Commit 2e356101 authored Feb 28, 2020 by Yang Xu Committed by Jarkko Sakkinen Mar 15, 2020

KEYS: reaching the keys quotas correctly



Currently, when we add a new user key, the calltrace as below:

add_key()
  key_create_or_update()
    key_alloc()
    __key_instantiate_and_link
      generic_key_instantiate
        key_payload_reserve
          ......

Since commit a08bf91c ("KEYS: allow reaching the keys quotas exactly"),
we can reach max bytes/keys in key_alloc, but we forget to remove this
limit when we reserver space for payload in key_payload_reserve. So we
can only reach max keys but not max bytes when having delta between plen
and type->def_datalen. Remove this limit when instantiating the key, so we
can keep consistent with key_alloc.

Also, fix the similar problem in keyctl_chown_key().

Fixes: 0b77f5bf ("keys: make the keyring quotas controllable through /proc/sys")
Fixes: a08bf91c ("KEYS: allow reaching the keys quotas exactly")
Cc: stable@vger.kernel.org # 5.0.x
Cc: Eric Biggers <ebiggers@google.com>
Signed-off-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

parent 18b3670d

security/keys/key.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -382,7 +382,7 @@ int key_payload_reserve(struct key *key, size_t datalen)
		spin_lock(&key->user->lock);

		if (delta > 0 &&
		(key->user->qnbytes + delta >= maxbytes \|\|
		(key->user->qnbytes + delta > maxbytes \|\|
		key->user->qnbytes + delta < key->user->qnbytes)) {
		ret = -EDQUOT;
		}

security/keys/keyctl.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -937,8 +937,8 @@ long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
		key_quota_root_maxbytes : key_quota_maxbytes;

		spin_lock(&newowner->lock);
		if (newowner->qnkeys + 1 >= maxkeys \|\|
		newowner->qnbytes + key->quotalen >= maxbytes \|\|
		if (newowner->qnkeys + 1 > maxkeys \|\|
		newowner->qnbytes + key->quotalen > maxbytes \|\|
		newowner->qnbytes + key->quotalen <
		newowner->qnbytes)
		goto quota_overrun;

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