Hilchos Issurei Mizbeiach 5:12

If someone brought an offering without any salt, he is subject to the penalty of lashes, as per Leviticus 2:13: “You shall not hold back salt, the covenant of your God.” Even though he is subject to lashes, the offering is fit and accepted by God, except in the case of a flour offering. Salt is an indispensable component of the fistful taken from flour offerings as per the aforementioned verse: “You shall not hold back salt, the covenant of your God, from your flour offering.”

Hilchos Issurei Mizbeiach 5:13

The salt used to salt the offerings is public property, just like the firewood. A private person may not bring salt or wood from home for his offering. Salt for the Temple service was stored in three places: the salt chamber, on the ramp of the altar, and on top of the altar. The hides of the offerings were salted in the salt chamber and the limbs were salted on the ramp. On the top of the altar, they salted the fistful of flour (from flour offerings), the frankincense (from the showbread), flour offerings that were burned, and birds that were brought as burnt offerings.