itflow/itflow-share-view-toctou.patch

diff --git a/functions/security.php b/functions/security.php
index cda79fc..24c9632 100644
--- a/functions/security.php
+++ b/functions/security.php
@@ -225,3 +225,24 @@ zgjRYR/zGN5l+az6RB3+0mJRdZdv/y2aRkBlwTxx2gOrPbQAco4a/IOmkE3EbHe7
 
     return false;
 }
+
+// Atomically claim one view against a shared item's view limit.
+// Returns true only if this request won the view; false means the share is
+// inactive, expired, or out of views. The UPDATE is the claim, so concurrent
+// requests cannot all pass - call this before any shared content is disclosed.
+function claimSharedItemView($item_id) {
+    global $mysqli;
+
+    $item_id = intval($item_id);
+
+    mysqli_query($mysqli, "UPDATE shared_items
+        SET item_views = item_views + 1
+        WHERE item_id = $item_id
+        AND item_active = 1
+        AND item_expire_at > NOW()
+        AND (COALESCE(item_view_limit, 0) = 0 OR item_views < item_view_limit)"
+    );
+
+    // -1 (query error) and 0 (limit reached / revoked / expired) both deny
+    return mysqli_affected_rows($mysqli) === 1;
+}
diff --git a/guest/guest_download_file.php b/guest/guest_download_file.php
index 22610f3..c6cd12b 100644
--- a/guest/guest_download_file.php
+++ b/guest/guest_download_file.php
@@ -56,6 +56,12 @@ if (isset($_GET['id']) && isset($_GET['key'])) {
         exit("Item cannot be viewed at this time (No file, may have been deleted).");
     }
 
+    // Claim the view before the file is served. The checks above stay as a
+    // fast path for messaging - this UPDATE is what enforces the limit.
+    if (!claimSharedItemView($item_id)) {
+        exit("Item cannot be viewed at this time (view limit exceeded).");
+    }
+
     $file_name = escapeSql($file_row['file_name']);
     $file_reference_name = escapeSql($file_row['file_reference_name']);
     $client_id = intval($file_row['file_client_id']);
@@ -67,10 +73,6 @@ if (isset($_GET['id']) && isset($_GET['key'])) {
     header('Content-Disposition: attachment; filename=' . $file_name);
     readfile($file_path);
 
-    // Update file view count
-    $new_item_views = $item_views + 1;
-    mysqli_query($mysqli, "UPDATE shared_items SET item_views = $new_item_views WHERE item_id = $item_id");
-
     //Logging
     logAudit("Share", "View", "Downloaded shared file $file_name via link", $client_id);
 
diff --git a/guest/guest_post.php b/guest/guest_post.php
index 7cec8a9..6ab945d 100644
--- a/guest/guest_post.php
+++ b/guest/guest_post.php
@@ -13,6 +13,10 @@ session_start();
 
 require_once "../includes/inc_set_timezone.php"; // Must be included after session_start to work
 
+// logAudit() reads these globals - without them guest audit rows have no IP
+$session_ip = escapeSql(getIP());
+$session_user_agent = escapeSql($_SERVER['HTTP_USER_AGENT']);
+
 if (isset($_GET['accept_quote'], $_GET['url_key'])) {
 
     $quote_id = intval($_GET['accept_quote']);
diff --git a/guest/guest_view_item.php b/guest/guest_view_item.php
index e6b0417..68f87fc 100644
--- a/guest/guest_view_item.php
+++ b/guest/guest_view_item.php
@@ -128,6 +128,14 @@ if ($item_type == "Document") {
         exit();
     }
 
+    // Claim the view before any content is disclosed
+    if (!claimSharedItemView($item_id)) {
+        echo "<div class='alert alert-danger'>Item cannot be viewed at this time. Check with the person that sent you this link to ensure it is correct and has not expired.</div>";
+        require_once $_SERVER['DOCUMENT_ROOT'] . '/includes/footer.php';
+
+        exit();
+    }
+
     $doc_title = escapeHtml($doc_row['document_name']);
     $doc_title_escaped = escapeSql($doc_row['document_name']);
     $doc_content = $purifier->purify($doc_row['document_content']);
@@ -135,10 +143,6 @@ if ($item_type == "Document") {
     echo "<h3>$doc_title</h3>";
     echo "<div class='prettyContent'>$doc_content</div>";
 
-    // Update document view count
-    $new_item_views = $item_views + 1;
-    mysqli_query($mysqli, "UPDATE shared_items SET item_views = $new_item_views WHERE item_id = $item_id");
-
     // Logging
     $name = mysqli_real_escape_string($mysqli, $doc_title);
     logAudit("Share", "View", "Viewed shared $item_type $doc_title_escaped via link", $client_id);
@@ -176,6 +180,14 @@ if ($item_type == "Document") {
         exit();
     }
 
+    // Claim the view before the credential is decrypted or rendered
+    if (!claimSharedItemView($item_id)) {
+        echo "<div class='alert alert-danger'>Item cannot be viewed at this time. Check with the person that sent you this link to ensure it is correct and has not expired.</div>";
+        require_once $_SERVER['DOCUMENT_ROOT'] . '/includes/footer.php';
+
+        exit();
+    }
+
     $credential_id = intval($credential_row['credential_id']);
     $credential_name = escapeHtml($credential_row['credential_name']);
     $credential_uri = escapeHtml($credential_row['credential_uri']);
@@ -254,10 +266,6 @@ if ($item_type == "Document") {
 
     <?php
 
-    // Update credential view count
-    $new_item_views = $item_views + 1;
-    mysqli_query($mysqli, "UPDATE shared_items SET item_views = $new_item_views WHERE item_id = $item_id");
-
     // Logging
     $name = escapeSql($credential_row['credential_name']);
     logAudit("Share", "View", "Viewed shared $item_type $name via link", $client_id);
diff --git a/guest/includes/inc_all_guest.php b/guest/includes/inc_all_guest.php
index 3a4bdce..5bb9505 100644
--- a/guest/includes/inc_all_guest.php
+++ b/guest/includes/inc_all_guest.php
@@ -14,6 +14,10 @@ $user_agent = escapeSql($_SERVER['HTTP_USER_AGENT']);
 $os = escapeSql(getOS($user_agent));
 $browser = escapeSql(getWebBrowser($user_agent));
 
+// logAudit() reads these globals - without them guest audit rows have no IP
+$session_ip = $ip;
+$session_user_agent = $user_agent;
+
 // Get Company Name
 $sql = mysqli_query($mysqli, "SELECT company_name FROM companies WHERE company_id = 1");
 $row = mysqli_fetch_assoc($sql);