tools/patch/patches/050-CVE-2019-13636.patch

   1 From dce4683cbbe107a95f1f0d45fabc304acfb5d71a Mon Sep 17 00:00:00 2001
   2 From: Andreas Gruenbacher <agruen@gnu.org>
   3 Date: Mon, 15 Jul 2019 16:21:48 +0200
   4 Subject: Don't follow symlinks unless --follow-symlinks is given
   5
   6 * src/inp.c (plan_a, plan_b), src/util.c (copy_to_fd, copy_file,
   7 append_to_file): Unless the --follow-symlinks option is given, open files with
   8 the O_NOFOLLOW flag to avoid following symlinks.  So far, we were only doing
   9 that consistently for input files.
  10 * src/util.c (create_backup): When creating empty backup files, (re)create them
  11 with O_CREAT | O_EXCL to avoid following symlinks in that case as well.
  12 ---
  13  src/inp.c  | 12 ++++++++++--
  14  src/util.c | 14 +++++++++++---
  15  2 files changed, 21 insertions(+), 5 deletions(-)
  16
  17 diff --git a/src/inp.c b/src/inp.c
  18 index 32d0919..22d7473 100644
  19 --- a/src/inp.c
  20 +++ b/src/inp.c
  21 @@ -238,8 +238,13 @@ plan_a (char const *filename)
  22      {
  23        if (S_ISREG (instat.st_mode))
  24          {
  25 -         int ifd = safe_open (filename, O_RDONLY|binary_transput, 0);
  26 +         int flags = O_RDONLY | binary_transput;
  27           size_t buffered = 0, n;
  28 +         int ifd;
  29 +
  30 +         if (! follow_symlinks)
  31 +           flags |= O_NOFOLLOW;
  32 +         ifd = safe_open (filename, flags, 0);
  33           if (ifd < 0)
  34             pfatal ("can't open file %s", quotearg (filename));
  35
  36 @@ -340,6 +345,7 @@ plan_a (char const *filename)
  37  static void
  38  plan_b (char const *filename)
  39  {
  40 +  int flags = O_RDONLY | binary_transput;
  41    int ifd;
  42    FILE *ifp;
  43    int c;
  44 @@ -353,7 +359,9 @@ plan_b (char const *filename)
  45
  46    if (instat.st_size == 0)
  47      filename = NULL_DEVICE;
  48 -  if ((ifd = safe_open (filename, O_RDONLY | binary_transput, 0)) < 0
  49 +  if (! follow_symlinks)
  50 +    flags |= O_NOFOLLOW;
  51 +  if ((ifd = safe_open (filename, flags, 0)) < 0
  52        || ! (ifp = fdopen (ifd, binary_transput ? "rb" : "r")))
  53      pfatal ("Can't open file %s", quotearg (filename));
  54    if (TMPINNAME_needs_removal)
  55 diff --git a/src/util.c b/src/util.c
  56 index 1cc08ba..fb38307 100644
  57 --- a/src/util.c
  58 +++ b/src/util.c
  59 @@ -388,7 +388,7 @@ create_backup (char const *to, const struct stat *to_st, bool leave_original)
  60
  61           try_makedirs_errno = ENOENT;
  62           safe_unlink (bakname);
  63 -         while ((fd = safe_open (bakname, O_CREAT | O_WRONLY | O_TRUNC, 0666)) < 0)
  64 +         while ((fd = safe_open (bakname, O_CREAT | O_EXCL | O_WRONLY | O_TRUNC, 0666)) < 0)
  65             {
  66               if (errno != try_makedirs_errno)
  67                 pfatal ("Can't create file %s", quotearg (bakname));
  68 @@ -579,10 +579,13 @@ create_file (char const *file, int open_flags, mode_t mode,
  69  static void
  70  copy_to_fd (const char *from, int tofd)
  71  {
  72 +  int from_flags = O_RDONLY | O_BINARY;
  73    int fromfd;
  74    ssize_t i;
  75
  76 -  if ((fromfd = safe_open (from, O_RDONLY | O_BINARY, 0)) < 0)
  77 +  if (! follow_symlinks)
  78 +    from_flags |= O_NOFOLLOW;
  79 +  if ((fromfd = safe_open (from, from_flags, 0)) < 0)
  80      pfatal ("Can't reopen file %s", quotearg (from));
  81    while ((i = read (fromfd, buf, bufsize)) != 0)
  82      {
  83 @@ -625,6 +628,8 @@ copy_file (char const *from, char const *to, struct stat *tost,
  84    else
  85      {
  86        assert (S_ISREG (mode));
  87 +      if (! follow_symlinks)
  88 +       to_flags |= O_NOFOLLOW;
  89        tofd = create_file (to, O_WRONLY | O_BINARY | to_flags, mode,
  90                           to_dir_known_to_exist);
  91        copy_to_fd (from, tofd);
  92 @@ -640,9 +645,12 @@ copy_file (char const *from, char const *to, struct stat *tost,
  93  void
  94  append_to_file (char const *from, char const *to)
  95  {
  96 +  int to_flags = O_WRONLY | O_APPEND | O_BINARY;
  97    int tofd;
  98
  99 -  if ((tofd = safe_open (to, O_WRONLY | O_BINARY | O_APPEND, 0)) < 0)
 100 +  if (! follow_symlinks)
 101 +    to_flags |= O_NOFOLLOW;
 102 +  if ((tofd = safe_open (to, to_flags, 0)) < 0)
 103      pfatal ("Can't reopen file %s", quotearg (to));
 104    copy_to_fd (from, tofd);
 105    if (close (tofd) != 0)
 106 --
 107 cgit v1.0-41-gc330
 108