On Wed, Sep 02, 2009 at 07:10:35PM +0200, Vladimir Kotal wrote:
> http://cr.opensolaris.org/~vkotal/daemon_libc-4471189.onnv/
- Could you make daemon() replace fildes 0, 1 and 2 the way the ssh
version (from OpenBSD) did it: open /dev/null, dup2() into 0, 1 and
2, then close the /dev/null fildes. Also, please check for errors
when opening /dev/null for this.
Something like:
if (noclose == 0) {
int fd = open("/dev/null", O_RDWR, 0);
if (fd == -1)
return (-1); /* XXX or maybe 0 would be fine too */
(void) dup2(fd, STDIN_FILENO);
(void) dup2(fd, STDOUT_FILENO);
(void) dup2(fd, STDERR_FILENO);
if (fd > STDERR_FILENO)
(void) close(fd);
}
return (0);
or:
int fd;
...
if (noclose == 0 && (fd = open("/dev/null", O_RDWR, 0)) != -1) {
(void) dup2(fd, STDIN_FILENO);
(void) dup2(fd, STDOUT_FILENO);
(void) dup2(fd, STDERR_FILENO);
if (fd > STDERR_FILENO)
(void) close(fd);
}
return (0);
Yes, this is paranoia. An error opening /dev/null will likely be
very fatal elsewhere, but it shouldn't be allowed to cause security
issues _here_.
- Also, Solaris Kerberos code (from MIT krb5) has a daemon() too:
$SRC/lib/gss_mechs/mech_krb5/krb5/posix/daemon.c
Aside: interesting that sshd's daemon() didn't fork() again after
setsid().
Nico
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