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Xirvik
efe258a137
Commit 6488131 ("Fix RPC/SCGI security and crash bugs by @sirus20x6")
replaced std::vector<std::unique_ptr<const char>> storage with
std::vector<std::string> and returned back().c_str() to the xmlrpc-c
registry as the per-method server_info pointer.
This is unsafe for any method name short enough to be SSO-stored
(<= 15 chars on libstdc++): such a string keeps its buffer inside the
std::string object itself. When a later push_back reallocates the
vector and move-constructs the existing elements into a new buffer,
the previously returned c_str() pointers — captured by xmlrpc-c at
registration time — dangle into freed memory.
Because xmlrpc-c does not dereference server_info until a call
dispatches, the failure surfaces later as nondeterministic garbage
in fault strings, e.g.
faultString: Command "thod." does not exist. (load.start, log.xmlrpc, log.execute)
faultString: Command "in_rate" does not exist. (log.add_output)
faultString: Command "" does not exist. (log.open_file)
faultString: Command "+U" does not exist. (method.set_key)
Long-named methods (e.g. system.client_version at 21 chars) are
heap-allocated above the SSO threshold and escape the bug because
the heap buffer's address is preserved across the vector move.
Switch the storage to std::deque<std::string>: per [deque.modifiers]
push_back does not invalidate references to existing elements, so
the std::string objects do not move and the c_str() pointers handed
to xmlrpc-c remain valid for the program's lifetime. The body of
store_command_name is unchanged.
Fixes the use-after-free; preserves the std::string-based storage
the original commit aimed for.
86 lines
2.6 KiB
C++
86 lines
2.6 KiB
C++
#ifndef RTORRENT_RPC_XMLRPC_H
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#define RTORRENT_RPC_XMLRPC_H
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#include <deque>
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#include <functional>
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#include <torrent/common.h>
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#include <torrent/hash_string.h>
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#include <torrent/tracker/tracker.h>
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#include "command.h"
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#include "scgi_task.h"
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namespace core {
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class Download;
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}
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namespace rpc {
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class XmlRpc {
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public:
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typedef std::function<core::Download* (const char*)> slot_download;
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typedef std::function<torrent::File* (core::Download*, uint32_t)> slot_file;
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typedef std::function<torrent::tracker::Tracker (core::Download*, uint32_t)> slot_tracker;
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typedef std::function<torrent::Peer* (core::Download*, const torrent::HashString&)> slot_peer;
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typedef std::function<bool (const char*, uint32_t)> slot_write;
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static const int dialect_generic = 0;
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static const int dialect_i8 = 1;
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static const int dialect_apache = 2;
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// These need to match CommandMap type values.
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static const int call_generic = 0;
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static const int call_any = 1;
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static const int call_download = 2;
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static const int call_peer = 3;
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static const int call_tracker = 4;
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static const int call_file = 5;
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static const int call_file_itr = 6;
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static void object_to_target(const torrent::Object& obj, int callFlags, rpc::target_type* target);
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bool is_valid() const;
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void initialize();
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void cleanup();
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bool process(const char* inBuffer, uint32_t length, slot_write slotWrite);
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void insert_command(const char* name, const char* parm, const char* doc);
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int dialect() { return m_dialect; }
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void set_dialect(int dialect);
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slot_download& slot_find_download() { return m_slotFindDownload; }
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slot_file& slot_find_file() { return m_slotFindFile; }
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slot_tracker& slot_find_tracker() { return m_slotFindTracker; }
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slot_peer& slot_find_peer() { return m_slotFindPeer; }
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int64_t size_limit();
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void set_size_limit(uint64_t size);
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private:
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static const char* store_command_name(const char* name);
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static std::deque<std::string> m_command_names;
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slot_download m_slotFindDownload;
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slot_file m_slotFindFile;
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slot_tracker m_slotFindTracker;
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slot_peer m_slotFindPeer;
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// Only used by xmlrpc-c
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void* m_env{};
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void* m_registry{};
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int m_dialect{dialect_i8};
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// Only used by tinyxml2
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bool m_isValid;
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uint64_t m_sizeLimit{SCgiTask::max_content_size};
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};
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}
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#endif
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