Diffusion (a passive transport of matter) is a movement of matter and its direction is determined by the matters gradient.
The only way I know of in witch matter can passively diffuse agains its gradient, is by sweeping it when solvent goes by its gradient (in Osmosis). solvent is attracted to an area with a higher salt concentration and drags with it some matter particles, so in this case that draged matter will go agains its gradient.
