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Systemd is causing mislabeled devices to be created and then attempting to read them.

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On 07/28/2010 05:57 AM, Kay Sievers wrote:
> On Wed, Jul 28, 2010 at 11:43, Lennart Poettering
> <lennart@poettering.net> wrote:
>> On Mon, 26.07.10 16:42, Daniel J Walsh (dwalsh@redhat.com) wrote:
>>> tcontext=system_u:object_r:device_t:s0 tclass=chr_file
>>> type=1400 audit(1280174589.476:7): avc:  denied  { read } for  pid=1
>>> comm="systemd" name="autofs" dev=devtmpfs ino=9482
>>> scontext=system_u:system_r:init_t:s0
>>> tcontext=system_u:object_r:device_t:s0 tclass=chr_file
>>> type=1400 audit(1280174589.476:8): avc:  denied  { read } for  pid=1
>>> comm="systemd" name="autofs" dev=devtmpfs ino=9482
>>> scontext=system_u:system_r:init_t:s0
>>> tcontext=system_u:object_r:device_t:s0 tclass=chr_file
>>>
>>> Lennart, we talked about this earlier.  I think this is caused by the
>>> modprobe calls to create /dev/autofs.  Since udev is not created at the
>>> point that init loads the kernel modules, the devices get created with
>>> the wrong label.  Once udev starts the labels get fixed.
>>>
>>> I can allow init_t to read device_t chr_files.
>>
>> Hmm, I think a cleaner fix would be to make systemd relabel this device
>> properly before accessing it? Given that this is only one device this
>> should not be a problem for us to maintain, I think? How would the
>> fixing of the label work? Would we have to spawn restorecon for this, or
>> can we actually do this in C without too much work?
>
> I guess we can just do what udev is doing, and call setfilecon(), with
> a context of an earlier matchpathcon().
>
> Kay
> _______________________________________________
> systemd-devel mailing list
> systemd-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/systemd-devel

Here is the updated patch with a fix for the labeling of /dev/autofs
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This commit is contained in:
Daniel J Walsh
2010-08-03 23:45:22 +02:00
committed by Lennart Poettering
parent 8b33e5ca72
commit 56cf987fe7
8 changed files with 293 additions and 99 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/socket.c
+13 -81
View File
@@ -27,7 +27,6 @@
#include <sys/epoll.h>
#include <signal.h>
#include <arpa/inet.h>
#include <selinux/selinux.h>
#include "unit.h"
#include "socket.h"
@@ -653,89 +652,25 @@ static void socket_apply_fifo_options(Socket *s, int fd) {
log_warning("F_SETPIPE_SZ: %m");
}
static int selinux_getconfromexe(
const char *exe,
security_context_t *newcon) {
security_context_t mycon = NULL, fcon = NULL;
security_class_t sclass;
int r = 0;
r = getcon(&mycon);
if (r < 0)
goto fail;
r = getfilecon(exe, &fcon);
if (r < 0)
goto fail;
sclass = string_to_security_class("process");
r = security_compute_create(mycon, fcon, sclass, newcon);
fail:
if (r < 0)
r = -errno;
freecon(mycon);
freecon(fcon);
return r;
}
static int selinux_getfileconfrompath(
const security_context_t scon,
const char *path,
const char *class,
security_context_t *fcon) {
security_context_t dir_con = NULL;
security_class_t sclass;
int r = 0;
r = getfilecon(path, &dir_con);
if (r >= 0) {
r = -1;
if ((sclass = string_to_security_class(class)) != 0)
r = security_compute_create(scon, dir_con, sclass, fcon);
}
if (r < 0)
r = -errno;
freecon(dir_con);
return r;
}
static int fifo_address_create(
const char *path,
mode_t directory_mode,
mode_t socket_mode,
security_context_t scon,
const char *label,
int *_fd) {
int fd = -1, r = 0;
struct stat st;
mode_t old_mask;
security_context_t filecon = NULL;
assert(path);
assert(_fd);
mkdir_parents(path, directory_mode);
if (scon) {
if (scon && ((r = selinux_getfileconfrompath(scon, path, "fifo_file", &filecon)) == 0)) {
r = setfscreatecon(filecon);
if (r < 0) {
log_error("Failed to set SELinux file context (%s) on %s: %m", scon, path);
r = -errno;
}
freecon(filecon);
}
if (r < 0 && security_getenforce() == 1)
goto fail;
}
if ((r = label_fifofile_set(label, path)) < 0)
goto fail;
/* Enforce the right access mode for the fifo */
old_mask = umask(~ socket_mode);
@@ -756,7 +691,7 @@ static int fifo_address_create(
goto fail;
}
setfscreatecon(NULL);
label_file_clear();
if (fstat(fd, &st) < 0) {
r = -errno;
@@ -776,7 +711,8 @@ static int fifo_address_create(
return 0;
fail:
setfscreatecon(NULL);
label_file_clear();
if (fd >= 0)
close_nointr_nofail(fd);
@@ -786,20 +722,16 @@ fail:
static int socket_open_fds(Socket *s) {
SocketPort *p;
int r;
security_context_t scon = NULL;
char *label = NULL;
assert(s);
if ((r = socket_instantiate_service(s)) < 0)
return r;
if (selinux_getconfromexe(s->service->exec_command[SERVICE_EXEC_START]->path, &scon) < 0) {
log_error("Failed to get SELinux exec context for %s \n", s->service->exec_command[SERVICE_EXEC_START]->path);
if (security_getenforce() == 1)
return -errno;
}
if ((r = label_get_socket_label_from_exe(s->service->exec_command[SERVICE_EXEC_START]->path, &label)) < 0)
return r;
log_debug("SELinux Socket context for %s set to %s\n", s->service->exec_command[SERVICE_EXEC_START]->path, scon);
LIST_FOREACH(port, p, s->ports) {
if (p->fd >= 0)
@@ -815,7 +747,7 @@ static int socket_open_fds(Socket *s) {
s->free_bind,
s->directory_mode,
s->socket_mode,
scon,
label,
&p->fd)) < 0)
goto rollback;
@@ -827,7 +759,7 @@ static int socket_open_fds(Socket *s) {
p->path,
s->directory_mode,
s->socket_mode,
scon,
label,
&p->fd)) < 0)
goto rollback;
@@ -837,12 +769,12 @@ static int socket_open_fds(Socket *s) {
assert_not_reached("Unknown port type");
}
freecon(scon);
label_free(label);
return 0;
rollback:
socket_close_fds(s);
freecon(scon);
label_free(label);
return r;
}