releases/2.6.32.3/generic_permission-may_open-is-not-write-access.patch

   1 From 7ea6600148c265b1fd53e521022b1d7aec81d974 Mon Sep 17 00:00:00 2001
   2 From: Serge E. Hallyn <serue@us.ibm.com>
   3 Date: Tue, 29 Dec 2009 14:50:19 -0600
   4 Subject: generic_permission: MAY_OPEN is not write access
   5
   6 From: Serge E. Hallyn <serue@us.ibm.com>
   7
   8 commit 7ea6600148c265b1fd53e521022b1d7aec81d974 upstream.
   9
  10 generic_permission was refusing CAP_DAC_READ_SEARCH-enabled
  11 processes from opening DAC-protected files read-only, because
  12 do_filp_open adds MAY_OPEN to the open mask.
  13
  14 Ignore MAY_OPEN.  After this patch, CAP_DAC_READ_SEARCH is
  15 again sufficient to open(fname, O_RDONLY) on a file to which
  16 DAC otherwise refuses us read permission.
  17
  18 Reported-by: Mike Kazantsev <mk.fraggod@gmail.com>
  19 Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
  20 Tested-by: Mike Kazantsev <mk.fraggod@gmail.com>
  21 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  22 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  23
  24 ---
  25  fs/namei.c |    1 +
  26  1 file changed, 1 insertion(+)
  27
  28 --- a/fs/namei.c
  29 +++ b/fs/namei.c
  30 @@ -234,6 +234,7 @@ int generic_permission(struct inode *ino
  31         /*
  32          * Searching includes executable on directories, else just read.
  33          */
  34 +       mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
  35         if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
  36                 if (capable(CAP_DAC_READ_SEARCH))
  37                         return 0;