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 92181472cea55b904f0c9dc4dd6da940479e3383..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.
@@ -306,7 +375,7 @@ bool WaitFd(int Fd,bool write,unsigned long timeout)
 /* This is used if you want to cleanse the environment for the forked 
    child, it fixes up the important signals and nukes all of the fds,
    otherwise acts like normal fork. */
-pid_t ExecFork(int dontCloseThisFd)
+pid_t ExecFork()
 {
    // Fork off the process
    pid_t Process = fork();
@@ -326,11 +395,27 @@ pid_t ExecFork(int dontCloseThisFd)
       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++)
-        if(K != dontCloseThisFd)
+      {
+        if(KeepFDs.find(K) == KeepFDs.end())
            fcntl(K,F_SETFD,FD_CLOEXEC);
+      }
    }
    
    return Process;
@@ -356,7 +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);
    }