Messages in this thread | | | Date | Thu, 5 Jul 2012 22:17:01 +0000 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH] force dentry revalidation after namespace change |
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Quoting Glauber Costa (glommer@parallels.com): > When we change the namespace tag of a sysfs entry, the associated dentry > is still kept around. readdir() will work correctly and not display the > old entries, but open() will still succeed, so will reads and writes. > > This will no longer happen if sysfs is remounted, hinting that this is a > cache-related problem. > > I am using the following sequence to demonstrate that: > > shell1: > ip link add type veth > unshare -nm > > shell2: > ip link set veth1 <pid_of_shell_1> > cat /sys/devices/virtual/net/veth1/ifindex > > Before that patch, this will succeed (fail to fail). After it, it will
Confirmed that it currently fails to fail :)
> correctly return an error. Differently from a normal rename, which we > handle fine, changing the object namespace will keep it's path intact. > So this check seems necessary as well. > > Signed-off-by: Glauber Costa <glommer@parallels.com>
Haven't run it, but the patch looks good. Thanks, Glauber.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
> CC: Tejun Heo <tj@kernel.org> > CC: Eric W. Biederman <ebiederm@xmission.com> > CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > --- > fs/sysfs/dir.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c > index e6bb9b2..c24bdd9 100644 > --- a/fs/sysfs/dir.c > +++ b/fs/sysfs/dir.c > @@ -307,6 +307,7 @@ static int sysfs_dentry_revalidate(struct dentry *dentry, struct nameidata *nd) > { > struct sysfs_dirent *sd; > int is_dir; > + int type; > > if (nd->flags & LOOKUP_RCU) > return -ECHILD; > @@ -314,6 +315,10 @@ static int sysfs_dentry_revalidate(struct dentry *dentry, struct nameidata *nd) > sd = dentry->d_fsdata; > mutex_lock(&sysfs_mutex); > > + type = sysfs_ns_type(sd); > + if (sd->s_ns && (sysfs_info(dentry->d_sb)->ns[type] != sd->s_ns)) > + goto out_bad; > + > /* The sysfs dirent has been deleted */ > if (sd->s_flags & SYSFS_FLAG_REMOVED) > goto out_bad; > -- > 1.7.10.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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