This is a note to let you know that I've just added the patch titled LoadPin: Ignore the "contents" argument of the LSM hooks to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: loadpin-ignore-the-contents-argument-of-the-lsm-hook.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit adee6bd6107417ec4e963b498511a0f4e39e243e Author: Kees Cook <keescook@xxxxxxxxxxxx> Date: Fri Dec 9 11:54:57 2022 -0800 LoadPin: Ignore the "contents" argument of the LSM hooks [ Upstream commit 1a17e5b513ceebf21100027745b8731b4728edf7 ] 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 <paul@xxxxxxxxxxxxxx> Cc: James Morris <jmorris@xxxxxxxxx> Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx> Cc: linux-security-module@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Acked-by: Serge Hallyn <serge@xxxxxxxxxx> Tested-by: Ping-Ke Shih <pkshih@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20221209195453.never.494-kees@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index b12f7d986b1e..5fce105a372d 100644 --- a/security/loadpin/loadpin.c +++ b/security/loadpin/loadpin.c @@ -118,21 +118,11 @@ 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]) { @@ -187,9 +177,25 @@ 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 = {