From b89999d004931ab2e5123611ace7dab77328f8d6 Mon Sep 17 00:00:00 2001 From: Scott Branden Date: Fri, 2 Oct 2020 10:38:15 -0700 Subject: fs/kernel_read_file: Split into separate include file Move kernel_read_file* out of linux/fs.h to its own linux/kernel_read_file.h include file. That header gets pulled in just about everywhere and doesn't really need functions not related to the general fs interface. Suggested-by: Christoph Hellwig Signed-off-by: Scott Branden Signed-off-by: Kees Cook Reviewed-by: Christoph Hellwig Reviewed-by: Mimi Zohar Reviewed-by: Luis Chamberlain Acked-by: Greg Kroah-Hartman Acked-by: James Morris Link: https://lore.kernel.org/r/20200706232309.12010-2-scott.branden@broadcom.com Link: https://lore.kernel.org/r/20201002173828.2099543-4-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman --- security/loadpin/loadpin.c | 1 + 1 file changed, 1 insertion(+) (limited to 'security/loadpin/loadpin.c') diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index 670a1aebb8a1..163c48216d13 100644 --- a/security/loadpin/loadpin.c +++ b/security/loadpin/loadpin.c @@ -11,6 +11,7 @@ #include #include +#include #include #include #include -- cgit From b64fcae74b6d6940d14243c963ab0089e8f0d82d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 2 Oct 2020 10:38:20 -0700 Subject: LSM: Introduce kernel_post_load_data() hook There are a few places in the kernel where LSMs would like to have visibility into the contents of a kernel buffer that has been loaded or read. While security_kernel_post_read_file() (which includes the buffer) exists as a pairing for security_kernel_read_file(), no such hook exists to pair with security_kernel_load_data(). Earlier proposals for just using security_kernel_post_read_file() with a NULL file argument were rejected (i.e. "file" should always be valid for the security_..._file hooks, but it appears at least one case was left in the kernel during earlier refactoring. (This will be fixed in a subsequent patch.) Since not all cases of security_kernel_load_data() can have a single contiguous buffer made available to the LSM hook (e.g. kexec image segments are separately loaded), there needs to be a way for the LSM to reason about its expectations of the hook coverage. In order to handle this, add a "contents" argument to the "kernel_load_data" hook that indicates if the newly added "kernel_post_load_data" hook will be called with the full contents once loaded. That way, LSMs requiring full contents can choose to unilaterally reject "kernel_load_data" with contents=false (which is effectively the existing hook coverage), but when contents=true they can allow it and later evaluate the "kernel_post_load_data" hook once the buffer is loaded. With this change, LSMs can gain coverage over non-file-backed data loads (e.g. init_module(2) and firmware userspace helper), which will happen in subsequent patches. Additionally prepare IMA to start processing these cases. Signed-off-by: Kees Cook Reviewed-by: KP Singh Link: https://lore.kernel.org/r/20201002173828.2099543-9-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman --- security/loadpin/loadpin.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'security/loadpin/loadpin.c') diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index 163c48216d13..28782412febb 100644 --- a/security/loadpin/loadpin.c +++ b/security/loadpin/loadpin.c @@ -177,7 +177,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id) return 0; } -static int loadpin_load_data(enum kernel_load_data_id 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); } -- cgit From 2039bda1fa8dad3f4275b29eeaffef545bcbc85d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 2 Oct 2020 10:38:23 -0700 Subject: LSM: Add "contents" flag to kernel_read_file hook As with the kernel_load_data LSM hook, add a "contents" flag to the kernel_read_file LSM hook that indicates whether the LSM can expect a matching call to the kernel_post_read_file LSM hook with the full contents of the file. With the coming addition of partial file read support for kernel_read_file*() API, the LSM will no longer be able to always see the entire contents of a file during the read calls. For cases where the LSM must read examine the complete file contents, it will need to do so on its own every time the kernel_read_file hook is called with contents=false (or reject such cases). Adjust all existing LSMs to retain existing behavior. Signed-off-by: Kees Cook Reviewed-by: Mimi Zohar Link: https://lore.kernel.org/r/20201002173828.2099543-12-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman --- security/loadpin/loadpin.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'security/loadpin/loadpin.c') diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index 28782412febb..b12f7d986b1e 100644 --- a/security/loadpin/loadpin.c +++ b/security/loadpin/loadpin.c @@ -118,11 +118,21 @@ 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) +static int loadpin_read_file(struct file *file, enum kernel_read_file_id id, + bool contents) { 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]) { @@ -179,7 +189,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id 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); + return loadpin_read_file(NULL, (enum kernel_read_file_id) id, contents); } static struct security_hook_list loadpin_hooks[] __lsm_ro_after_init = { -- cgit