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Message-ID: <20150829104304.GA2841@posteo.de>
Date: Sat, 29 Aug 2015 12:43:04 +0200
From: Dongsu Park <dpark@...teo.net>
To: Peter Hurley <peter@...leysoftware.com>
Cc: Al Viro <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
Josh Triplett <josh@...htriplett.org>,
David Howells <dhowells@...hat.com>,
Alban Crequy <alban@...ocode.com>,
Alexey Dobriyan <adobriyan@...il.com>
Subject: Re: [PATCH v2] devpts: allow mounting with uid/gid of uint32_t
On 28.08.2015 15:33, Peter Hurley wrote:
> On 08/18/2015 11:18 AM, Dongsu Park wrote:
> > ---
> > fs/devpts/inode.c | 20 ++++++++++++++++----
> > 1 file changed, 16 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
> > index c35ffdc12bba..49272fae40a7 100644
> > --- a/fs/devpts/inode.c
> > +++ b/fs/devpts/inode.c
> > @@ -188,23 +188,35 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
> > token = match_token(p, tokens, args);
> > switch (token) {
> > case Opt_uid:
> > - if (match_int(&args[0], &option))
>
> match_int() => make_kuid/kgid is a widespread pattern in filesystems
> for handling uid/gid mount parameters.
>
> How about adding a for-purpose string-to-uid/gid function, rather than
> open-coding?
Yeah, that sounds like a good idea.
Do you mean probably something like this? (on top of -mm tree)
Thanks,
Dongsu
----
>From ccfa5db398ba5ac31c5e0128e88abca1f6d1e6f5 Mon Sep 17 00:00:00 2001
Message-Id: <ccfa5db398ba5ac31c5e0128e88abca1f6d1e6f5.1440844226.git.dpark@...teo.net>
From: Dongsu Park <dpark@...teo.net>
Date: Sat, 29 Aug 2015 12:35:01 +0200
Subject: [PATCH v3] devpts: allow mounting with uid/gid of uint32_t
To allow devpts to be mounted with options of uid/gid of uint32_t,
we need to make use of general parsing API instead of match_int().
So introduce kstrto{uid,gid}(), wrappers around kstrtouint() as well
as make_k{uid,gid}() calls. And then make devpts parse options only
using kstrto{uid,gid}(). Doing that, mounting devpts with uid or
gid > (2^31 - 1) will work as expected, e.g.:
# mount -t devpts devpts /tmp/devptsdir -o \
newinstance,ptmxmode=0666,mode=620,uid=3598450688,gid=3598450693
It was originally by reported on github issue tracker of systemd:
https://github.com/systemd/systemd/issues/956
====
from v2:
* rebase on top of -mm tree
* split common parts for parsing uid/gid into kstrto{uid,gid}()
* fix minor format.
* continue to use kstrtouint() suggested by Alexey Dobriyan.
from v1: fix patch format correctly
Cc: Alexey Dobriyan <adobriyan@...il.com>
Reported-by: Alban Crequy <alban@...ocode.com>
Suggested-by: Peter Hurley <peter@...leysoftware.com>
Signed-off-by: Dongsu Park <dpark@...teo.net>
---
fs/devpts/inode.c | 19 +++++++++----------
include/linux/parse-integer.h | 4 ++++
lib/kstrtox.c | 40 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 53 insertions(+), 10 deletions(-)
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index c35ffdc12bba..fbbd71005dcb 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -181,6 +181,7 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
substring_t args[MAX_OPT_ARGS];
int token;
int option;
+ int rc;
if (!*p)
continue;
@@ -188,20 +189,18 @@ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
token = match_token(p, tokens, args);
switch (token) {
case Opt_uid:
- if (match_int(&args[0], &option))
- return -EINVAL;
- uid = make_kuid(current_user_ns(), option);
- if (!uid_valid(uid))
- return -EINVAL;
+ rc = kstrtouid(args[0].from, &uid);
+ if (rc)
+ return rc;
+
opts->uid = uid;
opts->setuid = 1;
break;
case Opt_gid:
- if (match_int(&args[0], &option))
- return -EINVAL;
- gid = make_kgid(current_user_ns(), option);
- if (!gid_valid(gid))
- return -EINVAL;
+ rc = kstrtogid(args[0].from, &gid);
+ if (rc)
+ return rc;
+
opts->gid = gid;
opts->setgid = 1;
break;
diff --git a/include/linux/parse-integer.h b/include/linux/parse-integer.h
index ba620cdf3df6..2cdc4f418e00 100644
--- a/include/linux/parse-integer.h
+++ b/include/linux/parse-integer.h
@@ -2,6 +2,7 @@
#define _PARSE_INTEGER_H
#include <linux/compiler.h>
#include <linux/types.h>
+#include <linux/uidgid.h>
/*
* int parse_integer(const char *s, unsigned int base, T *val);
@@ -155,6 +156,9 @@ static inline int __must_check kstrtos8(const char *s, unsigned int base, s8 *re
return parse_integer(s, base | PARSE_INTEGER_NEWLINE, res);
}
+int __must_check kstrtouid(const char *uidstr, kuid_t *kuid);
+int __must_check kstrtogid(const char *gidstr, kgid_t *kgid);
+
int __must_check kstrtoull_from_user(const char __user *s, size_t count, unsigned int base, unsigned long long *res);
int __must_check kstrtoll_from_user(const char __user *s, size_t count, unsigned int base, long long *res);
int __must_check kstrtoul_from_user(const char __user *s, size_t count, unsigned int base, unsigned long *res);
diff --git a/lib/kstrtox.c b/lib/kstrtox.c
index 1698b286d954..4c376716a72e 100644
--- a/lib/kstrtox.c
+++ b/lib/kstrtox.c
@@ -17,6 +17,8 @@
#include <linux/math64.h>
#include <linux/export.h>
#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
#include <asm/uaccess.h>
#include "kstrtox.h"
@@ -81,6 +83,44 @@ int f(const char __user *s, size_t count, unsigned int base, type *res) \
} \
EXPORT_SYMBOL(f)
+int kstrtouid(const char *uidstr, kuid_t *kuid)
+{
+ uid_t uidval;
+ kuid_t kuidtmp;
+
+ int rc = kstrtouint(uidstr, 0, &uidval);
+
+ if (rc)
+ return rc;
+
+ kuidtmp = make_kuid(current_user_ns(), uidval);
+ if (!uid_valid(kuidtmp))
+ return -EINVAL;
+
+ *kuid = kuidtmp;
+ return 0;
+}
+EXPORT_SYMBOL(kstrtouid);
+
+int kstrtogid(const char *gidstr, kgid_t *kgid)
+{
+ gid_t gidval;
+ kgid_t kgidtmp;
+
+ int rc = kstrtouint(gidstr, 0, &gidval);
+
+ if (rc)
+ return rc;
+
+ kgidtmp = make_kgid(current_user_ns(), gidval);
+ if (!gid_valid(kgidtmp))
+ return -EINVAL;
+
+ *kgid = kgidtmp;
+ return 0;
+}
+EXPORT_SYMBOL(kstrtogid);
+
kstrto_from_user(kstrtoull_from_user, kstrtoull, unsigned long long);
kstrto_from_user(kstrtoll_from_user, kstrtoll, long long);
kstrto_from_user(kstrtoul_from_user, kstrtoul, unsigned long);
--
2.1.0
--
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