299 lines
10 KiB
Diff
299 lines
10 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Chris Coulson <chris.coulson@canonical.com>
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Date: Fri, 19 Feb 2021 13:53:45 +0100
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Subject: [PATCH] kern/efi: Add initial stack protector implementation
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It works only on UEFI platforms but can be quite easily extended to
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others architectures and platforms if needed.
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Signed-off-by: Chris Coulson <chris.coulson@canonical.com>
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Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
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Reviewed-by: Marco A Benatto <mbenatto@redhat.com>
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Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
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---
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configure.ac | 44 ++++++++++++++++++++++++++++++----
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grub-core/kern/efi/init.c | 54 ++++++++++++++++++++++++++++++++++++++++++
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include/grub/efi/api.h | 19 +++++++++++++++
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include/grub/stack_protector.h | 30 +++++++++++++++++++++++
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acinclude.m4 | 38 +++++++++++++++++++++++++++--
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grub-core/Makefile.am | 1 +
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6 files changed, 179 insertions(+), 7 deletions(-)
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create mode 100644 include/grub/stack_protector.h
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diff --git a/configure.ac b/configure.ac
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index 0059b938a..f59a7b86c 100644
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--- a/configure.ac
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+++ b/configure.ac
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@@ -1330,12 +1330,41 @@ fi]
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CFLAGS="$TARGET_CFLAGS"
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-# Smashing stack protector.
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+# Stack smashing protector.
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grub_CHECK_STACK_PROTECTOR
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-# Need that, because some distributions ship compilers that include
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-# `-fstack-protector' in the default specs.
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-if test "x$ssp_possible" = xyes; then
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- TARGET_CFLAGS="$TARGET_CFLAGS -fno-stack-protector"
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+AC_ARG_ENABLE([stack-protector],
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+ AS_HELP_STRING([--enable-stack-protector],
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+ [enable the stack protector]),
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+ [],
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+ [enable_stack_protector=no])
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+if test "x$enable_stack_protector" = xno; then
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+ if test "x$ssp_possible" = xyes; then
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+ # Need that, because some distributions ship compilers that include
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+ # `-fstack-protector' in the default specs.
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+ TARGET_CFLAGS="$TARGET_CFLAGS -fno-stack-protector"
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+ fi
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+elif test "x$platform" != xefi; then
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+ AC_MSG_ERROR([--enable-stack-protector is only supported on EFI platforms])
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+elif test "x$ssp_global_possible" != xyes; then
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+ AC_MSG_ERROR([--enable-stack-protector is not supported (compiler doesn't support -mstack-protector-guard=global)])
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+else
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+ TARGET_CFLAGS="$TARGET_CFLAGS -mstack-protector-guard=global"
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+ if test "x$enable_stack_protector" = xyes; then
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+ if test "x$ssp_possible" != xyes; then
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+ AC_MSG_ERROR([--enable-stack-protector is not supported (compiler doesn't support -fstack-protector)])
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+ fi
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+ TARGET_CFLAGS="$TARGET_CFLAGS -fstack-protector"
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+ elif test "x$enable_stack_protector" = xstrong; then
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+ if test "x$ssp_strong_possible" != xyes; then
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+ AC_MSG_ERROR([--enable-stack-protector=strong is not supported (compiler doesn't support -fstack-protector-strong)])
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+ fi
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+ TARGET_CFLAGS="$TARGET_CFLAGS -fstack-protector-strong"
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+ else
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+ # Note, -fstack-protector-all requires that the protector is disabled for
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+ # functions that appear in the call stack when the canary is initialized.
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+ AC_MSG_ERROR([invalid value $enable_stack_protector for --enable-stack-protector])
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+ fi
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+ TARGET_CPPFLAGS="$TARGET_CPPFLAGS -DGRUB_STACK_PROTECTOR=1"
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fi
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CFLAGS="$TARGET_CFLAGS"
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@@ -2247,5 +2276,10 @@ echo "Without liblzma (no support for XZ-compressed mips images) ($liblzma_excus
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else
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echo "With liblzma from $LIBLZMA (support for XZ-compressed mips images)"
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fi
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+if test "x$enable_stack_protector" != xno; then
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+echo "With stack smashing protector: Yes"
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+else
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+echo "With stack smashing protector: No"
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+fi
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echo "*******************************************************"
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]
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diff --git a/grub-core/kern/efi/init.c b/grub-core/kern/efi/init.c
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index 97bf36906..501608f74 100644
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--- a/grub-core/kern/efi/init.c
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+++ b/grub-core/kern/efi/init.c
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@@ -28,6 +28,58 @@
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#include <grub/mm.h>
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#include <grub/kernel.h>
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#include <grub/lib/envblk.h>
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+#include <grub/stack_protector.h>
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+
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+#ifdef GRUB_STACK_PROTECTOR
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+
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+static grub_efi_guid_t rng_protocol_guid = GRUB_EFI_RNG_PROTOCOL_GUID;
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+
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+/*
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+ * Don't put this on grub_efi_init()'s local stack to avoid it
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+ * getting a stack check.
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+ */
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+static grub_efi_uint8_t stack_chk_guard_buf[32];
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+
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+grub_addr_t __stack_chk_guard;
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+
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+void __attribute__ ((noreturn))
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+__stack_chk_fail (void)
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+{
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+ /*
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+ * Assume it's not safe to call into EFI Boot Services. Sorry, that
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+ * means no console message here.
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+ */
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+ do
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+ {
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+ /* Do not optimize out the loop. */
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+ asm volatile ("");
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+ }
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+ while (1);
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+}
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+
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+static void
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+stack_protector_init (void)
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+{
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+ grub_efi_rng_protocol_t *rng;
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+
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+ /* Set up the stack canary. Make errors here non-fatal for now. */
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+ rng = grub_efi_locate_protocol (&rng_protocol_guid, NULL);
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+ if (rng != NULL)
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+ {
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+ grub_efi_status_t status;
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+
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+ status = efi_call_4 (rng->get_rng, rng, NULL, sizeof (stack_chk_guard_buf),
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+ stack_chk_guard_buf);
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+ if (status == GRUB_EFI_SUCCESS)
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+ grub_memcpy (&__stack_chk_guard, stack_chk_guard_buf, sizeof (__stack_chk_guard));
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+ }
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+}
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+#else
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+static void
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+stack_protector_init (void)
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+{
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+}
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+#endif
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grub_addr_t grub_modbase;
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@@ -92,6 +144,8 @@ grub_efi_init (void)
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messages. */
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grub_console_init ();
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+ stack_protector_init ();
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+
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/* Initialize the memory management system. */
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grub_efi_mm_init ();
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diff --git a/include/grub/efi/api.h b/include/grub/efi/api.h
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index a092fddb6..37e7b1628 100644
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--- a/include/grub/efi/api.h
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+++ b/include/grub/efi/api.h
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@@ -344,6 +344,11 @@
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{ 0x89, 0x29, 0x48, 0xbc, 0xd9, 0x0a, 0xd3, 0x1a } \
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}
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+#define GRUB_EFI_RNG_PROTOCOL_GUID \
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+ { 0x3152bca5, 0xeade, 0x433d, \
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+ { 0x86, 0x2e, 0xc0, 0x1c, 0xdc, 0x29, 0x1f, 0x44 } \
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+ }
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+
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struct grub_efi_sal_system_table
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{
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grub_uint32_t signature;
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@@ -2067,6 +2072,20 @@ struct grub_efi_ip6_config_manual_address {
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};
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typedef struct grub_efi_ip6_config_manual_address grub_efi_ip6_config_manual_address_t;
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+typedef grub_efi_guid_t grub_efi_rng_algorithm_t;
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+
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+struct grub_efi_rng_protocol
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+{
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+ grub_efi_status_t (*get_info) (struct grub_efi_rng_protocol *this,
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+ grub_efi_uintn_t *rng_algorithm_list_size,
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+ grub_efi_rng_algorithm_t *rng_algorithm_list);
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+ grub_efi_status_t (*get_rng) (struct grub_efi_rng_protocol *this,
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+ grub_efi_rng_algorithm_t *rng_algorithm,
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+ grub_efi_uintn_t rng_value_length,
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+ grub_efi_uint8_t *rng_value);
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+};
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+typedef struct grub_efi_rng_protocol grub_efi_rng_protocol_t;
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+
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#if (GRUB_TARGET_SIZEOF_VOID_P == 4) || defined (__ia64__) \
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|| defined (__aarch64__) || defined (__MINGW64__) || defined (__CYGWIN__)
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diff --git a/include/grub/stack_protector.h b/include/grub/stack_protector.h
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new file mode 100644
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index 000000000..c88dc00b5
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--- /dev/null
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+++ b/include/grub/stack_protector.h
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@@ -0,0 +1,30 @@
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+/*
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+ * GRUB -- GRand Unified Bootloader
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+ * Copyright (C) 2021 Free Software Foundation, Inc.
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+ *
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+ * GRUB is free software: you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License as published by
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+ * the Free Software Foundation, either version 3 of the License, or
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+ * (at your option) any later version.
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+ *
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+ * GRUB is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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+ */
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+
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+#ifndef GRUB_STACK_PROTECTOR_H
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+#define GRUB_STACK_PROTECTOR_H 1
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+
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+#include <grub/symbol.h>
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+#include <grub/types.h>
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+
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+#ifdef GRUB_STACK_PROTECTOR
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+extern grub_addr_t EXPORT_VAR (__stack_chk_guard);
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+extern void __attribute__ ((noreturn)) EXPORT_FUNC (__stack_chk_fail) (void);
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+#endif
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+
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+#endif /* GRUB_STACK_PROTECTOR_H */
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diff --git a/acinclude.m4 b/acinclude.m4
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index 242e829ff..21238fcfd 100644
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--- a/acinclude.m4
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+++ b/acinclude.m4
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@@ -324,9 +324,9 @@ fi
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])
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-dnl Check if the C compiler supports `-fstack-protector'.
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+dnl Check if the C compiler supports the stack protector
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AC_DEFUN([grub_CHECK_STACK_PROTECTOR],[
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-[# Smashing stack protector.
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+[# Stack smashing protector.
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ssp_possible=yes]
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AC_MSG_CHECKING([whether `$CC' accepts `-fstack-protector'])
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# Is this a reliable test case?
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@@ -343,6 +343,40 @@ else
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ssp_possible=no]
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AC_MSG_RESULT([no])
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[fi]
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+[# Strong stack smashing protector.
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+ssp_strong_possible=yes]
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+AC_MSG_CHECKING([whether `$CC' accepts `-fstack-protector-strong'])
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+# Is this a reliable test case?
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+AC_LANG_CONFTEST([AC_LANG_SOURCE([[
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+void foo (void) { volatile char a[8]; a[3]; }
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+]])])
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+[# `$CC -c -o ...' might not be portable. But, oh, well... Is calling
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+# `ac_compile' like this correct, after all?
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+if eval "$ac_compile -S -fstack-protector-strong -o conftest.s" 2> /dev/null; then]
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+ AC_MSG_RESULT([yes])
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+ [# Should we clear up other files as well, having called `AC_LANG_CONFTEST'?
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+ rm -f conftest.s
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+else
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+ ssp_strong_possible=no]
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+ AC_MSG_RESULT([no])
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+[fi]
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+[# Global stack smashing protector.
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+ssp_global_possible=yes]
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+AC_MSG_CHECKING([whether `$CC' accepts `-mstack-protector-guard=global'])
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+# Is this a reliable test case?
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+AC_LANG_CONFTEST([AC_LANG_SOURCE([[
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+void foo (void) { volatile char a[8]; a[3]; }
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+]])])
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+[# `$CC -c -o ...' might not be portable. But, oh, well... Is calling
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+# `ac_compile' like this correct, after all?
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+if eval "$ac_compile -S -fstack-protector -mstack-protector-guard=global -o conftest.s" 2> /dev/null; then]
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+ AC_MSG_RESULT([yes])
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+ [# Should we clear up other files as well, having called `AC_LANG_CONFTEST'?
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+ rm -f conftest.s
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+else
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+ ssp_global_possible=no]
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+ AC_MSG_RESULT([no])
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+[fi]
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])
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dnl Check if the C compiler supports `-mstack-arg-probe' (Cygwin).
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diff --git a/grub-core/Makefile.am b/grub-core/Makefile.am
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index a6f1b0dcd..308ad8850 100644
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--- a/grub-core/Makefile.am
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+++ b/grub-core/Makefile.am
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@@ -92,6 +92,7 @@ endif
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/mm.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/parser.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/partition.h
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+KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/stack_protector.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/term.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/time.h
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KERNEL_HEADER_FILES += $(top_srcdir)/include/grub/mm_private.h
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