From: Matthew Wilcox <willy@infradead.org>
To: Igor Stoppa <igor.stoppa@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
Thiago Jung Bauermann <bauerman@linux.ibm.com>,
igor.stoppa@huawei.com, Nadav Amit <nadav.amit@gmail.com>,
Kees Cook <keescook@chromium.org>,
Ahmed Soliman <ahmedsoliman@mena.vt.edu>,
linux-integrity@vger.kernel.org,
kernel-hardening@lists.openwall.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 03/12] __wr_after_init: generic functionality
Date: Fri, 21 Dec 2018 10:41:20 -0800 [thread overview]
Message-ID: <20181221184120.GG10600@bombadil.infradead.org> (raw)
In-Reply-To: <20181221181423.20455-4-igor.stoppa@huawei.com>
On Fri, Dec 21, 2018 at 08:14:14PM +0200, Igor Stoppa wrote:
> +static inline int memtst(void *p, int c, __kernel_size_t len)
I don't understand why you're verifying that writes actually happen
in production code. Sure, write lib/test_wrmem.c or something, but
verifying every single rare write seems like a mistake to me.
> +#ifndef CONFIG_PRMEM
So is this PRMEM or wr_mem? It's not obvious that CONFIG_PRMEM controls
wrmem.
> +#define wr_assign(var, val) ((var) = (val))
The hamming distance between 'var' and 'val' is too small. The convention
in the line immediately below (p and v) is much more readable.
> +#define wr_rcu_assign_pointer(p, v) rcu_assign_pointer(p, v)
> +#define wr_assign(var, val) ({ \
> + typeof(var) tmp = (typeof(var))val; \
> + \
> + wr_memcpy(&var, &tmp, sizeof(var)); \
> + var; \
> +})
Doesn't wr_memcpy return 'var' anyway?
> +/**
> + * wr_memcpy() - copyes size bytes from q to p
typo
> + * @p: beginning of the memory to write to
> + * @q: beginning of the memory to read from
> + * @size: amount of bytes to copy
> + *
> + * Returns pointer to the destination
> + * The architecture code must provide:
> + * void __wr_enable(wr_state_t *state)
> + * void *__wr_addr(void *addr)
> + * void *__wr_memcpy(void *p, const void *q, __kernel_size_t size)
> + * void __wr_disable(wr_state_t *state)
This section shouldn't be in the user documentation of wr_memcpy().
> + */
> +void *wr_memcpy(void *p, const void *q, __kernel_size_t size)
> +{
> + wr_state_t wr_state;
> + void *wr_poking_addr = __wr_addr(p);
> +
> + if (WARN_ONCE(!wr_ready, "No writable mapping available") ||
Surely not. If somebody's called wr_memcpy() before wr_ready is set,
that means we can just call memcpy().
next prev parent reply other threads:[~2018-12-21 18:41 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20181221181423.20455-1-igor.stoppa@huawei.com>
2018-12-21 18:14 ` [PATCH 01/12] x86_64: memset_user() Igor Stoppa
2018-12-21 18:25 ` Matthew Wilcox
2018-12-21 18:46 ` Igor Stoppa
2018-12-21 20:05 ` Cyrill Gorcunov
2018-12-21 20:29 ` Matthew Wilcox
2018-12-21 20:46 ` Cyrill Gorcunov
2018-12-21 21:07 ` Matthew Wilcox
2018-12-21 21:17 ` Cyrill Gorcunov
2018-12-21 18:14 ` [PATCH 02/12] __wr_after_init: linker section and label Igor Stoppa
2018-12-21 18:14 ` [PATCH 03/12] __wr_after_init: generic functionality Igor Stoppa
2018-12-21 18:41 ` Matthew Wilcox [this message]
2018-12-21 19:07 ` Igor Stoppa
2018-12-21 19:43 ` Matthew Wilcox
2018-12-21 21:54 ` Igor Stoppa
2018-12-21 18:14 ` [PATCH 04/12] __wr_after_init: debug writes Igor Stoppa
2018-12-21 18:14 ` [PATCH 05/12] __wr_after_init: x86_64: __wr_op Igor Stoppa
2018-12-21 18:14 ` [PATCH 06/12] __wr_after_init: Documentation: self-protection Igor Stoppa
2018-12-21 18:14 ` [PATCH 07/12] __wr_after_init: lkdtm test Igor Stoppa
2018-12-21 18:14 ` [PATCH 08/12] rodata_test: refactor tests Igor Stoppa
2018-12-21 18:14 ` [PATCH 09/12] rodata_test: add verification for __wr_after_init Igor Stoppa
2018-12-21 18:14 ` [PATCH 10/12] __wr_after_init: test write rare functionality Igor Stoppa
2018-12-21 18:14 ` [PATCH 11/12] IMA: turn ima_policy_flags into __wr_after_init Igor Stoppa
2018-12-21 18:14 ` [PATCH 12/12] x86_64: __clear_user as case of __memset_user Igor Stoppa
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