cert-cache: Prevent that a cached issuer is freed too early
Previously we got no reference to the cached issuer certificate before releasing the lock of the cache line, this allowed other threads, or even the same thread if it replaces a cache line, to destroy that issuer certificate in cache() (or flush()) before get_ref() for the issuer certificate is finally called.
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@ -143,6 +143,7 @@ METHOD(cert_cache_t, issued_by, bool,
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private_cert_cache_t *this, certificate_t *subject, certificate_t *issuer,
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signature_scheme_t *schemep)
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{
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certificate_t *cached_issuer = NULL;
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relation_t *found = NULL, *current;
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signature_scheme_t scheme;
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int i;
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@ -154,39 +155,41 @@ METHOD(cert_cache_t, issued_by, bool,
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current->lock->read_lock(current->lock);
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if (current->subject)
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{
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/* check for equal issuer */
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if (issuer->equals(issuer, current->issuer))
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{
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/* reuse issuer instance in cache() */
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issuer = current->issuer;
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if (subject->equals(subject, current->subject))
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{
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/* write hit counter is not locked, but not critical */
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current->hits++;
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found = current;;
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found = current;
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if (schemep)
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{
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*schemep = current->scheme;
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}
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}
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else if (!cached_issuer)
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{
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cached_issuer = current->issuer->get_ref(current->issuer);
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}
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}
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}
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current->lock->unlock(current->lock);
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if (found)
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{
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DESTROY_IF(cached_issuer);
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return TRUE;
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}
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}
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/* no cache hit, check and cache signature */
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if (subject->issued_by(subject, issuer, &scheme))
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{
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cache(this, subject, issuer, scheme);
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cache(this, subject, cached_issuer ?: issuer, scheme);
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if (schemep)
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{
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*schemep = scheme;
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}
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DESTROY_IF(cached_issuer);
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return TRUE;
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}
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DESTROY_IF(cached_issuer);
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return FALSE;
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}
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