Greek kédros 'cedar', Latin citrus 'thuja; citron'

As most terms related to Mediterranean flora, Greek kédros 'cedar' (borrowed into Latin cedrus) has no IE etymology. There're also the derivatives kédris, kédron 'juniper berry' (actually a modified conifer cone).

On the other hand, Latin citrus, which designates two different kinds of tree, 'thuja' (citrum 'thuja wood') and 'citron'¹, is somehow related to the Greek word, possibly through an Etruscan intermediate².

In my opinion, these are instances of a Wanderwort of Semitic origin: *kˁtr- 'smoke, incense', referring to the aromatic characteristics of these trees, either the wood (cedar, thuja) or the fruit (citron). 

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¹ Whose Greek names kítron, kítrion, kítrea, are seemingly loanwords from Latin.
² A. Ernout & A. Meillet (1959): Dictionnaire étymologique de la langue latine, pp. 123-124.