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Fix access to unaligned hidden TrueCrypt header.

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On native 4k-sector device the old hidden header is not aligned
with hw sector size and derect-io access with SEEK_END fails.

Let's extend blockwise functions to support a negative offset
and use the same logic as normal unaligned writes.

Fixes problem mentioned in
https://gitlab.com/cryptsetup/cryptsetup/merge_requests/18
This commit is contained in:
Milan Broz
2017-03-27 12:04:31 +02:00
parent 7c25327396
commit e91b90b8c9
2 changed files with 22 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
lib/tcrypt/tcrypt.c
View File

@@ -627,27 +627,26 @@ int TCRYPT_read_phdr(struct crypt_device *cd,
r = -EIO; r = -EIO;
if (params->flags & CRYPT_TCRYPT_SYSTEM_HEADER) { if (params->flags & CRYPT_TCRYPT_SYSTEM_HEADER) {
if (lseek(devfd, TCRYPT_HDR_SYSTEM_OFFSET, SEEK_SET) >= 0 && if (read_lseek_blockwise(devfd, bs, hdr, hdr_size,
read_blockwise(devfd, bs, hdr, hdr_size) == hdr_size) { TCRYPT_HDR_SYSTEM_OFFSET) == hdr_size) {
r = TCRYPT_init_hdr(cd, hdr, params); r = TCRYPT_init_hdr(cd, hdr, params);
} }
} else if (params->flags & CRYPT_TCRYPT_HIDDEN_HEADER) { } else if (params->flags & CRYPT_TCRYPT_HIDDEN_HEADER) {
if (params->flags & CRYPT_TCRYPT_BACKUP_HEADER) { if (params->flags & CRYPT_TCRYPT_BACKUP_HEADER) {
if (lseek(devfd, TCRYPT_HDR_HIDDEN_OFFSET_BCK, SEEK_END) >= 0 && if (read_lseek_blockwise(devfd, bs, hdr, hdr_size,
read_blockwise(devfd, bs, hdr, hdr_size) == hdr_size) TCRYPT_HDR_HIDDEN_OFFSET_BCK) == hdr_size)
r = TCRYPT_init_hdr(cd, hdr, params); r = TCRYPT_init_hdr(cd, hdr, params);
} else { } else {
if (lseek(devfd, TCRYPT_HDR_HIDDEN_OFFSET, SEEK_SET) >= 0 && if (read_lseek_blockwise(devfd, bs, hdr, hdr_size,
read_blockwise(devfd, bs, hdr, hdr_size) == hdr_size) TCRYPT_HDR_HIDDEN_OFFSET) == hdr_size)
r = TCRYPT_init_hdr(cd, hdr, params); r = TCRYPT_init_hdr(cd, hdr, params);
if (r && if (r && read_lseek_blockwise(devfd, bs, hdr, hdr_size,
lseek(devfd, TCRYPT_HDR_HIDDEN_OFFSET_OLD, SEEK_END) >= 0 && TCRYPT_HDR_HIDDEN_OFFSET_OLD) == hdr_size)
read_blockwise(devfd, bs, hdr, hdr_size) == hdr_size)
r = TCRYPT_init_hdr(cd, hdr, params); r = TCRYPT_init_hdr(cd, hdr, params);
} }
} else if (params->flags & CRYPT_TCRYPT_BACKUP_HEADER) { } else if (params->flags & CRYPT_TCRYPT_BACKUP_HEADER) {
if (lseek(devfd, TCRYPT_HDR_OFFSET_BCK, SEEK_END) >= 0 && if (read_lseek_blockwise(devfd, bs, hdr, hdr_size,
read_blockwise(devfd, bs, hdr, hdr_size) == hdr_size) TCRYPT_HDR_OFFSET_BCK) == hdr_size)
r = TCRYPT_init_hdr(cd, hdr, params); r = TCRYPT_init_hdr(cd, hdr, params);
} else if (read_blockwise(devfd, bs, hdr, hdr_size) == hdr_size) } else if (read_blockwise(devfd, bs, hdr, hdr_size) == hdr_size)
r = TCRYPT_init_hdr(cd, hdr, params); r = TCRYPT_init_hdr(cd, hdr, params);

12
lib/utils.c
View File

@@ -235,6 +235,12 @@ ssize_t write_lseek_blockwise(int fd, int bsize, void *buf, size_t count, off_t
if (fd == -1 || !buf || bsize <= 0) if (fd == -1 || !buf || bsize <= 0)
return -1; return -1;
if (offset < 0)
offset = lseek(fd, offset, SEEK_END);
if (offset < 0)
return -1;
frontHang = offset % bsize; frontHang = offset % bsize;
if (lseek(fd, offset - frontHang, SEEK_SET) < 0) if (lseek(fd, offset - frontHang, SEEK_SET) < 0)
@@ -287,6 +293,12 @@ ssize_t read_lseek_blockwise(int fd, int bsize, void *buf, size_t count, off_t o
if (fd == -1 || !buf || bsize <= 0) if (fd == -1 || !buf || bsize <= 0)
return -1; return -1;
if (offset < 0)
offset = lseek(fd, offset, SEEK_END);
if (offset < 0)
return -1;
frontHang = offset % bsize; frontHang = offset % bsize;
if (lseek(fd, offset - frontHang, SEEK_SET) < 0) if (lseek(fd, offset - frontHang, SEEK_SET) < 0)