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    SubjectRe: [PATCH 27/43] userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs
    Quoting Eric W. Biederman (ebiederm@xmission.com):
    > "Serge E. Hallyn" <serge@hallyn.com> writes:
    >
    > > Quoting Eric W. Beiderman (ebiederm@xmission.com):
    > >> From: Eric W. Biederman <ebiederm@xmission.com>
    > >>
    > >> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
    > >> ---
    > >> 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.

    -serge


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