Drop Privileges to "Debian-apt" in most acquire methods

Add a new "Debian-apt" user that owns the /var/lib/apt/lists
and /var/cache/apt/archive directories. The methods
http, https, ftp, gpgv, gzip switch to this user when they
start.

Thanks to Julian and "ioerror" and tors "switch_id()" code.

6 files changed, 15 insertions, 1 deletions

diff --git a/methods/copy.cc b/methods/copy.cc
index b78053d36..18d70e153 100644
--- a/methods/copy.cc
+++ b/methods/copy.cc
@@ -118,6 +118,8 @@ int main()
 {
    setlocale(LC_ALL, "");
 
+   DropPrivs();
+
    CopyMethod Mth;
    return Mth.Run();
 }
diff --git a/methods/ftp.cc b/methods/ftp.cc
index 66787a7be..9d58aa3b9 100644
--- a/methods/ftp.cc
+++ b/methods/ftp.cc
@@ -1107,6 +1107,9 @@ int main(int, const char *argv[])
 { 
    setlocale(LC_ALL, "");
 
+   // no more active ftp, sorry
+   DropPrivs();
+
    /* See if we should be come the http client - we do this for http
       proxy urls */
    if (getenv("ftp_proxy") != 0)
diff --git a/methods/gpgv.cc b/methods/gpgv.cc
index ae521a2ed..159417883 100644
--- a/methods/gpgv.cc
+++ b/methods/gpgv.cc
@@ -5,6 +5,7 @@
 #include <apt-pkg/error.h>
 #include <apt-pkg/gpgv.h>
 #include <apt-pkg/strutl.h>
+#include <apt-pkg/fileutl.h>
 
 #include <ctype.h>
 #include <errno.h>
@@ -262,6 +263,8 @@ int main()
 {
    setlocale(LC_ALL, "");
    
+   DropPrivs();
+
    GPGVMethod Mth;
 
    return Mth.Run();
diff --git a/methods/gzip.cc b/methods/gzip.cc
index df3f8828f..518e58f82 100644
--- a/methods/gzip.cc
+++ b/methods/gzip.cc
@@ -135,6 +135,8 @@ int main(int, char *argv[])
 {
    setlocale(LC_ALL, "");
 
+   DropPrivs();
+
    Prog = strrchr(argv[0],'/');
    ++Prog;
 
diff --git a/methods/http_main.cc b/methods/http_main.cc
index 3b346a514..788582632 100644
--- a/methods/http_main.cc
+++ b/methods/http_main.cc
@@ -1,5 +1,5 @@
 #include <config.h>
-
+#include <apt-pkg/fileutl.h>
 #include <signal.h>
 
 #include "http.h"
@@ -12,6 +12,8 @@ int main()
    // closes the connection (this is dealt with via ServerDie())
    signal(SIGPIPE, SIG_IGN);
 
+   DropPrivs();
+
    HttpMethod Mth;
    return Mth.Loop();
 }
diff --git a/methods/https.cc b/methods/https.cc
index 0499af0c5..a40f37710 100644
--- a/methods/https.cc
+++ b/methods/https.cc
@@ -443,6 +443,8 @@ int main()
 {
    setlocale(LC_ALL, "");
 
+   DropPrivs();
+
    HttpsMethod Mth;
    curl_global_init(CURL_GLOBAL_SSL) ;