| Message ID | 1391619853-10601-22-git-send-email-leif.lindholm@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 5 February 2014 18:04, Leif Lindholm <leif.lindholm@linaro.org> wrote: > From: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > Loading unauthenticated FDT blobs directly from storage is a security hazard, > so this should only be allowed when running with UEFI Secure Boot disabled. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org> > --- > drivers/firmware/efi/arm-stub.c | 4 +++- > drivers/firmware/efi/efi-stub-helper.c | 24 ++++++++++++++++++++++++ > 2 files changed, 27 insertions(+), 1 deletion(-) > > diff --git a/drivers/firmware/efi/arm-stub.c b/drivers/firmware/efi/arm-stub.c > index b505fde..c651082 100644 > --- a/drivers/firmware/efi/arm-stub.c > +++ b/drivers/firmware/efi/arm-stub.c > @@ -95,7 +95,9 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table, > > /* Load a device tree from the configuration table, if present. */ > fdt_addr = (uintptr_t)get_fdt(sys_table); > - if (!fdt_addr) { > + if (efi_secureboot_enabled(sys_table)) > + pr_efi(sys_table, "UEFI Secure Boot is enabled, ignoring dtb= commandline option.\n"); I am pretty sure my original patch had braces on both branches of the if () :-) Also, I think the precedence is backward here: dtb= should trump config table, not the other way around.
diff --git a/drivers/firmware/efi/arm-stub.c b/drivers/firmware/efi/arm-stub.c index b505fde..c651082 100644 --- a/drivers/firmware/efi/arm-stub.c +++ b/drivers/firmware/efi/arm-stub.c @@ -95,7 +95,9 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table, /* Load a device tree from the configuration table, if present. */ fdt_addr = (uintptr_t)get_fdt(sys_table); - if (!fdt_addr) { + if (efi_secureboot_enabled(sys_table)) + pr_efi(sys_table, "UEFI Secure Boot is enabled, ignoring dtb= commandline option.\n"); + else if (!fdt_addr) { status = handle_cmdline_files(sys_table, image, cmdline_ptr, "dtb=", ~0UL, (unsigned long *)&fdt_addr, diff --git a/drivers/firmware/efi/efi-stub-helper.c b/drivers/firmware/efi/efi-stub-helper.c index 2ee69ea..6221be7 100644 --- a/drivers/firmware/efi/efi-stub-helper.c +++ b/drivers/firmware/efi/efi-stub-helper.c @@ -721,3 +721,27 @@ static char *efi_convert_cmdline(efi_system_table_t *sys_table_arg, *cmd_line_len = options_bytes; return (char *)cmdline_addr; } + +static int __init efi_secureboot_enabled(efi_system_table_t *sys_table_arg) +{ + static efi_guid_t const var_guid __initconst = EFI_GLOBAL_VARIABLE_GUID; + static efi_char16_t const var_name[] __initconst = { + 'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 }; + + efi_get_variable_t *f_getvar = sys_table_arg->runtime->get_variable; + unsigned long size = sizeof(u8); + efi_status_t status; + u8 val; + + status = efi_call_phys5(f_getvar, (efi_char16_t *)var_name, + (efi_guid_t *)&var_guid, NULL, &size, &val); + + switch (status) { + case EFI_SUCCESS: + return val; + case EFI_NOT_FOUND: + return 0; + default: + return 1; + } +}