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Message-ID: <87wo86qxcs.fsf_-_@x220.int.ebiederm.org>
Date: Fri, 28 Feb 2020 14:18:43 -0600
From: ebiederm@...ssion.com (Eric W. Biederman)
To: <linux-kernel@...r.kernel.org>
Cc: Al Viro <viro@...iv.linux.org.uk>, Kernel Hardening
<kernel-hardening@...ts.openwall.com>, Linux API
<linux-api@...r.kernel.org>, Linux FS Devel
<linux-fsdevel@...r.kernel.org>, Linux Security Module
<linux-security-module@...r.kernel.org>, Akinobu Mita
<akinobu.mita@...il.com>, Alexey Dobriyan <adobriyan@...il.com>, Andrew
Morton <akpm@...ux-foundation.org>, Andy Lutomirski <luto@...nel.org>,
Daniel Micay <danielmicay@...il.com>, Djalal Harouni <tixxdz@...il.com>,
"Dmitry V . Levin" <ldv@...linux.org>, Greg Kroah-Hartman
<gregkh@...uxfoundation.org>, Ingo Molnar <mingo@...nel.org>, "J . Bruce
Fields" <bfields@...ldses.org>, Jeff Layton <jlayton@...chiereds.net>,
Jonathan Corbet <corbet@....net>, Kees Cook <keescook@...omium.org>,
Oleg Nesterov <oleg@...hat.com>, Alexey Gladkov
<gladkov.alexey@...il.com>, Linus Torvalds
<torvalds@...ux-foundation.org>, Jeff Dike <jdike@...toit.com>, Richard
Weinberger <richard@....at>, Anton Ivanov
<anton.ivanov@...bridgegreys.com>
Subject: [PATCH 2/3] uml: Create a private mount of proc for mconsole
The mconsole code only ever accesses proc for the initial pid
namespace. Instead of depending upon the proc_mnt which is
for proc_flush_task have uml create it's own mount of proc
instead.
This allows proc_flush_task to evolve and remove the
need for having a proc_mnt to do it's job.
Cc: Jeff Dike <jdike@...toit.com>
Cc: Richard Weinberger <richard@....at>
Cc: Anton Ivanov <anton.ivanov@...bridgegreys.com>
Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
arch/um/drivers/mconsole_kern.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index e8f5c81c2c6c..30575bd92975 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -36,6 +36,8 @@
#include "mconsole_kern.h"
#include <os.h>
+static struct vfsmount *proc_mnt = NULL;
+
static int do_unlink_socket(struct notifier_block *notifier,
unsigned long what, void *data)
{
@@ -123,7 +125,7 @@ void mconsole_log(struct mc_request *req)
void mconsole_proc(struct mc_request *req)
{
- struct vfsmount *mnt = init_pid_ns.proc_mnt;
+ struct vfsmount *mnt = proc_mnt;
char *buf;
int len;
struct file *file;
@@ -134,6 +136,10 @@ void mconsole_proc(struct mc_request *req)
ptr += strlen("proc");
ptr = skip_spaces(ptr);
+ if (!mnt) {
+ mconsole_reply(req, "Proc not available", 1, 0);
+ goto out;
+ }
file = file_open_root(mnt->mnt_root, mnt, ptr, O_RDONLY, 0);
if (IS_ERR(file)) {
mconsole_reply(req, "Failed to open file", 1, 0);
@@ -683,6 +689,24 @@ void mconsole_stack(struct mc_request *req)
with_console(req, stack_proc, to);
}
+static int __init mount_proc(void)
+{
+ struct file_system_type *proc_fs_type;
+ struct vfsmount *mnt;
+
+ proc_fs_type = get_fs_type("proc");
+ if (!proc_fs_type)
+ return -ENODEV;
+
+ mnt = kern_mount(proc_fs_type);
+ put_filesystem(proc_fs_type);
+ if (IS_ERR(mnt))
+ return PTR_ERR(mnt);
+
+ proc_mnt = mnt;
+ return 0;
+}
+
/*
* Changed by mconsole_setup, which is __setup, and called before SMP is
* active.
@@ -696,6 +720,8 @@ static int __init mconsole_init(void)
int err;
char file[UNIX_PATH_MAX];
+ mount_proc();
+
if (umid_file_name("mconsole", file, sizeof(file)))
return -1;
snprintf(mconsole_socket_name, sizeof(file), "%s", file);
--
2.25.0
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