[Buildroot] [PATCH] package/dropbear: Fix symlink only if pointing to the right directory

[Buildroot] [PATCH] package/dropbear: Fix symlink only if pointing to the right directory

[paul at crapouillou.net]

From: Paul Cercueil <paul@crapouillou.net>

This commit ensures that the /etc/dropbear symlink won't be removed if
it points elsewhere than /var/run/dropbear.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 package/dropbear/S50dropbear      | 4 ++--
 package/dropbear/dropbear.service | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/package/dropbear/S50dropbear b/package/dropbear/S50dropbear
index af50ccf..d42fb60 100644
--- a/package/dropbear/S50dropbear
+++ b/package/dropbear/S50dropbear
@@ -12,12 +12,12 @@ start() {
 	echo -n "Starting dropbear sshd: "
 	umask 077
 
-	# If /etc/dropbear is not a directory, and
+	# If /etc/dropbear is a symlink to /var/run/dropbear, 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 [ "$(readlink /etc/dropbear)" = "/var/run/dropbear" ]; then
 		if rm -f /etc/dropbear; then
 			mkdir -p /etc/dropbear
 		else
diff --git a/package/dropbear/dropbear.service b/package/dropbear/dropbear.service
index 0e2cf54..62ade1f 100644
--- a/package/dropbear/dropbear.service
+++ b/package/dropbear/dropbear.service
@@ -3,13 +3,13 @@ Description=Dropbear SSH daemon
 After=syslog.target network.target auditd.service
 
 [Service]
-# If /etc/dropbear is not a directory, and
+# If /etc/dropbear is a symlink to /var/run/dropbear, 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 [ "$(readlink /etc/dropbear)" = "/var/run/dropbear" ]; then \
     if rm -f /etc/dropbear; then \
         mkdir -p /etc/dropbear; \
     else \
-- 
2.1.4

[Buildroot] [PATCH] package/dropbear: Fix symlink only if pointing to the right directory

[Yann E. MORIN]

Paul, All,

On 2015-07-15 11:55 +0200, paul at crapouillou.net spake thusly:
> From: Paul Cercueil <paul@crapouillou.net>
> 
> This commit ensures that the /etc/dropbear symlink won't be removed if
> it points elsewhere than /var/run/dropbear.
> 
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  package/dropbear/S50dropbear      | 4 ++--
>  package/dropbear/dropbear.service | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/package/dropbear/S50dropbear b/package/dropbear/S50dropbear
> index af50ccf..d42fb60 100644
> --- a/package/dropbear/S50dropbear
> +++ b/package/dropbear/S50dropbear
> @@ -12,12 +12,12 @@ start() {
>  	echo -n "Starting dropbear sshd: "
>  	umask 077
>  
> -	# If /etc/dropbear is not a directory, and
> +	# If /etc/dropbear is a symlink to /var/run/dropbear, 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 [ "$(readlink /etc/dropbear)" = "/var/run/dropbear" ]; then

/etc/dropbear is a relative symlink, so readlink (at least from
coreutils) would return the relative path, not the absolute path.

So, I can't see a way this can work as-is. However, what about this:

    if [    -L /etc/dropbear \
         -a "$(readlink -f /etc/dropbear)" = "/var/run/dropbear" ]
    then
        # trick-trac on .etc.dropbear
    fi

(Ditto the unit file, of course! ;-)

Care to fix and resend, please?

Regards,
Yann E. MORIN.

>  		if rm -f /etc/dropbear; then
>  			mkdir -p /etc/dropbear
>  		else
> diff --git a/package/dropbear/dropbear.service b/package/dropbear/dropbear.service
> index 0e2cf54..62ade1f 100644
> --- a/package/dropbear/dropbear.service
> +++ b/package/dropbear/dropbear.service
> @@ -3,13 +3,13 @@ Description=Dropbear SSH daemon
>  After=syslog.target network.target auditd.service
>  
>  [Service]
> -# If /etc/dropbear is not a directory, and
> +# If /etc/dropbear is a symlink to /var/run/dropbear, 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 [ "$(readlink /etc/dropbear)" = "/var/run/dropbear" ]; then \
>      if rm -f /etc/dropbear; then \
>          mkdir -p /etc/dropbear; \
>      else \
> -- 
> 2.1.4
> 
> _______________________________________________
> buildroot mailing list
> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot

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[Buildroot] [PATCH] package/dropbear: Fix symlink only if pointing to the right directory

[Thomas Petazzoni]

Paul,

On Wed, 15 Jul 2015 11:55:03 +0200, paul at crapouillou.net wrote:
> From: Paul Cercueil <paul@crapouillou.net>
> 
> This commit ensures that the /etc/dropbear symlink won't be removed if
> it points elsewhere than /var/run/dropbear.
> 
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  package/dropbear/S50dropbear      | 4 ++--
>  package/dropbear/dropbear.service | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)

Following the comments from Yann E. Morin, I've marked your patch as
Changes Requested. Can you respin a new version?

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com