1 files changed, 89 insertions, 0 deletions
diff --git a/src/passwd/getspnam_r.c b/src/passwd/getspnam_r.c
new file mode 100644
index 0000000..1dd39ce
--- /dev/null
+++ b/src/passwd/getspnam_r.c
@@ -0,0 +1,89 @@
+#include <fcntl.h>
+#include <unistd.h>
+#include "pwf.h"
+
+/* This implementation support Openwall-style TCB passwords in place of
+ * traditional shadow, if the appropriate directories and files exist.
+ * Thus, it is careful to avoid following symlinks or blocking on fifos
+ * which a malicious user might create in place of his or her TCB shadow
+ * file. It also avoids any allocation to prevent memory-exhaustion
+ * attacks via huge TCB shadow files. */
+
+int getspnam_r(const char *name, struct spwd *sp, char *buf, size_t size, struct spwd **res)
+{
+	char path[20+NAME_MAX];
+	FILE *f = 0;
+	int rv = 0;
+	int fd;
+	size_t k, l = strlen(name);
+	char *s;
+	int skip = 0;
+
+	*res = 0;
+
+	/* Disallow potentially-malicious user names */
+	if (*name=='.' || strchr(name, '/') || !l)
+		return EINVAL;
+
+	/* Buffer size must at least be able to hold name, plus some.. */
+	if (size < l+100) return ERANGE;
+
+	/* Protect against truncation */
+	if (snprintf(path, sizeof path, "/etc/tcb/%s/shadow", name) >= sizeof path)
+		return EINVAL;
+
+	fd = open(path, O_RDONLY|O_NOFOLLOW|O_NONBLOCK);
+	if (fd >= 0) {
+		f = fdopen(fd, "rb");
+		if (!f) {
+			close(fd);
+			return errno;
+		}
+	} else {
+		f = fopen("/etc/shadow", "rb");
+		if (!f) return errno;
+	}
+
+	while (fgets(buf, size, f) && (k=strlen(buf))>0) {
+		if (skip || strncmp(name, buf, l)) {
+			skip = buf[k-1] != '\n';
+			continue;
+		}
+		if (buf[k-1] != '\n') {
+			rv = ERANGE;
+			break;
+		}
+		buf[k-1] = 0;
+
+		s = buf;
+		sp->sp_namp = s;
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; sp->sp_pwdp = s;
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; sp->sp_lstchg = atol(s);
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; sp->sp_min = atol(s);
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; sp->sp_max = atol(s);
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; sp->sp_warn = atol(s);
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; sp->sp_inact = atol(s);
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; sp->sp_expire = atol(s);
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; sp->sp_flag = atol(s);
+		*res = sp;
+		break;
+	}
+	fclose(f);
+	return rv;
+}