| Message ID | 1706654228-17180-13-git-send-email-wufan@linux.microsoft.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
| Series | Integrity Policy Enforcement LSM (IPE) | expand |
On Tue, Jan 30 2024 at 5:37P -0500, Fan Wu <wufan@linux.microsoft.com> wrote: > The device-mapper has a flag to mark targets as singleton, which is a > required flag for immutable targets. Without this flag, multiple > dm-verity targets can be added to a mapped device, which has no > practical use cases and will let dm_table_get_immutable_target return > NULL. This patch adds the missing flag, restricting only one > dm-verity target per mapped device. > > Signed-off-by: Fan Wu <wufan@linux.microsoft.com> > > --- > v1-v10: > + Not present > > v11: > + Introduced > > v12: > + No changes > --- > drivers/md/dm-verity-target.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c > index 14e58ae70521..66a850c02be4 100644 > --- a/drivers/md/dm-verity-target.c > +++ b/drivers/md/dm-verity-target.c > @@ -1507,7 +1507,7 @@ int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned i > > static struct target_type verity_target = { > .name = "verity", > - .features = DM_TARGET_IMMUTABLE, > + .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, > .version = {1, 9, 0}, > .module = THIS_MODULE, > .ctr = verity_ctr, > -- > 2.43.0 > > It is true this change will cause dm_table_get_immutable_target() to not return NULL, but: I'm curious how that is meaningful in the context of dm-verity? (given the only caller of dm_table_get_immutable_target() is request-based DM code in DM core.) Thanks, Mike
On 2/2/2024 10:51 AM, Mike Snitzer wrote: > On Tue, Jan 30 2024 at 5:37P -0500, > Fan Wu <wufan@linux.microsoft.com> wrote: > >> The device-mapper has a flag to mark targets as singleton, which is a >> required flag for immutable targets. Without this flag, multiple >> dm-verity targets can be added to a mapped device, which has no >> practical use cases and will let dm_table_get_immutable_target return >> NULL. This patch adds the missing flag, restricting only one >> dm-verity target per mapped device. >> >> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> >> >> --- >> v1-v10: >> + Not present >> >> v11: >> + Introduced >> >> v12: >> + No changes >> --- >> drivers/md/dm-verity-target.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c >> index 14e58ae70521..66a850c02be4 100644 >> --- a/drivers/md/dm-verity-target.c >> +++ b/drivers/md/dm-verity-target.c >> @@ -1507,7 +1507,7 @@ int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned i >> >> static struct target_type verity_target = { >> .name = "verity", >> - .features = DM_TARGET_IMMUTABLE, >> + .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, >> .version = {1, 9, 0}, >> .module = THIS_MODULE, >> .ctr = verity_ctr, >> -- >> 2.43.0 >> >> > > It is true this change will cause dm_table_get_immutable_target() to > not return NULL, but: I'm curious how that is meaningful in the > context of dm-verity? (given the only caller of > dm_table_get_immutable_target() is request-based DM code in DM core.) > > Thanks, > Mike Sorry for the confusion. The reference of dm_table_get_immutable_target() is only to justify an immutable target should also be a singleton(https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/md/dm-table.c#n982). It is not directly related to dm-verity. In the context of dm-verity. I found although veritysetup does ensure the dm-verity target as a singleton, users can still use dmsetup to configure multiple dm-verity targets within a single map table. This leads to a situation where only the first target can be accessed. Therefore to prevent this and similar misuse, I propose introducing DM_TARGET_SINGLETON to allow the kernel to enforce dm-verity targets as singletons. Thanks, Fan
diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c index 14e58ae70521..66a850c02be4 100644 --- a/drivers/md/dm-verity-target.c +++ b/drivers/md/dm-verity-target.c @@ -1507,7 +1507,7 @@ int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned i static struct target_type verity_target = { .name = "verity", - .features = DM_TARGET_IMMUTABLE, + .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, .version = {1, 9, 0}, .module = THIS_MODULE, .ctr = verity_ctr,
The device-mapper has a flag to mark targets as singleton, which is a required flag for immutable targets. Without this flag, multiple dm-verity targets can be added to a mapped device, which has no practical use cases and will let dm_table_get_immutable_target return NULL. This patch adds the missing flag, restricting only one dm-verity target per mapped device. Signed-off-by: Fan Wu <wufan@linux.microsoft.com> --- v1-v10: + Not present v11: + Introduced v12: + No changes --- drivers/md/dm-verity-target.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)