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avoid race between systemd-logind and systemd-udevd in setting ACLs (#36444)

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Follow-up for #36408.
Hopefully fixes #24026, #28512, and/or #23547.
This commit is contained in:
Lennart Poettering
2025-05-14 13:03:46 +02:00
committed by GitHub
parent 66d84090f4 003c6faff4
commit 798d140cac
41 changed files with 869 additions and 611 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/shared/acl-util.c
+1 -1
View File
@@ -16,7 +16,7 @@
#if HAVE_ACL
int acl_find_uid(acl_t acl, uid_t uid, acl_entry_t *ret_entry) {
static int acl_find_uid(acl_t acl, uid_t uid, acl_entry_t *ret_entry) {
acl_entry_t i;
int r;
src/shared/acl-util.h
-1
View File
@@ -15,7 +15,6 @@ int fd_acl_make_writable_fallback(int fd);
#include "macro.h"
#include "memory-util.h"
int acl_find_uid(acl_t acl, uid_t uid, acl_entry_t *entry);
int calc_acl_mask_if_needed(acl_t *acl_p);
int add_base_acls_if_needed(acl_t *acl_p, const char *path);
int acl_search_groups(const char* path, char ***ret_groups);
src/shared/blockdev-list.c
+3 -6
View File
@@ -37,15 +37,12 @@ int blockdev_list(BlockDevListFlags flags) {
}
if (FLAGS_SET(flags, BLOCKDEV_LIST_IGNORE_ZRAM)) {
const char *dn;
r = sd_device_get_sysname(dev, &dn);
r = device_sysname_startswith(dev, "zram");
if (r < 0) {
log_warning_errno(r, "Failed to get device name of discovered block device '%s', ignoring: %m", node);
log_warning_errno(r, "Failed to check device name of discovered block device '%s', ignoring: %m", node);
continue;
}
if (startswith(dn, "zram"))
if (r > 0)
continue;
}
src/shared/blockdev-util.c
+10 -2
View File
@@ -57,9 +57,14 @@ static int fd_get_devnum(int fd, BlockDeviceLookupFlag flags, dev_t *ret) {
}
int block_device_is_whole_disk(sd_device *dev) {
int r;
assert(dev);
if (!device_in_subsystem(dev, "block"))
r = device_in_subsystem(dev, "block");
if (r < 0)
return r;
if (r == 0)
return -ENOTBLK;
return device_is_devtype(dev, "disk");
@@ -414,7 +419,10 @@ int blockdev_partscan_enabled(sd_device *dev) {
/* Partition block devices never have partition scanning on, there's no concept of sub-partitions for
* partitions. */
if (device_is_devtype(dev, "partition"))
r = device_is_devtype(dev, "partition");
if (r < 0)
return r;
if (r > 0)
return false;
/* For loopback block device, especially for v5.19 or newer. Even if this is enabled, we also need to
src/shared/devnode-acl.c
-227
View File
@@ -1,227 +0,0 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <errno.h>
#include "sd-device.h"
#include "acl-util.h"
#include "alloc-util.h"
#include "device-util.h"
#include "devnode-acl.h"
#include "dirent-util.h"
#include "errno-util.h"
#include "fd-util.h"
#include "format-util.h"
#include "fs-util.h"
#include "glyph-util.h"
#include "set.h"
#include "string-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) {
_cleanup_(acl_freep) acl_t acl = NULL;
int r;
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)
return r;
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)
return r;
if (r > 0) {
if (acl_delete_entry(acl, entry) < 0)
return -errno;
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)
return r;
if (r == 0) {
if (acl_create_entry(&acl, &entry) < 0)
return -errno;
if (acl_set_tag_type(entry, ACL_USER) < 0 ||
acl_set_qualifier(entry, &new_uid) < 0)
return -errno;
}
if (acl_get_permset(entry, &permset) < 0)
return -errno;
rd = acl_get_perm(permset, ACL_READ);
if (rd < 0)
return -errno;
wt = acl_get_perm(permset, ACL_WRITE);
if (wt < 0)
return -errno;
if (!rd || !wt) {
if (acl_add_perm(permset, ACL_READ|ACL_WRITE) < 0)
return -errno;
changed = true;
}
}
if (!changed)
return 0;
if (acl_calc_mask(&acl) < 0)
return -errno;
if (acl_set_file(path, ACL_TYPE_ACCESS, acl) < 0)
return -errno;
return 0;
}
int devnode_acl_all(const char *seat,
bool flush,
bool del, uid_t old_uid,
bool add, uid_t new_uid) {
_cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
_cleanup_set_free_ Set *nodes = NULL;
_cleanup_closedir_ DIR *dir = NULL;
char *n;
int r;
r = sd_device_enumerator_new(&e);
if (r < 0)
return r;
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 = sd_device_enumerator_add_match_tag(e, "uaccess");
if (r < 0)
return r;
FOREACH_DEVICE(e, d) {
const char *node, *sn;
/* Make sure the tag is still in place */
if (sd_device_has_current_tag(d, "uaccess") <= 0)
continue;
if (sd_device_get_property_value(d, "ID_SEAT", &sn) < 0 || isempty(sn))
sn = "seat0";
if (!streq(seat, sn))
continue;
/* In case people mistag devices with nodes, we need to ignore this */
if (sd_device_get_devname(d, &node) < 0)
continue;
log_device_debug(d, "Found udev node %s for seat %s", node, seat);
r = set_put_strdup_full(&nodes, &path_hash_ops_free, node);
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(de, dir, return -errno) {
r = readlinkat_malloc(dirfd(dir), de->d_name, &n);
if (r == -ENOENT)
continue;
if (r < 0) {
log_debug_errno(r,
"Unable to read symlink '/run/udev/static_node-tags/uaccess/%s', ignoring: %m",
de->d_name);
continue;
}
log_debug("Found static node %s for seat %s", n, seat);
r = set_ensure_consume(&nodes, &path_hash_ops_free, n);
if (r < 0)
return r;
}
}
r = 0;
SET_FOREACH(n, nodes) {
int k;
log_debug("Changing ACLs at %s for seat %s (uid "UID_FMT"%s"UID_FMT"%s%s)",
n, seat, old_uid, glyph(GLYPH_ARROW_RIGHT), 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
RET_GATHER(r, k);
}
return r;
}
src/shared/devnode-acl.h
-34
View File
@@ -1,34 +0,0 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once
#include <stdbool.h>
#include <sys/types.h>
#if HAVE_ACL
int devnode_acl(const char *path,
bool flush,
bool del, uid_t old_uid,
bool add, uid_t new_uid);
int devnode_acl_all(const char *seat,
bool flush,
bool del, uid_t old_uid,
bool add, uid_t new_uid);
#else
static inline int devnode_acl(const char *path,
bool flush,
bool del, uid_t old_uid,
bool add, uid_t new_uid) {
return 0;
}
static inline int devnode_acl_all(const char *seat,
bool flush,
bool del, uid_t old_uid,
bool add, uid_t new_uid) {
return 0;
}
#endif
src/shared/meson.build
-4
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@@ -238,10 +238,6 @@ syscall_list_h = custom_target(
generated_sources += syscall_list_h
if conf.get('HAVE_ACL') == 1
shared_sources += files('devnode-acl.c')
endif
if conf.get('ENABLE_UTMP') == 1
shared_sources += files('utmp-wtmp.c')
endif