dropbear: patch CVE-2025-47203

Pick patch per Debian security page [1]. [1] https://security-tracker.debian.org/tracker/CVE-2025-47203 (From OE-Core rev: b109c117e68bf44f623124ea1bb2468f3657665c) Signed-off-by: Peter Marko <peter.marko@siemens.com> Signed-off-by: Steve Sakoman <steve@sakoman.com>
2026-04-04 05:02:21 +02:00 · 2025-08-10 15:22:18 +02:00
parent 2dc7ee3894
commit ae3cd7bd8a
2 changed files with 374 additions and 0 deletions
--- a/meta/recipes-core/dropbear/dropbear/CVE-2025-47203.patch
+++ b/meta/recipes-core/dropbear/dropbear/CVE-2025-47203.patch
@@ -0,0 +1,373 @@
+From e5a0ef27c227f7ae69d9a9fec98a056494409b9b Mon Sep 17 00:00:00 2001
+From: Matt Johnston <matt@ucc.asn.au>
+Date: Mon, 5 May 2025 23:14:19 +0800
+Subject: [PATCH] Execute multihop commands directly, no shell
+
+This avoids problems with shell escaping if arguments contain special
+characters.
+
+CVE: CVE-2025-47203
+Upstream-Status: Backport [https://github.com/mkj/dropbear/commit/e5a0ef27c227f7ae69d9a9fec98a056494409b9b]
+Signed-off-by: Peter Marko <peter.marko@siemens.com>
+---
+ src/cli-main.c    |  59 +++++++++++++++++---------
+ src/cli-runopts.c | 104 ++++++++++++++++++++++++++++------------------
+ src/dbutil.c      |   9 +++-
+ src/dbutil.h      |   1 +
+ src/runopts.h     |   5 +++
+ 5 files changed, 117 insertions(+), 61 deletions(-)
+
+diff --git a/src/cli-main.c b/src/cli-main.c
+index 065fd76..2fafa88 100644
+--- a/src/cli-main.c
+++ b/src/cli-main.c
+@@ -77,9 +77,8 @@ int main(int argc, char ** argv) {
+ 	}
+ 
+ #if DROPBEAR_CLI_PROXYCMD
+-	if (cli_opts.proxycmd) {
+	if (cli_opts.proxycmd || cli_opts.proxyexec) {
+ 		cli_proxy_cmd(&sock_in, &sock_out, &proxy_cmd_pid);
+-		m_free(cli_opts.proxycmd);
+ 		if (signal(SIGINT, kill_proxy_sighandler) == SIG_ERR ||
+ 			signal(SIGTERM, kill_proxy_sighandler) == SIG_ERR ||
+ 			signal(SIGHUP, kill_proxy_sighandler) == SIG_ERR) {
+@@ -101,7 +100,8 @@ int main(int argc, char ** argv) {
+ }
+ #endif /* DBMULTI stuff */
+ 
+-static void exec_proxy_cmd(const void *user_data_cmd) {
+#if DROPBEAR_CLI_PROXYCMD
+static void shell_proxy_cmd(const void *user_data_cmd) {
+ 	const char *cmd = user_data_cmd;
+ 	char *usershell;
+ 
+@@ -110,41 +110,62 @@ static void exec_proxy_cmd(const void *user_data_cmd) {
+ 	dropbear_exit("Failed to run '%s'\n", cmd);
+ }
+ 
+-#if DROPBEAR_CLI_PROXYCMD
+static void exec_proxy_cmd(const void *unused) {
+	(void)unused;
+	run_command(cli_opts.proxyexec[0], cli_opts.proxyexec, ses.maxfd);
+	dropbear_exit("Failed to run '%s'\n", cli_opts.proxyexec[0]);
+}
+
+ static void cli_proxy_cmd(int *sock_in, int *sock_out, pid_t *pid_out) {
+-	char * ex_cmd = NULL;
+-	size_t ex_cmdlen;
+	char * cmd_arg = NULL;
+	void (*exec_fn)(const void *user_data) = NULL;
+ 	int ret;
+ 
+	/* exactly one of cli_opts.proxycmd or cli_opts.proxyexec should be set */
+
+ 	/* File descriptor "-j &3" */
+-	if (*cli_opts.proxycmd == '&') {
+	if (cli_opts.proxycmd && *cli_opts.proxycmd == '&') {
+ 		char *p = cli_opts.proxycmd + 1;
+ 		int sock = strtoul(p, &p, 10);
+ 		/* must be a single number, and not stdin/stdout/stderr */
+ 		if (sock > 2 && sock < 1024 && *p == '\0') {
+ 			*sock_in = sock;
+ 			*sock_out = sock;
+-			return;
+			goto cleanup;
+ 		}
+ 	}
+ 
+-	/* Normal proxycommand */
+	if (cli_opts.proxycmd) {
+		/* Normal proxycommand */
+		size_t shell_cmdlen;
+		/* So that spawn_command knows which shell to run */
+		fill_passwd(cli_opts.own_user);
+ 
+-	/* So that spawn_command knows which shell to run */
+-	fill_passwd(cli_opts.own_user);
+		shell_cmdlen = strlen(cli_opts.proxycmd) + 6; /* "exec " + command + '\0' */
+		cmd_arg = m_malloc(shell_cmdlen);
+		snprintf(cmd_arg, shell_cmdlen, "exec %s", cli_opts.proxycmd);
+		exec_fn = shell_proxy_cmd;
+	} else {
+		/* No shell */
+		exec_fn = exec_proxy_cmd;
+	}
+ 
+-	ex_cmdlen = strlen(cli_opts.proxycmd) + 6; /* "exec " + command + '\0' */
+-	ex_cmd = m_malloc(ex_cmdlen);
+-	snprintf(ex_cmd, ex_cmdlen, "exec %s", cli_opts.proxycmd);
+-
+-	ret = spawn_command(exec_proxy_cmd, ex_cmd,
+-			sock_out, sock_in, NULL, pid_out);
+-	DEBUG1(("cmd: %s  pid=%d", ex_cmd,*pid_out))
+-	m_free(ex_cmd);
+	ret = spawn_command(exec_fn, cmd_arg, sock_out, sock_in, NULL, pid_out);
+ 	if (ret == DROPBEAR_FAILURE) {
+ 		dropbear_exit("Failed running proxy command");
+ 		*sock_in = *sock_out = -1;
+ 	}
+
+cleanup:
+	m_free(cli_opts.proxycmd);
+	m_free(cmd_arg);
+	if (cli_opts.proxyexec) {
+		char **a = NULL;
+		for (a = cli_opts.proxyexec; *a; a++) {
+			m_free_direct(*a);
+		}
+		m_free(cli_opts.proxyexec);
+	}
+ }
+ 
+ static void kill_proxy_sighandler(int UNUSED(signo)) {
+diff --git a/src/cli-runopts.c b/src/cli-runopts.c
+index b664293..a21b7a2 100644
+--- a/src/cli-runopts.c
+++ b/src/cli-runopts.c
+@@ -556,62 +556,88 @@ void loadidentityfile(const char* filename, int warnfail) {
+ 
+ /* Fill out -i, -y, -W options that make sense for all
+  * the intermediate processes */
+-static char* multihop_passthrough_args(void) {
+-	char *args = NULL;
+-	unsigned int len, total;
+static char** multihop_args(const char* argv0, const char* prior_hops) {
+	/* null terminated array */
+	char **args = NULL;
+	size_t max_args = 14, pos = 0, len;
+ #if DROPBEAR_CLI_PUBKEY_AUTH
+ 	m_list_elem *iter;
+ #endif
+-	/* Sufficient space for non-string args */
+-	len = 100;
+ 
+-	/* String arguments have arbitrary length, so determine space required */
+-	if (cli_opts.proxycmd) {
+-		len += strlen(cli_opts.proxycmd);
+-	}
+ #if DROPBEAR_CLI_PUBKEY_AUTH
+ 	for (iter = cli_opts.privkeys->first; iter; iter = iter->next)
+ 	{
+-		sign_key * key = (sign_key*)iter->item;
+-		len += 4 + strlen(key->filename);
+		/* "-i file" for each */
+		max_args += 2;
+ 	}
+ #endif
+ 
+-	args = m_malloc(len);
+-	total = 0;
+	args = m_malloc(sizeof(char*) * max_args);
+	pos = 0;
+ 
+-	/* Create new argument string */
+	args[pos] = m_strdup(argv0);
+	pos++;
+ 
+ 	if (cli_opts.quiet) {
+-		total += m_snprintf(args+total, len-total, "-q ");
+		args[pos] = m_strdup("-q");
+		pos++;
+ 	}
+ 
+ 	if (cli_opts.no_hostkey_check) {
+-		total += m_snprintf(args+total, len-total, "-y -y ");
+		args[pos] = m_strdup("-y");
+		pos++;
+		args[pos] = m_strdup("-y");
+		pos++;
+ 	} else if (cli_opts.always_accept_key) {
+-		total += m_snprintf(args+total, len-total, "-y ");
+		args[pos] = m_strdup("-y");
+		pos++;
+ 	}
+ 
+ 	if (cli_opts.batch_mode) {
+-		total += m_snprintf(args+total, len-total, "-o BatchMode=yes ");
+		args[pos] = m_strdup("-o");
+		pos++;
+		args[pos] = m_strdup("BatchMode=yes");
+		pos++;
+ 	}
+ 
+ 	if (cli_opts.proxycmd) {
+-		total += m_snprintf(args+total, len-total, "-J '%s' ", cli_opts.proxycmd);
+		args[pos] = m_strdup("-J");
+		pos++;
+		args[pos] = m_strdup(cli_opts.proxycmd);
+		pos++;
+ 	}
+ 
+ 	if (opts.recv_window != DEFAULT_RECV_WINDOW) {
+-		total += m_snprintf(args+total, len-total, "-W %u ", opts.recv_window);
+		args[pos] = m_strdup("-W");
+		pos++;
+		args[pos] = m_malloc(11);
+		m_snprintf(args[pos], 11, "%u", opts.recv_window);
+		pos++;
+ 	}
+ 
+ #if DROPBEAR_CLI_PUBKEY_AUTH
+ 	for (iter = cli_opts.privkeys->first; iter; iter = iter->next)
+ 	{
+ 		sign_key * key = (sign_key*)iter->item;
+-		total += m_snprintf(args+total, len-total, "-i %s ", key->filename);
+		args[pos] = m_strdup("-i");
+		pos++;
+		args[pos] = m_strdup(key->filename);
+		pos++;
+ 	}
+ #endif /* DROPBEAR_CLI_PUBKEY_AUTH */
+ 
+	/* last hop */
+	args[pos] = m_strdup("-B");
+	pos++;
+	len = strlen(cli_opts.remotehost) + strlen(cli_opts.remoteport) + 2;
+	args[pos] = m_malloc(len);
+	snprintf(args[pos], len, "%s:%s", cli_opts.remotehost, cli_opts.remoteport);
+	pos++;
+
+	/* hostnames of prior hops */
+	args[pos] = m_strdup(prior_hops);
+	pos++;
+
+ 	return args;
+ }
+ 
+@@ -626,7 +652,7 @@ static char* multihop_passthrough_args(void) {
+  * etc for as many hosts as we want.
+  *
+  * Note that "-J" arguments aren't actually used, instead
+- * below sets cli_opts.proxycmd directly.
+ * below sets cli_opts.proxyexec directly.
+  *
+  * Ports for hosts can be specified as host/port.
+  */
+@@ -634,7 +660,7 @@ static void parse_multihop_hostname(const char* orighostarg, const char* argv0)
+ 	char *userhostarg = NULL;
+ 	char *hostbuf = NULL;
+ 	char *last_hop = NULL;
+-	char *remainder = NULL;
+	char *prior_hops = NULL;
+ 
+ 	/* both scp and rsync parse a user@host argument
+ 	 * and turn it into "-l user host". This breaks
+@@ -652,6 +678,8 @@ static void parse_multihop_hostname(const char* orighostarg, const char* argv0)
+ 	}
+ 	userhostarg = hostbuf;
+ 
+	/* Split off any last hostname and use that as remotehost/remoteport.
+	 * That is used for authorized_keys checking etc */
+ 	last_hop = strrchr(userhostarg, ',');
+ 	if (last_hop) {
+ 		if (last_hop == userhostarg) {
+@@ -659,32 +687,28 @@ static void parse_multihop_hostname(const char* orighostarg, const char* argv0)
+ 		}
+ 		*last_hop = '\0';
+ 		last_hop++;
+-		remainder = userhostarg;
+		prior_hops = userhostarg;
+ 		userhostarg = last_hop;
+ 	}
+ 
+	/* Update cli_opts.remotehost and cli_opts.remoteport */
+ 	parse_hostname(userhostarg);
+ 
+-	if (last_hop) {
+-		/* Set up the proxycmd */
+-		unsigned int cmd_len = 0;
+-		char *passthrough_args = multihop_passthrough_args();
+-		cmd_len = strlen(argv0) + strlen(remainder)
+-			+ strlen(cli_opts.remotehost) + strlen(cli_opts.remoteport)
+-			+ strlen(passthrough_args)
+-			+ 30;
+-		/* replace proxycmd. old -J arguments have been copied
+-		   to passthrough_args */
+-		cli_opts.proxycmd = m_realloc(cli_opts.proxycmd, cmd_len);
+-		m_snprintf(cli_opts.proxycmd, cmd_len, "%s -B %s:%s %s %s",
+-				argv0, cli_opts.remotehost, cli_opts.remoteport,
+-				passthrough_args, remainder);
+	/* Construct any multihop proxy command. Use proxyexec to
+	 * avoid worrying about shell escaping. */
+	if (prior_hops) {
+		cli_opts.proxyexec = multihop_args(argv0, prior_hops);
+		/* Any -J argument has been copied to proxyexec */
+		if (cli_opts.proxycmd) {
+			m_free(cli_opts.proxycmd);
+		}
+
+ #ifndef DISABLE_ZLIB
+-		/* The stream will be incompressible since it's encrypted. */
+		/* This outer stream will be incompressible since it's encrypted. */
+ 		opts.compress_mode = DROPBEAR_COMPRESS_OFF;
+ #endif
+-		m_free(passthrough_args);
+ 	}
+
+ 	m_free(hostbuf);
+ }
+ #endif /* DROPBEAR_CLI_MULTIHOP */
+diff --git a/src/dbutil.c b/src/dbutil.c
+index 2b44921..a70025e 100644
+--- a/src/dbutil.c
+++ b/src/dbutil.c
+@@ -371,7 +371,6 @@ int spawn_command(void(*exec_fn)(const void *user_data), const void *exec_data,
+ void run_shell_command(const char* cmd, unsigned int maxfd, char* usershell) {
+ 	char * argv[4];
+ 	char * baseshell = NULL;
+-	unsigned int i;
+ 
+ 	baseshell = basename(usershell);
+ 
+@@ -393,6 +392,12 @@ void run_shell_command(const char* cmd, unsigned int maxfd, char* usershell) {
+ 		argv[1] = NULL;
+ 	}
+ 
+	run_command(usershell, argv, maxfd);
+}
+
+void run_command(const char* argv0, char** args, unsigned int maxfd) {
+	unsigned int i;
+
+ 	/* Re-enable SIGPIPE for the executed process */
+ 	if (signal(SIGPIPE, SIG_DFL) == SIG_ERR) {
+ 		dropbear_exit("signal() error");
+@@ -404,7 +409,7 @@ void run_shell_command(const char* cmd, unsigned int maxfd, char* usershell) {
+ 		m_close(i);
+ 	}
+ 
+-	execv(usershell, argv);
+	execv(argv0, args);
+ }
+ 
+ #if DEBUG_TRACE
+diff --git a/src/dbutil.h b/src/dbutil.h
+index 05fc50c..bfbed73 100644
+--- a/src/dbutil.h
+++ b/src/dbutil.h
+@@ -63,6 +63,7 @@ char * stripcontrol(const char * text);
+ int spawn_command(void(*exec_fn)(const void *user_data), const void *exec_data,
+ 		int *writefd, int *readfd, int *errfd, pid_t *pid);
+ void run_shell_command(const char* cmd, unsigned int maxfd, char* usershell);
+void run_command(const char* argv0, char** args, unsigned int maxfd);
+ #if ENABLE_CONNECT_UNIX
+ int connect_unix(const char* addr);
+ #endif
+diff --git a/src/runopts.h b/src/runopts.h
+index c4061a0..f255882 100644
+--- a/src/runopts.h
+++ b/src/runopts.h
+@@ -197,7 +197,12 @@ typedef struct cli_runopts {
+ 	unsigned int netcat_port;
+ #endif
+ #if DROPBEAR_CLI_PROXYCMD
+	/* A proxy command to run via the user's shell */
+ 	char *proxycmd;
+#endif
+#if DROPBEAR_CLI_MULTIHOP
+	/* Similar to proxycmd, but is arguments for execve(), not shell */
+	char **proxyexec;
+ #endif
+ 	const char *bind_arg;
+ 	char *bind_address;
--- a/meta/recipes-core/dropbear/dropbear_2024.86.bb
+++ b/meta/recipes-core/dropbear/dropbear_2024.86.bb
@@ -21,6 +21,7 @@ SRC_URI = "http://matt.ucc.asn.au/dropbear/releases/dropbear-${PV}.tar.bz2 \
           file://dropbear.default \
           ${@bb.utils.contains('DISTRO_FEATURES', 'pam', '${PAM_SRC_URI}', '', d)} \
           ${@bb.utils.contains('PACKAGECONFIG', 'disable-weak-ciphers', 'file://dropbear-disable-weak-ciphers.patch', '', d)} \
+           file://CVE-2025-47203.patch \
           "

 SRC_URI[sha256sum] = "e78936dffc395f2e0db099321d6be659190966b99712b55c530dd0a1822e0a5e"