From 00da8d65a3baea8c3745367bea99b1d76f8f129c Mon Sep 17 00:00:00 2001 From: Ilias Apalodimas Date: Thu, 18 Apr 2024 15:54:52 +0300 Subject: efi_loader: add an EFI variable with the file contents Previous patches enabled SetVariableRT using a RAM backend. Although EBBR [0] defines a variable format we can teach userspace tools and write the altered variables, it's better if we skip the ABI requirements completely. So let's add a new variable, in its own namespace called "VarToFile" which contains a binary dump of the updated RT, BS and, NV variables and will be updated when GetVariable is called. Some adjustments are needed to do that. Currently we discard BS-only variables in EBS(). We need to preserve those on the RAM backend that exposes the variables. Since BS-only variables can't appear at runtime we need to move the memory masking checks from efi_var_collect() to efi_get_next_variable_name_mem()/ efi_get_variable_mem() and do the filtering at runtime. We also need an efi_var_collect() variant available at runtime, in order to construct the "VarToFile" buffer on the fly. All users and applications (for linux) have to do when updating a variable is dd that variable in the file described by "RTStorageVolatile". Linux efivarfs uses a first 4 bytes of the output to represent attributes in little-endian format. So, storing variables works like this: $~ efibootmgr -n 0001 $~ dd if=/sys/firmware/efi/efivars/VarToFile-b2ac5fc9-92b7-4acd-aeac-11e818c3130c of=/boot/efi/ubootefi.var skip=4 bs=1 [0] https://arm-software.github.io/ebbr/index.html#document-chapter5-variable-storage Suggested-by: Ard Biesheuvel # dumping all variables to a variable Co-developed-by: Heinrich Schuchardt # contributed on efi_var_collect_mem() Signed-off-by: Heinrich Schuchardt Signed-off-by: Ilias Apalodimas --- lib/charset.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'lib/charset.c') diff --git a/lib/charset.c b/lib/charset.c index df4f0407485..182c92a50c4 100644 --- a/lib/charset.c +++ b/lib/charset.c @@ -387,7 +387,7 @@ int u16_strcasecmp(const u16 *s1, const u16 *s2) * > 0 if the first different u16 in s1 is greater than the * corresponding u16 in s2 */ -int u16_strncmp(const u16 *s1, const u16 *s2, size_t n) +int __efi_runtime u16_strncmp(const u16 *s1, const u16 *s2, size_t n) { int ret = 0; -- cgit v1.2.3