| Message ID | 1709168102-7677-15-git-send-email-wufan@linux.microsoft.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | Integrity Policy Enforcement LSM (IPE) | expand |
On Wed, Feb 28 2024 at 7:54P -0500, Fan Wu <wufan@linux.microsoft.com> wrote: > From: Deven Bowers <deven.desai@linux.microsoft.com> > > dm-verity provides a strong guarantee of a block device's integrity. As > a generic way to check the integrity of a block device, it provides > those integrity guarantees to its higher layers, including the filesystem > level. > > An LSM that control access to a resource on the system based on the > available integrity claims can use this transitive property of > dm-verity, by querying the underlying block_device of a particular > file. > > The digest and signature information need to be stored in the block > device to fulfill the next requirement of authorization via LSM policy. > This will enable the LSM to perform revocation of devices that are still > mounted, prohibiting execution of files that are no longer authorized > by the LSM in question. > > This patch added two security hook calls in dm-verity to save the > dm-verity roothash and the roothash signature to the block device's > LSM blobs. The hook calls are depended on CONFIG_IPE_PROP_DM_VERITY, > which will be introduced in the next commit. > > Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> > Signed-off-by: Fan Wu <wufan@linux.microsoft.com> > --- > v2: > + No Changes > > v3: > + No changes > > v4: > + No changes > > v5: > + No changes > > v6: > + Fix an improper cleanup that can result in > a leak > > v7: > + Squash patch 08/12, 10/12 to [11/16] > + Use part0 for block_device, to retrieve the block_device, when > calling security_bdev_setsecurity > > v8: > + Undo squash of 08/12, 10/12 - separating drivers/md/ from > security/ & block/ > + Use common-audit function for dmverity_signature. > + Change implementation for storing the dm-verity digest to use the > newly introduced dm_verity_digest structure introduced in patch > 14/20. > + Create new structure, dm_verity_digest, containing digest algorithm, > size, and digest itself to pass to the LSM layer. V7 was missing the > algorithm. > + Create an associated public header containing this new structure and > the key values for the LSM hook, specific to dm-verity. > + Additional information added to commit, discussing the layering of > the changes and how the information passed will be used. > > v9: > + No changes > > v10: > + No changes > > v11: > + Add an optional field to save signature > + Move the security hook call to the new finalize hook > > v12: > + No changes > > v13: > + No changes > --- > drivers/md/dm-verity-target.c | 71 +++++++++++++++++++++++++++++++++++ > drivers/md/dm-verity.h | 6 +++ > include/linux/dm-verity.h | 19 ++++++++++ > 3 files changed, 96 insertions(+) > create mode 100644 include/linux/dm-verity.h > > diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c > index a99ef30e45ca..e7bc6afae708 100644 > --- a/drivers/md/dm-verity-target.c > +++ b/drivers/md/dm-verity-target.c > @@ -13,6 +13,7 @@ > * access behavior. > */ > > +#include "dm-core.h" > #include "dm-verity.h" > #include "dm-verity-fec.h" > #include "dm-verity-verify-sig.h" > @@ -22,6 +23,9 @@ > #include <linux/scatterlist.h> > #include <linux/string.h> > #include <linux/jump_label.h> > +#include <linux/security.h> > +#include <linux/dm-verity.h> > +#include <crypto/hash_info.h> > > #define DM_MSG_PREFIX "verity" > > @@ -990,6 +994,17 @@ static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) > blk_limits_io_min(limits, limits->logical_block_size); > } > > +#ifdef CONFIG_IPE_PROP_DM_VERITY > +static void verity_free_sig(struct dm_verity *v) > +{ > + kfree(v->root_digest_sig); > +} > +#else > +static inline void verity_free_sig(struct dm_verity *v) > +{ > +} > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > + > static void verity_dtr(struct dm_target *ti) > { > struct dm_verity *v = ti->private; > @@ -1008,6 +1023,7 @@ static void verity_dtr(struct dm_target *ti) > kfree(v->salt); > kfree(v->root_digest); > kfree(v->zero_digest); > + verity_free_sig(v); > > if (v->tfm) > crypto_free_ahash(v->tfm); > @@ -1199,6 +1215,25 @@ static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, > return r; > } > > +#ifdef CONFIG_IPE_PROP_DM_VERITY > +static int verity_init_sig(struct dm_verity *v, const void *sig, > + size_t sig_size) > +{ > + v->sig_size = sig_size; > + v->root_digest_sig = kmalloc(v->sig_size, GFP_KERNEL); > + if (!v->root_digest) > + return -ENOMEM; > + > + return 0; > +} > +#else > +static inline int verity_init_sig(struct dm_verity *v, const void *sig, > + size_t sig_size) > +{ > + return 0; > +} > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > + Please move verity_init_sig() to be at beginning of same #ifdef block as verity_free_sig() above. Also, please add blank lines between #ifdef, #else and #endif. > /* > * Target parameters: > * <version> The current format is version 1. > @@ -1407,6 +1442,13 @@ static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) > ti->error = "Root hash verification failed"; > goto bad; > } > + > + r = verity_init_sig(v, verify_args.sig, verify_args.sig_size); > + if (r < 0) { > + ti->error = "Cannot allocate root digest signature"; > + goto bad; > + } > + > v->hash_per_block_bits = > __fls((1 << v->hash_dev_block_bits) / v->digest_size); > > @@ -1557,6 +1599,32 @@ int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned i > return 0; > } > > +#ifdef CONFIG_IPE_PROP_DM_VERITY > +static int verity_finalize(struct dm_target *ti) > +{ > + struct block_device *bdev; > + struct dm_verity_digest root_digest; > + struct dm_verity *v; > + int r; > + > + v = ti->private; > + bdev = dm_table_get_md(ti->table)->disk->part0; > + root_digest.digest = v->root_digest; > + root_digest.digest_len = v->digest_size; > + root_digest.alg = v->alg_name; > + > + r = security_bdev_setsecurity(bdev, DM_VERITY_ROOTHASH_SEC_NAME, &root_digest, > + sizeof(root_digest)); > + if (r) > + return r; > + > + return security_bdev_setsecurity(bdev, > + DM_VERITY_SIGNATURE_SEC_NAME, > + v->root_digest_sig, > + v->sig_size); > +} > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > + Again, blank line after #ifdef and before #endif Thanks, Mike
On Wed, Feb 28 2024 at 7:54P -0500, Fan Wu <wufan@linux.microsoft.com> wrote: > From: Deven Bowers <deven.desai@linux.microsoft.com> > > dm-verity provides a strong guarantee of a block device's integrity. As > a generic way to check the integrity of a block device, it provides > those integrity guarantees to its higher layers, including the filesystem > level. > > An LSM that control access to a resource on the system based on the > available integrity claims can use this transitive property of > dm-verity, by querying the underlying block_device of a particular > file. > > The digest and signature information need to be stored in the block > device to fulfill the next requirement of authorization via LSM policy. > This will enable the LSM to perform revocation of devices that are still > mounted, prohibiting execution of files that are no longer authorized > by the LSM in question. > > This patch added two security hook calls in dm-verity to save the > dm-verity roothash and the roothash signature to the block device's > LSM blobs. The hook calls are depended on CONFIG_IPE_PROP_DM_VERITY, > which will be introduced in the next commit. > > Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> > Signed-off-by: Fan Wu <wufan@linux.microsoft.com> > --- > v2: > + No Changes > > v3: > + No changes > > v4: > + No changes > > v5: > + No changes > > v6: > + Fix an improper cleanup that can result in > a leak > > v7: > + Squash patch 08/12, 10/12 to [11/16] > + Use part0 for block_device, to retrieve the block_device, when > calling security_bdev_setsecurity > > v8: > + Undo squash of 08/12, 10/12 - separating drivers/md/ from > security/ & block/ > + Use common-audit function for dmverity_signature. > + Change implementation for storing the dm-verity digest to use the > newly introduced dm_verity_digest structure introduced in patch > 14/20. > + Create new structure, dm_verity_digest, containing digest algorithm, > size, and digest itself to pass to the LSM layer. V7 was missing the > algorithm. > + Create an associated public header containing this new structure and > the key values for the LSM hook, specific to dm-verity. > + Additional information added to commit, discussing the layering of > the changes and how the information passed will be used. > > v9: > + No changes > > v10: > + No changes > > v11: > + Add an optional field to save signature > + Move the security hook call to the new finalize hook > > v12: > + No changes > > v13: > + No changes > --- > drivers/md/dm-verity-target.c | 71 +++++++++++++++++++++++++++++++++++ > drivers/md/dm-verity.h | 6 +++ > include/linux/dm-verity.h | 19 ++++++++++ > 3 files changed, 96 insertions(+) > create mode 100644 include/linux/dm-verity.h > > diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c > index a99ef30e45ca..e7bc6afae708 100644 > --- a/drivers/md/dm-verity-target.c > +++ b/drivers/md/dm-verity-target.c > @@ -13,6 +13,7 @@ > * access behavior. > */ > > +#include "dm-core.h" > #include "dm-verity.h" > #include "dm-verity-fec.h" > #include "dm-verity-verify-sig.h" Why are you including dm-core.h? (DM targets really shouldn't need it). And from that header: /* * DM core internal structures used directly by dm.c, dm-rq.c and dm-table.c. * DM targets must _not_ deference a mapped_device or dm_table to directly * access their members! */ > @@ -22,6 +23,9 @@ > #include <linux/scatterlist.h> > #include <linux/string.h> > #include <linux/jump_label.h> > +#include <linux/security.h> > +#include <linux/dm-verity.h> > +#include <crypto/hash_info.h> > > #define DM_MSG_PREFIX "verity" > > @@ -990,6 +994,17 @@ static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) > blk_limits_io_min(limits, limits->logical_block_size); > } > > +#ifdef CONFIG_IPE_PROP_DM_VERITY > +static void verity_free_sig(struct dm_verity *v) > +{ > + kfree(v->root_digest_sig); > +} > +#else > +static inline void verity_free_sig(struct dm_verity *v) > +{ > +} > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > + > static void verity_dtr(struct dm_target *ti) > { > struct dm_verity *v = ti->private; > @@ -1008,6 +1023,7 @@ static void verity_dtr(struct dm_target *ti) > kfree(v->salt); > kfree(v->root_digest); > kfree(v->zero_digest); > + verity_free_sig(v); > > if (v->tfm) > crypto_free_ahash(v->tfm); > @@ -1199,6 +1215,25 @@ static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, > return r; > } > > +#ifdef CONFIG_IPE_PROP_DM_VERITY > +static int verity_init_sig(struct dm_verity *v, const void *sig, > + size_t sig_size) > +{ > + v->sig_size = sig_size; > + v->root_digest_sig = kmalloc(v->sig_size, GFP_KERNEL); > + if (!v->root_digest) > + return -ENOMEM; > + > + return 0; > +} > +#else > +static inline int verity_init_sig(struct dm_verity *v, const void *sig, > + size_t sig_size) > +{ > + return 0; > +} > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > + > /* > * Target parameters: > * <version> The current format is version 1. > @@ -1407,6 +1442,13 @@ static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) > ti->error = "Root hash verification failed"; > goto bad; > } > + > + r = verity_init_sig(v, verify_args.sig, verify_args.sig_size); > + if (r < 0) { > + ti->error = "Cannot allocate root digest signature"; > + goto bad; > + } > + > v->hash_per_block_bits = > __fls((1 << v->hash_dev_block_bits) / v->digest_size); > > @@ -1557,6 +1599,32 @@ int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned i > return 0; > } > > +#ifdef CONFIG_IPE_PROP_DM_VERITY > +static int verity_finalize(struct dm_target *ti) > +{ > + struct block_device *bdev; > + struct dm_verity_digest root_digest; > + struct dm_verity *v; > + int r; > + > + v = ti->private; > + bdev = dm_table_get_md(ti->table)->disk->part0; Must be for dereferencing mapped_device struct here ^ Please remove the dm-core.h include and use this instead: struct gendisk *disk = dm_disk(dm_table_get_md(ti->table)); Mike > + root_digest.digest = v->root_digest; > + root_digest.digest_len = v->digest_size; > + root_digest.alg = v->alg_name; > + > + r = security_bdev_setsecurity(bdev, DM_VERITY_ROOTHASH_SEC_NAME, &root_digest, > + sizeof(root_digest)); > + if (r) > + return r; > + > + return security_bdev_setsecurity(bdev, > + DM_VERITY_SIGNATURE_SEC_NAME, > + v->root_digest_sig, > + v->sig_size); > +} > +#endif /* CONFIG_IPE_PROP_DM_VERITY */ > + > static struct target_type verity_target = { > .name = "verity", > .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c index a99ef30e45ca..e7bc6afae708 100644 --- a/drivers/md/dm-verity-target.c +++ b/drivers/md/dm-verity-target.c @@ -13,6 +13,7 @@ * access behavior. */ +#include "dm-core.h" #include "dm-verity.h" #include "dm-verity-fec.h" #include "dm-verity-verify-sig.h" @@ -22,6 +23,9 @@ #include <linux/scatterlist.h> #include <linux/string.h> #include <linux/jump_label.h> +#include <linux/security.h> +#include <linux/dm-verity.h> +#include <crypto/hash_info.h> #define DM_MSG_PREFIX "verity" @@ -990,6 +994,17 @@ static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) blk_limits_io_min(limits, limits->logical_block_size); } +#ifdef CONFIG_IPE_PROP_DM_VERITY +static void verity_free_sig(struct dm_verity *v) +{ + kfree(v->root_digest_sig); +} +#else +static inline void verity_free_sig(struct dm_verity *v) +{ +} +#endif /* CONFIG_IPE_PROP_DM_VERITY */ + static void verity_dtr(struct dm_target *ti) { struct dm_verity *v = ti->private; @@ -1008,6 +1023,7 @@ static void verity_dtr(struct dm_target *ti) kfree(v->salt); kfree(v->root_digest); kfree(v->zero_digest); + verity_free_sig(v); if (v->tfm) crypto_free_ahash(v->tfm); @@ -1199,6 +1215,25 @@ static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, return r; } +#ifdef CONFIG_IPE_PROP_DM_VERITY +static int verity_init_sig(struct dm_verity *v, const void *sig, + size_t sig_size) +{ + v->sig_size = sig_size; + v->root_digest_sig = kmalloc(v->sig_size, GFP_KERNEL); + if (!v->root_digest) + return -ENOMEM; + + return 0; +} +#else +static inline int verity_init_sig(struct dm_verity *v, const void *sig, + size_t sig_size) +{ + return 0; +} +#endif /* CONFIG_IPE_PROP_DM_VERITY */ + /* * Target parameters: * <version> The current format is version 1. @@ -1407,6 +1442,13 @@ static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) ti->error = "Root hash verification failed"; goto bad; } + + r = verity_init_sig(v, verify_args.sig, verify_args.sig_size); + if (r < 0) { + ti->error = "Cannot allocate root digest signature"; + goto bad; + } + v->hash_per_block_bits = __fls((1 << v->hash_dev_block_bits) / v->digest_size); @@ -1557,6 +1599,32 @@ int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned i return 0; } +#ifdef CONFIG_IPE_PROP_DM_VERITY +static int verity_finalize(struct dm_target *ti) +{ + struct block_device *bdev; + struct dm_verity_digest root_digest; + struct dm_verity *v; + int r; + + v = ti->private; + bdev = dm_table_get_md(ti->table)->disk->part0; + root_digest.digest = v->root_digest; + root_digest.digest_len = v->digest_size; + root_digest.alg = v->alg_name; + + r = security_bdev_setsecurity(bdev, DM_VERITY_ROOTHASH_SEC_NAME, &root_digest, + sizeof(root_digest)); + if (r) + return r; + + return security_bdev_setsecurity(bdev, + DM_VERITY_SIGNATURE_SEC_NAME, + v->root_digest_sig, + v->sig_size); +} +#endif /* CONFIG_IPE_PROP_DM_VERITY */ + static struct target_type verity_target = { .name = "verity", .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, @@ -1569,6 +1637,9 @@ static struct target_type verity_target = { .prepare_ioctl = verity_prepare_ioctl, .iterate_devices = verity_iterate_devices, .io_hints = verity_io_hints, +#ifdef CONFIG_IPE_PROP_DM_VERITY + .finalize = verity_finalize, +#endif /* CONFIG_IPE_PROP_DM_VERITY */ }; module_dm(verity); diff --git a/drivers/md/dm-verity.h b/drivers/md/dm-verity.h index db93a91169d5..4da3d2811aba 100644 --- a/drivers/md/dm-verity.h +++ b/drivers/md/dm-verity.h @@ -43,6 +43,9 @@ struct dm_verity { u8 *root_digest; /* digest of the root block */ u8 *salt; /* salt: its size is salt_size */ u8 *zero_digest; /* digest for a zero block */ +#ifdef CONFIG_IPE_PROP_DM_VERITY + u8 *root_digest_sig; /* digest signature of the root block */ +#endif /* CONFIG_IPE_PROP_DM_VERITY */ unsigned int salt_size; sector_t data_start; /* data offset in 512-byte sectors */ sector_t hash_start; /* hash start in blocks */ @@ -56,6 +59,9 @@ struct dm_verity { bool hash_failed:1; /* set if hash of any block failed */ bool use_tasklet:1; /* try to verify in tasklet before work-queue */ unsigned int digest_size; /* digest size for the current hash algorithm */ +#ifdef CONFIG_IPE_PROP_DM_VERITY + unsigned int sig_size; /* digest signature size */ +#endif /* CONFIG_IPE_PROP_DM_VERITY */ unsigned int ahash_reqsize;/* the size of temporary space for crypto */ enum verity_mode mode; /* mode for handling verification errors */ unsigned int corrupted_errs;/* Number of errors for corrupted blocks */ diff --git a/include/linux/dm-verity.h b/include/linux/dm-verity.h new file mode 100644 index 000000000000..7d9753445534 --- /dev/null +++ b/include/linux/dm-verity.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _LINUX_DM_VERITY_H +#define _LINUX_DM_VERITY_H + +#include <linux/types.h> +#include <crypto/hash_info.h> +#include <linux/device-mapper.h> + +struct dm_verity_digest { + const char *alg; + const u8 *digest; + size_t digest_len; +}; + +#define DM_VERITY_SIGNATURE_SEC_NAME DM_NAME ".verity-signature" +#define DM_VERITY_ROOTHASH_SEC_NAME DM_NAME ".verity-roothash" + +#endif /* _LINUX_DM_VERITY_H */