vim-patch:9.0.1833: [security] runtime file fixes (#24969)

Problem:  runtime files may execute code in current dir
Solution: only execute, if not run from current directory

The perl, zig and ruby filetype plugins and the zip and gzip autoload
plugins may try to load malicious executable files from the current
working directory.  This is especially a problem on windows, where the
current directory is implicitly in your $PATH and windows may even run a
file with the extension `.bat` because of $PATHEXT.

So make sure that we are not trying to execute a file from the current
directory. If this would be the case, error out (for the zip and gzip)
plugins or silently do not run those commands (for the ftplugins).

This assumes, that only the current working directory is bad. For all
other directories, it is assumed that those directories were
intentionally set to the $PATH by the user.

https://github.com/vim/vim/commit/816fbcc262687b81fc46f82f7bbeb1453addfe0c

Co-authored-by: Christian Brabandt <cb@256bit.org>

5 files changed, 54 insertions, 32 deletions

diff --git a/runtime/autoload/gzip.vim b/runtime/autoload/gzip.vim
index 95dd906794..ac9e37bf85 100644
--- a/runtime/autoload/gzip.vim
+++ b/runtime/autoload/gzip.vim
@@ -10,12 +10,17 @@
 fun s:check(cmd)
   let name = substitute(a:cmd, '\(\S*\).*', '\1', '')
   if !exists("s:have_" . name)
+    " safety check, don't execute anything from the current directory
+    let f = fnamemodify(exepath(name), ":p:h") !=# getcwd()
+    if !f
+      echoerr "Warning: NOT executing " .. name .. " from current directory!"
+    endif
     let e = executable(name)
     if e < 0
       let r = system(name . " --version")
       let e = (r !~ "not found" && r != "")
     endif
-    exe "let s:have_" . name . "=" . e
+    exe "let s:have_" . name . "=" . (e && f)
   endif
   exe "return s:have_" . name
 endfun
diff --git a/runtime/autoload/zip.vim b/runtime/autoload/zip.vim
index 8dda30c418..0331a542ac 100644
--- a/runtime/autoload/zip.vim
+++ b/runtime/autoload/zip.vim
@@ -57,6 +57,10 @@ if !exists("g:zip_extractcmd")
  let g:zip_extractcmd= g:zip_unzipcmd
 endif
 
+if fnamemodify(exepath(g:zip_unzipcmd), ":p:h") ==# getcwd()
+ echoerr "Warning: NOT executing " .. g:zip_unzipcmd .. " from current directory!"
+ finish
+endif
 " ----------------
 "  Functions: {{{1
 " ----------------
diff --git a/runtime/ftplugin/perl.vim b/runtime/ftplugin/perl.vim
index d0bdbc0cfb..edc7b960f1 100644
--- a/runtime/ftplugin/perl.vim
+++ b/runtime/ftplugin/perl.vim
@@ -54,7 +54,8 @@ endif
 
 " Set this once, globally.
 if !exists("perlpath")
-    if executable("perl")
+    " safety check: don't execute perl from current directory
+    if executable("perl") && fnamemodify(exepath("perl"), ":p:h") != getcwd()
       try
 	if &shellxquote != '"'
 	    let perlpath = system('perl -e "print join(q/,/,@INC)"')
diff --git a/runtime/ftplugin/ruby.vim b/runtime/ftplugin/ruby.vim
index 8c1f47731c..f4e1f60438 100644
--- a/runtime/ftplugin/ruby.vim
+++ b/runtime/ftplugin/ruby.vim
@@ -99,41 +99,51 @@ function! s:build_path(path) abort
   return path
 endfunction
 
-if !exists('b:ruby_version') && !exists('g:ruby_path') && isdirectory(expand('%:p:h'))
-  let s:version_file = findfile('.ruby-version', '.;')
-  if !empty(s:version_file) && filereadable(s:version_file)
-    let b:ruby_version = get(readfile(s:version_file, '', 1), '')
-    if !has_key(g:ruby_version_paths, b:ruby_version)
-      let g:ruby_version_paths[b:ruby_version] = s:query_path(fnamemodify(s:version_file, ':p:h'))
+let s:execute_ruby = 1
+" Security Check, don't execute ruby from the current directory
+if fnamemodify(exepath("ruby"), ":p:h") ==# getcwd()
+  let s:execute_ruby = 0
+endif
+
+function SetRubyPath()
+  if !exists('b:ruby_version') && !exists('g:ruby_path') && isdirectory(expand('%:p:h'))
+    let s:version_file = findfile('.ruby-version', '.;')
+    if !empty(s:version_file) && filereadable(s:version_file) && s:execute_ruby
+      let b:ruby_version = get(readfile(s:version_file, '', 1), '')
+      if !has_key(g:ruby_version_paths, b:ruby_version)
+	let g:ruby_version_paths[b:ruby_version] = s:query_path(fnamemodify(s:version_file, ':p:h'))
+      endif
     endif
   endif
-endif
 
-if exists("g:ruby_path")
-  let s:ruby_path = type(g:ruby_path) == type([]) ? join(g:ruby_path, ',') : g:ruby_path
-elseif has_key(g:ruby_version_paths, get(b:, 'ruby_version', ''))
-  let s:ruby_paths = g:ruby_version_paths[b:ruby_version]
-  let s:ruby_path = s:build_path(s:ruby_paths)
-else
-  if !exists('g:ruby_default_path')
-    if has("ruby") && has("win32")
-      ruby ::VIM::command( 'let g:ruby_default_path = split("%s",",")' % $:.join(%q{,}) )
-    elseif executable('ruby') && !empty($HOME)
-      let g:ruby_default_path = s:query_path($HOME)
-    else
-      let g:ruby_default_path = map(split($RUBYLIB,':'), 'v:val ==# "." ? "" : v:val')
+  if exists("g:ruby_path")
+    let s:ruby_path = type(g:ruby_path) == type([]) ? join(g:ruby_path, ',') : g:ruby_path
+  elseif has_key(g:ruby_version_paths, get(b:, 'ruby_version', '')) && s:execute_ruby
+    let s:ruby_paths = g:ruby_version_paths[b:ruby_version]
+    let s:ruby_path = s:build_path(s:ruby_paths)
+  else
+    if !exists('g:ruby_default_path')
+      if has("ruby") && has("win32")
+	ruby ::VIM::command( 'let g:ruby_default_path = split("%s",",")' % $:.join(%q{,}) )
+      elseif executable('ruby') && !empty($HOME) && s:execute_ruby
+	let g:ruby_default_path = s:query_path($HOME)
+      else
+	let g:ruby_default_path = map(split($RUBYLIB,':'), 'v:val ==# "." ? "" : v:val')
+      endif
     endif
+    let s:ruby_paths = g:ruby_default_path
+    let s:ruby_path = s:build_path(s:ruby_paths)
   endif
-  let s:ruby_paths = g:ruby_default_path
-  let s:ruby_path = s:build_path(s:ruby_paths)
-endif
 
-if stridx(&l:path, s:ruby_path) == -1
-  let &l:path = s:ruby_path
-endif
-if exists('s:ruby_paths') && stridx(&l:tags, join(map(copy(s:ruby_paths),'v:val."/tags"'),',')) == -1
-  let &l:tags = &tags . ',' . join(map(copy(s:ruby_paths),'v:val."/tags"'),',')
-endif
+  if stridx(&l:path, s:ruby_path) == -1
+    let &l:path = s:ruby_path
+  endif
+  if exists('s:ruby_paths') && stridx(&l:tags, join(map(copy(s:ruby_paths),'v:val."/tags"'),',')) == -1
+    let &l:tags = &tags . ',' . join(map(copy(s:ruby_paths),'v:val."/tags"'),',')
+  endif
+endfunction
+
+call SetRubyPath()
 
 if (has("gui_win32") || has("gui_gtk")) && !exists("b:browsefilter")
   let b:browsefilter = "Ruby Source Files (*.rb)\t*.rb\n" .
diff --git a/runtime/ftplugin/zig.vim b/runtime/ftplugin/zig.vim
index 5f453fc8d1..cd18bfe2bd 100644
--- a/runtime/ftplugin/zig.vim
+++ b/runtime/ftplugin/zig.vim
@@ -39,7 +39,9 @@ endif
 
 let &l:define='\v(<fn>|<const>|<var>|^\s*\#\s*define)'
 
-if !exists('g:zig_std_dir') && exists('*json_decode') && executable('zig')
+" Safety check: don't execute zip from current directory
+if !exists('g:zig_std_dir') && exists('*json_decode') &&
+    \  executable('zig') && fnamemodify(exepath("zig"), ":p:h") != getcwd()
     silent let s:env = system('zig env')
     if v:shell_error == 0
         let g:zig_std_dir = json_decode(s:env)['std_dir']