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udev: don't force device ownership and mode on every event

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This partially reverts 25de7aa7b9. I don't think the
change was intended there.

The problem I'm trying to solve: for /dev/kvm we get first an ADD uevent, and
then CHANGE whenever something connects or disconnects to the character device.
The rules in 50-default-udev.rules set UID, GID, and MODE on ADD, but not on
CHANGE. When the change event happens, we would reset the ownership and
permissions.

This happens because node_permissions_apply() would (after 25de7aa7b9)
set uid=gid=0 if they weren't set by the rules.

So let's only pass uid/gid/mode to node_permissions_apply() if appropriately
configured. Also let node_permissions_apply() do the skip of uid/gid/mode if
not set, and rename "always_apply" to more closely reflect its meaning.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2019-06-29 15:08:11 +02:00
parent ab3a7372d2
commit 3708c0f455
2 changed files with 23 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
src/udev/udev-event.c
View File

@ -819,7 +819,6 @@ static int rename_netif(UdevEvent *event) {
static int update_devnode(UdevEvent *event) { static int update_devnode(UdevEvent *event) {
sd_device *dev = event->dev; sd_device *dev = event->dev;
bool apply;
int r; int r;
r = sd_device_get_devnum(dev, NULL); r = sd_device_get_devnum(dev, NULL);
@ -834,17 +833,13 @@ static int update_devnode(UdevEvent *event) {
if (!uid_is_valid(event->uid)) { if (!uid_is_valid(event->uid)) {
r = device_get_devnode_uid(dev, &event->uid); r = device_get_devnode_uid(dev, &event->uid);
if (r == -ENOENT) if (r < 0 && r != -ENOENT)
event->uid = 0;
else if (r < 0)
return log_device_error_errno(dev, r, "Failed to get devnode UID: %m"); return log_device_error_errno(dev, r, "Failed to get devnode UID: %m");
} }
if (!gid_is_valid(event->gid)) { if (!gid_is_valid(event->gid)) {
r = device_get_devnode_gid(dev, &event->gid); r = device_get_devnode_gid(dev, &event->gid);
if (r == -ENOENT) if (r < 0 && r != -ENOENT)
event->gid = 0;
else if (r < 0)
return log_device_error_errno(dev, r, "Failed to get devnode GID: %m"); return log_device_error_errno(dev, r, "Failed to get devnode GID: %m");
} }
@ -852,21 +847,14 @@ static int update_devnode(UdevEvent *event) {
r = device_get_devnode_mode(dev, &event->mode); r = device_get_devnode_mode(dev, &event->mode);
if (r < 0 && r != -ENOENT) if (r < 0 && r != -ENOENT)
return log_device_error_errno(dev, r, "Failed to get devnode mode: %m"); return log_device_error_errno(dev, r, "Failed to get devnode mode: %m");
if (r == -ENOENT) {
if (event->gid > 0)
/* default 0660 if a group is assigned */
event->mode = 0660;
else
/* default 0600 */
event->mode = 0600;
}
} }
if (event->mode == MODE_INVALID && gid_is_valid(event->gid) && event->gid > 0)
/* If group is set, but mode is not set, "upgrade" mode for the group. */
event->mode = 0660;
apply = device_for_action(dev, DEVICE_ACTION_ADD) || bool apply_mac = device_for_action(dev, DEVICE_ACTION_ADD);
uid_is_valid(event->uid) ||
gid_is_valid(event->gid) || return udev_node_add(dev, apply_mac, event->mode, event->uid, event->gid, event->seclabel_list);
event->mode != MODE_INVALID;
return udev_node_add(dev, apply, event->mode, event->uid, event->gid, event->seclabel_list);
} }
static void event_execute_rules_on_remove( static void event_execute_rules_on_remove(

22
src/udev/udev-node.c
View File

@ -26,6 +26,7 @@
#include "string-util.h" #include "string-util.h"
#include "strxcpyx.h" #include "strxcpyx.h"
#include "udev-node.h" #include "udev-node.h"
#include "user-util.h"
static int node_symlink(sd_device *dev, const char *node, const char *slink) { static int node_symlink(sd_device *dev, const char *node, const char *slink) {
_cleanup_free_ char *slink_dirname = NULL, *target = NULL; _cleanup_free_ char *slink_dirname = NULL, *target = NULL;
@ -270,13 +271,14 @@ int udev_node_update_old_links(sd_device *dev, sd_device *dev_old) {
return 0; return 0;
} }
static int node_permissions_apply(sd_device *dev, bool apply, static int node_permissions_apply(sd_device *dev, bool apply_mac,
mode_t mode, uid_t uid, gid_t gid, mode_t mode, uid_t uid, gid_t gid,
OrderedHashmap *seclabel_list) { OrderedHashmap *seclabel_list) {
const char *devnode, *subsystem, *id_filename = NULL; const char *devnode, *subsystem, *id_filename = NULL;
struct stat stats; struct stat stats;
dev_t devnum; dev_t devnum;
int r = 0; bool apply_mode, apply_uid, apply_gid;
int r;
assert(dev); assert(dev);
@ -299,21 +301,27 @@ static int node_permissions_apply(sd_device *dev, bool apply,
if (lstat(devnode, &stats) < 0) if (lstat(devnode, &stats) < 0)
return log_device_debug_errno(dev, errno, "cannot stat() node %s: %m", devnode); return log_device_debug_errno(dev, errno, "cannot stat() node %s: %m", devnode);
if (((stats.st_mode & S_IFMT) != (mode & S_IFMT)) || (stats.st_rdev != devnum)) if ((mode != MODE_INVALID && (stats.st_mode & S_IFMT) != (mode & S_IFMT)) || stats.st_rdev != devnum)
return log_device_debug_errno(dev, SYNTHETIC_ERRNO(EEXIST), "Found node '%s' with non-matching devnum %s, skip handling", return log_device_debug_errno(dev, SYNTHETIC_ERRNO(EEXIST),
"Found node '%s' with non-matching devnum %s, skip handling",
devnode, id_filename); devnode, id_filename);
if (apply) { apply_mode = mode != MODE_INVALID && (stats.st_mode & 0777) != (mode & 0777);
apply_uid = uid_is_valid(uid) && stats.st_uid != uid;
apply_gid = gid_is_valid(gid) && stats.st_gid != gid;
if (apply_mode || apply_uid || apply_gid || apply_mac) {
bool selinux = false, smack = false; bool selinux = false, smack = false;
const char *name, *label; const char *name, *label;
Iterator i; Iterator i;
if ((stats.st_mode & 0777) != (mode & 0777) || stats.st_uid != uid || stats.st_gid != gid) { if (apply_mode || apply_uid || apply_gid) {
log_device_debug(dev, "Setting permissions %s, %#o, uid=%u, gid=%u", devnode, mode, uid, gid); log_device_debug(dev, "Setting permissions %s, %#o, uid=%u, gid=%u", devnode, mode, uid, gid);
r = chmod_and_chown(devnode, mode, uid, gid); r = chmod_and_chown(devnode, mode, uid, gid);
if (r < 0) if (r < 0)
log_device_warning_errno(dev, r, "Failed to set owner/mode of %s to uid=" UID_FMT ", gid=" GID_FMT ", mode=%#o: %m", devnode, uid, gid, mode); log_device_warning_errno(dev, r, "Failed to set owner/mode of %s to uid=" UID_FMT ", gid=" GID_FMT ", mode=%#o: %m",
devnode, uid, gid, mode);
} else } else
log_device_debug(dev, "Preserve permissions of %s, %#o, uid=%u, gid=%u", devnode, mode, uid, gid); log_device_debug(dev, "Preserve permissions of %s, %#o, uid=%u, gid=%u", devnode, mode, uid, gid);