From f62231a54abff6566415ea82aa8773e61f5688d6 Mon Sep 17 00:00:00 2001

From: Michal Sekletar <msekleta@redhat.com>

Date: Tue, 15 Mar 2022 19:02:05 +0100

Subject: [PATCH] core: shorten long unit names that are based on paths and

 append path hash at the end

Fixes #18077

(cherry picked from commit 1d0727e76fd5e9a07cc9991ec9a10ea1d78a99c7)

Resolves: #1940973

---

 src/basic/string-util.h   | 23 +++++-----

 src/basic/unit-name.c     | 88 ++++++++++++++++++++++++++++++++++++++-

 src/basic/unit-name.h     |  3 ++

 src/core/mount.c          |  3 ++

 src/test/test-unit-name.c | 25 ++++++++++-

 5 files changed, 129 insertions(+), 13 deletions(-)

diff --git a/src/basic/string-util.h b/src/basic/string-util.h

index 742b566932..0d406ff64a 100644

--- a/src/basic/string-util.h

+++ b/src/basic/string-util.h

@@ -9,17 +9,18 @@

 #include "macro.h"

 /* What is interpreted as whitespace? */

-#define WHITESPACE        " \t\n\r"

-#define NEWLINE           "\n\r"

-#define QUOTES            "\"\'"

-#define COMMENTS          "#;"

-#define GLOB_CHARS        "*?["

-#define DIGITS            "0123456789"

-#define LOWERCASE_LETTERS "abcdefghijklmnopqrstuvwxyz"

-#define UPPERCASE_LETTERS "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

-#define LETTERS           LOWERCASE_LETTERS UPPERCASE_LETTERS

-#define ALPHANUMERICAL    LETTERS DIGITS

-#define HEXDIGITS         DIGITS "abcdefABCDEF"

+#define WHITESPACE          " \t\n\r"

+#define NEWLINE             "\n\r"

+#define QUOTES              "\"\'"

+#define COMMENTS            "#;"

+#define GLOB_CHARS          "*?["

+#define DIGITS              "0123456789"

+#define LOWERCASE_LETTERS   "abcdefghijklmnopqrstuvwxyz"

+#define UPPERCASE_LETTERS   "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

+#define LETTERS             LOWERCASE_LETTERS UPPERCASE_LETTERS

+#define ALPHANUMERICAL      LETTERS DIGITS

+#define HEXDIGITS           DIGITS "abcdefABCDEF"

+#define LOWERCASE_HEXDIGITS DIGITS "abcdef"

 #define streq(a,b) (strcmp((a),(b)) == 0)

 #define strneq(a, b, n) (strncmp((a), (b), (n)) == 0)

diff --git a/src/basic/unit-name.c b/src/basic/unit-name.c

index f9b3fafd4d..65ed979e39 100644

--- a/src/basic/unit-name.c

+++ b/src/basic/unit-name.c

@@ -6,11 +6,17 @@

 #include <stdlib.h>

 #include <string.h>

+#include "sd-id128.h"

+

 #include "alloc-util.h"

 #include "glob-util.h"

 #include "hexdecoct.h"

 #include "path-util.h"

+#include "random-util.h"

+#include "siphash24.h"

+#include "sparse-endian.h"

 #include "special.h"

+#include "stdio-util.h"

 #include "string-util.h"

 #include "strv.h"

 #include "unit-name.h"

@@ -31,6 +37,9 @@

         VALID_CHARS_WITH_AT                     \

         "[]!-*?"

+#define LONG_UNIT_NAME_HASH_KEY SD_ID128_MAKE(ec,f2,37,fb,58,32,4a,32,84,9f,06,9b,0d,21,eb,9a)

+#define UNIT_NAME_HASH_LENGTH_CHARS 16

+

 bool unit_name_is_valid(const char *n, UnitNameFlags flags) {

         const char *e, *i, *at;

@@ -513,6 +522,68 @@ int unit_name_template(const char *f, char **ret) {

         return 0;

 }

+bool unit_name_is_hashed(const char *name) {

+        char *s;

+

+        if (!unit_name_is_valid(name, UNIT_NAME_PLAIN))

+                return false;

+

+        assert_se(s = strrchr(name, '.'));

+

+        if (s - name < UNIT_NAME_HASH_LENGTH_CHARS + 1)

+                return false;

+

+        s -= UNIT_NAME_HASH_LENGTH_CHARS;

+        if (s[-1] != '_')

+                return false;

+

+        for (size_t i = 0; i < UNIT_NAME_HASH_LENGTH_CHARS; i++)

+                if (!strchr(LOWERCASE_HEXDIGITS, s[i]))

+                        return false;

+

+        return true;

+}

+

+int unit_name_hash_long(const char *name, char **ret) {

+        _cleanup_free_ char *n = NULL, *hash = NULL;

+        char *suffix;

+        le64_t h;

+        size_t len;

+

+        if (strlen(name) < UNIT_NAME_MAX)

+                return -EMSGSIZE;

+

+        suffix = strrchr(name, '.');

+        if (!suffix)

+                return -EINVAL;

+

+        if (unit_type_from_string(suffix+1) < 0)

+                return -EINVAL;

+

+        h = htole64(siphash24(name, strlen(name) + 1, LONG_UNIT_NAME_HASH_KEY.bytes));

+

+        hash = hexmem(&h, sizeof(h));

+        if (!hash)

+                return -ENOMEM;

+

+        assert_se(strlen(hash) == UNIT_NAME_HASH_LENGTH_CHARS);

+

+        len = UNIT_NAME_MAX - 1 - strlen(suffix+1) - UNIT_NAME_HASH_LENGTH_CHARS - 2;

+        assert(len > 0 && len < UNIT_NAME_MAX);

+

+        n = strndup(name, len);

+        if (!n)

+                return -ENOMEM;

+

+        if (!strextend(&n, "_", hash, suffix, NULL))

+                return -ENOMEM;

+        assert_se(unit_name_is_valid(n, UNIT_NAME_PLAIN));

+

+        *ret = TAKE_PTR(n);

+

+        return 0;

+}

+

 int unit_name_from_path(const char *path, const char *suffix, char **ret) {

         _cleanup_free_ char *p = NULL, *s = NULL;

         int r;

@@ -532,7 +603,19 @@ int unit_name_from_path(const char *path, const char *suffix, char **ret) {

         if (!s)

                 return -ENOMEM;

-        /* Refuse this if this got too long or for some other reason didn't result in a valid name */

+        if (strlen(s) >= UNIT_NAME_MAX) {

+                _cleanup_free_ char *n = NULL;

+

+                log_debug("Unit name \"%s\" too long, falling back to hashed unit name.", s);

+

+                r = unit_name_hash_long(s, &n);

+                if (r < 0)

+                        return r;

+

+                free_and_replace(s, n);

+        }

+

+        /* Refuse if this for some other reason didn't result in a valid name */

         if (!unit_name_is_valid(s, UNIT_NAME_PLAIN))

                 return -EINVAL;

@@ -582,6 +665,9 @@ int unit_name_to_path(const char *name, char **ret) {

         if (r < 0)

                 return r;

+        if (unit_name_is_hashed(name))

+                return -ENAMETOOLONG;

+

         return unit_name_path_unescape(prefix, ret);

 }

diff --git a/src/basic/unit-name.h b/src/basic/unit-name.h

index 61abcd585b..602295af8f 100644

--- a/src/basic/unit-name.h

+++ b/src/basic/unit-name.h

@@ -45,6 +45,9 @@ int unit_name_replace_instance(const char *f, const char *i, char **ret);

 int unit_name_template(const char *f, char **ret);

+int unit_name_hash_long(const char *name, char **ret);

+bool unit_name_is_hashed(const char *name);

+

 int unit_name_from_path(const char *path, const char *suffix, char **ret);

 int unit_name_from_path_instance(const char *prefix, const char *path, const char *suffix, char **ret);

 int unit_name_to_path(const char *name, char **ret);

diff --git a/src/core/mount.c b/src/core/mount.c

index d37b5731f8..e69ecb7ce3 100644

--- a/src/core/mount.c

+++ b/src/core/mount.c

@@ -572,6 +572,9 @@ static int mount_add_extras(Mount *m) {

         if (!m->where) {

                 r = unit_name_to_path(u->id, &m->where);

+                if (r == -ENAMETOOLONG)

+                        log_unit_error_errno(u, r, "Failed to derive mount point path from unit name, because unit name is hashed. "

+                                                   "Set \"Where=\" in the unit file explicitly.");

                 if (r < 0)

                         return r;

         }

diff --git a/src/test/test-unit-name.c b/src/test/test-unit-name.c

index 2b00ef8cb7..35cfaafd30 100644

--- a/src/test/test-unit-name.c

+++ b/src/test/test-unit-name.c

@@ -82,6 +82,7 @@ static void test_unit_name_replace_instance(void) {

 static void test_unit_name_from_path_one(const char *path, const char *suffix, const char *expected, int ret) {

         _cleanup_free_ char *t = NULL;

+        int r;

         assert_se(unit_name_from_path(path, suffix, &t) == ret);

         puts(strna(t));

@@ -89,12 +90,31 @@ static void test_unit_name_from_path_one(const char *path, const char *suffix, c

         if (t) {

                 _cleanup_free_ char *k = NULL;

-                assert_se(unit_name_to_path(t, &k) == 0);

+

+                /* We don't support converting hashed unit names back to paths */

+                r = unit_name_to_path(t, &k);

+                if (r == -ENAMETOOLONG)

+                        return;

+                assert(r == 0);

+

                 puts(strna(k));

                 assert_se(path_equal(k, empty_to_root(path)));

         }

 }

+static void test_unit_name_is_hashed(void) {

+        assert_se(!unit_name_is_hashed(""));

+        assert_se(!unit_name_is_hashed("foo@bar.service"));

+        assert_se(!unit_name_is_hashed("foo@.service"));

+        assert_se(unit_name_is_hashed("waldoaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa_7736d9ed33c2ec55.mount"));

+        assert_se(!unit_name_is_hashed("waldoaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa_7736D9ED33C2EC55.mount"));

+        assert_se(!unit_name_is_hashed("waldoaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa!7736d9ed33c2ec55.mount"));

+        assert_se(!unit_name_is_hashed("waldoaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa_7736d9gd33c2ec55.mount"));

+        assert_se(!unit_name_is_hashed("waldoaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa_.mount"));

+        assert_se(!unit_name_is_hashed("waldoaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa_2103e1466b87f7f7@waldo.mount"));

+        assert_se(!unit_name_is_hashed("waldoaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa_2103e1466b87f7f7@.mount"));

+}

+

 static void test_unit_name_from_path(void) {

         puts("-------------------------------------------------");

         test_unit_name_from_path_one("/waldo", ".mount", "waldo.mount", 0);

@@ -105,6 +125,8 @@ static void test_unit_name_from_path(void) {

         test_unit_name_from_path_one("///", ".mount", "-.mount", 0);

         test_unit_name_from_path_one("/foo/../bar", ".mount", NULL, -EINVAL);

         test_unit_name_from_path_one("/foo/./bar", ".mount", NULL, -EINVAL);

+        test_unit_name_from_path_one("/waldoaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", ".mount",

+                                     "waldoaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa_7736d9ed33c2ec55.mount", 0);

 }

 static void test_unit_name_from_path_instance_one(const char *pattern, const char *path, const char *suffix, const char *expected, int ret) {

@@ -824,6 +846,7 @@ int main(int argc, char* argv[]) {

         test_unit_name_is_valid();

         test_unit_name_replace_instance();

+        test_unit_name_is_hashed();

         test_unit_name_from_path();

         test_unit_name_from_path_instance();

         test_unit_name_mangle();