don't change owner/perms/times through file:// symlinks

If we have files in partial/ from a previous invocation or similar such
those could be symlinks created by file:// sources. The code is
expecting only real files through and happily changes owner,
modification times and permission on the file the symlink points to
which tend to be files we have no business in touching in this way.
Permissions of symlinks shouldn't be changed, changing owner is usually
pointless to, but just to be sure we pick the easy way out and use
lchown, check for symlinks before chmod/utimes.

Reported-By: Mattia Rizzolo on IRC

apt-pkg/contrib/fileutl.cc

@@ -916,9 +916,12 @@ bool ChangeOwnerAndPermissionOfFile(char const * const requester, char const * c
       // ensure the file is owned by root and has good permissions
       struct passwd const * const pw = getpwnam(user);
       struct group const * const gr = getgrnam(group);
-      if (pw != NULL && gr != NULL && chown(file, pw->pw_uid, gr->gr_gid) != 0)
+      if (pw != NULL && gr != NULL && lchown(file, pw->pw_uid, gr->gr_gid) != 0)
 	 Res &= _error->WarningE(requester, "chown to %s:%s of file %s failed", user, group, file);
    }
+   struct stat Buf;
+   if (lstat(file, &Buf) != 0 || S_ISLNK(Buf.st_mode))
+      return Res;
    if (chmod(file, mode) != 0)
       Res &= _error->WarningE(requester, "chmod 0%o of file %s failed", mode, file);
    return Res;

methods/aptmethod.h

@@ -3,10 +3,18 @@
 
 #include <apt-pkg/acquire-method.h>
 #include <apt-pkg/configuration.h>
+#include <apt-pkg/error.h>
 
 #include <locale>
 #include <string>
 
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <apti18n.h>
+
 class aptMethod : public pkgAcqMethod
 {
    char const * const Binary;
@@ -43,6 +51,29 @@ public:
       va_end(args);
    }
 
+   bool TransferModificationTimes(char const * const From, char const * const To, time_t &LastModified)
+   {
+      if (strcmp(To, "/dev/null") == 0)
+	 return true;
+
+      struct stat Buf2;
+      if (lstat(To, &Buf2) != 0 || S_ISLNK(Buf2.st_mode))
+	 return true;
+
+      struct stat Buf;
+      if (stat(From, &Buf) != 0)
+	 return _error->Errno("stat",_("Failed to stat"));
+
+      // we don't use utimensat here for compatibility reasons: #738567
+      struct timeval times[2];
+      times[0].tv_sec = Buf.st_atime;
+      LastModified = times[1].tv_sec = Buf.st_mtime;
+      times[0].tv_usec = times[1].tv_usec = 0;
+      if (utimes(To, times) != 0)
+	 return _error->Errno("utimes",_("Failed to set modification time"));
+      return true;
+   }
+
    aptMethod(char const * const Binary, char const * const Ver, unsigned long const Flags) :
       pkgAcqMethod(Ver, Flags), Binary(Binary)
    {

methods/copy.cc

@@ -78,13 +78,8 @@ bool CopyMethod::Fetch(FetchItem *Itm)
    From.Close();
    To.Close();
 
-   // Transfer the modification times
-   struct timeval times[2];
-   times[0].tv_sec = Buf.st_atime;
-   times[1].tv_sec = Buf.st_mtime;
-   times[0].tv_usec = times[1].tv_usec = 0;
-   if (utimes(Res.Filename.c_str(), times) != 0)
-      return _error->Errno("utimes",_("Failed to set modification time"));
+   if (TransferModificationTimes(File.c_str(), Res.Filename.c_str(), Res.LastModified) == false)
+      return false;
 
    CalculateHashes(Itm, Res);
    URIDone(Res);

methods/store.cc

@@ -126,20 +126,8 @@ bool StoreMethod::Fetch(FetchItem *Itm)					/*{{{*/
    if (Failed == true)
       return false;
 
-   // Transfer the modification times
-   if (Itm->DestFile != "/dev/null")
-   {
-      struct stat Buf;
-      if (stat(Path.c_str(),&Buf) != 0)
-	 return _error->Errno("stat",_("Failed to stat"));
-
-      struct timeval times[2];
-      times[0].tv_sec = Buf.st_atime;
-      Res.LastModified = times[1].tv_sec = Buf.st_mtime;
-      times[0].tv_usec = times[1].tv_usec = 0;
-      if (utimes(Itm->DestFile.c_str(), times) != 0)
-	 return _error->Errno("utimes",_("Failed to set modification time"));
-   }
+   if (TransferModificationTimes(Path.c_str(), Itm->DestFile.c_str(), Res.LastModified) == false)
+      return false;
 
    // Return a Done response
    Res.TakeHashes(Hash);

test/integration/framework

@@ -1886,6 +1886,11 @@ pause() {
 	read IGNORE
 }
 
+logcurrentarchivedirectory() {
+	find "${TMPWORKINGDIRECTORY}/aptarchive/dists" -type f | while read line; do
+		stat --format '%U:%G:%a:%n' "$line"
+	done | sort > "${TMPWORKINGDIRECTORY}/rootdir/var/log/aptgetupdate.before.lst"
+}
 listcurrentlistsdirectory() {
 	{
 		find rootdir/var/lib/apt/lists -maxdepth 1 -type d | while read line; do
@@ -1964,6 +1969,10 @@ aptautotest_aptget_update() {
 		# failure cases can retain partial files and such
 		testempty find "${TMPWORKINGDIRECTORY}/rootdir/var/lib/apt/lists/partial" -mindepth 1 ! \( -name 'lock' -o -name '*.FAILED' \)
 	fi
+	if [ -s "${TMPWORKINGDIRECTORY}/rootdir/var/log/aptgetupdate.before.lst" ]; then
+		testfileequal "${TMPWORKINGDIRECTORY}/rootdir/var/log/aptgetupdate.before.lst" \
+			"$(find "${TMPWORKINGDIRECTORY}/aptarchive/dists" -type f | while read line; do stat --format '%U:%G:%a:%n' "$line"; done | sort)"
+	fi
 }
 aptautotest_apt_update() { aptautotest_aptget_update "$@"; }
 aptautotest_aptcdrom_add() { aptautotest_aptget_update "$@"; }

test/integration/test-apt-update-file

@@ -18,6 +18,7 @@ insertpackage 'unstable' 'bar' 'amd64' '1'
 insertsource 'unstable' 'foo' 'all' '1'
 
 setupaptarchive --no-update
+logcurrentarchivedirectory
 
 # ensure the archive is not writable
 addtrap 'prefix' 'chmod 755 aptarchive/dists/unstable/main/binary-all;'
@@ -37,8 +38,11 @@ if [ "$(id -u)" = '0' ]; then
 	rm -rf rootdir/var/lib/apt/lists
 	chmod 500 aptarchive/dists/
 	testsuccesswithnotice aptget update
-	exit
+	chmod 755 aptarchive/dists/
+else
+	testsuccess aptget update
 fi
+mv rootdir/var/lib/apt/lists/_* rootdir/var/lib/apt/lists/partial
 chmod 555 aptarchive/dists/unstable/main/binary-all
 testsuccess aptget update -o Debug::pkgAcquire::Worker=1
 cp -a rootdir/tmp/testsuccess.output rootdir/tmp/update.output

test/integration/test-apt-update-ims

@@ -12,6 +12,7 @@ insertsource 'unstable' 'unrelated' 'all' '0.5~squeeze1'
 
 export APT_DONT_SIGN=""
 setupaptarchive --no-update
+logcurrentarchivedirectory
 changetowebserver
 
 runtest() {
@@ -71,6 +72,7 @@ EXPECT="Ign:1 http://localhost:${APTHTTPPORT} unstable InRelease
 Hit:2 http://localhost:${APTHTTPPORT} unstable Release
 Reading package lists..."
 find aptarchive -name 'InRelease' -delete
+logcurrentarchivedirectory
 echo 'Acquire::GzipIndexes "0";' > rootdir/etc/apt/apt.conf.d/02compressindex
 runtest
 echo 'Acquire::GzipIndexes "1";' > rootdir/etc/apt/apt.conf.d/02compressindex
@@ -87,6 +89,7 @@ W: The repository 'http://localhost:${APTHTTPPORT} unstable Release' is not sign
 N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
 N: See apt-secure(8) manpage for repository creation and user configuration details."
 find aptarchive -name 'Release.gpg' -delete
+logcurrentarchivedirectory
 echo 'Acquire::GzipIndexes "0";' > rootdir/etc/apt/apt.conf.d/02compressindex
 runtest 'warning'
 echo 'Acquire::GzipIndexes "1";' > rootdir/etc/apt/apt.conf.d/02compressindex
@@ -99,6 +102,7 @@ find aptarchive -name '*Release' -exec sed -i \
 	-e '/^Valid-Until: / d' -e "/^Date: / a\
 Valid-Until: $(date -ud '-1 weeks' '+%a, %d %b %Y %H:%M:%S %Z')" '{}' \;
 signreleasefiles
+logcurrentarchivedirectory
 
 msgmsg 'expired InRelease'
 EXPECT="Hit:1 http://localhost:${APTHTTPPORT} unstable InRelease
@@ -116,6 +120,7 @@ Hit:2 http://localhost:${APTHTTPPORT} unstable Release
 Reading package lists...
 E: Release file for http://localhost:${APTHTTPPORT}/dists/unstable/Release is expired (invalid since). Updates for this repository will not be applied."
 find aptarchive -name 'InRelease' -delete
+logcurrentarchivedirectory
 echo 'Acquire::GzipIndexes "0";' > rootdir/etc/apt/apt.conf.d/02compressindex
 runtest 'failure'
 echo 'Acquire::GzipIndexes "1";' > rootdir/etc/apt/apt.conf.d/02compressindex
@@ -133,6 +138,7 @@ N: Data from such a repository can't be authenticated and is therefore potential
 N: See apt-secure(8) manpage for repository creation and user configuration details.
 E: Release file for http://localhost:${APTHTTPPORT}/dists/unstable/Release is expired (invalid since). Updates for this repository will not be applied."
 find aptarchive -name 'Release.gpg' -delete
+logcurrentarchivedirectory
 echo 'Acquire::GzipIndexes "0";' > rootdir/etc/apt/apt.conf.d/02compressindex
 runtest 'failure' 'warning'
 echo 'Acquire::GzipIndexes "1";' > rootdir/etc/apt/apt.conf.d/02compressindex
@@ -177,6 +183,7 @@ W: The repository 'http://localhost:${APTHTTPPORT} unstable Release' does not ha
 N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
 N: See apt-secure(8) manpage for repository creation and user configuration details."
 find aptarchive -name '*Release*' -delete
+logcurrentarchivedirectory
 echo 'Acquire::GzipIndexes "0";
 Acquire::PDiffs "0";' > rootdir/etc/apt/apt.conf.d/02compressindex
 runtest 'warning'