Messages in this thread | | | Subject | Re: [PATCH] ovl: filter of trusted xattr results in audit | From | Mark Salyzyn <> | Date | Mon, 7 Oct 2019 09:43:03 -0700 |
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On 10/7/19 9:40 AM, Greg Kroah-Hartman wrote: > On Mon, Oct 07, 2019 at 06:17:25PM +0200, Greg Kroah-Hartman wrote: >> On Mon, Oct 07, 2019 at 06:16:16PM +0200, Greg Kroah-Hartman wrote: >>> On Mon, Oct 07, 2019 at 09:09:16AM -0700, Mark Salyzyn wrote: >>>> When filtering xattr list for reading, presence of trusted xattr >>>> results in a security audit log. However, if there is other content >>>> no errno will be set, and if there isn't, the errno will be -ENODATA >>>> and not -EPERM as is usually associated with a lack of capability. >>>> The check does not block the request to list the xattrs present. >>>> >>>> Switch to has_capability_noaudit to reflect a more appropriate check. >>>> >>>> Signed-off-by: Mark Salyzyn <salyzyn@android.com> >>>> Cc: linux-security-module@vger.kernel.org >>>> Cc: kernel-team@android.com >>>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >>>> Cc: stable@vger.kernel.org # v3.18 >>>> Fixes: upstream a082c6f680da ("ovl: filter trusted xattr for non-admin") >>>> Fixes: 3.18 4bcc9b4b3a0a ("ovl: filter trusted xattr for non-admin") >>>> --- >>>> Replaced ns_capable_noaudit with 3.18.y tree specific >>>> has_capability_noaudit present in original submission to kernel.org >>>> commit 5c2e9f346b815841f9bed6029ebcb06415caf640 >>>> ("ovl: filter of trusted xattr results in audit") >>>> >>>> fs/overlayfs/inode.c | 3 ++- >>>> 1 file changed, 2 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c >>>> index a01ec1836a72..1175efa5e956 100644 >>>> --- a/fs/overlayfs/inode.c >>>> +++ b/fs/overlayfs/inode.c >>>> @@ -265,7 +265,8 @@ static bool ovl_can_list(const char *s) >>>> return true; >>>> >>>> /* Never list trusted.overlay, list other trusted for superuser only */ >>>> - return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN); >>>> + return !ovl_is_private_xattr(s) && >>>> + has_capability_noaudit(current, CAP_SYS_ADMIN); >>>> } >>>> >>>> ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) >>>> -- >>>> 2.23.0.581.g78d2f28ef7-goog >>>> >>> Thanks for the backport, this one worked! >> I spoke too soon: >> >> ERROR: "has_capability_noaudit" [fs/overlayfs/overlay.ko] undefined! >> >> That function isn't exported for modules :( > But, if this really is needed, and it fixes the issue, I'll go export > that symbol with EXPORT_SYMBOL_GPL() to fix the problem. Any > objections? > > thanks, > > greg k-h
Ok, you just answered my question in cross-emails. Yes, EXPORT_SYMBOL_GPL() (my option 2).
Thanks
-- Mark Salyzyn
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