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path: root/fs/efivarfs/vars.c
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2025-01-22efivarfs: add variable resync after hibernationJames Bottomley
Hibernation allows other OSs to boot and thus the variable state might be altered by the time the hibernation image is resumed. Resync the variable state by looping over all the dentries and update the size (in case of alteration) delete any which no-longer exist. Finally, loop over all efi variables creating any which don't have corresponding dentries. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> [ardb: - apply error pointer fixup from Dan Carpenter - rebase onto latest version of James's efivarfs rework] Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-01-19efivarfs: remove unused efivarfs_listJames Bottomley
Remove all function helpers and mentions of the efivarfs_list now that all consumers of the list have been removed and entry management goes exclusively through the inode. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-01-19efivarfs: move variable lifetime management into the inodesJames Bottomley
Make the inodes the default management vehicle for struct efivar_entry, so they are now all freed automatically if the file is removed and on unmount in kill_litter_super(). Remove the now superfluous iterator to free the entries after kill_litter_super(). Also fixes a bug where some entry freeing was missing causing efivarfs to leak memory. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-01-09efivarfs: make variable_is_present use dcache lookupJames Bottomley
Instead of searching the variable entry list for a variable, use the dcache lookup functions to find it instead. Also add an efivarfs_ prefix to the function now it is no longer static. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-01-09efivarfs: add helper to convert from UC16 name and GUID to utf8 nameJames Bottomley
These will be used by a later patch to check for uniqueness on initial EFI variable iteration. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2024-12-02module: Convert symbol namespace to string literalPeter Zijlstra
Clean up the existing export namespace code along the same lines of commit 33def8498fdd ("treewide: Convert macro and uses of __section(foo) to __section("foo")") and for the same reason, it is not desired for the namespace argument to be a macro expansion itself. Scripted using git grep -l -e MODULE_IMPORT_NS -e EXPORT_SYMBOL_NS | while read file; do awk -i inplace ' /^#define EXPORT_SYMBOL_NS/ { gsub(/__stringify\(ns\)/, "ns"); print; next; } /^#define MODULE_IMPORT_NS/ { gsub(/__stringify\(ns\)/, "ns"); print; next; } /MODULE_IMPORT_NS/ { $0 = gensub(/MODULE_IMPORT_NS\(([^)]*)\)/, "MODULE_IMPORT_NS(\"\\1\")", "g"); } /EXPORT_SYMBOL_NS/ { if ($0 ~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+),/) { if ($0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)\)/ && $0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(\)/ && $0 !~ /^my/) { getline line; gsub(/[[:space:]]*\\$/, ""); gsub(/[[:space:]]/, "", line); $0 = $0 " " line; } $0 = gensub(/(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)\)/, "\\1(\\2, \"\\3\")", "g"); } } { print }' $file; done Requested-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://mail.google.com/mail/u/2/#inbox/FMfcgzQXKWgMmjdFwwdsfgxzKpVHWPlc Acked-by: Greg KH <gregkh@linuxfoundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2024-04-13efi: Clear up misconceptions about a maximum variable name sizeTim Schumacher
The UEFI specification does not make any mention of a maximum variable name size, so the headers and implementation shouldn't claim that one exists either. Comments referring to this limit have been removed or rewritten, as this is an implementation detail local to the Linux kernel. Where appropriate, the magic value of 1024 has been replaced with EFI_VAR_NAME_LEN, as this is used for the efi_variable struct definition. This in itself does not change any behavior, but should serve as points of interest when making future changes in the same area. A related build-time check has been added to ensure that the special 512 byte sized buffer will not overflow with a potentially decreased EFI_VAR_NAME_LEN. Signed-off-by: Tim Schumacher <timschumi@gmx.de> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2024-02-25efivarfs: Drop 'duplicates' bool parameter on efivar_init()Ard Biesheuvel
The 'duplicates' bool argument is always true when efivar_init() is called from its only caller so let's just drop it instead. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2024-02-25efivarfs: Request at most 512 bytes for variable namesTim Schumacher
Work around a quirk in a few old (2011-ish) UEFI implementations, where a call to `GetNextVariableName` with a buffer size larger than 512 bytes will always return EFI_INVALID_PARAMETER. There is some lore around EFI variable names being up to 1024 bytes in size, but this has no basis in the UEFI specification, and the upper bounds are typically platform specific, and apply to the entire variable (name plus payload). Given that Linux does not permit creating files with names longer than NAME_MAX (255) bytes, 512 bytes (== 256 UTF-16 characters) is a reasonable limit. Cc: <stable@vger.kernel.org> # 6.1+ Signed-off-by: Tim Schumacher <timschumi@gmx.de> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2023-12-11efivarfs: Move efivarfs list into superblock s_fs_infoArd Biesheuvel
syzbot reports issues with concurrent fsopen()/fsconfig() invocations on efivarfs, which are the result of the fact that the efivarfs list (which caches the names and GUIDs of existing EFI variables) is a global structure. In normal use, these issues are unlikely to trigger, even in the presence of multiple mounts of efivarfs, but the execution pattern used by the syzkaller reproducer may result in multiple instances of the superblock that share the global efivarfs list, and this causes list corruption when the list is reinitialized by one user while another is traversing it. So let's move the list head into the superblock s_fs_info field, so that it will never be shared between distinct instances of the superblock. In the common case, there will still be a single instance of this list, but in the artificial syzkaller case, no list corruption can occur any longer. Reported-by: syzbot+1902c359bfcaf39c46f2@syzkaller.appspotmail.com Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-10-21efi: efivars: Fix variable writes without query_variable_store()Ard Biesheuvel
Commit bbc6d2c6ef22 ("efi: vars: Switch to new wrapper layer") refactored the efivars layer so that the 'business logic' related to which UEFI variables affect the boot flow in which way could be moved out of it, and into the efivarfs driver. This inadvertently broke setting variables on firmware implementations that lack the QueryVariableInfo() boot service, because we no longer tolerate a EFI_UNSUPPORTED result from check_var_size() when calling efivar_entry_set_get_size(), which now ends up calling check_var_size() a second time inadvertently. If QueryVariableInfo() is missing, we support writes of up to 64k - let's move that logic into check_var_size(), and drop the redundant call. Cc: <stable@vger.kernel.org> # v6.0 Fixes: bbc6d2c6ef22 ("efi: vars: Switch to new wrapper layer") Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-06-24efi: vars: Move efivar caching layer into efivarfsArd Biesheuvel
Move the fiddly bits of the efivar layer into its only remaining user, efivarfs, and confine its use to that particular module. All other uses of the EFI variable store have no need for this additional layer of complexity, given that they either only read variables, or read and write variables into a separate GUIDed namespace, and cannot be used to manipulate EFI variables that are covered by the EFI spec and/or affect the boot flow. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>