From 008643b86c5f33c115c84ccdda1725cac3ad50ad Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 30 Aug 2013 16:07:37 +0100 Subject: [PATCH] KEYS: Add a 'trusted' flag and a 'trusted only' flag 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 f58737bcb050..a74c3a84dfdd 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 010dbb618aca..80d677483e31 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -168,6 +168,8 @@ 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 key type and key description string * - the desc is used to match a key against search criteria @@ -218,6 +220,7 @@ 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 51c35141a13a..5296721eca5b 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 a819b5c7d4ec..d331ea9ef380 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -300,6 +300,8 @@ 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 = index_key.type->def_datalen; + prep.trusted = flags & KEY_ALLOC_TRUSTED; if (index_key.type->preparse) { ret = index_key.type->preparse(&prep); if (ret < 0) { @@ -827,6 +830,11 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, } index_key.desc_len = strlen(index_key.description); + 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, &index_key, &edit); if (ret < 0) { key_ref = ERR_PTR(ret); diff --git a/security/keys/keyring.c b/security/keys/keyring.c index f7cdea22214f..9b6f6e09b50c 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -1183,6 +1183,10 @@ 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->index_key, &edit); if (ret == 0) { kdebug("begun {%d,%d}", keyring->serial, atomic_read(&keyring->usage)); -- 2.20.1