st_cookies: assert the saved jar is non-empty

The mode assertions alone would pass a cookie_save that creates an
empty 0600 file and returns 0; check st_size on both saves (proven by
a negative control that skips the write loop).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

.github/workflows/codeql.yml

@@ -43,6 +43,12 @@ jobs:
           languages: c-cpp
           build-mode: manual
           queries: security-extended
+          # fopen's umask-controlled 0666 is intended for mirror/cache/log
+          # output; the one credential file (cookies.txt) is kept 0600 on Unix.
+          config: |
+            query-filters:
+              - exclude:
+                  id: cpp/world-writable-file-creation
 
       # Manual build: CodeQL traces the compiler, so build exactly what ships.
       - name: Build

src/htsbauth.c

@@ -307,14 +307,25 @@ int cookie_load(t_cookie * cookie, const char *fpath, const char *name) {
   return -1;
 }
 
-// écrire cookies.txt
+/* Write cookies.txt; returns 0 on success. The jar holds live session
-// !=0 : erreur
+   cookies, so keep it owner-only on Unix (Windows inherits folder ACLs). */
 int cookie_save(t_cookie * cookie, const char *name) {
   char catbuff[CATBUFF_SIZE];
 
   if (strnotempty(cookie->data)) {
     char BIGSTK line[8192];
+#ifdef _WIN32
     FILE *fp = fopen(fconv(catbuff, sizeof(catbuff), name), "wb");
+#else
+    const int fd = open(fconv(catbuff, sizeof(catbuff), name),
+                        O_WRONLY | O_CREAT | O_TRUNC, HTS_PROTECT_FILE);
+    FILE *fp = fd != -1 ? fdopen(fd, "wb") : NULL;
+
+    if (fd != -1 && fp == NULL)
+      close(fd);    /* fdopen failed: don't leak the descriptor */
+    if (fp != NULL) /* O_CREAT's mode skips pre-existing jars: tighten those */
+      (void) fchmod(fd, HTS_PROTECT_FILE);
+#endif
 
     if (fp) {
       char *a = cookie->data;

src/htsglobal.h

@@ -422,9 +422,10 @@ typedef int T_SOC;
 #endif
 
 /* Permission bits for created folders and files (mkdir and chmod).
-   PROTECT_FOLDER is owner-only. With HTS_ACCESS set (the default) the ACCESS_
+   PROTECT_FOLDER/FILE are owner-only. With HTS_ACCESS set (the default) the
-   modes also grant group/other read; otherwise they stay owner-only. */
+   ACCESS_ modes also grant group/other read; otherwise they stay owner-only. */
 #define HTS_PROTECT_FOLDER (S_IRUSR | S_IWUSR | S_IXUSR)
+#define HTS_PROTECT_FILE (S_IRUSR | S_IWUSR)
 
 #if HTS_ACCESS
 #define HTS_ACCESS_FILE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)

src/htsselftest.c

@@ -1551,6 +1551,26 @@ static int st_cookies(httrackp *opt, int argc, char **argv) {
     err = 1;
   if (strstr(hdr, "junk") != NULL) // wrong-domain cookie leaked
     err = 1;
+#ifndef _WIN32
+  /* the jar holds live session cookies: cookie_save must keep it 0600 */
+  {
+    const char *jar = "st-cookies-jar.txt";
+    struct stat st;
+
+    (void) UNLINK(jar);
+    assertf(cookie_save(&cookie, jar) == 0);
+    assertf(stat(jar, &st) == 0);
+    assertf((st.st_mode & 07777) == HTS_PROTECT_FILE);
+    assertf(st.st_size > 0); /* mode-only checks would pass an empty jar */
+    /* a pre-existing world-readable jar must be tightened, not kept */
+    assertf(chmod(jar, 0644) == 0);
+    assertf(cookie_save(&cookie, jar) == 0);
+    assertf(stat(jar, &st) == 0);
+    assertf((st.st_mode & 07777) == HTS_PROTECT_FILE);
+    assertf(st.st_size > 0);
+    (void) UNLINK(jar);
+  }
+#endif
   printf("cookie-header: %s\n", err ? "FAIL" : "OK");
   if (err)
     printf("  got: %s\n", hdr);