Apply patch to avoid truncating of arbitrary files. Thanks to Bryan

[apt.git] / apt-pkg / contrib / fileutl.cc

diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc
index 7c9f5c0dd5470b16520512a2e9d707778405fa5d..a5976cf3af811fb3abe6b3d0c966a6b2b6779b02 100644 (file)
--- a/apt-pkg/contrib/fileutl.cc
+++ b/apt-pkg/contrib/fileutl.cc
@@ -8,21 +8,25 @@
    CopyFile - Buffered copy of a single file
    GetLock - dpkg compatible lock file manipulation (fcntl)
    
-   This source is placed in the Public Domain, do with it what you will
+   Most of this source is placed in the Public Domain, do with it what 
+   you will
    It was originally written by Jason Gunthorpe <jgg@debian.org>.
    
+   The exception is RunScripts() it is under the GPLv2
+
    ##################################################################### */
                                                                        /*}}}*/
 // Include Files                                                       /*{{{*/
-#ifdef __GNUG__
-#pragma implementation "apt-pkg/fileutl.h"
-#endif 
 #include <apt-pkg/fileutl.h>
 #include <apt-pkg/error.h>
 #include <apt-pkg/sptr.h>
+#include <apt-pkg/configuration.h>
 
 #include <apti18n.h>
 
+#include <cstdlib>
+#include <cstring>
+
 #include <iostream>
 #include <unistd.h>
 #include <fcntl.h>
@@ -32,10 +36,73 @@
 #include <sys/wait.h>
 #include <signal.h>
 #include <errno.h>
+#include <set>
                                                                        /*}}}*/
 
 using namespace std;
 
+// RunScripts - Run a set of scripts from a configuration subtree      /*{{{*/
+// ---------------------------------------------------------------------
+/* */
+bool RunScripts(const char *Cnf)
+{
+   Configuration::Item const *Opts = _config->Tree(Cnf);
+   if (Opts == 0 || Opts->Child == 0)
+      return true;
+   Opts = Opts->Child;
+
+   // Fork for running the system calls
+   pid_t Child = ExecFork();
+   
+   // This is the child
+   if (Child == 0)
+   {
+      if (chdir("/tmp/") != 0)
+        _exit(100);
+        
+      unsigned int Count = 1;
+      for (; Opts != 0; Opts = Opts->Next, Count++)
+      {
+        if (Opts->Value.empty() == true)
+           continue;
+        
+        if (system(Opts->Value.c_str()) != 0)
+           _exit(100+Count);
+      }
+      _exit(0);
+   }      
+
+   // Wait for the child
+   int Status = 0;
+   while (waitpid(Child,&Status,0) != Child)
+   {
+      if (errno == EINTR)
+        continue;
+      return _error->Errno("waitpid","Couldn't wait for subprocess");
+   }
+
+   // Restore sig int/quit
+   signal(SIGQUIT,SIG_DFL);
+   signal(SIGINT,SIG_DFL);   
+
+   // Check for an error code.
+   if (WIFEXITED(Status) == 0 || WEXITSTATUS(Status) != 0)
+   {
+      unsigned int Count = WEXITSTATUS(Status);
+      if (Count > 100)
+      {
+        Count -= 100;
+        for (; Opts != 0 && Count != 1; Opts = Opts->Next, Count--);
+        _error->Error("Problem executing scripts %s '%s'",Cnf,Opts->Value.c_str());
+      }
+      
+      return _error->Error("Sub-process returned an error code");
+   }
+   
+   return true;
+}
+                                                                       /*}}}*/
+
 // CopyFile - Buffered copy of a file                                  /*{{{*/
 // ---------------------------------------------------------------------
 /* The caller is expected to set things so that failure causes erasure */
@@ -71,7 +138,9 @@ bool CopyFile(FileFd &From,FileFd &To)
    close at some time. */
 int GetLock(string File,bool Errors)
 {
-   int FD = open(File.c_str(),O_RDWR | O_CREAT | O_TRUNC,0640);
+   // GetLock() is used in aptitude on directories with public-write access
+   // Use O_NOFOLLOW here to prevent symlink traversal attacks
+   int FD = open(File.c_str(),O_RDWR | O_CREAT | O_NOFOLLOW,0640);
    if (FD < 0)
    {
       // Read only .. cant have locking problems there.
@@ -326,10 +395,27 @@ pid_t ExecFork()
       signal(SIGWINCH,SIG_DFL);
       signal(SIGCONT,SIG_DFL);
       signal(SIGTSTP,SIG_DFL);
-      
+
+      set<int> KeepFDs;
+      Configuration::Item const *Opts = _config->Tree("APT::Keep-Fds");
+      if (Opts != 0 && Opts->Child != 0)
+      {
+        Opts = Opts->Child;
+        for (; Opts != 0; Opts = Opts->Next)
+        {
+           if (Opts->Value.empty() == true)
+              continue;
+           int fd = atoi(Opts->Value.c_str());
+           KeepFDs.insert(fd);
+        }
+      }
+
       // Close all of our FDs - just in case
       for (int K = 3; K != 40; K++)
-        fcntl(K,F_SETFD,FD_CLOEXEC);
+      {
+        if(KeepFDs.find(K) == KeepFDs.end())
+           fcntl(K,F_SETFD,FD_CLOEXEC);
+      }
    }
    
    return Process;
@@ -355,7 +441,7 @@ bool ExecWait(pid_t Pid,const char *Name,bool Reap)
       if (Reap == true)
         return false;
       
-      return _error->Error(_("Waited, for %s but it wasn't there"),Name);
+      return _error->Error(_("Waited for %s but it wasn't there"),Name);
    }