cryptsetup: add support for sector-size= option (#9936)

Bug-Ubuntu: https://launchpad.net/bugs/1776626

Closes #8881.

(cherry picked from commit a9fc640671ef60ac949f1ace6fa687ff242fc233)

Resolves: #1572563

3 files changed, 45 insertions, 0 deletions

diff --git a/man/crypttab.xml b/man/crypttab.xml
index dcaf03d2ca..3574ce00da 100644
--- a/man/crypttab.xml
+++ b/man/crypttab.xml
@@ -251,6 +251,15 @@
       </varlistentry>
 
       <varlistentry>
+        <term><option>sector-size=</option></term>
+
+        <listitem><para>Specifies the sector size in bytes. See
+        <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+        for possible values and the default value of this
+        option.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><option>swap</option></term>
 
         <listitem><para>The encrypted block device will be used as a
diff --git a/meson.build b/meson.build
index a0e7240708..f308db2631 100644
--- a/meson.build
+++ b/meson.build
@@ -927,11 +927,17 @@ if want_libcryptsetup != 'false' and not fuzzer_build
                                    version : '>= 1.6.0',
                                    required : want_libcryptsetup == 'true')
         have = libcryptsetup.found()
+        have_sector = cc.has_member(
+                    'struct crypt_params_plain',
+                    'sector_size',
+                    prefix : '#include <libcryptsetup.h>')
 else
         have = false
+        have_sector = false
         libcryptsetup = []
 endif
 conf.set10('HAVE_LIBCRYPTSETUP', have)
+conf.set10('HAVE_LIBCRYPTSETUP_SECTOR_SIZE', have_sector)
 
 want_libcurl = get_option('libcurl')
 if want_libcurl != 'false' and not fuzzer_build
diff --git a/src/cryptsetup/cryptsetup.c b/src/cryptsetup/cryptsetup.c
index 832168184a..87008cb969 100644
--- a/src/cryptsetup/cryptsetup.c
+++ b/src/cryptsetup/cryptsetup.c
@@ -23,10 +23,14 @@
 
 /* internal helper */
 #define ANY_LUKS "LUKS"
+/* as in src/cryptsetup.h */
+#define CRYPT_SECTOR_SIZE 512
+#define CRYPT_MAX_SECTOR_SIZE 4096
 
 static const char *arg_type = NULL; /* ANY_LUKS, CRYPT_LUKS1, CRYPT_LUKS2, CRYPT_TCRYPT or CRYPT_PLAIN */
 static char *arg_cipher = NULL;
 static unsigned arg_key_size = 0;
+static unsigned arg_sector_size = CRYPT_SECTOR_SIZE;
 static int arg_key_slot = CRYPT_ANY_SLOT;
 static unsigned arg_keyfile_size = 0;
 static uint64_t arg_keyfile_offset = 0;
@@ -86,6 +90,29 @@ static int parse_one_option(const char *option) {
 
                 arg_key_size /= 8;
 
+        } else if ((val = startswith(option, "sector-size="))) {
+
+#if HAVE_LIBCRYPTSETUP_SECTOR_SIZE
+                r = safe_atou(val, &arg_sector_size);
+                if (r < 0) {
+                        log_error_errno(r, "Failed to parse %s, ignoring: %m", option);
+                        return 0;
+                }
+
+                if (arg_sector_size % 2) {
+                        log_error("sector-size= not a multiple of 2, ignoring.");
+                        return 0;
+                }
+
+                if (arg_sector_size < CRYPT_SECTOR_SIZE || arg_sector_size > CRYPT_MAX_SECTOR_SIZE) {
+                        log_error("sector-size= is outside of %u and %u, ignoring.", CRYPT_SECTOR_SIZE, CRYPT_MAX_SECTOR_SIZE);
+                        return 0;
+                }
+#else
+                log_error("sector-size= is not supported, compiled with old libcryptsetup.");
+                return 0;
+#endif
+
         } else if ((val = startswith(option, "key-slot="))) {
 
                 arg_type = ANY_LUKS;
@@ -471,6 +498,9 @@ static int attach_luks_or_plain(struct crypt_device *cd,
                 struct crypt_params_plain params = {
                         .offset = arg_offset,
                         .skip = arg_skip,
+#if HAVE_LIBCRYPTSETUP_SECTOR_SIZE
+                        .sector_size = arg_sector_size,
+#endif
                 };
                 const char *cipher, *cipher_mode;
                 _cleanup_free_ char *truncated_cipher = NULL;