debug_putstr(" i8254");
random ^= i8254();
}
@@ -86,7 +91,8 @@ unsigned long kaslr_get_random_long(const char *purpose)
: "a" (random), "rm" (mix_const));
random += raw;
- debug_putstr("...\n");
+ if (purpose)
+ debug_putstr("...\n");
return random;
}
--
2.20.1
next prev parent reply other threads:[~2020-05-21 16:57 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 16:56 [PATCH v2 0/9] Function Granular KASLR Kristen Carlson Accardi
2020-05-21 16:56 ` [PATCH v2 1/9] objtool: Do not assume order of parent/child functions Kristen Carlson Accardi
2020-05-21 16:56 ` [PATCH v2 2/9] x86: tools/relocs: Support >64K section headers Kristen Carlson Accardi
2020-05-21 16:56 ` Kristen Carlson Accardi [this message]
2020-05-21 16:56 ` [PATCH v2 4/9] x86: Makefile: Add build and config option for CONFIG_FG_KASLR Kristen Carlson Accardi
2020-05-21 20:00 ` Kees Cook
2020-05-21 16:56 ` [PATCH v2 5/9] x86: Make sure _etext includes function sections Kristen Carlson Accardi
2020-05-21 18:11 ` Kees Cook
2020-05-21 16:56 ` [PATCH v2 6/9] x86/tools: Add relative relocs for randomized functions Kristen Carlson Accardi
2020-05-21 19:54 ` Kees Cook
2020-05-21 16:56 ` [PATCH v2 7/9] x86: Add support for function granular KASLR Kristen Carlson Accardi
2020-05-21 21:08 ` Kees Cook
2020-05-21 21:42 ` Kristen Carlson Accardi
2020-05-21 21:42 ` Kristen Carlson Accardi
2020-06-04 17:27 ` Kristen Carlson Accardi
2020-06-04 17:27 ` Kristen Carlson Accardi
2020-06-04 22:37 ` Kees Cook
2020-05-21 16:56 ` [PATCH v2 8/9] kallsyms: Hide layout Kristen Carlson Accardi
2020-05-21 21:14 ` Kees Cook
2020-05-21 16:56 ` [PATCH v2 9/9] module: Reorder functions Kristen Carlson Accardi
2020-05-21 21:33 ` Kees Cook
2020-06-09 20:14 ` Kristen Carlson Accardi
2020-06-09 20:14 ` Kristen Carlson Accardi
2020-06-09 20:42 ` Kees Cook
2020-06-09 20:59 ` Kristen Carlson Accardi
2020-06-09 20:59 ` Kristen Carlson Accardi
2020-05-21 21:54 ` [PATCH v2 0/9] Function Granular KASLR Kees Cook
2020-05-21 22:26 ` Thomas Gleixner
2020-05-21 23:30 ` Kees Cook
2020-05-21 23:43 ` Thomas Gleixner
2020-05-21 23:44 ` Kristen Carlson Accardi
2020-05-21 23:44 ` Kristen Carlson Accardi
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