package/dropbear: fix generating 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

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Acked-by: "Maxime Hadjinlian" <maxime.hadjinlian@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
This commit is contained in:
Yann E. MORIN 2015-07-14 00:44:01 +02:00 committed by Thomas Petazzoni
parent 36480eab8f
commit e7d04dd2df
3 changed files with 28 additions and 1 deletions

View File

@ -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 /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"

View File

@ -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))

View File

@ -3,6 +3,19 @@ Description=Dropbear SSH daemon
After=syslog.target network.target auditd.service
[Service]
# 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
ExecStartPre=/bin/sh -c '\
if ! [ -d /etc/dropbear ]; then \
if rm -f /etc/dropbear; then \
mkdir -p /etc/dropbear; \
else \
mkdir -p $(readlink /etc/dropbear); \
fi; \
fi'
ExecStart=/usr/sbin/dropbear -F -R
ExecReload=/bin/kill -HUP $MAINPID