On Wed, May 18, 2022 at 03:52:21PM -0400, Mike Snitzer wrote: > On Tue, May 17 2022 at 7:34P -0400, > Matthias Kaehlcke <mka@xxxxxxxxxxxx> wrote: > > > 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 <mka@xxxxxxxxxxxx> > > --- > > > > Changes in v4: > > - a trusted verity device must have a single target of > > type 'verity' > > - share list of verity digests with loadpin, deleted > > dm_verity_loadpin_set_trusted_root_digests() > > - dm_verity_loadpin_is_md_trusted() is now dm_verity_loadpin_is_sb_trusted(), > > it receives a super_block instead of mapped_device. Updated kernel doc. > > - changed struct trusted_root_digest to have an unsized > > u8 array instead of a pointer > > - extend 'dm-verity-objs' instead of 'dm-mod-objs' > > > > Changes in v3: > > - none > > > > Changes in v2: > > - none > > > > drivers/md/Makefile | 6 +++ > > drivers/md/dm-verity-loadpin.c | 74 +++++++++++++++++++++++++++++++ > > drivers/md/dm-verity-target.c | 33 ++++++++++++++ > > drivers/md/dm-verity.h | 4 ++ > > include/linux/dm-verity-loadpin.h | 27 +++++++++++ > > 5 files changed, 144 insertions(+) > > create mode 100644 drivers/md/dm-verity-loadpin.c > > create mode 100644 include/linux/dm-verity-loadpin.h > > > > 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..3226fbe4a1fe > > --- /dev/null > > +++ b/drivers/md/dm-verity-loadpin.c > > @@ -0,0 +1,74 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > + > > +#include <linux/list.h> > > +#include <linux/kernel.h> > > +#include <linux/dm-verity-loadpin.h> > > + > > +#include "dm.h" > > +#include "dm-verity.h" > > + > > +#define DM_MSG_PREFIX "verity-loadpin" > > + > > +LIST_HEAD(loadpin_trusted_verity_root_digests); > > + > > +static bool is_trusted_verity_target(struct dm_target *ti) > > +{ > > + u8 *root_digest; > > + unsigned int digest_size; > > + struct 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, &loadpin_trusted_verity_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_sb_trusted(struct super_block *sb) > > +{ > > + struct mapped_device *md; > > + struct dm_table *table; > > + struct dm_target *ti; > > + int srcu_idx; > > + bool trusted = false; > > + > > + if (list_empty(&loadpin_trusted_verity_root_digests)) > > + return false; > > + > > + md = dm_get_md(sb->s_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; > > +} > > Not seeing why passing a super_block a block layer interface was > chosen. > > Please pass the super_block's block_device and rename to > dm_verity_loadpin_is_bdev_trusted() Agreed, passing a block_device is a better choice here, I'll change it as suggested. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel