linux-kernel - [PATCH v11 09/14] kernel, arm64: untag user pointers in prctl_set

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Date:   Fri, 15 Mar 2019 20:51:33 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Mark Rutland <mark.rutland@....com>,
        Robin Murphy <robin.murphy@....com>,
        Kees Cook <keescook@...omium.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Shuah Khan <shuah@...nel.org>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
        linux-mm@...ck.org, linux-arch@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Kostya Serebryany <kcc@...gle.com>,
        Evgeniy Stepanov <eugenis@...gle.com>,
        Lee Smith <Lee.Smith@....com>,
        Ramana Radhakrishnan <Ramana.Radhakrishnan@....com>,
        Jacob Bramley <Jacob.Bramley@....com>,
        Ruben Ayrapetyan <Ruben.Ayrapetyan@....com>,
        Chintan Pandya <cpandya@...eaurora.org>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        Dave Martin <Dave.Martin@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        Szabolcs Nagy <Szabolcs.Nagy@....com>,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH v11 09/14] kernel, arm64: untag user pointers in prctl_set_mm*

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

prctl_set_mm() and prctl_set_mm_map() use provided user pointers for vma
lookups, which can only by done with untagged pointers.

Untag user pointers in these functions.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 kernel/sys.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/kernel/sys.c b/kernel/sys.c
index 12df0e5434b8..8e56d87cc6db 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1993,6 +1993,18 @@ static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data
 	if (copy_from_user(&prctl_map, addr, sizeof(prctl_map)))
 		return -EFAULT;
 
+	prctl_map->start_code	= untagged_addr(prctl_map.start_code);
+	prctl_map->end_code	= untagged_addr(prctl_map.end_code);
+	prctl_map->start_data	= untagged_addr(prctl_map.start_data);
+	prctl_map->end_data	= untagged_addr(prctl_map.end_data);
+	prctl_map->start_brk	= untagged_addr(prctl_map.start_brk);
+	prctl_map->brk		= untagged_addr(prctl_map.brk);
+	prctl_map->start_stack	= untagged_addr(prctl_map.start_stack);
+	prctl_map->arg_start	= untagged_addr(prctl_map.arg_start);
+	prctl_map->arg_end	= untagged_addr(prctl_map.arg_end);
+	prctl_map->env_start	= untagged_addr(prctl_map.env_start);
+	prctl_map->env_end	= untagged_addr(prctl_map.env_end);
+
 	error = validate_prctl_map(&prctl_map);
 	if (error)
 		return error;
@@ -2106,6 +2118,8 @@ static int prctl_set_mm(int opt, unsigned long addr,
 			      opt != PR_SET_MM_MAP_SIZE)))
 		return -EINVAL;
 
+	addr = untagged_addr(addr);
+
 #ifdef CONFIG_CHECKPOINT_RESTORE
 	if (opt == PR_SET_MM_MAP || opt == PR_SET_MM_MAP_SIZE)
 		return prctl_set_mm_map(opt, (const void __user *)addr, arg4);
-- 
2.21.0.360.g471c308f928-goog