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<20260225211907.7368-1-James.Bottomley@HansenPartnership.com> <20260226021331.GA55502@quark> <3900433c727c1e7ab6e131003de7ca53bb0d23d1.camel@HansenPartnership.com> <20260305075511.GA155793@sol> <20260305185156.GD2796@quark> Autocrypt: addr=James.Bottomley@HansenPartnership.com; prefer-encrypt=mutual; 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AHBLpBdnl9SOe8ETkv6GqbZrXUED/dAbRVIT5vHP51zyYB8rAUjp3PnzxsXFG8eQaacEyKSl0DKDlgKuQ+k292LVGJhEva8z4cwg3JcrQWzbpTRskQRP624aQ7t0LKbNfXqfYT13TvZNTDdjQaCJRJ3EG8uXOszVKuc0guXunZPmmq6x1Y3bOfOezcFYoywwL3nKef+Z5sQrjG3/5NLeu+W Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2026-03-05 at 10:51 -0800, Eric Biggers wrote: > On Thu, Mar 05, 2026 at 09:46:42AM -0500, James Bottomley wrote: > > On Wed, 2026-03-04 at 23:55 -0800, Eric Biggers wrote: > > > On Thu, Feb 26, 2026 at 07:43:54AM -0500, James Bottomley wrote: > > > > > If this is for some out-of-tree module, we don't do that. > > > > >=20 > > > > > I'll also note that we should generally be aiming to simplify > > > > > the PKCS#7 signature verification code, not making it even > > > > > more complex. > > > >=20 > > > > I'm fine with the general goal, but since the current code > > > > verifies the signature, pulls out the message hash and other > > > > attributes, compares the message against the MessageDigest one > > > > and then frees the whole structure it's a bit hard to see how > > > > the current goal can be achieved without extracting at least > > > > the first part of that > > > > ... > > > > but if you have=C2=A0=C2=A0 suggestion, I'm happy to implement. > > >=20 > > > Sure, just incorporate your auxiliary data into the actual > > > message being signed and verified.=C2=A0 Something like: > > > =C2=A0=C2=A0=C2=A0=20 > > > =C2=A0=C2=A0=C2=A0 program_len || program || hash* > >=20 > > We can't do that because the second hash is for the LSM.=C2=A0 If > > there's no LSM then we need the signature to pass the current eBPF > > signature check because the second hash will be verified by the > > loader, which means the program hash and nothing else must be in > > the messageDigest attr. > >=20 >=20 > Why does the loader need to verify the signature if the kernel has to > do it anyway, and why does the loader need to skip verifying the > maps? Well, I didn't say kernel, I said LSM. The problem is that the last hook in the LSM chain for eBPF loading occurs before the loader has actually run. This means that either the LSM needs to be assured verification will complete (by running it itself), which is what the patch set I pointed to does; or that we need an additional verification hook in eBPF somewhere in the verifier after the loader has run, which the eBPF people are looking at but haven't actually found anything yet. The OID helps the LSM do the additional verification without changing any of the eBPF loading flow. Regards, James