From mboxrd@z Thu Jan 1 00:00:00 1970 From: dchinner@redhat.com (Dave Chinner) Date: Thu, 22 Feb 2018 08:36:29 +1100 Subject: [RFC PATCH v16 0/6] mm: security: ro protection for dynamic data In-Reply-To: <46a9610a-182b-4765-9d83-cab6297377f3@huawei.com> 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> <20180221013636.GE3728@rh> <46a9610a-182b-4765-9d83-cab6297377f3@huawei.com> Message-ID: <20180221213629.GF3728@rh> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On Wed, Feb 21, 2018 at 11:56:22AM +0200, Igor Stoppa wrote: > On 21/02/18 03:36, Dave Chinner wrote: > > 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" > > I would prefer to use a different terminology, because, if I have > understood the use case, this is not exactly the same as __ro_after_init I want a dynamically allocated "write once" structure. A "write once" structure is, conceptually, is exactly the same as "ro after init". Implementation wise, it may be different to "__ro_after_init", especially when compared to static/global variables. It seems lots of people get confused when discussing concepts vs implementation... :) > >>> ...... > >> > >> No, you'd do: > >> > >> struct xfs_mount_ro { > >> [...] > >> }; > > is this something that is readonly from the beginning and then shared > among mount points or is it specific to each mount point? It's dynamically allocated for each mount point, made read-only before the mount completes and lives for the length of the mount point. > >> struct xfs_mount { > >> const struct xfs_mount_ro *ro; > >> [...] > >> }; > > > > .... so that's pretty much the same thing :P > > The "const" modifier is a nice way to catch errors through the compiler, > iff the ro data will not be initialized through this handle, when it's > still writable. That's kinda implied by the const, isn't it? If we don't do it that way, then the compiler will throw errors.... 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