[PATCH] Revised - git-daemon extra paranoia

["H. Peter Anvin" <hpa@zytor.com>]

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This patch adds some extra paranoia to the git-daemon filename test.  In 
particular, it now rejects pathnames containing //; it also adds a 
redundant test for pathname absoluteness (belts and suspenders.)

A single / at the end of the path is still permitted, however.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

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diff --git a/daemon.c b/daemon.c
--- a/daemon.c
+++ b/daemon.c
@@ -80,17 +80,29 @@ static int path_ok(const char *dir)
 {
 	const char *p = dir;
 	char **pp;
-	int sl = 1, ndot = 0;
+	int sl, ndot;
+
+	/* The pathname here should be an absolute path. */
+	if ( *p++ != '/' )
+		return 0;
+
+	sl = 1;  ndot = 0;
 
 	for (;;) {
 		if ( *p == '.' ) {
 			ndot++;
-		} else if ( *p == '/' || *p == '\0' ) {
+		} else if ( *p == '\0' ) {
+			/* Reject "." and ".." at the end of the path */
 			if ( sl && ndot > 0 && ndot < 3 )
-				return 0; /* . or .. in path */
+				return 0;
+
+			/* Otherwise OK */
+			break;
+		} else if ( *p == '/' ) {
+			/* Refuse "", "." or ".." */
+			if ( sl && ndot < 3 )
+				return 0;
 			sl = 1;
-			if ( *p == '\0' )
-				break; /* End of string and all is good */
 		} else {
 			sl = ndot = 0;
 		}