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Mon, 24 Feb 2025 11:10:33 -0800 (PST) MIME-Version: 1.0 References: <20250224174513.3600914-1-jeffxu@google.com> <20250224174513.3600914-2-jeffxu@google.com> <443992d7-f694-4e46-b120-545350a5d598@intel.com> <3nxcy7zshqxmjia7y6cyajeoclcxizkrhhsitji5ujbafbvhlu@7hqs6uodor56> In-Reply-To: <3nxcy7zshqxmjia7y6cyajeoclcxizkrhhsitji5ujbafbvhlu@7hqs6uodor56> From: Jeff Xu Date: Mon, 24 Feb 2025 11:10:22 -0800 X-Gm-Features: AWEUYZmwpnqiN9sqZHdi21X3o8pzG8dSdU0zfO4HZpkMFe9rZXpLE-Vov3pXiB0 Message-ID: Subject: Re: [PATCH v6 1/7] mseal, system mappings: kernel config and header change To: "Liam R. Howlett" , Jeff Xu , Dave Hansen , akpm@linux-foundation.org, keescook@chromium.org, jannh@google.com, torvalds@linux-foundation.org, vbabka@suse.cz, lorenzo.stoakes@oracle.com, adhemerval.zanella@linaro.org, oleg@redhat.com, avagin@gmail.com, benjamin@sipsolutions.net, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, linux-mm@kvack.org, jorgelo@chromium.org, sroettger@google.com, hch@lst.de, ojeda@kernel.org, thomas.weissschuh@linutronix.de, adobriyan@gmail.com, johannes@sipsolutions.net, pedro.falcato@gmail.com, hca@linux.ibm.com, willy@infradead.org, anna-maria@linutronix.de, mark.rutland@arm.com, linus.walleij@linaro.org, Jason@zx2c4.com, deller@gmx.de, rdunlap@infradead.org, davem@davemloft.net, peterx@redhat.com, f.fainelli@gmail.com, gerg@kernel.org, dave.hansen@linux.intel.com, mingo@kernel.org, ardb@kernel.org, mhocko@suse.com, 42.hyeyoo@gmail.com, peterz@infradead.org, ardb@google.com, enh@google.com, rientjes@google.com, groeck@chromium.org, mpe@ellerman.id.au, aleksandr.mikhalitsyn@canonical.com, mike.rapoport@gmail.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 57DBBA0004 X-Stat-Signature: ogbis7am6p6xjggtk69g7yikxhw8iwar X-HE-Tag: 1740424234-148744 X-HE-Meta: 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 zIxkAzRt w4/KBUaAchnZwe0K7dBXc+lMcGT8RuPdpTMwarJVt347tAFnwmjcCoFeUvh6ZP87MOrPC0FHUXgLy/BxZwh6GwDamNRl7SAvO7Vt5hRX9cQcln3jJJHzy8ld0IVXcmFh11q7BYz9JRh/D5vmclp+uDVeR73fn9lvZkBnrFGBV/oD9MlC1HH0sm/deNIOxy4bLuYfGye2VOgoKI17R0VnJYJB+zBA2Qmh4huRNfOH4F+JGn8Q/nT37XxAOoLPa8AJaM3HWRgvGDzUuOTnp/0uGpRq/5Y6QYJ3DhEdHdDKImwteiVWBQMIWPx1mJVlgMiy5f7mVA7mPdHXPFkIpZr5TH+Fy7g== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Feb 24, 2025 at 11:03=E2=80=AFAM Liam R. Howlett wrote: > > * Jeff Xu [250224 13:44]: > > On Mon, Feb 24, 2025 at 10:21=E2=80=AFAM Dave Hansen wrote: > > > > > > On 2/24/25 09:45, jeffxu@chromium.org wrote: > > > > +/* > > > > + * mseal of userspace process's system mappings. > > > > + */ > > > > +#ifdef CONFIG_MSEAL_SYSTEM_MAPPINGS > > > > +#define MSEAL_SYSTEM_MAPPINGS_VM_FLAG VM_SEALED > > > > +#else > > > > +#define MSEAL_SYSTEM_MAPPINGS_VM_FLAG VM_NONE > > > > +#endif > > > > > > This ends up looking pretty wonky in practice: > > > > > > > + vm_flags =3D VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|VM_PFNMAP; > > > > + vm_flags |=3D MSEAL_SYSTEM_MAPPINGS_VM_FLAG; > > > > > > because MSEAL_SYSTEM_MAPPINGS_VM_FLAG is so much different from the > > > other ones. > > > > > > Would it really hurt to have > > > > > > #ifdef CONFIG_64BIT > > > /* VM is sealed, in vm_flags */ > > > #define VM_SEALED _BITUL(63) > > > +#else > > > +#define VM_SEALED VM_NONE > > > #endif > > > > > > ? > > > > > VM_SEALED isn't defined in 32-bit systems, and mseal.c isn't part of > > the build. This is intentional. Any 32-bit code trying to use the > > sealing function or the VM_SEALED flag will immediately fail > > compilation. This makes it easier to identify incorrect usage. > > > > The reason that two #defines are needed is because you can have mseal > enabled while not sealing system mappings, so for this to be clean we > need two defines. > > However MSEAL_SYSTEM_MAPPINGS_VM_FLAG, is _way_ too long, in my opinion. > Keeping with "VM_SEALED" I'd suggest "VM_SYSTEM_SEALED". > How about MSEAL_SYSTME_MAPPINGS as Kees suggested ? The VM_SYSTEM_SEALED doesn't have the MSEAL key or the MAPPING, so it might take longer for the new reader to understand what it is. -Jeff