mirror of https://gitee.com/openkylin/linux.git
MIPS: initial stack protector support
Implements basic stack protector support based on ARM version in
c743f38013
, with Kconfig option,
constant canary value set at boot time, and script to check if
compiler actually supports stack protector.
Tested by creating a kernel module that writes past end of char[].
Signed-off-by: Gregory Fong <gregory.0xf0@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: Filippo Arcidiacono <filippo.arcidiacono@st.com>
Cc: Carmelo Amoroso <carmelo.amoroso@st.com>
Patchwork: https://patchwork.linux-mips.org/patch/5448/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
parent
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commit
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@ -2367,6 +2367,19 @@ config SECCOMP
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If unsure, say Y. Only embedded should say N here.
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config CC_STACKPROTECTOR
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bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
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help
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This option turns on the -fstack-protector GCC feature. This
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feature puts, at the beginning of functions, a canary value on
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the stack just before the return address, and validates
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the value just before actually returning. Stack based buffer
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overflows (that need to overwrite this return address) now also
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overwrite the canary, which gets detected and the attack is then
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neutralized via a kernel panic.
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This feature requires gcc version 4.2 or above.
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config USE_OF
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bool
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select OF
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@ -227,6 +227,10 @@ KBUILD_CPPFLAGS += -DDATAOFFSET=$(if $(dataoffset-y),$(dataoffset-y),0)
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LDFLAGS += -m $(ld-emul)
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ifdef CONFIG_CC_STACKPROTECTOR
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KBUILD_CFLAGS += -fstack-protector
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endif
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ifdef CONFIG_MIPS
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CHECKFLAGS += $(shell $(CC) $(KBUILD_CFLAGS) -dM -E -x c /dev/null | \
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egrep -vw '__GNUC_(|MINOR_|PATCHLEVEL_)_' | \
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@ -0,0 +1,40 @@
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/*
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* GCC stack protector support.
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*
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* (This is directly adopted from the ARM implementation)
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*
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* Stack protector works by putting predefined pattern at the start of
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* the stack frame and verifying that it hasn't been overwritten when
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* returning from the function. The pattern is called stack canary
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* and gcc expects it to be defined by a global variable called
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* "__stack_chk_guard" on MIPS. This unfortunately means that on SMP
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* we cannot have a different canary value per task.
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*/
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#ifndef _ASM_STACKPROTECTOR_H
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#define _ASM_STACKPROTECTOR_H 1
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#include <linux/random.h>
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#include <linux/version.h>
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extern unsigned long __stack_chk_guard;
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/*
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* Initialize the stackprotector canary value.
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*
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* NOTE: this must only be called from functions that never return,
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* and it must always be inlined.
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*/
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static __always_inline void boot_init_stack_canary(void)
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{
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unsigned long canary;
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/* Try to get a semi random initial value. */
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get_random_bytes(&canary, sizeof(canary));
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canary ^= LINUX_VERSION_CODE;
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current->stack_canary = canary;
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__stack_chk_guard = current->stack_canary;
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}
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#endif /* _ASM_STACKPROTECTOR_H */
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@ -201,6 +201,12 @@ int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
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return 1;
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}
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#ifdef CONFIG_CC_STACKPROTECTOR
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#include <linux/stackprotector.h>
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unsigned long __stack_chk_guard __read_mostly;
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EXPORT_SYMBOL(__stack_chk_guard);
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#endif
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/*
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*
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*/
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