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logind: apply ACL's to "dead" device nodes

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Based on a patch by Kay Sievers.

When a dead device nodes is tagged with "uaccess" using the static_node mechanism,
it's ACL's are managed by logind in the same way as "live" device nodes.

This allows in particular /dev/snd/{seq,timer} to cause modules to be loaded
on-demand when accessed by a non-privileged user.
This commit is contained in:
Tom Gundersen
2013-07-07 21:29:12 +02:00
parent 84b6ad702e
commit 6b78df0a6e
1 changed files with 64 additions and 11 deletions
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75
src/login/logind-acl.c
View File

@@ -28,6 +28,7 @@
#include "logind-acl.h"
#include "util.h"
#include "acl-util.h"
#include "set.h"
static int flush_acl(acl_t acl) {
acl_entry_t i;
@@ -179,23 +180,34 @@ int devnode_acl_all(struct udev *udev,
struct udev_list_entry *item = NULL, *first = NULL;
struct udev_enumerate *e;
Set *nodes;
Iterator i;
char *n;
DIR *dir;
struct dirent *dent;
int r;
assert(udev);
if (isempty(seat))
seat = "seat0";
nodes = set_new(string_hash_func, string_compare_func);
if (!nodes) {
return -ENOMEM;
}
e = udev_enumerate_new(udev);
if (!e)
return -ENOMEM;
if (!e) {
r = -ENOMEM;
goto finish;
}
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)
goto finish;
@@ -231,18 +243,59 @@ int devnode_acl_all(struct udev *udev,
continue;
}
log_debug("Fixing up %s for seat %s...", node, sn);
r = devnode_acl(node, flush, del, old_uid, add, new_uid);
n = strdup(node);
udev_device_unref(d);
if (!n)
goto finish;
log_debug("Found udev node %s for seat %s", n, seat);
r = set_put(nodes, n);
if (r < 0)
goto finish;
}
finish:
if (e)
udev_enumerate_unref(e);
/* 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) {
for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
_cleanup_free_ char *unescaped_devname = NULL;
if (dent->d_name[0] == '.')
continue;
unescaped_devname = cunescape(dent->d_name);
if (unescaped_devname == NULL) {
r = -ENOMEM;
closedir(dir);
goto finish;
}
n = strappend("/dev/", unescaped_devname);
if (!n) {
r = -ENOMEM;
closedir(dir);
goto finish;
}
log_debug("Found static node %s for seat %s", n, seat);
r = set_put(nodes, n);
if (0 && r < 0 && r != -EEXIST) {
closedir(dir);
goto finish;
} else
r = 0;
}
closedir(dir);
}
SET_FOREACH(n, nodes, i) {
log_debug("Fixing up ACLs at %s for seat %s", n, seat);
r = devnode_acl(n, flush, del, old_uid, add, new_uid);
}
finish:
udev_enumerate_unref(e);
set_free_free(nodes);
return r;
}