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patch 9.0.1481: decrypting with libsodium may fail if the library changes

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Problem:    Decrypting with libsodium may fail if the library changes.
Solution:   Add parameters used to the encrypted file header. (Christian
            Brabandt, closes #12279)
This commit is contained in:
Christian Brabandt
2023-04-23 17:50:22 +01:00
committed by Bram Moolenaar
parent dcd40cfca0
commit aae583441b
16 changed files with 422 additions and 121 deletions
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35
src/fileio.c
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@@ -218,6 +218,9 @@ readfile(
int using_b_fname;
static char *msg_is_a_directory = N_("is a directory");
int eof;
#ifdef FEAT_SODIUM
int may_need_lseek = FALSE;
#endif
au_did_filetype = FALSE; // reset before triggering any autocommands
@@ -1282,15 +1285,43 @@ retry:
*/
# ifdef FEAT_SODIUM
// Let the crypt layer work with a buffer size of 8192
//
// Sodium encryption requires a fixed block size to
// successfully decrypt. However, unfortunately the file
// header size changes between xchacha20 and xchacha20v2 by
// 'add_len' bytes.
// So we will now read the maximum header size + encryption
// metadata, but after determining to read an xchacha20
// encrypted file, we have to rewind the file descriptor by
// 'add_len' bytes in the second round.
//
// Be careful with changing it, it needs to stay the same
// for reading back previously encrypted files!
if (filesize == 0)
{
// set size to 8K + Sodium Crypt Metadata
size = WRITEBUFSIZE + crypt_get_max_header_len()
+ crypto_secretstream_xchacha20poly1305_HEADERBYTES
+ crypto_secretstream_xchacha20poly1305_ABYTES;
may_need_lseek = TRUE;
}
else if (filesize > 0 && (curbuf->b_cryptstate != NULL &&
curbuf->b_cryptstate->method_nr == CRYPT_M_SOD))
else if (filesize > 0 && (curbuf->b_cryptstate != NULL
&& crypt_method_is_sodium(
curbuf->b_cryptstate->method_nr)))
{
size = WRITEBUFSIZE + crypto_secretstream_xchacha20poly1305_ABYTES;
// need to rewind by - add_len from CRYPT_M_SOD2 (see
// description above)
if (curbuf->b_cryptstate->method_nr == CRYPT_M_SOD
&& !eof && may_need_lseek)
{
lseek(fd, crypt_get_header_len(
curbuf->b_cryptstate->method_nr)
- crypt_get_max_header_len(), SEEK_CUR);
may_need_lseek = FALSE;
}
}
# endif
eof = size;
size = read_eintr(fd, ptr, size);