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keys: update key quotas in key_put()

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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@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@kernel.org>
This commit is contained in:
Luis Henriques 2024-01-30 10:13:44 +00:00 committed by Jarkko Sakkinen
parent 45db3ab700
commit 9578e327b2
3 changed files with 28 additions and 23 deletions
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8
security/keys/gc.c
View File

@ -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);

32
security/keys/key.c
View File

@ -230,6 +230,7 @@ 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)
@ -259,7 +260,7 @@ 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 ||
@ -269,7 +270,7 @@ 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 */
@ -327,10 +328,10 @@ security_error:
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);
@ -340,10 +341,10 @@ no_memory_3:
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:
@ -351,7 +352,7 @@ no_memory_1:
goto error;
no_quota:
spin_unlock(&user->lock);
spin_unlock_irqrestore(&user->lock, irqflags);
key_user_put(user);
key = ERR_PTR(-EDQUOT);
goto error;
@ -380,8 +381,9 @@ 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 ||
@ -392,7 +394,7 @@ 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 */
@ -645,8 +647,18 @@ 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);

11
security/keys/keyctl.c
View File

@ -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 @@ error:
return ret;
quota_overrun:
spin_unlock(&newowner->lock);
spin_unlock_irqrestore(&newowner->lock, flags);
zapowner = newowner;
ret = -EDQUOT;
goto error_put;