diff mbox series

file: strengthen exec access control

Message ID 20230529175423.4046928-1-erik.r.karlsson@gmail.com
State Handled Elsewhere
Delegated to: Hauke Mehrtens
Headers show
Series file: strengthen exec access control | expand

Commit Message

Erik Karlsson May 29, 2023, 5:54 p.m. UTC 
From: Erik Karlsson <erik.karlsson@genexis.eu>

Do not allow setting environment variables if there is a session as
there is no access control for environment variables and allowing
arbitrary data into the environment is unsafe. Do not leak arguments
through unchecked if the size of the buffer for access checking the
whole command line is exceeded. Adjust the maximum number of allowed
arguments so it matches the actual implementation.

Signed-off-by: Erik Karlsson <erik.karlsson@genexis.eu>
---
 file.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/file.c b/file.c
index 07b4d3c..1e5b2f4 100644
--- a/file.c
+++ b/file.c
@@ -809,6 +809,9 @@  rpc_file_exec_run(const char *cmd, const struct blob_attr *sid,
 
 	struct rpc_file_exec_context *c;
 
+	if (sid && env)
+		return UBUS_STATUS_PERMISSION_DENIED;
+
 	cmd = rpc_file_exec_lookup(cmd);
 
 	if (!cmd)
@@ -824,7 +827,7 @@  rpc_file_exec_run(const char *cmd, const struct blob_attr *sid,
 		if (arg == NULL || strlen(executable) >= sizeof(cmdstr))
 			return UBUS_STATUS_PERMISSION_DENIED;
 
-		arglen = 0;
+		arglen = 2;
 		p = cmdstr + sprintf(cmdstr, "%s", executable);
 
 		blobmsg_for_each_attr(cur, arg, rem)
@@ -834,7 +837,7 @@  rpc_file_exec_run(const char *cmd, const struct blob_attr *sid,
 
 			if (arglen == 255 ||
 			    p + blobmsg_data_len(cur) >= cmdstr + sizeof(cmdstr))
-				break;
+				return UBUS_STATUS_PERMISSION_DENIED;
 
 			p += sprintf(p, " %s", blobmsg_get_string(cur));
 			arglen++;