From mboxrd@z Thu Jan 1 00:00:00 1970 From: dchinner@redhat.com (Dave Chinner) Date: Wed, 21 Feb 2018 12:36:36 +1100 Subject: [RFC PATCH v16 0/6] mm: security: ro protection for dynamic data In-Reply-To: <20180220235600.GA3706@bombadil.infradead.org> References: <20180212165301.17933-1-igor.stoppa@huawei.com> <20180220012111.GC3728@rh> <24e65dec-f452-a444-4382-d1f88fbb334c@huawei.com> <20180220213604.GD3728@rh> <20180220235600.GA3706@bombadil.infradead.org> Message-ID: <20180221013636.GE3728@rh> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On Tue, Feb 20, 2018 at 03:56:00PM -0800, Matthew Wilcox wrote: > On Wed, Feb 21, 2018 at 08:36:04AM +1100, Dave Chinner wrote: > > FWIW, I'm not wanting to use it to replace static variables. All the > > structures are dynamically allocated right now, and get assigned to > > other dynamically allocated pointers. I'd likely split the current > > structures into a "ro after init" structure and rw structure, so > > how does the "__ro_after_init" attribute work in that case? Is it > > something like this? > > > > struct xfs_mount { > > struct xfs_mount_ro{ > > ....... > > } *ro __ro_after_init; ^^^^^^^^ pointer, not embedded structure.... > > ...... > > No, you'd do: > > struct xfs_mount_ro { > [...] > }; > > struct xfs_mount { > const struct xfs_mount_ro *ro; > [...] > }; .... so that's pretty much the same thing :P > > Also, what compile time checks are in place to catch writes to > > ro structure members? Is sparse going to be able to check this sort > > of thing, like is does with endian-specific variables? > > Just labelling the pointer const should be enough for the compiler to > catch unintended writes. Ok. > > > I'd be interested to have your review of the pmalloc API, if you think > > > something is missing, once I send out the next revision. > > > > I'll look at it in more depth when it comes past again. :P > > I think the key question is whether you want a slab-style interface > or whether you want a kmalloc-style interface. I'd been assuming > the former, but Igor has implemented the latter already. Slabs are rally only useful when you have lots of a specific type of object. I'm concerned mostly about one-off per-mount point structures, of which there are relatively few. A heap-like pool per mount is fine for this. Cheers, Dave. -- Dave Chinner dchinner at redhat.com -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html