On Thu, 06 Dec 2007 09:21:53 +0100 Giacomo Catenazzi <[email protected]> wrote:
> Andrew Morton wrote:
> > On Mon, 3 Dec 2007 19:00:25 GMT Linux Kernel Mailing List <[email protected]> wrote:
> >
> >> Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=2b1e300a9dfc3196ccddf6f1d74b91b7af55e416
> >> Commit: 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416
> >> Parent: e03ba84adb62fbc6049325a5bc00ef6932fa5e39
> >> Author: Eric W. Biederman <[email protected]>
> >> AuthorDate: Sun Dec 2 00:33:17 2007 +1100
> >> Committer: Herbert Xu <[email protected]>
> >> CommitDate: Sun Dec 2 00:33:17 2007 +1100
> >>
> >> [NETNS]: Fix /proc/net breakage
> >>
> >> Well I clearly goofed when I added the initial network namespace support
> >> for /proc/net. Currently things work but there are odd details visible to
> >> user space, even when we have a single network namespace.
> >>
> >> Since we do not cache proc_dir_entry dentries at the moment we can just
> >> modify ->lookup to return a different directory inode depending on the
> >> network namespace of the process looking at /proc/net, replacing the
> >> current technique of using a magic and fragile follow_link method.
> >>
> >> To accomplish that this patch:
> >> - introduces a shadow_proc method to allow different dentries to
> >> be returned from proc_lookup.
> >> - Removes the old /proc/net follow_link magic
> >> - Fixes a weakness in our not caching of proc generic dentries.
> >>
> >> As shadow_proc uses a task struct to decided which dentry to return we can
> >> go back later and fix the proc generic caching without modifying any code
> >> that uses the shadow_proc method.
> >
> > This patch caused the binfmt_misc regression reported in
> > http://bugzilla.kernel.org/show_bug.cgi?id=9504
>
> This patch also doesn't allow to mount /proc/bus/usb
>
Does Denis's patch fix it?
Thanks.
From: "Denis V. Lunev" <[email protected]>
/proc/sys/fs/binfmt_misc dentry disappeared during d_revalidate.
d_revalidate only dentries from shadowed one and below.
http://bugzilla.kernel.org/show_bug.cgi?id=9504
Cc: Eric W. Biederman <[email protected]>
Cc: Marcus Better <[email protected]>
Signed-off-by: Denis V. Lunev <[email protected]>
Cc: Marcus Better <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
fs/proc/generic.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff -puN fs/proc/generic.c~lost-content-of-proc-sys-fs-binfmt_misc fs/proc/generic.c
--- a/fs/proc/generic.c~lost-content-of-proc-sys-fs-binfmt_misc
+++ a/fs/proc/generic.c
@@ -380,12 +380,17 @@ static int proc_revalidate_dentry(struct
return 0;
}
-static struct dentry_operations proc_dentry_operations =
+static struct dentry_operations proc_dentry_shadow_operations =
{
.d_delete = proc_delete_dentry,
.d_revalidate = proc_revalidate_dentry,
};
+static struct dentry_operations proc_dentry_operations =
+{
+ .d_delete = proc_delete_dentry,
+};
+
/*
* Don't create negative dentries here, return -ENOENT by hand
* instead.
@@ -394,6 +399,7 @@ struct dentry *proc_lookup(struct inode
{
struct inode *inode = NULL;
struct proc_dir_entry * de;
+ int use_shadow = 0;
int error = -ENOENT;
lock_kernel();
@@ -406,8 +412,10 @@ struct dentry *proc_lookup(struct inode
if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
unsigned int ino;
- if (de->shadow_proc)
+ if (de->shadow_proc) {
de = de->shadow_proc(current, de);
+ use_shadow = 1;
+ }
ino = de->low_ino;
de_get(de);
spin_unlock(&proc_subdir_lock);
@@ -423,6 +431,8 @@ struct dentry *proc_lookup(struct inode
if (inode) {
dentry->d_op = &proc_dentry_operations;
+ dentry->d_op = use_shadow ?
+ &proc_dentry_shadow_operations : dentry->d_parent->d_op;
d_add(dentry, inode);
return NULL;
}
_
--
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