From: David Howells Subject: [PATCH 3/3] KEYS: Add a 'trusted' flag and a 'trusted only' flag Date: Thu, 17 Jan 2013 18:04:07 +0000 Message-ID: <20130117180407.27885.54342.stgit@warthog.procyon.org.uk> References: <20130117180352.27885.79893.stgit@warthog.procyon.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, keyrings@linux-nfs.org, linux-security-module@vger.kernel.org, linux-crypto@vger.kernel.org To: dmitry.kasatkin@intel.com, zohar@linux.vnet.ibm.com Return-path: In-Reply-To: <20130117180352.27885.79893.stgit@warthog.procyon.org.uk> Sender: linux-security-module-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Add KEY_FLAG_TRUSTED to indicate that a key either comes from a trusted source or had a cryptographic signature chain that led back to a trusted key the kernel already possessed. Add KEY_FLAGS_TRUSTED_ONLY to indicate that a keyring will only accept links to keys marked with KEY_FLAGS_TRUSTED. Signed-off-by: David Howells Reviewed-by: Kees Cook --- include/linux/key-type.h | 1 + include/linux/key.h | 3 +++ kernel/system_keyring.c | 4 +++- security/keys/key.c | 8 ++++++++ security/keys/keyring.c | 4 ++++ 5 files changed, 19 insertions(+), 1 deletion(-) diff --git a/include/linux/key-type.h b/include/linux/key-type.h index 518a53a..f942b2d 100644 --- a/include/linux/key-type.h +++ b/include/linux/key-type.h @@ -45,6 +45,7 @@ struct key_preparsed_payload { const void *data; /* Raw data */ size_t datalen; /* Raw datalen */ size_t quotalen; /* Quota length for proposed payload */ + bool trusted; /* True if key is trusted */ }; typedef int (*request_key_actor_t)(struct key_construction *key, diff --git a/include/linux/key.h b/include/linux/key.h index 4dfde11..0b32a09 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -162,6 +162,8 @@ struct key { #define KEY_FLAG_NEGATIVE 5 /* set if key is negative */ #define KEY_FLAG_ROOT_CAN_CLEAR 6 /* set if key can be cleared by root without permission */ #define KEY_FLAG_INVALIDATED 7 /* set if key has been invalidated */ +#define KEY_FLAG_TRUSTED 8 /* set if key is trusted */ +#define KEY_FLAG_TRUSTED_ONLY 9 /* set if keyring only accepts links to trusted keys */ /* the description string * - this is used to match a key against search criteria @@ -203,6 +205,7 @@ extern struct key *key_alloc(struct key_type *type, #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */ #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */ #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */ +#define KEY_ALLOC_TRUSTED 0x0004 /* Key should be flagged as trusted */ extern void key_revoke(struct key *key); extern void key_invalidate(struct key *key); diff --git a/kernel/system_keyring.c b/kernel/system_keyring.c index a3ca76f..dae8778 100644 --- a/kernel/system_keyring.c +++ b/kernel/system_keyring.c @@ -40,6 +40,7 @@ static __init int system_trusted_keyring_init(void) if (IS_ERR(system_trusted_keyring)) panic("Can't allocate system trusted keyring\n"); + set_bit(KEY_FLAG_TRUSTED_ONLY, &system_trusted_keyring->flags); return 0; } @@ -82,7 +83,8 @@ static __init int load_system_certificate_list(void) plen, (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW, - KEY_ALLOC_NOT_IN_QUOTA); + KEY_ALLOC_NOT_IN_QUOTA | + KEY_ALLOC_TRUSTED); if (IS_ERR(key)) pr_err("Problem loading in-kernel X.509 certificate (%ld)\n", PTR_ERR(key)); diff --git a/security/keys/key.c b/security/keys/key.c index 8fb7c7b..f3de9e4 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -299,6 +299,8 @@ struct key *key_alloc(struct key_type *type, const char *desc, if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) key->flags |= 1 << KEY_FLAG_IN_QUOTA; + if (flags & KEY_ALLOC_TRUSTED) + key->flags |= 1 << KEY_FLAG_TRUSTED; memset(&key->type_data, 0, sizeof(key->type_data)); @@ -813,6 +815,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, prep.data = payload; prep.datalen = plen; prep.quotalen = ktype->def_datalen; + prep.trusted = flags & KEY_ALLOC_TRUSTED; if (ktype->preparse) { ret = ktype->preparse(&prep); if (ret < 0) { @@ -826,6 +829,11 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, goto error_free_prep; } + key_ref = ERR_PTR(-EPERM); + if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags)) + goto error_free_prep; + flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0; + ret = __key_link_begin(keyring, ktype, description, &prealloc); if (ret < 0) { key_ref = ERR_PTR(ret); diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 6ece7f2..f18d7ff 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -1006,6 +1006,10 @@ int key_link(struct key *keyring, struct key *key) key_check(keyring); key_check(key); + if (test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags) && + !test_bit(KEY_FLAG_TRUSTED, &key->flags)) + return -EPERM; + ret = __key_link_begin(keyring, key->type, key->description, &prealloc); if (ret == 0) { ret = __key_link_check_live_key(keyring, key);