From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: Re: [PATCH 27/43] userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs Date: Wed, 25 Apr 2012 22:33:06 -0700 Message-ID: References: <1333862139-31737-27-git-send-email-ebiederm@xmission.com> <20120418190337.GE5186@mail.hallyn.com> <20120426001101.GA10308@mail.hallyn.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120426001101.GA10308-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org> (Serge E. Hallyn's message of "Thu, 26 Apr 2012 00:11:01 +0000") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "Serge E. Hallyn" Cc: Linux Containers , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Al Viro , Cyrill Gorcunov , Andrew Morton , Linus Torvalds List-Id: containers.vger.kernel.org "Serge E. Hallyn" writes: > Quoting Eric W. Biederman (ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org): >> "Serge E. Hallyn" writes: >> >> > Quoting Eric W. Beiderman (ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org): >> >> From: Eric W. Biederman >> >> >> >> Signed-off-by: Eric W. Biederman >> >> --- >> >> fs/attr.c | 8 ++++---- >> >> fs/exec.c | 10 +++++----- >> >> fs/fcntl.c | 6 +++--- >> >> fs/ioprio.c | 4 ++-- >> >> fs/locks.c | 2 +- >> >> fs/namei.c | 8 ++++---- >> >> include/linux/quotaops.h | 4 ++-- >> >> 7 files changed, 21 insertions(+), 21 deletions(-) >> >> >> >> >> @@ -2120,7 +2120,7 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs) >> >> if (__get_dumpable(cprm.mm_flags) == 2) { >> >> /* Setuid core dump mode */ >> >> flag = O_EXCL; /* Stop rewrite attacks */ >> >> - cred->fsuid = 0; /* Dump root private */ >> >> + cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */ >> > >> > Sorry, one more - can this be the per-ns root uid? The coredumps should >> > be ok to belong to privileged users in the namespace right? >> >> I'm not certain it was clear when you were looking at this that >> this is about dumping core from suid applications, not normal >> applications. >> >> Looking at the code in commoncap and commit_creds it looks like it is a >> bug that we don't call set_dumpable(new, suid_dumpable) in common cap >> when we use file capabilities. I might be wrong but I think we escape > > We do, check kernel/cred.c:commit_creds(). So long as the new permitted > set is not a subset of the old one. > > Tested it to make absolutely sure. When I add file capabilities to a > program that otherwise dumps core (int *x = 0; *x = 0;), core dumps are > no longer generated. Thanks for testing. Just reading through I was not certain if we had the change in creds that commit_creds needed to trigger the set_dumpable logic. Eric