From 1a17e5b513ceebf21100027745b8731b4728edf7 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 9 Dec 2022 11:54:57 -0800 Subject: LoadPin: Ignore the "contents" argument of the LSM hooks LoadPin only enforces the read-only origin of kernel file reads. Whether or not it was a partial read isn't important. Remove the overly conservative checks so that things like partial firmware reads will succeed (i.e. reading a firmware header). Fixes: 2039bda1fa8d ("LSM: Add "contents" flag to kernel_read_file hook") Cc: Paul Moore Cc: James Morris Cc: "Serge E. Hallyn" Cc: linux-security-module@vger.kernel.org Signed-off-by: Kees Cook Acked-by: Serge Hallyn Tested-by: Ping-Ke Shih Link: https://lore.kernel.org/r/20221209195453.never.494-kees@kernel.org --- security/loadpin/loadpin.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) (limited to 'security') diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index de41621f4998..110a5ab2b46b 100644 --- a/security/loadpin/loadpin.c +++ b/security/loadpin/loadpin.c @@ -122,21 +122,11 @@ static void loadpin_sb_free_security(struct super_block *mnt_sb) } } -static int loadpin_read_file(struct file *file, enum kernel_read_file_id id, - bool contents) +static int loadpin_check(struct file *file, enum kernel_read_file_id id) { struct super_block *load_root; const char *origin = kernel_read_file_id_str(id); - /* - * If we will not know that we'll be seeing the full contents - * then we cannot trust a load will be complete and unchanged - * off disk. Treat all contents=false hooks as if there were - * no associated file struct. - */ - if (!contents) - file = NULL; - /* If the file id is excluded, ignore the pinning. */ if ((unsigned int)id < ARRAY_SIZE(ignore_read_file_id) && ignore_read_file_id[id]) { @@ -192,9 +182,25 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id, return 0; } +static int loadpin_read_file(struct file *file, enum kernel_read_file_id id, + bool contents) +{ + /* + * LoadPin only cares about the _origin_ of a file, not its + * contents, so we can ignore the "are full contents available" + * argument here. + */ + return loadpin_check(file, id); +} + static int loadpin_load_data(enum kernel_load_data_id id, bool contents) { - return loadpin_read_file(NULL, (enum kernel_read_file_id) id, contents); + /* + * LoadPin only cares about the _origin_ of a file, not its + * contents, so a NULL file is passed, and we can ignore the + * state of "contents". + */ + return loadpin_check(NULL, (enum kernel_read_file_id) id); } static struct security_hook_list loadpin_hooks[] __lsm_ro_after_init = { -- cgit v1.2.3 From d6a9fb87e9d18f3394a9845546bbe868efdccfd2 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Wed, 14 Dec 2022 16:26:03 -0700 Subject: security: Restrict CONFIG_ZERO_CALL_USED_REGS to gcc or clang > 15.0.6 A bad bug in clang's implementation of -fzero-call-used-regs can result in NULL pointer dereferences (see the links above the check for more information). Restrict CONFIG_CC_HAS_ZERO_CALL_USED_REGS to either a supported GCC version or a clang newer than 15.0.6, which will catch both a theoretical 15.0.7 and the upcoming 16.0.0, which will both have the bug fixed. Cc: stable@vger.kernel.org # v5.15+ Signed-off-by: Nathan Chancellor Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20221214232602.4118147-1-nathan@kernel.org --- security/Kconfig.hardening | 3 +++ 1 file changed, 3 insertions(+) (limited to 'security') diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening index d766b7d0ffd1..53baa95cb644 100644 --- a/security/Kconfig.hardening +++ b/security/Kconfig.hardening @@ -257,6 +257,9 @@ config INIT_ON_FREE_DEFAULT_ON config CC_HAS_ZERO_CALL_USED_REGS def_bool $(cc-option,-fzero-call-used-regs=used-gpr) + # https://github.com/ClangBuiltLinux/linux/issues/1766 + # https://github.com/llvm/llvm-project/issues/59242 + depends on !CC_IS_CLANG || CLANG_VERSION > 150006 config ZERO_CALL_USED_REGS bool "Enable register zeroing on function exit" -- cgit v1.2.3