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-rw-r--r--Config.in8
-rw-r--r--lib/lib.c10
-rw-r--r--lib/lib.h1
-rw-r--r--main.c15
-rw-r--r--toys.h5
5 files changed, 39 insertions, 0 deletions
diff --git a/Config.in b/Config.in
index aa3100ff..ad8a2426 100644
--- a/Config.in
+++ b/Config.in
@@ -11,6 +11,14 @@ config TOYBOX
With no arguments, shows available commands. First argument is
name of a command to run, followed by any arguments to that command.
+config TOYBOX_SUID
+ bool "SUID support"
+ default y
+ help
+ Support for suid commands, which run as root. This means toybox must
+ be installed suid root, and drops permissions before running commands
+ which do not require root access.
+
config TOYBOX_FREE
bool "Free memory unnecessarily"
default n
diff --git a/lib/lib.c b/lib/lib.c
index 48689d3d..08c991dd 100644
--- a/lib/lib.c
+++ b/lib/lib.c
@@ -369,6 +369,16 @@ void xmkpath(char *path, int mode)
if (!*p) break;
}
}
+
+// setuid() can fail (for example, too many processes belonging to that user),
+// which opens a security hole if the process continues as the original user.
+
+void xsetuid(uid_t uid)
+{
+ if (setuid(uid)) perror_exit("xsetuid");
+}
+
+
// Find all file in a colon-separated path with access type "type" (generally
// X_OK or R_OK). Returns a list of absolute paths to each file found, in
// order.
diff --git a/lib/lib.h b/lib/lib.h
index c6226aae..fb2215cf 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -81,6 +81,7 @@ void xstat(char *path, struct stat *st);
char *xabspath(char *path);
void xchdir(char *path);
void xmkpath(char *path, int mode);
+void xsetuid(uid_t uid);
struct string_list *find_in_path(char *path, char *filename);
void utoa_to_buf(unsigned n, char *buf, unsigned buflen);
void itoa_to_buf(int n, char *buf, unsigned buflen);
diff --git a/main.c b/main.c
index 4e6a31e7..e0dab1cc 100644
--- a/main.c
+++ b/main.c
@@ -64,6 +64,21 @@ static const int NEED_OPTIONS =
void toy_init(struct toy_list *which, char *argv[])
{
+ // Drop permissions for non-suid commands.
+
+ if (CFG_TOYBOX_SUID) {
+ uid_t uid = getuid(), euid = geteuid();
+
+ if (!(which->flags & TOYFLAG_STAYROOT)) {
+ if (uid != euid) xsetuid(euid=uid);
+ } else if (CFG_TOYBOX_DEBUG && uid)
+ error_exit("Not installed suid root");
+
+ if ((which->flags & TOYFLAG_NEEDROOT) && euid)
+ error_exit("Not root");
+
+ }
+
// Free old toys contents here?
toys.which = which;
diff --git a/toys.h b/toys.h
index 93907fb6..e5cde838 100644
--- a/toys.h
+++ b/toys.h
@@ -68,6 +68,11 @@ void toy_exec(char *argv[]);
// Start applet with a umask of 0 (saves old umask in this.old_umask)
#define TOYFLAG_UMASK (1<<5)
+// This applet runs as root.
+#define TOYFLAG_STAYROOT (1<<6)
+#define TOYFLAG_NEEDROOT (1<<7)
+#define TOYFLAG_ROOTONLY (TOYFLAG_STAYROOT|TOYFLAG_NEEDROOT)
+
// Array of available applets
extern struct toy_list {