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udev: use hashed path as a filename to save devlink

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This commit is contained in:
Yu Watanabe 2021-06-02 22:33:34 +09:00
parent 130298ba10
commit e64943363a
2 changed files with 31 additions and 15 deletions
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44
src/udev/udev-node.c
View File

@ -7,6 +7,8 @@
#include <sys/stat.h>
#include <unistd.h>
#include "sd-id128.h"
#include "alloc-util.h"
#include "device-nodes.h"
#include "device-private.h"
@ -15,6 +17,7 @@
#include "fd-util.h"
#include "format-util.h"
#include "fs-util.h"
#include "hexdecoct.h"
#include "mkdir.h"
#include "path-util.h"
#include "selinux-util.h"
@ -27,6 +30,7 @@
#include "user-util.h"
#define LINK_UPDATE_MAX_RETRIES 128
#define UDEV_NODE_HASH_KEY SD_ID128_MAKE(b9,6a,f1,ce,40,31,44,1a,9e,19,ec,8b,ae,f3,e3,2f)
static int node_symlink(sd_device *dev, const char *node, const char *slink) {
_cleanup_free_ char *slink_dirname = NULL, *target = NULL;
@ -191,45 +195,54 @@ static int link_find_prioritized(sd_device *dev, bool add, const char *stackdir,
return 0;
}
static size_t escape_path(const char *src, char *dest, size_t size) {
size_t udev_node_escape_path(const char *src, char *dest, size_t size) {
size_t i, j;
uint64_t h;
assert(src);
assert(dest);
for (i = 0, j = 0; src[i] != '\0'; i++) {
if (src[i] == '/') {
if (j+4 >= size) {
j = 0;
break;
}
if (j+4 >= size)
goto toolong;
memcpy(&dest[j], "\\x2f", 4);
j += 4;
} else if (src[i] == '\\') {
if (j+4 >= size) {
j = 0;
break;
}
if (j+4 >= size)
goto toolong;
memcpy(&dest[j], "\\x5c", 4);
j += 4;
} else {
if (j+1 >= size) {
j = 0;
break;
}
if (j+1 >= size)
goto toolong;
dest[j] = src[i];
j++;
}
}
dest[j] = '\0';
return j;
toolong:
/* If the input path is too long to encode as a filename, then let's suffix with a string
* generated from the hash of the path. */
h = siphash24_string(src, UDEV_NODE_HASH_KEY.bytes);
assert(size >= 12);
for (unsigned k = 0; k <= 10; k++)
dest[size - k - 2] = urlsafe_base64char((h >> (k * 6)) & 63);
dest[size - 1] = '\0';
return size - 1;
}
/* manage "stack of names" with possibly specified device priorities */
static int link_update(sd_device *dev, const char *slink, bool add) {
_cleanup_free_ char *filename = NULL, *dirname = NULL;
const char *slink_name, *id;
char name_enc[PATH_MAX];
char name_enc[NAME_MAX+1];
int i, r, retries;
assert(dev);
@ -244,10 +257,11 @@ static int link_update(sd_device *dev, const char *slink, bool add) {
if (r < 0)
return log_device_debug_errno(dev, r, "Failed to get device id: %m");
escape_path(slink_name, name_enc, sizeof(name_enc));
(void) udev_node_escape_path(slink_name, name_enc, sizeof(name_enc));
dirname = path_join("/run/udev/links/", name_enc);
if (!dirname)
return log_oom();
filename = path_join(dirname, id);
if (!filename)
return log_oom();

2
src/udev/udev-node.h
View File

@ -13,3 +13,5 @@ int udev_node_add(sd_device *dev, bool apply,
OrderedHashmap *seclabel_list);
int udev_node_remove(sd_device *dev);
int udev_node_update_old_links(sd_device *dev, sd_device *dev_old);
size_t udev_node_escape_path(const char *src, char *dest, size_t size);