  We report an analysis of the octet baryon masses using the covariant baryon
chiral perturbation theory up to next-to-next-to-next-to-leading order with and
without the virtual decuplet contributions. Particular attention is paid to the
finite-volume corrections and the finite lattice spacing effects on the baryon
masses. A reasonable description of all the publicly available $n_f=2+1$
lattice QCD data is achieved.Utilyzing the Feynman-Hellmann theorem, we
determine the nucleon sigma terms as $\sigma_{\pi N}=55(1)(4)$ MeV and
$\sigma_{sN}=27(27)(4)$ MeV.
