From e59428f721ee096d8a020504ea908a6f0d952735 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 19 Jun 2019 16:10:15 +0100 Subject: keys: Move the RCU locks outwards from the keyring search functions Move the RCU locks outwards from the keyring search functions so that it will become possible to provide an RCU-capable partial request_key() function in a later commit. Signed-off-by: David Howells --- security/keys/keyring.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'security/keys/keyring.c') diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 67066bb58b83..afa6d4024c67 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -835,7 +835,7 @@ found: } /** - * keyring_search_aux - Search a keyring tree for a key matching some criteria + * keyring_search_rcu - Search a keyring tree for a matching key under RCU * @keyring_ref: A pointer to the keyring with possession indicator. * @ctx: The keyring search context. * @@ -847,7 +847,9 @@ found: * addition, the LSM gets to forbid keyring searches and key matches. * * The search is performed as a breadth-then-depth search up to the prescribed - * limit (KEYRING_SEARCH_MAX_DEPTH). + * limit (KEYRING_SEARCH_MAX_DEPTH). The caller must hold the RCU read lock to + * prevent keyrings from being destroyed or rearranged whilst they are being + * searched. * * Keys are matched to the type provided and are then filtered by the match * function, which is given the description to use in any way it sees fit. The @@ -866,7 +868,7 @@ found: * In the case of a successful return, the possession attribute from * @keyring_ref is propagated to the returned key reference. */ -key_ref_t keyring_search_aux(key_ref_t keyring_ref, +key_ref_t keyring_search_rcu(key_ref_t keyring_ref, struct keyring_search_context *ctx) { struct key *keyring; @@ -888,11 +890,9 @@ key_ref_t keyring_search_aux(key_ref_t keyring_ref, return ERR_PTR(err); } - rcu_read_lock(); ctx->now = ktime_get_real_seconds(); if (search_nested_keyrings(keyring, ctx)) __key_get(key_ref_to_ptr(ctx->result)); - rcu_read_unlock(); return ctx->result; } @@ -902,7 +902,7 @@ key_ref_t keyring_search_aux(key_ref_t keyring_ref, * @type: The type of keyring we want to find. * @description: The name of the keyring we want to find. * - * As keyring_search_aux() above, but using the current task's credentials and + * As keyring_search_rcu() above, but using the current task's credentials and * type's default matching function and preferred search method. */ key_ref_t keyring_search(key_ref_t keyring, @@ -928,7 +928,9 @@ key_ref_t keyring_search(key_ref_t keyring, return ERR_PTR(ret); } - key = keyring_search_aux(keyring, &ctx); + rcu_read_lock(); + key = keyring_search_rcu(keyring, &ctx); + rcu_read_unlock(); if (type->match_free) type->match_free(&ctx.match_data); -- cgit v1.2.3