While keys of differing type have a common struct key definition, there is
no common scheme to the payload and key material extraction differs.
For kernel functionality that supports different key types,
this means duplicated code for key material extraction and because key type
is discriminated by a pointer to a global, users need to replicate
reachability checks as well, so builtin code doesn't depend on a key
type symbol offered by a module.
Make this easier by adding a common helper with initial support for
user, logon, encrypted and trusted keys.
This series contains two example of its use: dm-crypt uses it to reduce
boilerplate and ubifs authentication uses it to gain support for trusted
and encrypted keys alongside the already supported logon keys.
Looking forward to your feedback,
Ahmad
---
To: David Howells <[email protected]>
To: Jarkko Sakkinen <[email protected]>
To: James Morris <[email protected]>
To: "Serge E. Hallyn" <[email protected]>
To: Alasdair Kergon <[email protected]>
To: Mike Snitzer <[email protected]>
To: [email protected]
To: Song Liu <[email protected]>
To: Richard Weinberger <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Ahmad Fatoum (4):
keys: introduce key_extract_material helper
dm: crypt: use new key_extract_material helper
ubifs: auth: remove never hit key type error check
ubifs: auth: consult encrypted and trusted keys if no logon key was found
Documentation/filesystems/ubifs.rst | 2 +-
drivers/md/dm-crypt.c | 65 ++++--------------------------
fs/ubifs/auth.c | 25 +++++-------
include/linux/key.h | 45 +++++++++++++++++++++-
security/keys/key.c | 40 ++++++++++++++++++-
5 files changed, 107 insertions(+), 70 deletions(-)
base-commit: 2734d6c1b1a089fb593ef6a23d4b70903526fe0c
--
git-series 0.9.1
key_request accepts a key type as its first argument. If it returns a
valid pointer, it should always have this same requested key type.
Indeed other request_key users surveyed such as dm-crypt, ecryptfs
and fscrypt v1 also don't check the key type. Therefore drop the
apparently unneeded check.
Signed-off-by: Ahmad Fatoum <[email protected]>
---
To: David Howells <[email protected]>
To: Jarkko Sakkinen <[email protected]>
To: James Morris <[email protected]>
To: "Serge E. Hallyn" <[email protected]>
To: Alasdair Kergon <[email protected]>
To: Mike Snitzer <[email protected]>
To: [email protected]
To: Song Liu <[email protected]>
To: Richard Weinberger <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
fs/ubifs/auth.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/fs/ubifs/auth.c b/fs/ubifs/auth.c
index e564d5ff8781..6a0b8d858d81 100644
--- a/fs/ubifs/auth.c
+++ b/fs/ubifs/auth.c
@@ -286,12 +286,6 @@ int ubifs_init_authentication(struct ubifs_info *c)
down_read(&keyring_key->sem);
- if (keyring_key->type != &key_type_logon) {
- ubifs_err(c, "key type must be logon");
- err = -ENOKEY;
- goto out;
- }
-
ukp = user_key_payload_locked(keyring_key);
if (!ukp) {
/* key was revoked before we acquired its semaphore */
--
git-series 0.9.1
There is a common function now to extract key material out of a few
different key types, which includes all types currently supported by
dm-crypt. Make use of it.
Signed-off-by: Ahmad Fatoum <[email protected]>
---
To: David Howells <[email protected]>
To: Jarkko Sakkinen <[email protected]>
To: James Morris <[email protected]>
To: "Serge E. Hallyn" <[email protected]>
To: Alasdair Kergon <[email protected]>
To: Mike Snitzer <[email protected]>
To: [email protected]
To: Song Liu <[email protected]>
To: Richard Weinberger <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
drivers/md/dm-crypt.c | 65 ++++++--------------------------------------
1 file changed, 9 insertions(+), 56 deletions(-)
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 50f4cbd600d5..576d6b7ce231 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2421,61 +2421,14 @@ static bool contains_whitespace(const char *str)
return false;
}
-static int set_key_user(struct crypt_config *cc, struct key *key)
-{
- const struct user_key_payload *ukp;
-
- ukp = user_key_payload_locked(key);
- if (!ukp)
- return -EKEYREVOKED;
-
- if (cc->key_size != ukp->datalen)
- return -EINVAL;
-
- memcpy(cc->key, ukp->data, cc->key_size);
-
- return 0;
-}
-
-static int set_key_encrypted(struct crypt_config *cc, struct key *key)
-{
- const struct encrypted_key_payload *ekp;
-
- ekp = key->payload.data[0];
- if (!ekp)
- return -EKEYREVOKED;
-
- if (cc->key_size != ekp->decrypted_datalen)
- return -EINVAL;
-
- memcpy(cc->key, ekp->decrypted_data, cc->key_size);
-
- return 0;
-}
-
-static int set_key_trusted(struct crypt_config *cc, struct key *key)
-{
- const struct trusted_key_payload *tkp;
-
- tkp = key->payload.data[0];
- if (!tkp)
- return -EKEYREVOKED;
-
- if (cc->key_size != tkp->key_len)
- return -EINVAL;
-
- memcpy(cc->key, tkp->key, cc->key_size);
-
- return 0;
-}
-
static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string)
{
char *new_key_string, *key_desc;
int ret;
+ unsigned int len;
struct key_type *type;
struct key *key;
- int (*set_key)(struct crypt_config *cc, struct key *key);
+ const void *key_material;
/*
* Reject key_string with whitespace. dm core currently lacks code for
@@ -2493,18 +2446,14 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
if (!strncmp(key_string, "logon:", key_desc - key_string + 1)) {
type = &key_type_logon;
- set_key = set_key_user;
} else if (!strncmp(key_string, "user:", key_desc - key_string + 1)) {
type = &key_type_user;
- set_key = set_key_user;
} else if (IS_ENABLED(CONFIG_ENCRYPTED_KEYS) &&
!strncmp(key_string, "encrypted:", key_desc - key_string + 1)) {
type = &key_type_encrypted;
- set_key = set_key_encrypted;
} else if (IS_ENABLED(CONFIG_TRUSTED_KEYS) &&
!strncmp(key_string, "trusted:", key_desc - key_string + 1)) {
type = &key_type_trusted;
- set_key = set_key_trusted;
} else {
return -EINVAL;
}
@@ -2521,14 +2470,18 @@ static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string
down_read(&key->sem);
- ret = set_key(cc, key);
- if (ret < 0) {
+ key_material = key_extract_material(key, &len);
+ if (!IS_ERR(key_material) && len != cc->key_size)
+ key_material = ERR_PTR(-EINVAL);
+ if (IS_ERR(key_material)) {
up_read(&key->sem);
key_put(key);
kfree_sensitive(new_key_string);
- return ret;
+ return PTR_ERR(key_material);
}
+ memcpy(cc->key, key_material, len);
+
up_read(&key->sem);
key_put(key);
--
git-series 0.9.1
While keys of differing type have a common struct key definition, there is
no common scheme to the payload and key material extraction differs.
For kernel functionality that supports different key types,
this means duplicated code for key material extraction and because key type
is discriminated by a pointer to a global, users need to replicate
reachability checks as well, so builtin code doesn't depend on a key
type symbol offered by a module.
Make this easier by adding a common helper with initial support for
user, logon, encrypted and trusted keys. The code is taken from
dm-crypt, which is migrated to use the helper in a later commit.
The implementation must be partially in a header to support configurations
where the key type symbol is defined in a module, but key support in general
is built-in.
Signed-off-by: Ahmad Fatoum <[email protected]>
---
I am not sure whether the chosen header and source file are the best
places for this. This could be made header-only too if that's preferred.
To: David Howells <[email protected]>
To: Jarkko Sakkinen <[email protected]>
To: James Morris <[email protected]>
To: "Serge E. Hallyn" <[email protected]>
To: Alasdair Kergon <[email protected]>
To: Mike Snitzer <[email protected]>
To: [email protected]
To: Song Liu <[email protected]>
To: Richard Weinberger <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
include/linux/key.h | 45 +++++++++++++++++++++++++++++++++++++++++++++
security/keys/key.c | 40 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 85 insertions(+)
diff --git a/include/linux/key.h b/include/linux/key.h
index 7febc4881363..916612f5b313 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -20,6 +20,8 @@
#include <linux/assoc_array.h>
#include <linux/refcount.h>
#include <linux/time64.h>
+#include <linux/err.h>
+#include <linux/kconfig.h>
#ifdef __KERNEL__
#include <linux/uidgid.h>
@@ -487,6 +489,48 @@ extern void key_fsuid_changed(struct cred *new_cred);
extern void key_fsgid_changed(struct cred *new_cred);
extern void key_init(void);
+/*
+ * internal use, so key core code need not link against
+ * all supported key types
+ * */
+enum __key_type {
+ KEY_TYPE_UNKNOWN, KEY_TYPE_USER, KEY_TYPE_ENCRYPTED, KEY_TYPE_TRUSTED
+};
+
+const void *__key_extract_material(const struct key *key, enum __key_type type,
+ unsigned int *len);
+
+/**
+ * key_extract_material - Extract decrypted data out of a key
+ * @key: a logon, user, encrypted or trusted key
+ * @len: pointer to variable to store key size into
+ *
+ * Extract decrypted data out of supported key types
+ *
+ * Returns a pointer to the key material if successfull or an error
+ * pointer if key type is not compiled in, the buffer is too
+ * small or the key was revoked.
+ */
+static inline const void *key_extract_material(const struct key *key,
+ unsigned int *len)
+{
+ extern struct key_type key_type_user;
+ extern struct key_type key_type_logon;
+ extern struct key_type key_type_encrypted;
+ extern struct key_type key_type_trusted;
+ enum __key_type type = KEY_TYPE_UNKNOWN;
+ const struct key_type *t = key->type;
+
+ if (t == &key_type_logon || t == &key_type_user)
+ type = KEY_TYPE_USER;
+ else if (IS_REACHABLE(CONFIG_ENCRYPTED_KEYS) && t == &key_type_encrypted)
+ type = KEY_TYPE_ENCRYPTED;
+ else if (IS_REACHABLE(CONFIG_TRUSTED_KEYS) && t == &key_type_trusted)
+ type = KEY_TYPE_TRUSTED;
+
+ return __key_extract_material(key, type, len);
+}
+
#else /* CONFIG_KEYS */
#define key_validate(k) 0
@@ -504,6 +548,7 @@ extern void key_init(void);
#define key_init() do { } while(0)
#define key_free_user_ns(ns) do { } while(0)
#define key_remove_domain(d) do { } while(0)
+#define key_extract_material(k, l) ERR_PTR(-EINVAL)
#endif /* CONFIG_KEYS */
#endif /* __KERNEL__ */
diff --git a/security/keys/key.c b/security/keys/key.c
index c45afdd1dfbb..69cd1cb8c413 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -15,6 +15,9 @@
#include <linux/random.h>
#include <linux/ima.h>
#include <linux/err.h>
+#include <keys/user-type.h>
+#include <keys/encrypted-type.h>
+#include <keys/trusted-type.h>
#include "internal.h"
struct kmem_cache *key_jar;
@@ -1140,6 +1143,43 @@ int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
}
EXPORT_SYMBOL(generic_key_instantiate);
+const void *__key_extract_material(const struct key *key,
+ enum __key_type type, unsigned int *len)
+{
+ const struct encrypted_key_payload *ekp;
+ const struct trusted_key_payload *tkp;
+ const struct user_key_payload *ukp;
+
+ switch (type) {
+ case KEY_TYPE_USER:
+ ukp = user_key_payload_locked(key);
+ if (!ukp)
+ break;
+
+ *len = ukp->datalen;
+ return ukp->data;
+ case KEY_TYPE_ENCRYPTED:
+ ekp = key->payload.data[0];
+ if (!ekp)
+ break;
+
+ *len = ekp->decrypted_datalen;
+ return ekp->decrypted_data;
+ case KEY_TYPE_TRUSTED:
+ tkp = key->payload.data[0];
+ if (!tkp)
+ break;
+
+ *len = tkp->key_len;
+ return tkp->key;
+ default:
+ return ERR_PTR(-EINVAL);
+ }
+
+ return ERR_PTR(-EKEYREVOKED);
+}
+EXPORT_SYMBOL(__key_extract_material);
+
/**
* register_key_type - Register a type of key.
* @ktype: The new key type.
--
git-series 0.9.1
Hello everyone,
On 22.07.21 11:17, Ahmad Fatoum wrote:
> While keys of differing type have a common struct key definition, there is
> no common scheme to the payload and key material extraction differs.
>
> For kernel functionality that supports different key types,
> this means duplicated code for key material extraction and because key type
> is discriminated by a pointer to a global, users need to replicate
> reachability checks as well, so builtin code doesn't depend on a key
> type symbol offered by a module.
>
> Make this easier by adding a common helper with initial support for
> user, logon, encrypted and trusted keys.
>
> This series contains two example of its use: dm-crypt uses it to reduce
> boilerplate and ubifs authentication uses it to gain support for trusted
> and encrypted keys alongside the already supported logon keys.
>
> Looking forward to your feedback,
@Mike, Aliasdair: Do you think of key_extract_material as an improvement?
Does someone share the opinion that the helper is useful or should I drop
it and just send out the ubifs auth patch seperately?
Cheers,
Ahmad
> Ahmad
>
> ---
> To: David Howells <[email protected]>
> To: Jarkko Sakkinen <[email protected]>
> To: James Morris <[email protected]>
> To: "Serge E. Hallyn" <[email protected]>
> To: Alasdair Kergon <[email protected]>
> To: Mike Snitzer <[email protected]>
> To: [email protected]
> To: Song Liu <[email protected]>
> To: Richard Weinberger <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
>
> Ahmad Fatoum (4):
> keys: introduce key_extract_material helper
> dm: crypt: use new key_extract_material helper
> ubifs: auth: remove never hit key type error check
> ubifs: auth: consult encrypted and trusted keys if no logon key was found
>
> Documentation/filesystems/ubifs.rst | 2 +-
> drivers/md/dm-crypt.c | 65 ++++--------------------------
> fs/ubifs/auth.c | 25 +++++-------
> include/linux/key.h | 45 +++++++++++++++++++++-
> security/keys/key.c | 40 ++++++++++++++++++-
> 5 files changed, 107 insertions(+), 70 deletions(-)
>
> base-commit: 2734d6c1b1a089fb593ef6a23d4b70903526fe0c
>
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |