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Message-ID: <20240130101344.28936-1-lhenriques@suse.de>
Date: Tue, 30 Jan 2024 10:13:44 +0000
From: Luis Henriques <lhenriques@...e.de>
To: David Howells <dhowells@...hat.com>,
Jarkko Sakkinen <jarkko@...nel.org>,
Eric Biggers <ebiggers@...nel.org>
Cc: keyrings@...r.kernel.org,
linux-kernel@...r.kernel.org,
Luis Henriques <lhenriques@...e.de>
Subject: [PATCH v3] keys: update key quotas in key_put()
Delaying key quotas update when key's refcount reaches 0 in key_put() has
been causing some issues in fscrypt testing, specifically in fstest
generic/581. This commit fixes this test flakiness by dealing with the
quotas immediately, and leaving all the other clean-ups to the key garbage
collector.
This is done by moving the updates to the qnkeys and qnbytes fields in
struct key_user from key_gc_unused_keys() into key_put(). Unfortunately,
this also means that we need to switch to the irq-version of the spinlock
that protects these fields and use spin_lock_{irqsave,irqrestore} in all the
code that touches these fields.
Signed-off-by: Luis Henriques <lhenriques@...e.de>
---
Changes since v2:
- Updated commit message as suggested by Jarkko, adding details on the
implementation
security/keys/gc.c | 8 --------
security/keys/key.c | 32 ++++++++++++++++++++++----------
security/keys/keyctl.c | 11 ++++++-----
3 files changed, 28 insertions(+), 23 deletions(-)
diff --git a/security/keys/gc.c b/security/keys/gc.c
index eaddaceda14e..7d687b0962b1 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -155,14 +155,6 @@ static noinline void key_gc_unused_keys(struct list_head *keys)
security_key_free(key);
- /* deal with the user's key tracking and quota */
- if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
- spin_lock(&key->user->lock);
- key->user->qnkeys--;
- key->user->qnbytes -= key->quotalen;
- spin_unlock(&key->user->lock);
- }
-
atomic_dec(&key->user->nkeys);
if (state != KEY_IS_UNINSTANTIATED)
atomic_dec(&key->user->nikeys);
diff --git a/security/keys/key.c b/security/keys/key.c
index 5b10641debd5..ec155cfaae38 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -231,6 +231,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
struct key *key;
size_t desclen, quotalen;
int ret;
+ unsigned long irqflags;
key = ERR_PTR(-EINVAL);
if (!desc || !*desc)
@@ -260,7 +261,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
key_quota_root_maxbytes : key_quota_maxbytes;
- spin_lock(&user->lock);
+ spin_lock_irqsave(&user->lock, irqflags);
if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
if (user->qnkeys + 1 > maxkeys ||
user->qnbytes + quotalen > maxbytes ||
@@ -270,7 +271,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
user->qnkeys++;
user->qnbytes += quotalen;
- spin_unlock(&user->lock);
+ spin_unlock_irqrestore(&user->lock, irqflags);
}
/* allocate and initialise the key and its description */
@@ -328,10 +329,10 @@ struct key *key_alloc(struct key_type *type, const char *desc,
kfree(key->description);
kmem_cache_free(key_jar, key);
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
- spin_lock(&user->lock);
+ spin_lock_irqsave(&user->lock, irqflags);
user->qnkeys--;
user->qnbytes -= quotalen;
- spin_unlock(&user->lock);
+ spin_unlock_irqrestore(&user->lock, irqflags);
}
key_user_put(user);
key = ERR_PTR(ret);
@@ -341,10 +342,10 @@ struct key *key_alloc(struct key_type *type, const char *desc,
kmem_cache_free(key_jar, key);
no_memory_2:
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
- spin_lock(&user->lock);
+ spin_lock_irqsave(&user->lock, irqflags);
user->qnkeys--;
user->qnbytes -= quotalen;
- spin_unlock(&user->lock);
+ spin_unlock_irqrestore(&user->lock, irqflags);
}
key_user_put(user);
no_memory_1:
@@ -352,7 +353,7 @@ struct key *key_alloc(struct key_type *type, const char *desc,
goto error;
no_quota:
- spin_unlock(&user->lock);
+ spin_unlock_irqrestore(&user->lock, irqflags);
key_user_put(user);
key = ERR_PTR(-EDQUOT);
goto error;
@@ -381,8 +382,9 @@ int key_payload_reserve(struct key *key, size_t datalen)
if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
key_quota_root_maxbytes : key_quota_maxbytes;
+ unsigned long flags;
- spin_lock(&key->user->lock);
+ spin_lock_irqsave(&key->user->lock, flags);
if (delta > 0 &&
(key->user->qnbytes + delta > maxbytes ||
@@ -393,7 +395,7 @@ int key_payload_reserve(struct key *key, size_t datalen)
key->user->qnbytes += delta;
key->quotalen += delta;
}
- spin_unlock(&key->user->lock);
+ spin_unlock_irqrestore(&key->user->lock, flags);
}
/* change the recorded data length if that didn't generate an error */
@@ -646,8 +648,18 @@ void key_put(struct key *key)
if (key) {
key_check(key);
- if (refcount_dec_and_test(&key->usage))
+ if (refcount_dec_and_test(&key->usage)) {
+ unsigned long flags;
+
+ /* deal with the user's key tracking and quota */
+ if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
+ spin_lock_irqsave(&key->user->lock, flags);
+ key->user->qnkeys--;
+ key->user->qnbytes -= key->quotalen;
+ spin_unlock_irqrestore(&key->user->lock, flags);
+ }
schedule_work(&key_gc_work);
+ }
}
}
EXPORT_SYMBOL(key_put);
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 10ba439968f7..4bc3e9398ee3 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -954,6 +954,7 @@ long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
long ret;
kuid_t uid;
kgid_t gid;
+ unsigned long flags;
uid = make_kuid(current_user_ns(), user);
gid = make_kgid(current_user_ns(), group);
@@ -1010,7 +1011,7 @@ long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
key_quota_root_maxbytes : key_quota_maxbytes;
- spin_lock(&newowner->lock);
+ spin_lock_irqsave(&newowner->lock, flags);
if (newowner->qnkeys + 1 > maxkeys ||
newowner->qnbytes + key->quotalen > maxbytes ||
newowner->qnbytes + key->quotalen <
@@ -1019,12 +1020,12 @@ long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
newowner->qnkeys++;
newowner->qnbytes += key->quotalen;
- spin_unlock(&newowner->lock);
+ spin_unlock_irqrestore(&newowner->lock, flags);
- spin_lock(&key->user->lock);
+ spin_lock_irqsave(&key->user->lock, flags);
key->user->qnkeys--;
key->user->qnbytes -= key->quotalen;
- spin_unlock(&key->user->lock);
+ spin_unlock_irqrestore(&key->user->lock, flags);
}
atomic_dec(&key->user->nkeys);
@@ -1056,7 +1057,7 @@ long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
return ret;
quota_overrun:
- spin_unlock(&newowner->lock);
+ spin_unlock_irqrestore(&newowner->lock, flags);
zapowner = newowner;
ret = -EDQUOT;
goto error_put;
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