revised^2: git-daemon extra paranoia, and path DWIM

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, and the
.git and /.git append DWIM stuff is now handled in an integrated manner,
which means the resulting path will always be subjected to pathname checks.

[jc: backported to 0.99.8 maintenance branch]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/daemon.c b/daemon.c
index 65e62d7..08e3b15 100644 (file)
--- a/daemon.c
+++ b/daemon.c
@@ -79,17 +79,30 @@ 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 */
+                       ndot = 0;
                } else {
                        sl = ndot = 0;
                }
@@ -98,7 +111,7 @@ static int path_ok(const char *dir)
 
        if ( ok_paths && *ok_paths ) {
                int ok = 0;
-               int dirlen = strlen(dir); /* read_packet_line can return embedded \0 */
+               int dirlen = strlen(dir);
 
                for ( pp = ok_paths ; *pp ; pp++ ) {
                        int len = strlen(*pp);
@@ -117,22 +130,16 @@ static int path_ok(const char *dir)
        return 1;               /* Path acceptable */
 }
 
-static int upload(char *dir, int dirlen)
+static int set_dir(const char *dir)
 {
-       loginfo("Request for '%s'", dir);
-
        if (!path_ok(dir)) {
-               logerror("Forbidden directory: %s\n", dir);
+               errno = EACCES;
                return -1;
        }
 
-       if (chdir(dir) < 0) {
-               logerror("Cannot chdir('%s'): %s", dir, strerror(errno));
+       if ( chdir(dir) )
                return -1;
-       }
-
-       chdir(".git");
-
+       
        /*
         * Security on the cheap.
         *
@@ -140,10 +147,39 @@ static int upload(char *dir, int dirlen)
         * a "git-daemon-export-ok" flag that says that the other side
         * is ok with us doing this.
         */
-       if ((!export_all_trees && access("git-daemon-export-ok", F_OK)) ||
-           access("objects/00", X_OK) ||
-           access("HEAD", R_OK)) {
-               logerror("Not a valid git-daemon-enabled repository: '%s'", dir);
+       if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
+               errno = EACCES;
+               return -1;
+       }
+
+       if (access("objects/", X_OK) || access("HEAD", R_OK)) {
+               errno = EINVAL;
+               return -1;
+       }
+
+       /* If all this passed, we're OK */
+       return 0;
+}
+
+static int upload(char *dir)
+{
+       /* Try paths in this order */
+       static const char *paths[] = { "%s", "%s/.git", "%s.git", "%s.git/.git", NULL };
+       const char **pp;
+       /* Enough for the longest path above including final null */
+       int buflen = strlen(dir)+10;
+       char *dirbuf = xmalloc(buflen);
+
+       loginfo("Request for '%s'", dir);
+
+       for ( pp = paths ; *pp ; pp++ ) {
+               snprintf(dirbuf, buflen, *pp, dir);
+               if ( !set_dir(dirbuf) )
+                       break;
+       }
+
+       if ( !*pp ) {
+               logerror("Cannot set directory '%s': %s", dir, strerror(errno));
                return -1;
        }
 
@@ -169,7 +205,7 @@ static int execute(void)
                line[--len] = 0;
 
        if (!strncmp("git-upload-pack /", line, 17))
-               return upload(line + 16, len - 16);
+               return upload(line+16);
 
        logerror("Protocol error: '%s'", line);
        return -1;