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KEYS: reaching the keys quotas correctly

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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 a08bf91ce2 ("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: 0b77f5bfb4 ("keys: make the keyring quotas controllable through /proc/sys")
Fixes: a08bf91ce2 ("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>
This commit is contained in:
Yang Xu 2020-02-28 12:41:51 +08:00 committed by Jarkko Sakkinen
parent 18b3670d79
commit 2e356101e7
2 changed files with 3 additions and 3 deletions
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2
security/keys/key.c
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@ -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;
}

4
security/keys/keyctl.c
View File

@ -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;