From: Kees Cook keescook@chromium.org
[ 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@paul-moore.com Cc: James Morris jmorris@namei.org Cc: "Serge E. Hallyn" serge@hallyn.com Cc: linux-security-module@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org Acked-by: Serge Hallyn serge@hallyn.com Tested-by: Ping-Ke Shih pkshih@realtek.com Link: https://lore.kernel.org/r/20221209195453.never.494-kees@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- security/loadpin/loadpin.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-)
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 = {