| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <4a8ae74e-2f90-4da8-9511-325ca6f67aa6@huawei.com>
Date: Wed, 24 Jul 2024 17:49:16 +0800
From: Hongbo Li <lihongbo22@...wei.com>
To: Maciej Żenczykowski <maze@...gle.com>, Christian Brauner
<brauner@...nel.org>
CC: Matthew Wilcox <willy@...radead.org>, Kernel hackers
<linux-kernel@...r.kernel.org>, Patrick Rohr <prohr@...gle.com>, Linus
Torvalds <torvalds@...ux-foundation.org>
Subject: Re: UML/hostfs - mount failure at tip of tree
On 2024/7/24 11:59, Maciej Żenczykowski wrote:
> On Tue, Jul 23, 2024 at 7:55 PM Maciej Żenczykowski <maze@...gle.com> wrote:
>>
>> On Tue, Jul 23, 2024 at 7:22 PM Linus Torvalds
>> <torvalds@...ux-foundation.org> wrote:
>>>
>>> On Tue, 23 Jul 2024 at 18:35, Hongbo Li <lihongbo22@...wei.com> wrote:
>>>>
>>>> I apologize for causing this issue. I am currently tracking it down. If
>>>> reverting this can solve the problem, you can revert it first.
>>>
>>> I don't get the feeling that this is _so_ urgent that it needs to be
>>> reverted immediately - let's give it at least a few days and see if
>>> you (or somebody else) figures out the bug.
>>>
>>> Maciej - if you can verify that folio conversion fix suggestion of
>>> mine (or alternatively report that it doesn't help and I was barking
>>> up the wrong tree), that would be great.
>>
>> That appears to fix the folio patch indeed (ie. I no longer need to revert it).
>>
>> The tests are still super unhappy, but I've yet to fix our tests very
>> broken netlink parser for changes that released in 6.10, so that may
>> be unrelated ;-)
>
> +++ fs/hostfs/hostfs_kern.c:
> static int hostfs_fill_super(struct super_block *sb, struct fs_context *fc)
> {
> struct hostfs_fs_info *fsi = sb->s_fs_info;
> - const char *host_root = fc->source;
> + const char *host_root = "/";
>
This doesn't work in case where the host directory is designated (such
as mount -t hostfs hostfs -o /home /host).
I can fix this by the following patch, the root cause of this issue is
the incorrect parsing of the host directory. The original mount path
will use `parse_monolithic` to parse the host directory. For the new
mount api, it use `parse_param` directly. So we should call
`fsconfig(fd, FSCONFIG_SET_STRING, "hostfs", "xxx", 0)` to mount the
hostfs(I think may be we should add hostfs as the key for host
directory.). This may need Christian's reviews.:
```
From e7cc3be86a01b8382e9510f6ae1a2764942c7cba Mon Sep 17 00:00:00 2001
From: Hongbo Li <lihongbo22@...wei.com>
Date: Wed, 24 Jul 2024 16:08:32 +0800
Subject: [PATCH] hostfs: fix the host directory parse when mounting.
hostfs not keep the host directory when mounting. When the host
directory is none (default), fc->source is used as the host root
directory, and this is wrong. Here we use `parse_monolithic` to
handle the old mount path for parsing the root directory. For new
mount path, The `parse_param` is used for the host directory parse.
Fixes: cd140ce9f611 ("hostfs: convert hostfs to use the new mount API")
Signed-off-by: Hongbo Li <lihongbo22@...wei.com>
---
fs/hostfs/hostfs_kern.c | 64 ++++++++++++++++++++++++++++++++++-------
1 file changed, 54 insertions(+), 10 deletions(-)
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index 3eb747d26924..205c3700a035 100644
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -17,6 +17,7 @@
#include <linux/writeback.h>
#include <linux/mount.h>
#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
#include <linux/namei.h>
#include "hostfs.h"
#include <init.h>
@@ -927,7 +928,6 @@ static const struct inode_operations
hostfs_link_iops = {
static int hostfs_fill_super(struct super_block *sb, struct fs_context
*fc)
{
struct hostfs_fs_info *fsi = sb->s_fs_info;
- const char *host_root = fc->source;
struct inode *root_inode;
int err;
@@ -941,15 +941,6 @@ static int hostfs_fill_super(struct super_block
*sb, struct fs_context *fc)
if (err)
return err;
- /* NULL is printed as '(null)' by printf(): avoid that. */
- if (fc->source == NULL)
- host_root = "";
-
- fsi->host_root_path =
- kasprintf(GFP_KERNEL, "%s/%s", root_ino, host_root);
- if (fsi->host_root_path == NULL)
- return -ENOMEM;
-
root_inode = hostfs_iget(sb, fsi->host_root_path);
if (IS_ERR(root_inode))
return PTR_ERR(root_inode);
@@ -975,6 +966,57 @@ static int hostfs_fill_super(struct super_block
*sb, struct fs_context *fc)
return 0;
}
+enum hostfs_parma {
+ Opt_hostfs,
+};
+
+static const struct fs_parameter_spec hostfs_param_specs[] = {
+ fsparam_string_empty("hostfs", Opt_hostfs),
+ {}
+};
+
+static int hostfs_parse_param(struct fs_context *fc, struct
fs_parameter *param)
+{
+ struct hostfs_fs_info *fsi = fc->s_fs_info;
+ struct fs_parse_result result;
+ char *host_root;
+ int opt;
+
+ opt = fs_parse(fc, hostfs_param_specs, param, &result);
+ if (opt < 0)
+ return opt;
+
+ switch (opt) {
+ case Opt_hostfs:
+ host_root = param->string;
+ if (!host_root)
+ host_root = "";
+ fsi->host_root_path =
+ kasprintf(GFP_KERNEL, "%s/%s", root_ino, host_root);
+ if (fsi->host_root_path == NULL)
+ return -ENOMEM;
+ break;
+ }
+
+ return 0;
+}
+static int hostfs_parse_monolithic(struct fs_context *fc, void *data)
+{
+ struct hostfs_fs_info *fsi = fc->s_fs_info;
+ char *host_root = (char *)data;
+
+ /* NULL is printed as '(null)' by printf(): avoid that. */
+ if (host_root == NULL)
+ host_root = "";
+
+ fsi->host_root_path =
+ kasprintf(GFP_KERNEL, "%s/%s", root_ino, host_root);
+ if (fsi->host_root_path == NULL)
+ return -ENOMEM;
+
+ return 0;
+}
+
static int hostfs_fc_get_tree(struct fs_context *fc)
{
return get_tree_nodev(fc, hostfs_fill_super);
@@ -992,6 +1034,8 @@ static void hostfs_fc_free(struct fs_context *fc)
}
static const struct fs_context_operations hostfs_context_ops = {
+ .parse_monolithic = hostfs_parse_monolithic,
+ .parse_param = hostfs_parse_param,
.get_tree = hostfs_fc_get_tree,
.free = hostfs_fc_free,
};
--
2.34.1
```
Thanks,
Hongbo
> appears to fix the problem (when combined with Linus' folio fix).
>
> I think fc->source is just the 'block device' passed to mount, and
> thus for a virtual filesystem like hostfs, it is just garbage...
>
> (and with the appropriate netlink fixes all the tests now pass at tip-of-tree:
> 87f3073c2871 (HEAD) hostfs_fill_super(): host_root := "/" (not fc->source)
> 2743a4aabac6 fs/hostfs/hostfs_kern.c:445 buffer =
> folio_zero_tail(folio, bytes_read, buffer + bytes_read);
> a2caf678d7e1 neighbour: add RTNL_FLAG_DUMP_SPLIT_NLM_DONE to RTM_GETNEIGH
> 3bb0c5772acf net: add RTNL_FLAG_DUMP_SPLIT_NLM_DONE to RTM_GET(RULE|ROUTE)
> 786c8248dbd3 (linux/master) Merge tag
> 'perf-tools-fixes-for-v6.11-2024-07-23' of
> git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools
> )
>
>>> And perhaps remind me about this mount API thing too if it doesn't
>>> seem to be resolved by the end of the week when I'm starting to get
>>> ready to do the rc1?
>>>
>>> Linus
>>
>> --
>> Maciej Żenczykowski, Kernel Networking Developer @ Google
>
> --
> Maciej Żenczykowski, Kernel Networking Developer @ Google
>
Powered by blists - more mailing lists