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Groups > linux.kernel > #1666768
| From | David Howells <dhowells@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 25/27] ipc: Convert mqueue fs to fs_context [ver #5] |
| Date | 2017-06-15 16:50 +0200 |
| Message-ID | <tSEfT-3Hl-9@gated-at.bofh.it> (permalink) |
| References | <tSzSV-18C-1@gated-at.bofh.it> <tSifn-6QJ-7@gated-at.bofh.it> <tSifp-6QJ-41@gated-at.bofh.it> <tSzSV-18C-1@gated-at.bofh.it> |
| Organization | Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 |
Al Viro <viro@ZenIV.linux.org.uk> wrote:
> > + if (ctx->ipc_ns != ns) {
>
> How could they possibly be equal? You are setting that ns up here, right?
> How could it be in any process' nsproxy?
Fair point.
> Ugh, again... Is there any reason for dynamic allocation of that thing in
> this particular case? AFAICS, these contortions are all due to going through
> vfs_new_fs_context()/put_fs_context(). And it's not as if they had been
> refcounted...
I can statically initialise it as below, but whilst I don't need to call
vfs_new_fs_context() and put_fs_context(), I do have to call the security
hooks (Smack makes no distinction for internal filesystems) to set up the
security context and clean it up, and I do have to have the error handling for
in case kern_mount_data_fc() fails.
So it actually makes both the source and the object file bigger. Now, I could
hide some of this inside a pair of inline functions, but it doesn't help that
much.
What might be better is to provide a function that wraps the vfs_get_tree()
and kern_mount_data_fc() calls and the cleanup.
David
---
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index f2e1d1d69961..a18a5f6763f9 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -1431,8 +1431,15 @@ static struct file_system_type mqueue_fs_type = {
int mq_init_ns(struct ipc_namespace *ns)
{
- struct mqueue_fs_context *ctx;
- struct fs_context *fc;
+ struct mqueue_fs_context ctx = {
+ .fc.ops = &mqueue_fs_context_ops,
+ .fc.fs_type = &mqueue_fs_type,
+ .fc.cred = current_cred(),
+ .fc.user_ns = current_user_ns(),
+ .fc.purpose = FS_CONTEXT_FOR_NEW,
+ .ipc_ns = ns,
+ };
+ struct super_block *sb;
struct vfsmount *mnt;
int ret;
@@ -1443,29 +1450,32 @@ int mq_init_ns(struct ipc_namespace *ns)
ns->mq_msg_default = DFLT_MSG;
ns->mq_msgsize_default = DFLT_MSGSIZE;
- fc = vfs_new_fs_context(&mqueue_fs_type, NULL, 0, FS_CONTEXT_FOR_NEW);
- if (IS_ERR(fc))
- return PTR_ERR(fc);
-
- ctx = container_of(fc, struct mqueue_fs_context, fc);
- put_ipc_ns(ctx->ipc_ns);
- ctx->ipc_ns = get_ipc_ns(ns);
+ ret = security_fs_context_alloc(&ctx.fc, NULL);
+ if (ret < 0)
+ return ret;
- ret = vfs_get_tree(fc);
+ ret = vfs_get_tree(&ctx.fc);
if (ret < 0)
goto out_fc;
- mnt = kern_mount_data_fc(fc);
+ mnt = kern_mount_data_fc(&ctx.fc);
if (IS_ERR(mnt)) {
ret = PTR_ERR(mnt);
- goto out_fc;
+ goto out_root;
}
ns->mq_mnt = mnt;
ret = 0;
out_fc:
- put_fs_context(fc);
+ security_fs_context_free(&ctx.fc);
return ret;
+
+out_root:
+ sb = ctx.fc.root->d_sb;
+ dput(ctx.fc.root);
+ ctx.fc.root = NULL;
+ deactivate_super(sb);
+ goto out_fc;
}
void mq_clear_sbinfo(struct ipc_namespace *ns)
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[RFC][PATCH 00/27] VFS: Introduce filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 11/27] VFS: Remove unused code after filesystem context changes [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 20/27] NFS: Split nfs_parse_mount_options() [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 03/27] VFS: Make get_mnt_ns() return the namespace [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
Re: [PATCH 03/27] VFS: Make get_mnt_ns() return the namespace [ver #5] Al Viro <viro@ZenIV.linux.org.uk> - 2017-06-15 11:20 +0200
[PATCH 27/27] kernfs, sysfs, cgroup: Support fs_context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
Re: [PATCH 27/27] kernfs, sysfs, cgroup: Support fs_context [ver #5] Tejun Heo <tj@kernel.org> - 2017-06-14 20:00 +0200
Re: [PATCH 27/27] ... and the intel_rdt driver David Howells <dhowells@redhat.com> - 2017-06-15 00:40 +0200
[PATCH 26/27] cpuset: Use fs_context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 16/27] proc: Add fs_context support to procfs [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
Re: [PATCH 16/27] proc: Add fs_context support to procfs [ver #5] Al Viro <viro@ZenIV.linux.org.uk> - 2017-06-15 12:20 +0200
[PATCH 01/27] Provide a function to create a NUL-terminated string from unterminated data [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 09/27] VFS: Add LSM hooks for filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 25/27] ipc: Convert mqueue fs to fs_context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
Re: [PATCH 25/27] ipc: Convert mqueue fs to fs_context [ver #5] Al Viro <viro@ZenIV.linux.org.uk> - 2017-06-15 12:10 +0200
Re: [PATCH 25/27] ipc: Convert mqueue fs to fs_context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-15 16:50 +0200
[PATCH 23/27] NFS: Do some tidying of the parsing code [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 22/27] NFS: Add a small buffer in nfs_fs_context to avoid string dup [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 14/27] VFS: Add a sample program for fsopen/fsmount [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 02/27] VFS: Clean up whitespace in fs/namespace.c and fs/super.c [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 04/27] VFS: Make get_filesystem() return the affected filesystem [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 18/27] NFS: Constify mount argument match tables [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
[PATCH 05/27] VFS: Provide empty name qstr [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:30 +0200
[PATCH 15/27] procfs: Move proc_fill_super() to fs/proc/root.c [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:30 +0200
[PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:30 +0200
Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] Randy Dunlap <rdunlap@infradead.org> - 2017-06-14 20:10 +0200
Updated docs David Howells <dhowells@redhat.com> - 2017-06-15 01:00 +0200
Re: Updated docs Randy Dunlap <rdunlap@infradead.org> - 2017-06-15 04:00 +0200
Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] Casey Schaufler <casey@schaufler-ca.com> - 2017-06-14 22:10 +0200
Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 22:50 +0200
Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] Casey Schaufler <casey@schaufler-ca.com> - 2017-06-14 23:00 +0200
Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] Theodore Ts'o <tytso@mit.edu> - 2017-06-17 12:00 +0200
Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-17 16:20 +0200
Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] Jeff Layton <jlayton@redhat.com> - 2017-06-17 17:00 +0200
Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] Randy Dunlap <rdunlap@infradead.org> - 2017-06-17 17:20 +0200
Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-19 09:50 +0200
[PATCH 21/27] NFS: Deindent nfs_fs_context_parse_option() [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:30 +0200
Re: [PATCH 07/27] VFS: Differentiate mount flags (MS_*) from internal superblock flags [ver #5] Al Viro <viro@ZenIV.linux.org.uk> - 2017-06-15 11:50 +0200
Re: [PATCH 07/27] VFS: Differentiate mount flags (MS_*) from internal superblock flags [ver #5] Christoph Hellwig <hch@infradead.org> - 2017-06-16 11:10 +0200
Re: [PATCH 07/27] VFS: Differentiate mount flags (MS_*) from internal superblock flags [ver #5] David Howells <dhowells@redhat.com> - 2017-06-16 17:00 +0200
Re: [PATCH 07/27] VFS: Differentiate mount flags (MS_*) from internal superblock flags [ver #5] Christoph Hellwig <hch@infradead.org> - 2017-06-16 18:00 +0200
Re: [PATCH 07/27] VFS: Differentiate mount flags (MS_*) from internal superblock flags [ver #5] David Howells <dhowells@redhat.com> - 2017-06-16 18:00 +0200
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