logind-acl.c revision b26fa1a2fbcfee7d03b0c8fd15ec3aa64ae70b9f
/***
This file is part of systemd.
Copyright 2011 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <string.h>
#include "acl-util.h"
#include "alloc-util.h"
#include "dirent-util.h"
#include "escape.h"
#include "fd-util.h"
#include "formats-util.h"
#include "logind-acl.h"
#include "set.h"
#include "string-util.h"
#include "udev-util.h"
#include "util.h"
static int flush_acl(acl_t acl) {
acl_entry_t i;
int found;
bool changed = false;
assert(acl);
for (found = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
found > 0;
found = acl_get_entry(acl, ACL_NEXT_ENTRY, &i)) {
acl_tag_t tag;
if (acl_get_tag_type(i, &tag) < 0)
return -errno;
if (tag != ACL_USER)
continue;
if (acl_delete_entry(acl, i) < 0)
return -errno;
changed = true;
}
if (found < 0)
return -errno;
return changed;
}
int devnode_acl(const char *path,
bool flush,
bool del, uid_t old_uid,
bool add, uid_t new_uid) {
acl_t acl;
int r = 0;
bool changed = false;
assert(path);
acl = acl_get_file(path, ACL_TYPE_ACCESS);
if (!acl)
return -errno;
if (flush) {
r = flush_acl(acl);
if (r < 0)
goto finish;
if (r > 0)
changed = true;
} else if (del && old_uid > 0) {
acl_entry_t entry;
r = acl_find_uid(acl, old_uid, &entry);
if (r < 0)
goto finish;
if (r > 0) {
if (acl_delete_entry(acl, entry) < 0) {
r = -errno;
goto finish;
}
changed = true;
}
}
if (add && new_uid > 0) {
acl_entry_t entry;
acl_permset_t permset;
int rd, wt;
r = acl_find_uid(acl, new_uid, &entry);
if (r < 0)
goto finish;
if (r == 0) {
if (acl_create_entry(&acl, &entry) < 0) {
r = -errno;
goto finish;
}
if (acl_set_tag_type(entry, ACL_USER) < 0 ||
acl_set_qualifier(entry, &new_uid) < 0) {
r = -errno;
goto finish;
}
}
if (acl_get_permset(entry, &permset) < 0) {
r = -errno;
goto finish;
}
rd = acl_get_perm(permset, ACL_READ);
if (rd < 0) {
r = -errno;
goto finish;
}
wt = acl_get_perm(permset, ACL_WRITE);
if (wt < 0) {
r = -errno;
goto finish;
}
if (!rd || !wt) {
if (acl_add_perm(permset, ACL_READ|ACL_WRITE) < 0) {
r = -errno;
goto finish;
}
changed = true;
}
}
if (!changed)
goto finish;
if (acl_calc_mask(&acl) < 0) {
r = -errno;
goto finish;
}
if (acl_set_file(path, ACL_TYPE_ACCESS, acl) < 0) {
r = -errno;
goto finish;
}
r = 0;
finish:
acl_free(acl);
return r;
}
int devnode_acl_all(struct udev *udev,
const char *seat,
bool flush,
bool del, uid_t old_uid,
bool add, uid_t new_uid) {
_cleanup_udev_enumerate_unref_ struct udev_enumerate *e = NULL;
struct udev_list_entry *item = NULL, *first = NULL;
_cleanup_set_free_free_ Set *nodes = NULL;
_cleanup_closedir_ DIR *dir = NULL;
struct dirent *dent;
Iterator i;
char *n;
int r;
assert(udev);
nodes = set_new(&string_hash_ops);
if (!nodes)
return -ENOMEM;
e = udev_enumerate_new(udev);
if (!e)
return -ENOMEM;
if (isempty(seat))
seat = "seat0";
/* We can only match by one tag in libudev. We choose
* "uaccess" for that. If we could match for two tags here we
* could add the seat name as second match tag, but this would
* be hardly optimizable in libudev, and hence checking the
* second tag manually in our loop is a good solution. */
r = udev_enumerate_add_match_tag(e, "uaccess");
if (r < 0)
return r;
r = udev_enumerate_add_match_is_initialized(e);
if (r < 0)
return r;
r = udev_enumerate_scan_devices(e);
if (r < 0)
return r;
first = udev_enumerate_get_list_entry(e);
udev_list_entry_foreach(item, first) {
_cleanup_udev_device_unref_ struct udev_device *d = NULL;
const char *node, *sn;
d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
if (!d)
return -ENOMEM;
sn = udev_device_get_property_value(d, "ID_SEAT");
if (isempty(sn))
sn = "seat0";
if (!streq(seat, sn))
continue;
node = udev_device_get_devnode(d);
/* In case people mistag devices with nodes, we need to ignore this */
if (!node)
continue;
n = strdup(node);
if (!n)
return -ENOMEM;
log_debug("Found udev node %s for seat %s", n, seat);
r = set_consume(nodes, n);
if (r < 0)
return r;
}
/* udev exports "dead" device nodes to allow module on-demand loading,
* these devices are not known to the kernel at this moment */
dir = opendir("/run/udev/static_node-tags/uaccess");
if (dir) {
FOREACH_DIRENT(dent, dir, return -errno) {
_cleanup_free_ char *unescaped_devname = NULL;
if (cunescape(dent->d_name, UNESCAPE_RELAX, &unescaped_devname) < 0)
return -ENOMEM;
n = strappend("/dev/", unescaped_devname);
if (!n)
return -ENOMEM;
log_debug("Found static node %s for seat %s", n, seat);
r = set_consume(nodes, n);
if (r == -EEXIST)
continue;
if (r < 0)
return r;
}
}
r = 0;
SET_FOREACH(n, nodes, i) {
int k;
log_debug("Changing ACLs at %s for seat %s (uid "UID_FMT"→"UID_FMT"%s%s)",
n, seat, old_uid, new_uid,
del ? " del" : "", add ? " add" : "");
k = devnode_acl(n, flush, del, old_uid, add, new_uid);
if (k == -ENOENT)
log_debug("Device %s disappeared while setting ACLs", n);
else if (k < 0 && r == 0)
r = k;
}
return r;
}