C# Implementation (#2)
C# implementation of SEP-1763 --------- Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Peder Holdgaard Pedersen
GitHub
parent
46d96779d6
commit
45f9e0ef27
1 changed files with 13862 additions and 21 deletions
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using ModelContextProtocol.Interceptors;
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using ModelContextProtocol.Interceptors.Server;
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using ModelContextProtocol.Protocol;
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using System.Text.Json;
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using System.Text.Json.Nodes;
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/// <summary>
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/// A sample validation interceptor that validates tool call parameters for security issues.
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/// This interceptor can be deployed as a separate MCP service to validate requests
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/// before they reach the actual tool implementation.
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/// </summary>
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[McpServerInterceptorType]
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public class ParameterValidator
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{
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/// <summary>
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/// Validates tool call parameters for potential security issues.
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/// </summary>
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[McpServerInterceptor(
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Name = "parameter-validator",
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Description = "Validates tool call parameters for security issues",
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Events = new[] { InterceptorEvents.ToolsCall },
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Phase = InterceptorPhase.Request)]
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public ValidationInterceptorResult ValidateToolCall(JsonNode? payload)
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{
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if (payload is null)
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{
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return new ValidationInterceptorResult
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{
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Valid = false,
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Severity = ValidationSeverity.Error,
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Messages = [new() { Message = "Payload is required", Severity = ValidationSeverity.Error }]
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};
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}
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// Parse the tool call request
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CallToolRequestParams? toolCall;
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try
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{
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toolCall = payload.Deserialize<CallToolRequestParams>();
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}
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catch (JsonException ex)
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{
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return new ValidationInterceptorResult
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{
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Valid = false,
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Severity = ValidationSeverity.Error,
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Messages = [new() { Message = $"Invalid payload format: {ex.Message}", Severity = ValidationSeverity.Error }]
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};
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}
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if (toolCall is null || string.IsNullOrEmpty(toolCall.Name))
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{
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return new ValidationInterceptorResult
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{
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Valid = false,
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Severity = ValidationSeverity.Error,
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Messages = [new() { Message = "Tool name is required", Severity = ValidationSeverity.Error }]
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};
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}
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// Validate tool arguments for security issues
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var messages = new List<ValidationMessage>();
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if (toolCall.Arguments is not null)
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{
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foreach (var arg in toolCall.Arguments)
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{
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var value = arg.Value.ToString();
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if (string.IsNullOrEmpty(value))
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{
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continue;
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}
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// Check for SQL injection patterns
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if (ContainsSqlInjectionPattern(value))
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{
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messages.Add(new ValidationMessage
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{
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Path = $"arguments.{arg.Key}",
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Message = "Potentially malicious SQL content detected",
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Severity = ValidationSeverity.Error
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});
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}
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// Check for command injection patterns
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if (ContainsCommandInjectionPattern(value))
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{
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messages.Add(new ValidationMessage
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{
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Path = $"arguments.{arg.Key}",
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Message = "Potentially malicious command content detected",
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Severity = ValidationSeverity.Error
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});
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}
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// Check for path traversal patterns
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if (ContainsPathTraversalPattern(value))
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{
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messages.Add(new ValidationMessage
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{
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Path = $"arguments.{arg.Key}",
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Message = "Potentially malicious path traversal detected",
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Severity = ValidationSeverity.Warn
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});
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}
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}
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}
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if (messages.Count > 0)
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{
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return new ValidationInterceptorResult
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{
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Valid = false,
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Severity = messages.Max(m => m.Severity),
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Messages = messages
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};
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}
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return new ValidationInterceptorResult { Valid = true };
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}
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/// <summary>
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/// Validates that required fields are present in tool calls.
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/// </summary>
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[McpServerInterceptor(
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Name = "required-fields-validator",
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Description = "Validates that required fields are present in tool calls",
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Events = new[] { InterceptorEvents.ToolsCall },
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Phase = InterceptorPhase.Request,
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PriorityHint = 10)]
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public ValidationInterceptorResult ValidateRequiredFields(JsonNode? payload, string @event)
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{
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if (payload is null)
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{
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return new ValidationInterceptorResult
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{
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Valid = false,
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Severity = ValidationSeverity.Error,
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Messages = [new() { Message = $"Payload is required for event '{@event}'", Severity = ValidationSeverity.Error }]
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};
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}
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return new ValidationInterceptorResult { Valid = true };
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}
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private static bool ContainsSqlInjectionPattern(string value)
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{
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var patterns = new[]
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{
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"'; DROP TABLE",
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"'; DELETE FROM",
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"' OR '1'='1",
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"' OR 1=1",
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"'; EXEC ",
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"'; INSERT INTO",
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"UNION SELECT",
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"-- "
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};
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return patterns.Any(p => value.Contains(p, StringComparison.OrdinalIgnoreCase));
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}
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private static bool ContainsCommandInjectionPattern(string value)
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{
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var patterns = new[]
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{
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"; rm -rf",
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"| rm -rf",
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"&& rm -rf",
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"; cat /etc/passwd",
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"| cat /etc/passwd",
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"`rm -rf`",
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"$(rm -rf",
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"; wget ",
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"| wget ",
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"; curl "
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};
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return patterns.Any(p => value.Contains(p, StringComparison.OrdinalIgnoreCase));
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}
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private static bool ContainsPathTraversalPattern(string value)
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{
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var patterns = new[]
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{
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"../",
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"..\\",
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"/etc/passwd",
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"/etc/shadow",
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"C:\\Windows\\System32"
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};
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return patterns.Any(p => value.Contains(p, StringComparison.OrdinalIgnoreCase));
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}
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}
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