  We present a lattice-QCD based analysis of the nucleon sigma terms using
gauge ensembles with $N_f = 2 + 1$ flavors of ${\cal O}(a)$-improved Wilson
fermions, with a complete error budget concerning excited-state contaminations,
the chiral interpolation as well as finite-size and lattice spacing effects. We
compute the sigma terms determined directly from the matrix elements of the
scalar currents. The chiral interpolation is based on SU(3) baryon chiral
perturbation theory using the extended on-mass shell renormalization scheme.
For the pion nucleon sigma term, we obtain $\sigma_{\pi N} = (43.7\pm3.6)$ MeV,
where the error includes our estimate of the aforementioned systematics. The
tension with extractions based on dispersion theory persists at the
2.4-$\sigma$ level. For the strange sigma term, we obtain a non-zero value,
$\sigma_s=(28.6\pm9.3)$ MeV.
