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/* $Id: port-linux.c,v 1.5 2008/03/26 20:27:21 dtucker Exp $ */
/*
* Copyright (c) 2005 Daniel Walsh <dwalsh@redhat.com>
* Copyright (c) 2006 Damien Miller <djm@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Linux-specific portability code
*/
#include "includes.h"
#include <errno.h>
#include <stdarg.h>
#include <string.h>
#ifdef OOM_ADJUST
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#endif
#include "log.h"
#ifdef WITH_SELINUX
#include "key.h"
#include "hostfile.h"
#include "auth.h"
#ifdef HAVE_GETSEUSERBYNAME
#include "xmalloc.h"
#endif
#include "port-linux.h"
#include <selinux/selinux.h>
#include <selinux/flask.h>
#include <selinux/get_context_list.h>
extern Authctxt *the_authctxt;
/* Wrapper around is_selinux_enabled() to log its return value once only */
int
ssh_selinux_enabled(void)
{
static int enabled = -1;
if (enabled == -1) {
enabled = is_selinux_enabled();
debug("SELinux support %s", enabled ? "enabled" : "disabled");
}
return (enabled);
}
/* Return the default security context for the given username */
static security_context_t
ssh_selinux_getctxbyname(char *pwname)
{
security_context_t sc;
char *sename = NULL, *role = NULL, *lvl = NULL;
int r;
#ifdef HAVE_GETSEUSERBYNAME
if (getseuserbyname(pwname, &sename, &lvl) != 0)
return NULL;
#else
sename = pwname;
lvl = NULL;
#endif
if (the_authctxt)
role = the_authctxt->role;
#ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL
if (role != NULL && role[0])
r = get_default_context_with_rolelevel(sename, role, lvl, NULL,
&sc);
else
r = get_default_context_with_level(sename, lvl, NULL, &sc);
#else
if (role != NULL && role[0])
r = get_default_context_with_role(sename, role, NULL, &sc);
else
r = get_default_context(sename, NULL, &sc);
#endif
if (r != 0) {
switch (security_getenforce()) {
case -1:
fatal("%s: ssh_selinux_getctxbyname: "
"security_getenforce() failed", __func__);
case 0:
error("%s: Failed to get default SELinux security "
"context for %s", __func__, pwname);
break;
default:
fatal("%s: Failed to get default SELinux security "
"context for %s (in enforcing mode)",
__func__, pwname);
}
}
#ifdef HAVE_GETSEUSERBYNAME
if (sename != NULL)
xfree(sename);
if (lvl != NULL)
xfree(lvl);
#endif
return (sc);
}
/* Set the execution context to the default for the specified user */
void
ssh_selinux_setup_exec_context(char *pwname)
{
security_context_t user_ctx = NULL;
if (!ssh_selinux_enabled())
return;
debug3("%s: setting execution context", __func__);
user_ctx = ssh_selinux_getctxbyname(pwname);
if (setexeccon(user_ctx) != 0) {
switch (security_getenforce()) {
case -1:
fatal("%s: security_getenforce() failed", __func__);
case 0:
error("%s: Failed to set SELinux execution "
"context for %s", __func__, pwname);
break;
default:
fatal("%s: Failed to set SELinux execution context "
"for %s (in enforcing mode)", __func__, pwname);
}
}
if (user_ctx != NULL)
freecon(user_ctx);
debug3("%s: done", __func__);
}
/* Set the TTY context for the specified user */
void
ssh_selinux_setup_pty(char *pwname, const char *tty)
{
security_context_t new_tty_ctx = NULL;
security_context_t user_ctx = NULL;
security_context_t old_tty_ctx = NULL;
if (!ssh_selinux_enabled())
return;
debug3("%s: setting TTY context on %s", __func__, tty);
user_ctx = ssh_selinux_getctxbyname(pwname);
/* XXX: should these calls fatal() upon failure in enforcing mode? */
if (getfilecon(tty, &old_tty_ctx) == -1) {
error("%s: getfilecon: %s", __func__, strerror(errno));
goto out;
}
if (security_compute_relabel(user_ctx, old_tty_ctx,
SECCLASS_CHR_FILE, &new_tty_ctx) != 0) {
error("%s: security_compute_relabel: %s",
__func__, strerror(errno));
goto out;
}
if (setfilecon(tty, new_tty_ctx) != 0)
error("%s: setfilecon: %s", __func__, strerror(errno));
out:
if (new_tty_ctx != NULL)
freecon(new_tty_ctx);
if (old_tty_ctx != NULL)
freecon(old_tty_ctx);
if (user_ctx != NULL)
freecon(user_ctx);
debug3("%s: done", __func__);
}
#endif /* WITH_SELINUX */
#ifdef OOM_ADJUST
/* Get the out-of-memory adjustment file for the current process */
static int
oom_adj_open(int oflag)
{
int fd = open("/proc/self/oom_adj", oflag);
if (fd < 0)
logit("error opening /proc/self/oom_adj: %s", strerror(errno));
return fd;
}
/* Get the current OOM adjustment */
int
oom_adj_get(char *buf, size_t maxlen)
{
ssize_t n;
int fd = oom_adj_open(O_RDONLY);
if (fd < 0)
return -1;
n = read(fd, buf, maxlen);
if (n < 0)
logit("error reading /proc/self/oom_adj: %s", strerror(errno));
else
buf[n] = '\0';
close(fd);
return n < 0 ? -1 : 0;
}
/* Set the current OOM adjustment */
int
oom_adj_set(const char *buf)
{
ssize_t n;
int fd = oom_adj_open(O_WRONLY);
if (fd < 0)
return -1;
n = write(fd, buf, strlen(buf));
if (n < 0)
logit("error writing /proc/self/oom_adj: %s", strerror(errno));
close(fd);
return n < 0 ? -1 : 0;
}
#endif
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