On Mon, Feb 24, 2025 at 11:25 AM Kees Cook <k...@kernel.org> wrote: > > On Mon, Feb 24, 2025 at 11:10:22AM -0800, Jeff Xu wrote: > > On Mon, Feb 24, 2025 at 11:03 AM Liam R. Howlett > > <liam.howl...@oracle.com> wrote: > > > > > > * Jeff Xu <jef...@chromium.org> [250224 13:44]: > > > > On Mon, Feb 24, 2025 at 10:21 AM Dave Hansen <dave.han...@intel.com> > > > > wrote: > > > > > > > > > > On 2/24/25 09:45, jef...@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 = VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|VM_PFNMAP; > > > > > > + vm_flags |= 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. > > I think to address Dave's concern, it should start with "VM_". We use > "SEAL" already with VM_SEALED, so the "M" in "MSEAL" may be redundant, > and to clarify the system mapping, how avout VM_SEAL_SYSMAP ? That > capture's, hopefully, Dave, Liam, and your thoughts about the naming? > Liam had a comment in the previous version, asking everything related with mseal() to have the MSEAL keyword, that is why KCONFIG change has MSEAL.
How about VM_MSEAL_SYSMAP ? -Jeff > -- > Kees Cook
