The classic way which is based on file-descriptors table size is
pretty expensive (due to table size) and forces code to do many
unnecessary close() calls. It seems better to use /proc/self/fds and
close used descriptors only.
Addresses: https://github.com/karelzak/util-linux/issues/883
Signed-off-by: Karel Zak <kzak@redhat.com>
Check if a file descriptor and path or stat structure are represent the same
file. This function is needed for TACTOU avoidance.
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
The utils when compiled WITHOUT libuser then mkostemp()ing
"/etc/%s.XXXXXX" where the filename prefix is argv[0] basename.
An attacker could repeatedly execute the util with modified argv[0]
and after many many attempts mkostemp() may generate suffix which
makes sense. The result maybe temporary file with name like rc.status
ld.so.preload or krb5.keytab, etc.
Note that distros usually use libuser based ch{sh,fn} or stuff from
shadow-utils.
It's probably very minor security bug.
Addresses: CVE-2015-5224
Signed-off-by: Karel Zak <kzak@redhat.com>
This function duplicates and marks a file descriptor as close-on-exec.
Takes care of build and run-time support for the fcntl F_DUPFD_CLOEXEC
command, and other errors.
Signed-off-by: Guillem Jover <guillem@hadrons.org>
It's usually enough to us [e]poll() to monitor kernel mount table, but
there is no way how to monitor changes in userspace mount options
(e.g. _netdev). The management of these mount options is completely
hidden in libmount and /rub/mount/utab is private libmount file.
This patch introduces new libmnt_mount API to monitor also userspace
mount table.
Signed-off-by: Karel Zak <kzak@redhat.com>
We can not let the user control where TMPDIR is for this tempfile.
This will be where we write the updated passwd file, and must be
capable of being moved atomically with rename(2). Therefore, it
cannot be on a different device, or setpwnam() and vipw/vigr programs
will invariably fail with EXDEV.
Signed-off-by: Dave Reisner <dreisner@archlinux.org>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
Let developer to choose, case by case, what sort of return value is
best in her code. The xmkstemp() is for users who want file
descriptor as return value of the function, xfmkstemp() will return
FILE pointer.
Proposed-By: Karel Zak <kzak@redhat.com>
CC: Davidlohr Bueso <dave@gnu.org>
Reference: http://marc.info/?l=util-linux-ng&m=133129570124003&w=2
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
