From b6c1c5745ccc68ac5d57c7ffb51ea25a86d0e97b Mon Sep 17 00:00:00 2001 From: Matthias Kaehlcke Date: Mon, 27 Jun 2022 08:35:24 -0700 Subject: dm: Add verity helpers for LoadPin LoadPin limits loading of kernel modules, firmware and certain other files to a 'pinned' file system (typically a read-only rootfs). To provide more flexibility LoadPin is being extended to also allow loading these files from trusted dm-verity devices. For that purpose LoadPin can be provided with a list of verity root digests that it should consider as trusted. Add a bunch of helpers to allow LoadPin to check whether a DM device is a trusted verity device. The new functions broadly fall in two categories: those that need access to verity internals (like the root digest), and the 'glue' between LoadPin and verity. The new file dm-verity-loadpin.c contains the glue functions. Signed-off-by: Matthias Kaehlcke Acked-by: Mike Snitzer Link: https://lore.kernel.org/lkml/20220627083512.v7.1.I3e928575a23481121e73286874c4c2bdb403355d@changeid Signed-off-by: Kees Cook --- drivers/md/Makefile | 6 ++++ drivers/md/dm-verity-loadpin.c | 74 ++++++++++++++++++++++++++++++++++++++++++ drivers/md/dm-verity-target.c | 33 ++++++++++++++++++- drivers/md/dm-verity.h | 4 +++ 4 files changed, 116 insertions(+), 1 deletion(-) create mode 100644 drivers/md/dm-verity-loadpin.c (limited to 'drivers') diff --git a/drivers/md/Makefile b/drivers/md/Makefile index 0454b0885b01..71771901c823 100644 --- a/drivers/md/Makefile +++ b/drivers/md/Makefile @@ -108,6 +108,12 @@ ifeq ($(CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG),y) dm-verity-objs += dm-verity-verify-sig.o endif +ifeq ($(CONFIG_DM_VERITY),y) +ifeq ($(CONFIG_SECURITY_LOADPIN),y) +dm-verity-objs += dm-verity-loadpin.o +endif +endif + ifeq ($(CONFIG_DM_AUDIT),y) dm-mod-objs += dm-audit.o endif diff --git a/drivers/md/dm-verity-loadpin.c b/drivers/md/dm-verity-loadpin.c new file mode 100644 index 000000000000..10c18bc1652c --- /dev/null +++ b/drivers/md/dm-verity-loadpin.c @@ -0,0 +1,74 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include +#include +#include + +#include "dm.h" +#include "dm-verity.h" + +#define DM_MSG_PREFIX "verity-loadpin" + +LIST_HEAD(dm_verity_loadpin_trusted_root_digests); + +static bool is_trusted_verity_target(struct dm_target *ti) +{ + u8 *root_digest; + unsigned int digest_size; + struct dm_verity_loadpin_trusted_root_digest *trd; + bool trusted = false; + + if (!dm_is_verity_target(ti)) + return false; + + if (dm_verity_get_root_digest(ti, &root_digest, &digest_size)) + return false; + + list_for_each_entry(trd, &dm_verity_loadpin_trusted_root_digests, node) { + if ((trd->len == digest_size) && + !memcmp(trd->data, root_digest, digest_size)) { + trusted = true; + break; + } + } + + kfree(root_digest); + + return trusted; +} + +/* + * Determines whether the file system of a superblock is located on + * a verity device that is trusted by LoadPin. + */ +bool dm_verity_loadpin_is_bdev_trusted(struct block_device *bdev) +{ + struct mapped_device *md; + struct dm_table *table; + struct dm_target *ti; + int srcu_idx; + bool trusted = false; + + if (list_empty(&dm_verity_loadpin_trusted_root_digests)) + return false; + + md = dm_get_md(bdev->bd_dev); + if (!md) + return false; + + table = dm_get_live_table(md, &srcu_idx); + + if (dm_table_get_num_targets(table) != 1) + goto out; + + ti = dm_table_get_target(table, 0); + + if (is_trusted_verity_target(ti)) + trusted = true; + +out: + dm_put_live_table(md, srcu_idx); + dm_put(md); + + return trusted; +} diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c index d6dbd47492a8..e5a01e2f96e9 100644 --- a/drivers/md/dm-verity-target.c +++ b/drivers/md/dm-verity-target.c @@ -19,6 +19,7 @@ #include #include #include +#include #define DM_MSG_PREFIX "verity" @@ -1310,10 +1311,40 @@ bad: return r; } +/* + * Check whether a DM target is a verity target. + */ +bool dm_is_verity_target(struct dm_target *ti) +{ + return ti->type->module == THIS_MODULE; +} + +/* + * Get the root digest of a verity target. + * + * Returns a copy of the root digest, the caller is responsible for + * freeing the memory of the digest. + */ +int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) +{ + struct dm_verity *v = ti->private; + + if (!dm_is_verity_target(ti)) + return -EINVAL; + + *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); + if (*root_digest == NULL) + return -ENOMEM; + + *digest_size = v->digest_size; + + return 0; +} + static struct target_type verity_target = { .name = "verity", .features = DM_TARGET_IMMUTABLE, - .version = {1, 8, 0}, + .version = {1, 8, 1}, .module = THIS_MODULE, .ctr = verity_ctr, .dtr = verity_dtr, diff --git a/drivers/md/dm-verity.h b/drivers/md/dm-verity.h index 4e769d13473a..c832cc3e3d24 100644 --- a/drivers/md/dm-verity.h +++ b/drivers/md/dm-verity.h @@ -129,4 +129,8 @@ extern int verity_hash(struct dm_verity *v, struct ahash_request *req, extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, sector_t block, u8 *digest, bool *is_zero); +extern bool dm_is_verity_target(struct dm_target *ti); +extern int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, + unsigned int *digest_size); + #endif /* DM_VERITY_H */ -- cgit From 231af4709018a8e4f20e511da4b6506346d662d3 Mon Sep 17 00:00:00 2001 From: Matthias Kaehlcke Date: Mon, 27 Jun 2022 08:35:26 -0700 Subject: dm: verity-loadpin: Use CONFIG_SECURITY_LOADPIN_VERITY for conditional compilation The verity glue for LoadPin is only needed when CONFIG_SECURITY_LOADPIN_VERITY is set, use this option for conditional compilation instead of the combo of CONFIG_DM_VERITY and CONFIG_SECURITY_LOADPIN. Signed-off-by: Matthias Kaehlcke Acked-by: Mike Snitzer Link: https://lore.kernel.org/lkml/20220627083512.v7.3.I5aca2dcc3b06de4bf53696cd21329dce8272b8aa@changeid Signed-off-by: Kees Cook --- drivers/md/Makefile | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) (limited to 'drivers') diff --git a/drivers/md/Makefile b/drivers/md/Makefile index 71771901c823..a96441752ec7 100644 --- a/drivers/md/Makefile +++ b/drivers/md/Makefile @@ -83,6 +83,7 @@ obj-$(CONFIG_DM_LOG_WRITES) += dm-log-writes.o obj-$(CONFIG_DM_INTEGRITY) += dm-integrity.o obj-$(CONFIG_DM_ZONED) += dm-zoned.o obj-$(CONFIG_DM_WRITECACHE) += dm-writecache.o +obj-$(CONFIG_SECURITY_LOADPIN_VERITY) += dm-verity-loadpin.o ifeq ($(CONFIG_DM_INIT),y) dm-mod-objs += dm-init.o @@ -108,12 +109,6 @@ ifeq ($(CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG),y) dm-verity-objs += dm-verity-verify-sig.o endif -ifeq ($(CONFIG_DM_VERITY),y) -ifeq ($(CONFIG_SECURITY_LOADPIN),y) -dm-verity-objs += dm-verity-loadpin.o -endif -endif - ifeq ($(CONFIG_DM_AUDIT),y) dm-mod-objs += dm-audit.o endif -- cgit From b4909252da9be56fe1e0a23c2c1908c5630525fa Mon Sep 17 00:00:00 2001 From: Justin Stitt Date: Thu, 21 Jul 2022 14:57:06 -0700 Subject: drivers: lkdtm: fix clang -Wformat warning When building with Clang we encounter the following warning (ARCH=hexagon + CONFIG_FRAME_WARN=0): | ../drivers/misc/lkdtm/bugs.c:107:3: error: format specifies type | 'unsigned long' but the argument has type 'int' [-Werror,-Wformat] | REC_STACK_SIZE, recur_count); | ^~~~~~~~~~~~~~ Cast REC_STACK_SIZE to `unsigned long` to match format specifier `%lu` as well as maintain symmetry with `#define REC_STACK_SIZE (_AC(CONFIG_FRAME_WARN, UL) / 2)`. Link: https://github.com/ClangBuiltLinux/linux/issues/378 Reported-by: Nathan Chancellor Suggested-by: Nathan Chancellor Suggested-by: Nick Desaulniers Signed-off-by: Justin Stitt Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor Acked-by: Kees Cook Fixes: 24cccab42c419 ("lkdtm/bugs: Adjust recursion test to avoid elision") Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220721215706.4153027-1-justinstitt@google.com --- drivers/misc/lkdtm/bugs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c index 009239ad1d8a..48821f4c2b21 100644 --- a/drivers/misc/lkdtm/bugs.c +++ b/drivers/misc/lkdtm/bugs.c @@ -29,7 +29,7 @@ struct lkdtm_list { #if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0) #define REC_STACK_SIZE (_AC(CONFIG_FRAME_WARN, UL) / 2) #else -#define REC_STACK_SIZE (THREAD_SIZE / 8) +#define REC_STACK_SIZE (THREAD_SIZE / 8UL) #endif #define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2) -- cgit From 27603a606fda0806d7c08914bc976931aa42020e Mon Sep 17 00:00:00 2001 From: Matthias Kaehlcke Date: Thu, 28 Jul 2022 08:54:41 -0700 Subject: dm: verity-loadpin: Drop use of dm_table_get_num_targets() Commit 2aec377a2925 ("dm table: remove dm_table_get_num_targets() wrapper") in linux-dm/for-next removed the function dm_table_get_num_targets() which is used by verity-loadpin. Access table->num_targets directly instead of using the defunct wrapper. Fixes: b6c1c5745ccc ("dm: Add verity helpers for LoadPin") Reported-by: Stephen Rothwell Signed-off-by: Matthias Kaehlcke Reviewed-by: Douglas Anderson Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220728085412.1.I242d21b378410eb6f9897a3160efb56e5608c59d@changeid --- drivers/md/dm-verity-loadpin.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/md/dm-verity-loadpin.c b/drivers/md/dm-verity-loadpin.c index 10c18bc1652c..387ec43aef72 100644 --- a/drivers/md/dm-verity-loadpin.c +++ b/drivers/md/dm-verity-loadpin.c @@ -5,6 +5,7 @@ #include #include "dm.h" +#include "dm-core.h" #include "dm-verity.h" #define DM_MSG_PREFIX "verity-loadpin" @@ -58,7 +59,7 @@ bool dm_verity_loadpin_is_bdev_trusted(struct block_device *bdev) table = dm_get_live_table(md, &srcu_idx); - if (dm_table_get_num_targets(table) != 1) + if (table->num_targets != 1) goto out; ti = dm_table_get_target(table, 0); -- cgit