From 63056e8b5ebf41d52170e9f5ba1fc83d1855278c Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 21 Feb 2020 09:48:46 +0100 Subject: [PATCH 1/4] efi/x86: Align GUIDs to their size in the mixed mode runtime wrapper Hans reports that his mixed mode systems running v5.6-rc1 kernels hit the WARN_ON() in virt_to_phys_or_null_size(), caused by the fact that efi_guid_t objects on the vmap'ed stack happen to be misaligned with respect to their sizes. As a quick (i.e., backportable) fix, copy GUID pointer arguments to the local stack into a buffer that is naturally aligned to its size, so that it is guaranteed to cover only one physical page. Note that on x86, we cannot rely on the stack pointer being aligned the way the compiler expects, so we need to allocate an 8-byte aligned buffer of sufficient size, and copy the GUID into that buffer at an offset that is aligned to 16 bytes. Fixes: f6697df36bdf0bf7 ("x86/efi: Prevent mixed mode boot corruption with CONFIG_VMAP_STACK=y") Reported-by: Hans de Goede Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Tested-by: Hans de Goede Cc: linux-efi@vger.kernel.org Cc: Ingo Molnar Cc: Thomas Gleixner Link: https://lore.kernel.org/r/20200221084849.26878-2-ardb@kernel.org --- arch/x86/platform/efi/efi_64.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index fa8506e76bbe..543edfdcd1b9 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -658,6 +658,8 @@ static efi_status_t efi_thunk_get_variable(efi_char16_t *name, efi_guid_t *vendor, u32 *attr, unsigned long *data_size, void *data) { + u8 buf[24] __aligned(8); + efi_guid_t *vnd = PTR_ALIGN((efi_guid_t *)buf, sizeof(*vnd)); efi_status_t status; u32 phys_name, phys_vendor, phys_attr; u32 phys_data_size, phys_data; @@ -665,8 +667,10 @@ efi_thunk_get_variable(efi_char16_t *name, efi_guid_t *vendor, spin_lock_irqsave(&efi_runtime_lock, flags); + *vnd = *vendor; + phys_data_size = virt_to_phys_or_null(data_size); - phys_vendor = virt_to_phys_or_null(vendor); + phys_vendor = virt_to_phys_or_null(vnd); phys_name = virt_to_phys_or_null_size(name, efi_name_size(name)); phys_attr = virt_to_phys_or_null(attr); phys_data = virt_to_phys_or_null_size(data, *data_size); @@ -683,14 +687,18 @@ static efi_status_t efi_thunk_set_variable(efi_char16_t *name, efi_guid_t *vendor, u32 attr, unsigned long data_size, void *data) { + u8 buf[24] __aligned(8); + efi_guid_t *vnd = PTR_ALIGN((efi_guid_t *)buf, sizeof(*vnd)); u32 phys_name, phys_vendor, phys_data; efi_status_t status; unsigned long flags; spin_lock_irqsave(&efi_runtime_lock, flags); + *vnd = *vendor; + phys_name = virt_to_phys_or_null_size(name, efi_name_size(name)); - phys_vendor = virt_to_phys_or_null(vendor); + phys_vendor = virt_to_phys_or_null(vnd); phys_data = virt_to_phys_or_null_size(data, data_size); /* If data_size is > sizeof(u32) we've got problems */ @@ -707,6 +715,8 @@ efi_thunk_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor, u32 attr, unsigned long data_size, void *data) { + u8 buf[24] __aligned(8); + efi_guid_t *vnd = PTR_ALIGN((efi_guid_t *)buf, sizeof(*vnd)); u32 phys_name, phys_vendor, phys_data; efi_status_t status; unsigned long flags; @@ -714,8 +724,10 @@ efi_thunk_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor, if (!spin_trylock_irqsave(&efi_runtime_lock, flags)) return EFI_NOT_READY; + *vnd = *vendor; + phys_name = virt_to_phys_or_null_size(name, efi_name_size(name)); - phys_vendor = virt_to_phys_or_null(vendor); + phys_vendor = virt_to_phys_or_null(vnd); phys_data = virt_to_phys_or_null_size(data, data_size); /* If data_size is > sizeof(u32) we've got problems */ @@ -732,14 +744,18 @@ efi_thunk_get_next_variable(unsigned long *name_size, efi_char16_t *name, efi_guid_t *vendor) { + u8 buf[24] __aligned(8); + efi_guid_t *vnd = PTR_ALIGN((efi_guid_t *)buf, sizeof(*vnd)); efi_status_t status; u32 phys_name_size, phys_name, phys_vendor; unsigned long flags; spin_lock_irqsave(&efi_runtime_lock, flags); + *vnd = *vendor; + phys_name_size = virt_to_phys_or_null(name_size); - phys_vendor = virt_to_phys_or_null(vendor); + phys_vendor = virt_to_phys_or_null(vnd); phys_name = virt_to_phys_or_null_size(name, *name_size); status = efi_thunk(get_next_variable, phys_name_size, @@ -747,6 +763,7 @@ efi_thunk_get_next_variable(unsigned long *name_size, spin_unlock_irqrestore(&efi_runtime_lock, flags); + *vendor = *vnd; return status; } From f80c9f6476db6c0802545aaa44eb9a38e751786a Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 21 Feb 2020 09:48:47 +0100 Subject: [PATCH 2/4] efi/x86: Remove support for EFI time and counter services in mixed mode Mixed mode calls at runtime are rather tricky with vmap'ed stacks, as we can no longer assume that data passed in by the callers of the EFI runtime wrapper routines is contiguous in physical memory. We need to fix this, but before we do, let's drop the implementations of routines that we know are never used on x86, i.e., the RTC related ones. Given that UEFI rev2.8 permits any runtime service to return EFI_UNSUPPORTED at runtime, let's return that instead. As get_next_high_mono_count() is never used at all, even on other architectures, let's make that return EFI_UNSUPPORTED too. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: linux-efi@vger.kernel.org Cc: Ingo Molnar Cc: Thomas Gleixner Link: https://lore.kernel.org/r/20200221084849.26878-3-ardb@kernel.org --- arch/x86/platform/efi/efi_64.c | 81 +++------------------------------- 1 file changed, 5 insertions(+), 76 deletions(-) diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index 543edfdcd1b9..ae398587f264 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -568,85 +568,25 @@ efi_thunk_set_virtual_address_map(unsigned long memory_map_size, static efi_status_t efi_thunk_get_time(efi_time_t *tm, efi_time_cap_t *tc) { - efi_status_t status; - u32 phys_tm, phys_tc; - unsigned long flags; - - spin_lock(&rtc_lock); - spin_lock_irqsave(&efi_runtime_lock, flags); - - phys_tm = virt_to_phys_or_null(tm); - phys_tc = virt_to_phys_or_null(tc); - - status = efi_thunk(get_time, phys_tm, phys_tc); - - spin_unlock_irqrestore(&efi_runtime_lock, flags); - spin_unlock(&rtc_lock); - - return status; + return EFI_UNSUPPORTED; } static efi_status_t efi_thunk_set_time(efi_time_t *tm) { - efi_status_t status; - u32 phys_tm; - unsigned long flags; - - spin_lock(&rtc_lock); - spin_lock_irqsave(&efi_runtime_lock, flags); - - phys_tm = virt_to_phys_or_null(tm); - - status = efi_thunk(set_time, phys_tm); - - spin_unlock_irqrestore(&efi_runtime_lock, flags); - spin_unlock(&rtc_lock); - - return status; + return EFI_UNSUPPORTED; } static efi_status_t efi_thunk_get_wakeup_time(efi_bool_t *enabled, efi_bool_t *pending, efi_time_t *tm) { - efi_status_t status; - u32 phys_enabled, phys_pending, phys_tm; - unsigned long flags; - - spin_lock(&rtc_lock); - spin_lock_irqsave(&efi_runtime_lock, flags); - - phys_enabled = virt_to_phys_or_null(enabled); - phys_pending = virt_to_phys_or_null(pending); - phys_tm = virt_to_phys_or_null(tm); - - status = efi_thunk(get_wakeup_time, phys_enabled, - phys_pending, phys_tm); - - spin_unlock_irqrestore(&efi_runtime_lock, flags); - spin_unlock(&rtc_lock); - - return status; + return EFI_UNSUPPORTED; } static efi_status_t efi_thunk_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm) { - efi_status_t status; - u32 phys_tm; - unsigned long flags; - - spin_lock(&rtc_lock); - spin_lock_irqsave(&efi_runtime_lock, flags); - - phys_tm = virt_to_phys_or_null(tm); - - status = efi_thunk(set_wakeup_time, enabled, phys_tm); - - spin_unlock_irqrestore(&efi_runtime_lock, flags); - spin_unlock(&rtc_lock); - - return status; + return EFI_UNSUPPORTED; } static unsigned long efi_name_size(efi_char16_t *name) @@ -770,18 +710,7 @@ efi_thunk_get_next_variable(unsigned long *name_size, static efi_status_t efi_thunk_get_next_high_mono_count(u32 *count) { - efi_status_t status; - u32 phys_count; - unsigned long flags; - - spin_lock_irqsave(&efi_runtime_lock, flags); - - phys_count = virt_to_phys_or_null(count); - status = efi_thunk(get_next_high_mono_count, phys_count); - - spin_unlock_irqrestore(&efi_runtime_lock, flags); - - return status; + return EFI_UNSUPPORTED; } static void From 8319e9d5ad98ffccd19f35664382c73cea216193 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 21 Feb 2020 09:48:48 +0100 Subject: [PATCH 3/4] efi/x86: Handle by-ref arguments covering multiple pages in mixed mode The mixed mode runtime wrappers are fragile when it comes to how the memory referred to by its pointer arguments are laid out in memory, due to the fact that it translates these addresses to physical addresses that the runtime services can dereference when running in 1:1 mode. Since vmalloc'ed pages (including the vmap'ed stack) are not contiguous in the physical address space, this scheme only works if the referenced memory objects do not cross page boundaries. Currently, the mixed mode runtime service wrappers require that all by-ref arguments that live in the vmalloc space have a size that is a power of 2, and are aligned to that same value. While this is a sensible way to construct an object that is guaranteed not to cross a page boundary, it is overly strict when it comes to checking whether a given object violates this requirement, as we can simply take the physical address of the first and the last byte, and verify that they point into the same physical page. When this check fails, we emit a WARN(), but then simply proceed with the call, which could cause data corruption if the next physical page belongs to a mapping that is entirely unrelated. Given that with vmap'ed stacks, this condition is much more likely to trigger, let's relax the condition a bit, but fail the runtime service call if it does trigger. Fixes: f6697df36bdf0bf7 ("x86/efi: Prevent mixed mode boot corruption with CONFIG_VMAP_STACK=y") Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: linux-efi@vger.kernel.org Cc: Ingo Molnar Cc: Thomas Gleixner Link: https://lore.kernel.org/r/20200221084849.26878-4-ardb@kernel.org --- arch/x86/platform/efi/efi_64.c | 45 ++++++++++++++++++++-------------- 1 file changed, 26 insertions(+), 19 deletions(-) diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index ae398587f264..d19a2edd63cb 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -180,7 +180,7 @@ void efi_sync_low_kernel_mappings(void) static inline phys_addr_t virt_to_phys_or_null_size(void *va, unsigned long size) { - bool bad_size; + phys_addr_t pa; if (!va) return 0; @@ -188,16 +188,13 @@ virt_to_phys_or_null_size(void *va, unsigned long size) if (virt_addr_valid(va)) return virt_to_phys(va); - /* - * A fully aligned variable on the stack is guaranteed not to - * cross a page bounary. Try to catch strings on the stack by - * checking that 'size' is a power of two. - */ - bad_size = size > PAGE_SIZE || !is_power_of_2(size); + pa = slow_virt_to_phys(va); - WARN_ON(!IS_ALIGNED((unsigned long)va, size) || bad_size); + /* check if the object crosses a page boundary */ + if (WARN_ON((pa ^ (pa + size - 1)) & PAGE_MASK)) + return 0; - return slow_virt_to_phys(va); + return pa; } #define virt_to_phys_or_null(addr) \ @@ -615,8 +612,11 @@ efi_thunk_get_variable(efi_char16_t *name, efi_guid_t *vendor, phys_attr = virt_to_phys_or_null(attr); phys_data = virt_to_phys_or_null_size(data, *data_size); - status = efi_thunk(get_variable, phys_name, phys_vendor, - phys_attr, phys_data_size, phys_data); + if (!phys_name || (data && !phys_data)) + status = EFI_INVALID_PARAMETER; + else + status = efi_thunk(get_variable, phys_name, phys_vendor, + phys_attr, phys_data_size, phys_data); spin_unlock_irqrestore(&efi_runtime_lock, flags); @@ -641,9 +641,11 @@ efi_thunk_set_variable(efi_char16_t *name, efi_guid_t *vendor, phys_vendor = virt_to_phys_or_null(vnd); phys_data = virt_to_phys_or_null_size(data, data_size); - /* If data_size is > sizeof(u32) we've got problems */ - status = efi_thunk(set_variable, phys_name, phys_vendor, - attr, data_size, phys_data); + if (!phys_name || !phys_data) + status = EFI_INVALID_PARAMETER; + else + status = efi_thunk(set_variable, phys_name, phys_vendor, + attr, data_size, phys_data); spin_unlock_irqrestore(&efi_runtime_lock, flags); @@ -670,9 +672,11 @@ efi_thunk_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor, phys_vendor = virt_to_phys_or_null(vnd); phys_data = virt_to_phys_or_null_size(data, data_size); - /* If data_size is > sizeof(u32) we've got problems */ - status = efi_thunk(set_variable, phys_name, phys_vendor, - attr, data_size, phys_data); + if (!phys_name || !phys_data) + status = EFI_INVALID_PARAMETER; + else + status = efi_thunk(set_variable, phys_name, phys_vendor, + attr, data_size, phys_data); spin_unlock_irqrestore(&efi_runtime_lock, flags); @@ -698,8 +702,11 @@ efi_thunk_get_next_variable(unsigned long *name_size, phys_vendor = virt_to_phys_or_null(vnd); phys_name = virt_to_phys_or_null_size(name, *name_size); - status = efi_thunk(get_next_variable, phys_name_size, - phys_name, phys_vendor); + if (!phys_name) + status = EFI_INVALID_PARAMETER; + else + status = efi_thunk(get_next_variable, phys_name_size, + phys_name, phys_vendor); spin_unlock_irqrestore(&efi_runtime_lock, flags); From be36f9e7517e17810ec369626a128d7948942259 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Fri, 21 Feb 2020 09:48:49 +0100 Subject: [PATCH 4/4] efi: READ_ONCE rng seed size before munmap This function is consistent with using size instead of seed->size (except for one place that this patch fixes), but it reads seed->size without using READ_ONCE, which means the compiler might still do something unwanted. So, this commit simply adds the READ_ONCE wrapper. Fixes: 636259880a7e ("efi: Add support for seeding the RNG from a UEFI ...") Signed-off-by: Jason A. Donenfeld Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: linux-efi@vger.kernel.org Cc: Ingo Molnar Cc: Thomas Gleixner Link: https://lore.kernel.org/r/20200217123354.21140-1-Jason@zx2c4.com Link: https://lore.kernel.org/r/20200221084849.26878-5-ardb@kernel.org --- drivers/firmware/efi/efi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 621220ab3d0e..21ea99f65113 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -552,7 +552,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz, seed = early_memremap(efi.rng_seed, sizeof(*seed)); if (seed != NULL) { - size = seed->size; + size = READ_ONCE(seed->size); early_memunmap(seed, sizeof(*seed)); } else { pr_err("Could not map UEFI random seed!\n"); @@ -562,7 +562,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz, sizeof(*seed) + size); if (seed != NULL) { pr_notice("seeding entropy pool\n"); - add_bootloader_randomness(seed->bits, seed->size); + add_bootloader_randomness(seed->bits, size); early_memunmap(seed, sizeof(*seed) + size); } else { pr_err("Could not map UEFI random seed!\n");