randstruct: Move seed generation into scripts/basic/
To enable Clang randstruct support, move the structure layout randomization seed generation out of scripts/gcc-plugins/ into scripts/basic/ so it happens early enough that it can be used by either compiler implementation. The gcc-plugin still builds its own header file, but now does so from the common "randstruct.seed" file. Cc: linux-hardening@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220503205503.3054173-6-keescook@chromium.org
This commit is contained in:
Kees Cook
parent
613f4b3ed7
commit
be2b34fa9b
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@ -211,6 +211,7 @@ r200_reg_safe.h
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r300_reg_safe.h
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r420_reg_safe.h
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r600_reg_safe.h
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randstruct.seed
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randomize_layout_hash.h
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randomize_layout_seed.h
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recordmcount
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@ -100,8 +100,9 @@ Structure randomisation
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-----------------------
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If you enable ``CONFIG_RANDSTRUCT``, you will need to pre-generate
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the random seed in ``scripts/gcc-plugins/randomize_layout_seed.h``
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so the same value is used in rebuilds.
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the random seed in ``scripts/basic/randstruct.seed`` so the same
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value is used by each build. See ``scripts/gen-randstruct-seed.sh``
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for details.
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Debug info conflicts
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--------------------
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@ -33,7 +33,7 @@
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#define MODULE_VERMAGIC_MODVERSIONS ""
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#endif
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#ifdef RANDSTRUCT
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#include <generated/randomize_layout_hash.h>
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#include <generated/randstruct_hash.h>
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#define MODULE_RANDSTRUCT "RANDSTRUCT_" RANDSTRUCT_HASHED_SEED
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#else
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#define MODULE_RANDSTRUCT
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@ -1,2 +1,3 @@
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# SPDX-License-Identifier: GPL-2.0-only
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/fixdep
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/randstruct.seed
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@ -3,3 +3,14 @@
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# fixdep: used to generate dependency information during build process
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hostprogs-always-y += fixdep
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# randstruct: the seed is needed before building the gcc-plugin or
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# before running a Clang kernel build.
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gen-randstruct-seed := $(srctree)/scripts/gen-randstruct-seed.sh
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quiet_cmd_create_randstruct_seed = GENSEED $@
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cmd_create_randstruct_seed = \
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$(CONFIG_SHELL) $(gen-randstruct-seed) \
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$@ $(objtree)/include/generated/randstruct_hash.h
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$(obj)/randstruct.seed: $(gen-randstruct-seed) FORCE
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$(call if_changed,create_randstruct_seed)
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always-$(CONFIG_RANDSTRUCT) += randstruct.seed
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@ -1,12 +1,17 @@
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# SPDX-License-Identifier: GPL-2.0
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$(obj)/randomize_layout_plugin.so: $(objtree)/$(obj)/randomize_layout_seed.h
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quiet_cmd_create_randomize_layout_seed = GENSEED $@
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$(obj)/randomize_layout_plugin.so: $(obj)/randomize_layout_seed.h
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quiet_cmd_create_randomize_layout_seed = SEEDHDR $@
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cmd_create_randomize_layout_seed = \
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$(CONFIG_SHELL) $(srctree)/$(src)/gen-random-seed.sh $@ $(objtree)/include/generated/randomize_layout_hash.h
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$(objtree)/$(obj)/randomize_layout_seed.h: FORCE
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SEED=$$(cat $(filter-out FORCE,$^) </dev/null); \
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echo '/*' > $@; \
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echo ' * This file is automatically generated. Keep it private.' >> $@; \
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echo ' * Exposing this value will expose the layout of randomized structures.' >> $@; \
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echo ' */' >> $@; \
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echo "const char *randstruct_seed = \"$$SEED\";" >> $@
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$(obj)/randomize_layout_seed.h: $(objtree)/scripts/basic/randstruct.seed FORCE
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$(call if_changed,create_randomize_layout_seed)
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targets += randomize_layout_seed.h randomize_layout_hash.h
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targets += randomize_layout_seed.h
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# Build rules for plugins
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#
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@ -1,9 +0,0 @@
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#!/bin/sh
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# SPDX-License-Identifier: GPL-2.0
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if [ ! -f "$1" ]; then
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SEED=`od -A n -t x8 -N 32 /dev/urandom | tr -d ' \n'`
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echo "const char *randstruct_seed = \"$SEED\";" > "$1"
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HASH=`echo -n "$SEED" | sha256sum | cut -d" " -f1 | tr -d ' \n'`
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echo "#define RANDSTRUCT_HASHED_SEED \"$HASH\"" > "$2"
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fi
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@ -0,0 +1,7 @@
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#!/bin/sh
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# SPDX-License-Identifier: GPL-2.0
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SEED=$(od -A n -t x8 -N 32 /dev/urandom | tr -d ' \n')
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echo "$SEED" > "$1"
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HASH=$(echo -n "$SEED" | sha256sum | cut -d" " -f1)
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echo "#define RANDSTRUCT_HASHED_SEED \"$HASH\"" > "$2"
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@ -284,10 +284,11 @@ choice
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tools like Volatility against the system (unless the kernel
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source tree isn't cleaned after kernel installation).
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The seed used for compilation is located at
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scripts/randomize_layout_seed.h. It remains after a "make clean"
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to allow for external modules to be compiled with the existing
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seed and will be removed by a "make mrproper" or "make distclean".
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The seed used for compilation is in scripts/basic/randomize.seed.
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It remains after a "make clean" to allow for external modules to
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be compiled with the existing seed and will be removed by a
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"make mrproper" or "make distclean". This file should not be made
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public, or the structure layout can be determined.
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config RANDSTRUCT_NONE
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bool "Disable structure layout randomization"
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