From 6e10fc74fd569b71b6f64f5a2420dc624d73bee2 Mon Sep 17 00:00:00 2001 From: Kevin Darbyshire-Bryant Date: Sat, 20 May 2017 12:54:11 +0100 Subject: [PATCH] dropbear: bump to 2017.75 - Security: Fix double-free in server TCP listener cleanup A double-free in the server could be triggered by an authenticated user if dropbear is running with -a (Allow connections to forwarded ports from any host) This could potentially allow arbitrary code execution as root by an authenticated user. Affects versions 2013.56 to 2016.74. Thanks to Mark Shepard for reporting the crash. CVE-2017-9078 https://secure.ucc.asn.au/hg/dropbear/rev/c8114a48837c - Security: Fix information disclosure with ~/.ssh/authorized_keys symlink. Dropbear parsed authorized_keys as root, even if it were a symlink. The fix is to switch to user permissions when opening authorized_keys A user could symlink their ~/.ssh/authorized_keys to a root-owned file they couldn't normally read. If they managed to get that file to contain valid authorized_keys with command= options it might be possible to read other contents of that file. This information disclosure is to an already authenticated user. Thanks to Jann Horn of Google Project Zero for reporting this. CVE-2017-9079 https://secure.ucc.asn.au/hg/dropbear/rev/0d889b068123 Refresh patches, rework 100-pubkey_path.patch to work with new authorized_keys validation. Signed-off-by: Kevin Darbyshire-Bryant --- package/network/services/dropbear/Makefile | 6 ++--- .../dropbear/patches/100-pubkey_path.patch | 24 ++++++++----------- 2 files changed, 13 insertions(+), 17 deletions(-) diff --git a/package/network/services/dropbear/Makefile b/package/network/services/dropbear/Makefile index 5e518dabd4..1e2588d619 100644 --- a/package/network/services/dropbear/Makefile +++ b/package/network/services/dropbear/Makefile @@ -8,14 +8,14 @@ include $(TOPDIR)/rules.mk PKG_NAME:=dropbear -PKG_VERSION:=2016.74 -PKG_RELEASE:=2 +PKG_VERSION:=2017.75 +PKG_RELEASE:=1 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2 PKG_SOURCE_URL:= \ http://matt.ucc.asn.au/dropbear/releases/ \ https://dropbear.nl/mirror/releases/ -PKG_HASH:=2720ea54ed009af812701bcc290a2a601d5c107d12993e5d92c0f5f81f718891 +PKG_HASH:=6cbc1dcb1c9709d226dff669e5604172a18cf5dbf9a201474d5618ae4465098c PKG_LICENSE:=MIT PKG_LICENSE_FILES:=LICENSE libtomcrypt/LICENSE libtommath/LICENSE diff --git a/package/network/services/dropbear/patches/100-pubkey_path.patch b/package/network/services/dropbear/patches/100-pubkey_path.patch index 41fdc1adab..401c7e1ba5 100644 --- a/package/network/services/dropbear/patches/100-pubkey_path.patch +++ b/package/network/services/dropbear/patches/100-pubkey_path.patch @@ -1,6 +1,6 @@ --- a/svr-authpubkey.c +++ b/svr-authpubkey.c -@@ -218,17 +218,21 @@ static int checkpubkey(char* algo, unsig +@@ -220,14 +220,20 @@ static int checkpubkey(char* algo, unsig goto out; } @@ -12,9 +12,6 @@ - filename = m_malloc(len + 22); - snprintf(filename, len + 22, "%s/.ssh/authorized_keys", - ses.authstate.pw_dir); -- -- /* open the file */ -- authfile = fopen(filename, "r"); + if (ses.authstate.pw_uid != 0) { + /* we don't need to check pw and pw_dir for validity, since + * its been done in checkpubkeyperms. */ @@ -22,18 +19,17 @@ + /* allocate max required pathname storage, + * = path + "/.ssh/authorized_keys" + '\0' = pathlen + 22 */ + filename = m_malloc(len + 22); -+ snprintf(filename, len + 22, "%s/.ssh/authorized_keys", -+ ses.authstate.pw_dir); -+ -+ /* open the file */ -+ authfile = fopen(filename, "r"); ++ snprintf(filename, len + 22, "%s/.ssh/authorized_keys", ++ ses.authstate.pw_dir); + } else { -+ authfile = fopen("/etc/dropbear/authorized_keys","r"); ++ filename = m_malloc(30); ++ strncpy(filename, "/etc/dropbear/authorized_keys", 30); + } - if (authfile == NULL) { - goto out; - } -@@ -381,26 +385,35 @@ static int checkpubkeyperms() { ++ + + /* open the file as the authenticating user. */ + origuid = getuid(); +@@ -396,26 +402,35 @@ static int checkpubkeyperms() { goto out; } -- 2.25.1