From: Ross Lagerwall <ross.lagerwall@citrix.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: sstabellini@kernel.org, Andrew Cooper <andrew.cooper3@citrix.com>,
julien.grall@arm.com, Jan Beulich <jbeulich@suse.com>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH v5 08/16] livepatch/arm/x86: Check payload for for unwelcomed symbols.
Date: Fri, 23 Sep 2016 15:49:15 +0100 [thread overview]
Message-ID: <dbc9cabe-cb88-816c-c4f7-b96f5ea34bc7@citrix.com> (raw)
In-Reply-To: <1474479154-20991-9-git-send-email-konrad.wilk@oracle.com>
On 09/21/2016 06:32 PM, Konrad Rzeszutek Wilk wrote:
> Certain platforms, such as ARM [32|64] add extra mapping symbols
> such as $x (for ARM64 instructions), or more interesting to
> this patch: $t (for Thumb instructions). These symbols are suppose
> to help the final linker to make any adjustments (such as
> add an veneer). But more importantly - we do not compile Xen
> with any Thumb instructions (which are variable length) - and
> if we find these mapping symbols we should disallow such payload.
>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Ross Lagerwall <ross.lagerwall@citrix.com>
> Cc: Stefano Stabellini <sstabellini@kernel.org>
> Cc: Julien Grall <julien.grall@arm.com
> Cc: Jan Beulich <jbeulich@suse.com>
> Cc: Andrew Cooper <andrew.cooper3@citrix.com>
>
> v3: New submission.
> Use &sym[i] instead of sym (as that will always be NULL).
> v4: Use bool instead of int for return
> Update comment in common code about ARM odd symbols.
> s/_check/_deny/ to make it more clear.
> v5: Also check for $t.* wildcard.
> Use Julien's variant where we roll the [2] check in the return.
> ---
> xen/arch/arm/livepatch.c | 16 ++++++++++++++++
> xen/arch/x86/livepatch.c | 7 +++++++
> xen/common/livepatch_elf.c | 7 +++++++
> xen/include/xen/livepatch.h | 2 ++
> 4 files changed, 32 insertions(+)
>
> diff --git a/xen/arch/arm/livepatch.c b/xen/arch/arm/livepatch.c
> index 9959315..5a99ab5 100644
> --- a/xen/arch/arm/livepatch.c
> +++ b/xen/arch/arm/livepatch.c
> @@ -117,6 +117,22 @@ bool arch_livepatch_symbol_ok(const struct livepatch_elf *elf,
> return true;
> }
>
> +bool arch_livepatch_symbol_deny(const struct livepatch_elf *elf,
> + const struct livepatch_elf_sym *sym)
> +{
> +#ifdef CONFIG_ARM_32
> + /*
> + * Xen does not use Thumb instructions - and we should not see any of
> + * them. If we do, abort.
> + */
> + if ( sym->name && sym->name[0] == '$' && sym->name[1] == 't' )
> + {
> + return ( !sym->name[2] || sym->name[2] == '.' );
> + }
> +#endif
> + return false;
> +}
> +
> int arch_livepatch_perform_rel(struct livepatch_elf *elf,
> const struct livepatch_elf_sec *base,
> const struct livepatch_elf_sec *rela)
> diff --git a/xen/arch/x86/livepatch.c b/xen/arch/x86/livepatch.c
> index 7a369a0..9663ef6 100644
> --- a/xen/arch/x86/livepatch.c
> +++ b/xen/arch/x86/livepatch.c
> @@ -131,6 +131,13 @@ bool arch_livepatch_symbol_ok(const struct livepatch_elf *elf,
> return true;
> }
>
> +bool arch_livepatch_symbol_deny(const struct livepatch_elf *elf,
> + const struct livepatch_elf_sym *sym)
> +{
> + /* No special checks on x86. */
> + return false;
> +}
> +
> int arch_livepatch_perform_rel(struct livepatch_elf *elf,
> const struct livepatch_elf_sec *base,
> const struct livepatch_elf_sec *rela)
> diff --git a/xen/common/livepatch_elf.c b/xen/common/livepatch_elf.c
> index f46990e..ec74beb 100644
> --- a/xen/common/livepatch_elf.c
> +++ b/xen/common/livepatch_elf.c
> @@ -251,6 +251,13 @@ static int elf_get_sym(struct livepatch_elf *elf, const void *data)
>
> sym[i].sym = s;
> sym[i].name = strtab_sec->data + delta;
> + /* e.g. On ARM we should NEVER see $t* symbols. */
I'd prefer this comment in ARM's arch_livepatch_symbol_deny.
Either way,
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
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next prev parent reply other threads:[~2016-09-23 14:49 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 17:32 [PATCH v5] Livepatch for ARM 64 and 32 Konrad Rzeszutek Wilk
2016-09-21 17:32 ` [PATCH v5 01/16] arm64: s/ALTERNATIVE/HAS_ALTERNATIVE/ Konrad Rzeszutek Wilk
2016-09-22 12:21 ` Julien Grall
2016-09-21 17:32 ` [PATCH v5 02/16] arm/x86/common: Add HAS_[ALTERNATIVE|EX_TABLE] Konrad Rzeszutek Wilk
2016-09-22 12:23 ` Julien Grall
2016-09-22 15:30 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 03/16] livepatch: Reject payloads with .alternative or .ex_table if support is not built-in Konrad Rzeszutek Wilk
2016-09-23 12:47 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 04/16] arm: poison initmem when it is freed Konrad Rzeszutek Wilk
2016-09-22 12:28 ` Julien Grall
2016-09-21 17:32 ` [PATCH v5 05/16] livepatch: Initial ARM64 support Konrad Rzeszutek Wilk
2016-09-22 12:49 ` Julien Grall
2016-09-23 13:38 ` Ross Lagerwall
2016-09-23 15:44 ` Konrad Rzeszutek Wilk
2016-09-27 16:42 ` Julien Grall
2016-09-21 17:32 ` [PATCH v5 06/16] livepatch: ARM/x86: Check displacement of old_addr and new_addr Konrad Rzeszutek Wilk
2016-09-22 12:55 ` Julien Grall
2016-09-23 14:36 ` Ross Lagerwall
2016-09-23 15:37 ` Konrad Rzeszutek Wilk
2016-09-23 15:59 ` Konrad Rzeszutek Wilk
2016-09-28 10:21 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 07/16] livepatch: ARM 32|64: Ignore mapping symbols: $[d, a, x] Konrad Rzeszutek Wilk
2016-09-22 12:56 ` Julien Grall
2016-09-23 14:44 ` Ross Lagerwall
2016-09-23 16:13 ` Konrad Rzeszutek Wilk
2016-09-21 17:32 ` [PATCH v5 08/16] livepatch/arm/x86: Check payload for for unwelcomed symbols Konrad Rzeszutek Wilk
2016-09-22 13:00 ` Julien Grall
2016-09-23 1:29 ` Konrad Rzeszutek Wilk
2016-09-27 8:49 ` Ross Lagerwall
2016-09-23 14:49 ` Ross Lagerwall [this message]
2016-09-23 16:15 ` Konrad Rzeszutek Wilk
2016-09-21 17:32 ` [PATCH v5 09/16] livepatch: Move test-cases to their own sub-directory in test Konrad Rzeszutek Wilk
2016-09-22 13:01 ` Julien Grall
2016-09-23 14:51 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 10/16] livepatch: x86, ARM, alternative: Expose FEATURE_LIVEPATCH Konrad Rzeszutek Wilk
2016-09-22 13:03 ` Julien Grall
2016-09-27 9:49 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 11/16] livepatch: tests: Make them compile under ARM64 Konrad Rzeszutek Wilk
2016-09-22 13:10 ` Julien Grall
2016-09-22 19:26 ` Konrad Rzeszutek Wilk
2016-09-23 1:33 ` Konrad Rzeszutek Wilk
2016-09-23 9:50 ` Julien Grall
2016-09-27 9:49 ` Ross Lagerwall
2016-09-21 17:32 ` [PATCH v5 12/16] xen/arm32: Add an helper to invalidate all instruction caches Konrad Rzeszutek Wilk
2016-09-22 13:17 ` Julien Grall
2016-09-21 17:32 ` [PATCH v5 13/16] bug/x86/arm: Align bug_frames sections Konrad Rzeszutek Wilk
2016-09-21 17:32 ` [PATCH v5 14/16] livepatch: Initial ARM32 support Konrad Rzeszutek Wilk
2016-09-27 16:39 ` Julien Grall
2016-09-27 17:50 ` Konrad Rzeszutek Wilk
2016-09-27 23:13 ` Julien Grall
2016-09-21 17:32 ` [PATCH v5 15/16] livepatch, arm[32|64]: Share arch_livepatch_revert Konrad Rzeszutek Wilk
2016-09-23 14:59 ` Ross Lagerwall
2016-09-23 16:15 ` Konrad Rzeszutek Wilk
2016-09-21 17:32 ` [PATCH v5 16/16] livepatch: arm[32, 64], x86: NOP test-case Konrad Rzeszutek Wilk
2016-09-22 13:23 ` Julien Grall
2016-09-23 1:35 ` Konrad Rzeszutek Wilk
2016-09-23 9:53 ` Julien Grall
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