From 42b0ab437a6ef332dd33e1eda144d2c3d9a70d23 Mon Sep 17 00:00:00 2001
From: Milan Broz <gmazyland@gmail.com>
Date: Sun, 23 Jun 2013 15:26:45 +0200
Subject: [PATCH] Print a warning if system encryption is used and device is a
 partition.

System encryption hav metadata in space located ouside of
partition itself.

Ideally the check should be automatic but for virtualized systems
(where a partition could be "whole device" for another sustem this
can be dangerous.
---
 lib/internal.h      |  1 +
 lib/tcrypt/tcrypt.c | 11 +++++++++--
 lib/utils_devpath.c | 27 +++++++++++++++++++++++----
 3 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/lib/internal.h b/lib/internal.h
index 71d5709..b1a1936 100644
--- a/lib/internal.h
+++ b/lib/internal.h
@@ -97,6 +97,7 @@ int crypt_confirm(struct crypt_device *cd, const char *msg);
 
 char *crypt_lookup_dev(const char *dev_id);
 int crypt_sysfs_get_rotational(int major, int minor, int *rotational);
+int crypt_sysfs_get_partition(const char *dev_path, int *partition);
 
 ssize_t write_blockwise(int fd, int bsize, void *buf, size_t count);
 ssize_t read_blockwise(int fd, int bsize, void *_buf, size_t count);
diff --git a/lib/tcrypt/tcrypt.c b/lib/tcrypt/tcrypt.c
index 3bab4ba..6de62fa 100644
--- a/lib/tcrypt/tcrypt.c
+++ b/lib/tcrypt/tcrypt.c
@@ -565,7 +565,7 @@ int TCRYPT_read_phdr(struct crypt_device *cd,
 {
 	struct device *device = crypt_metadata_device(cd);
 	ssize_t hdr_size = sizeof(struct tcrypt_phdr);
-	int devfd = 0, r, bs;
+	int devfd = 0, r, bs, partition;
 
 	assert(sizeof(struct tcrypt_phdr) == 512);
 
@@ -585,8 +585,15 @@ int TCRYPT_read_phdr(struct crypt_device *cd,
 	r = -EIO;
 	if (params->flags & CRYPT_TCRYPT_SYSTEM_HEADER) {
 		if (lseek(devfd, TCRYPT_HDR_SYSTEM_OFFSET, SEEK_SET) >= 0 &&
-		    read_blockwise(devfd, bs, hdr, hdr_size) == hdr_size)
+		    read_blockwise(devfd, bs, hdr, hdr_size) == hdr_size) {
 			r = TCRYPT_init_hdr(cd, hdr, params);
+			if (r == -EPERM &&
+			    crypt_sysfs_get_partition(device_path(device), &partition) &&
+			    partition)
+				log_std(cd, _("WARNING: device %s is a partition, for TCRYPT "
+					      "system encryption you usually need to use "
+					      "whole block device path.\n"), device_path(device));
+		}
 	} else if (params->flags & CRYPT_TCRYPT_HIDDEN_HEADER) {
 		if (params->flags & CRYPT_TCRYPT_BACKUP_HEADER) {
 			if (lseek(devfd, TCRYPT_HDR_HIDDEN_OFFSET_BCK, SEEK_END) >= 0 &&
diff --git a/lib/utils_devpath.c b/lib/utils_devpath.c
index 835f040..6c07b5b 100644
--- a/lib/utils_devpath.c
+++ b/lib/utils_devpath.c
@@ -170,13 +170,13 @@ char *crypt_lookup_dev(const char *dev_id)
 	return devpath;
 }
 
-int crypt_sysfs_get_rotational(int major, int minor, int *rotational)
+static int _sysfs_get_int(int major, int minor, int *value, const char *attr)
 {
 	char path[PATH_MAX], tmp[64] = {0};
 	int fd, r;
 
-	if (snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/queue/rotational",
-		     major, minor) < 0)
+	if (snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/%s",
+		     major, minor, attr) < 0)
 		return 0;
 
 	if ((fd = open(path, O_RDONLY)) < 0)
@@ -187,8 +187,27 @@ int crypt_sysfs_get_rotational(int major, int minor, int *rotational)
 	if (r <= 0)
 		return 0;
 
-        if (sscanf(tmp, "%d", rotational) != 1)
+        if (sscanf(tmp, "%d", value) != 1)
 		return 0;
 
 	return 1;
 }
+
+int crypt_sysfs_get_rotational(int major, int minor, int *rotational)
+{
+	return _sysfs_get_int(major, minor, rotational, "queue/rotational");
+}
+
+int crypt_sysfs_get_partition(const char *dev_path, int *partition)
+{
+	struct stat st;
+
+	if (stat(dev_path, &st) < 0)
+		return 0;
+
+	if (!S_ISBLK(st.st_mode))
+		return 0;
+
+	return _sysfs_get_int(major(st.st_rdev), minor(st.st_rdev),
+			      partition, "partition");
+}
-- 
2.7.4