From 4ecfca89893843d4ae266485bb878aa760ba82da Mon Sep 17 00:00:00 2001 From: Sami Tolvanen Date: Thu, 8 Apr 2021 11:28:37 -0700 Subject: arm64: implement function_nocfi With CONFIG_CFI_CLANG, the compiler replaces function addresses in instrumented C code with jump table addresses. This change implements the function_nocfi() macro, which returns the actual function address instead. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Acked-by: Mark Rutland Tested-by: Nathan Chancellor Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210408182843.1754385-13-samitolvanen@google.com --- arch/arm64/include/asm/memory.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'arch/arm64/include/asm') diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 0aabc3be9a75..3a6f9df63606 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -321,6 +321,22 @@ static inline void *phys_to_virt(phys_addr_t x) #define virt_to_pfn(x) __phys_to_pfn(__virt_to_phys((unsigned long)(x))) #define sym_to_pfn(x) __phys_to_pfn(__pa_symbol(x)) +#ifdef CONFIG_CFI_CLANG +/* + * With CONFIG_CFI_CLANG, the compiler replaces function address + * references with the address of the function's CFI jump table + * entry. The function_nocfi macro always returns the address of the + * actual function instead. + */ +#define function_nocfi(x) ({ \ + void *addr; \ + asm("adrp %0, " __stringify(x) "\n\t" \ + "add %0, %0, :lo12:" __stringify(x) \ + : "=r" (addr)); \ + addr; \ +}) +#endif + /* * virt_to_page(x) convert a _valid_ virtual address to struct page * * virt_addr_valid(x) indicates whether a virtual address is valid -- cgit v1.2.3 From bde33977bf24b7ed52e2bac0eb9235769a0a11f6 Mon Sep 17 00:00:00 2001 From: Sami Tolvanen Date: Thu, 8 Apr 2021 11:28:38 -0700 Subject: arm64: use function_nocfi with __pa_symbol With CONFIG_CFI_CLANG, the compiler replaces function address references with the address of the function's CFI jump table entry. This means that __pa_symbol(function) returns the physical address of the jump table entry, which can lead to address space confusion as the jump table points to the function's virtual address. Therefore, use the function_nocfi() macro to ensure we are always taking the address of the actual function instead. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Acked-by: Mark Rutland Tested-by: Nathan Chancellor Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210408182843.1754385-14-samitolvanen@google.com --- arch/arm64/include/asm/mmu_context.h | 2 +- arch/arm64/kernel/acpi_parking_protocol.c | 3 ++- arch/arm64/kernel/cpu-reset.h | 2 +- arch/arm64/kernel/cpufeature.c | 2 +- arch/arm64/kernel/psci.c | 3 ++- arch/arm64/kernel/smp_spin_table.c | 3 ++- 6 files changed, 9 insertions(+), 6 deletions(-) (limited to 'arch/arm64/include/asm') diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index bd02e99b1a4c..386b96400a57 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -140,7 +140,7 @@ static inline void cpu_replace_ttbr1(pgd_t *pgdp) ttbr1 |= TTBR_CNP_BIT; } - replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1); + replace_phys = (void *)__pa_symbol(function_nocfi(idmap_cpu_replace_ttbr1)); cpu_install_idmap(); replace_phys(ttbr1); diff --git a/arch/arm64/kernel/acpi_parking_protocol.c b/arch/arm64/kernel/acpi_parking_protocol.c index e7c941d8340d..bfeeb5319abf 100644 --- a/arch/arm64/kernel/acpi_parking_protocol.c +++ b/arch/arm64/kernel/acpi_parking_protocol.c @@ -99,7 +99,8 @@ static int acpi_parking_protocol_cpu_boot(unsigned int cpu) * that read this address need to convert this address to the * Boot-Loader's endianness before jumping. */ - writeq_relaxed(__pa_symbol(secondary_entry), &mailbox->entry_point); + writeq_relaxed(__pa_symbol(function_nocfi(secondary_entry)), + &mailbox->entry_point); writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id); arch_send_wakeup_ipi_mask(cpumask_of(cpu)); diff --git a/arch/arm64/kernel/cpu-reset.h b/arch/arm64/kernel/cpu-reset.h index ed50e9587ad8..f3adc574f969 100644 --- a/arch/arm64/kernel/cpu-reset.h +++ b/arch/arm64/kernel/cpu-reset.h @@ -22,7 +22,7 @@ static inline void __noreturn cpu_soft_restart(unsigned long entry, unsigned long el2_switch = !is_kernel_in_hyp_mode() && is_hyp_mode_available(); - restart = (void *)__pa_symbol(__cpu_soft_restart); + restart = (void *)__pa_symbol(function_nocfi(__cpu_soft_restart)); cpu_install_idmap(); restart(el2_switch, entry, arg0, arg1, arg2); diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index e5281e1c8f1d..0b2e0d7b13ec 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1462,7 +1462,7 @@ kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) if (arm64_use_ng_mappings) return; - remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings); + remap_fn = (void *)__pa_symbol(function_nocfi(idmap_kpti_install_ng_mappings)); cpu_install_idmap(); remap_fn(cpu, num_online_cpus(), __pa_symbol(swapper_pg_dir)); diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c index 62d2bda7adb8..ab7f4c476104 100644 --- a/arch/arm64/kernel/psci.c +++ b/arch/arm64/kernel/psci.c @@ -38,7 +38,8 @@ static int __init cpu_psci_cpu_prepare(unsigned int cpu) static int cpu_psci_cpu_boot(unsigned int cpu) { - int err = psci_ops.cpu_on(cpu_logical_map(cpu), __pa_symbol(secondary_entry)); + phys_addr_t pa_secondary_entry = __pa_symbol(function_nocfi(secondary_entry)); + int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry); if (err) pr_err("failed to boot CPU%d (%d)\n", cpu, err); diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c index 056772c26098..c45a83512805 100644 --- a/arch/arm64/kernel/smp_spin_table.c +++ b/arch/arm64/kernel/smp_spin_table.c @@ -66,6 +66,7 @@ static int smp_spin_table_cpu_init(unsigned int cpu) static int smp_spin_table_cpu_prepare(unsigned int cpu) { __le64 __iomem *release_addr; + phys_addr_t pa_holding_pen = __pa_symbol(function_nocfi(secondary_holding_pen)); if (!cpu_release_addr[cpu]) return -ENODEV; @@ -88,7 +89,7 @@ static int smp_spin_table_cpu_prepare(unsigned int cpu) * boot-loader's endianness before jumping. This is mandated by * the boot protocol. */ - writeq_relaxed(__pa_symbol(secondary_holding_pen), release_addr); + writeq_relaxed(pa_holding_pen, release_addr); __flush_dcache_area((__force void *)release_addr, sizeof(*release_addr)); -- cgit v1.2.3 From cbdac8413e33bd1b9de45eeb10221c4686d743a6 Mon Sep 17 00:00:00 2001 From: Sami Tolvanen Date: Thu, 8 Apr 2021 11:28:39 -0700 Subject: arm64: add __nocfi to functions that jump to a physical address Disable CFI checking for functions that switch to linear mapping and make an indirect call to a physical address, since the compiler only understands virtual addresses and the CFI check for such indirect calls would always fail. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Nathan Chancellor Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210408182843.1754385-15-samitolvanen@google.com --- arch/arm64/include/asm/mmu_context.h | 2 +- arch/arm64/kernel/cpu-reset.h | 8 ++++---- arch/arm64/kernel/cpufeature.c | 2 +- 3 files changed, 6 insertions(+), 6 deletions(-) (limited to 'arch/arm64/include/asm') diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index 386b96400a57..d3cef9133539 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -119,7 +119,7 @@ static inline void cpu_install_idmap(void) * Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible PGD, * avoiding the possibility of conflicting TLB entries being allocated. */ -static inline void cpu_replace_ttbr1(pgd_t *pgdp) +static inline void __nocfi cpu_replace_ttbr1(pgd_t *pgdp) { typedef void (ttbr_replace_func)(phys_addr_t); extern ttbr_replace_func idmap_cpu_replace_ttbr1; diff --git a/arch/arm64/kernel/cpu-reset.h b/arch/arm64/kernel/cpu-reset.h index f3adc574f969..9a7b1262ef17 100644 --- a/arch/arm64/kernel/cpu-reset.h +++ b/arch/arm64/kernel/cpu-reset.h @@ -13,10 +13,10 @@ void __cpu_soft_restart(unsigned long el2_switch, unsigned long entry, unsigned long arg0, unsigned long arg1, unsigned long arg2); -static inline void __noreturn cpu_soft_restart(unsigned long entry, - unsigned long arg0, - unsigned long arg1, - unsigned long arg2) +static inline void __noreturn __nocfi cpu_soft_restart(unsigned long entry, + unsigned long arg0, + unsigned long arg1, + unsigned long arg2) { typeof(__cpu_soft_restart) *restart; diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 0b2e0d7b13ec..c2f94a5206e0 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1445,7 +1445,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, } #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 -static void +static void __nocfi kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) { typedef void (kpti_remap_fn)(int, int, phys_addr_t); -- cgit v1.2.3