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package/dropbear: fix generatign keys on RO file systems

PATCH New Yann E. MORIN 3 participants 4 messages Jul 13, 2015

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PATCH 1/1 package/dropbear: fix generatign keys on RO file systems

dropbear generates its keys at the first connection, and wants to save them in /etc/dropbear (not configurable).

Currently, our /etc/dropbear is a directory.

When the filesystem is read-only, dropbear can't save its keys, so refuses all connections.

Fix that with:

- at build time, create /etc/dropbear as a symlink to /var/run/dropbear

- at runtime, if the filesystem is RW (we can rm /etc/dropbear), we replace the symlink with an actual directory; otherwise, when the filesystem is RO (we can't rm /etc/dropbear), we create /var/run/dropbear so the symlink points to an existing directory

Cc Thomas Petazzoni <[email protected]>
Cc Arnout Vandecappelle <[email protected]>
Cc Maxime Hadjinlian <[email protected]>
---
 package/dropbear/S50dropbear | 14 ++++++++++++++
 package/dropbear/dropbear.mk |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)
package/dropbear/S50dropbear +14 -0
index 2694931..790d95a 100644
@@ -11,6 +11,20 @@ start() {
 
 	echo -n "Starting dropbear sshd: "
 	umask 077
+
+    # If /etc/dropbear is not a directory, and
+    #   - the filesystem is RO (i.e. we can not rm the symlink),
+    #     create the directory pointed to by the symlink.
+    #   - the filesystem is RW (i.e. we can rm the symlink),
+    #     replace the symlink with an actual directory
+	if ! [ -d /etc/dropbear ]; then
+		if ! rm -f /etc/dropbear; then
+			mkdir -p /etc/dropbear
+		else
+			mkdir -p $(readlink -f /etc/dropbear)
+		fi
+	fi
+
 	start-stop-daemon -S -q -p /var/run/dropbear.pid \
 		--exec /usr/sbin/dropbear -- $DROPBEAR_ARGS
 	[ $? = 0 ] && echo "OK" || echo "FAIL"
package/dropbear/dropbear.mk +1 -1
index bc65d69..5bbe864 100644
@@ -93,7 +93,7 @@ define DROPBEAR_INSTALL_TARGET_CMDS
 	for f in $(DROPBEAR_TARGET_BINS); do \
 		ln -snf ../sbin/dropbear $(TARGET_DIR)/usr/bin/$$f ; \
 	done
-	mkdir -p $(TARGET_DIR)/etc/dropbear
+	ln -snf ../var/run/dropbear $(TARGET_DIR)/etc/dropbear
 endef
 
 $(eval $(autotools-package))
Signature · 1 line
1.9.1
#1 lore raw

PATCH 1/1 package/dropbear: fix generatign keys on RO file systems

Hi Yann, all

Quoted 42 lines · Yann E. MORIN

dropbear generates its keys at the first connection, and wants to save them in /etc/dropbear (not configurable).

Currently, our /etc/dropbear is a directory.

When the filesystem is read-only, dropbear can't save its keys, so refuses all connections.

Fix that with:

- at build time, create /etc/dropbear as a symlink to /var/run/dropbear

- at runtime, if the filesystem is RW (we can rm /etc/dropbear), we replace the symlink with an actual directory; otherwise, when the filesystem is RO (we can't rm /etc/dropbear), we create /var/run/dropbear so the symlink points to an existing directory

Cc Thomas Petazzoni <[email protected]>
Cc Arnout Vandecappelle <[email protected]>
Cc Maxime Hadjinlian <[email protected]>
---
 package/dropbear/S50dropbear | 14 ++++++++++++++
 package/dropbear/dropbear.mk |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)
package/dropbear/S50dropbear +7 -0
index 2694931..790d95a 100644
@@ -11,6 +11,20 @@ start() {
 
        echo -n "Starting dropbear sshd: "
        umask 077
+
+    # If /etc/dropbear is not a directory, and
+    #   - the filesystem is RO (i.e. we can not rm the symlink),
+    #     create the directory pointed to by the symlink.
+    #   - the filesystem is RW (i.e. we can rm the symlink),
+    #     replace the symlink with an actual directory
+       if ! [ -d /etc/dropbear ]; then

package/dropbear/S50dropbear start() { · line 30

Quoted 10 lines
package/dropbear/S50dropbear +7 -0
+               if ! rm -f /etc/dropbear; then
+                       mkdir -p /etc/dropbear
+               else
+                       mkdir -p $(readlink -f /etc/dropbear)
+               fi
+       fi
+
        start-stop-daemon -S -q -p /var/run/dropbear.pid \
                --exec /usr/sbin/dropbear -- $DROPBEAR_ARGS
        [ $? = 0 ] && echo "OK" || echo "FAIL"

So systemd users are left behind ? :(

Quoted 16 lines
package/dropbear/dropbear.mk +1 -2
index bc65d69..5bbe864 100644
@@ -93,7 +93,7 @@ define DROPBEAR_INSTALL_TARGET_CMDS
        for f in $(DROPBEAR_TARGET_BINS); do \
                ln -snf ../sbin/dropbear $(TARGET_DIR)/usr/bin/$$f ; \
        done
-       mkdir -p $(TARGET_DIR)/etc/dropbear
+       ln -snf ../var/run/dropbear $(TARGET_DIR)/etc/dropbear
 endef
 
 $(eval $(autotools-package))
--

1.9.1

#2 lore raw

PATCH 1/1 package/dropbear: fix generatign keys on RO file systems

In reply to Yann E. MORIN

Hi Yann,

package/dropbear/S50dropbear start() { · line 21

Quoted 2 lines · Yann E. MORIN
package/dropbear/S50dropbear +2 -0
+	if ! [ -d /etc/dropbear ]; then
+		if ! rm -f /etc/dropbear; then

'rm -f' always succeeds.

package/dropbear/S50dropbear start() { · line 26

Quoted 5 lines
package/dropbear/S50dropbear +5 -0
+			mkdir -p /etc/dropbear
+		else
+			mkdir -p $(readlink -f /etc/dropbear)
+		fi
+	fi

baruch

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#3 lore raw

PATCH 1/1 package/dropbear: fix generatign keys on RO file systems

Baruch, All,

On 2015-07-13 18:01 +0300, Baruch Siach spake thusly:

Quoted 5 lines · Yann E. MORIN

package/dropbear/S50dropbear start() { · line 21

Quoted 2 lines
package/dropbear/S50dropbear +2 -0
+	if ! [ -d /etc/dropbear ]; then
+		if ! rm -f /etc/dropbear; then

'rm -f' always succeeds.

No, it does not succeeds if the filesystem is readonly.

Regards,
Yann E. MORIN.

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