i386/linux/linux-2.3.21/fs/ufs/acl.c

   1 /*
   2  *  linux/fs/ufs/acl.c
   3  *
   4  * Copyright (C) 1998
   5  * Daniel Pirkl <daniel.pirkl@email.cz>
   6  * Charles University, Faculty of Mathematics and Physics
   7  *
   8  *  from
   9  *
  10  *  linux/fs/ext2/acl.c
  11  *
  12  * Copyright (C) 1993, 1994, 1995
  13  * Remy Card (card@masi.ibp.fr)
  14  * Laboratoire MASI - Institut Blaise Pascal
  15  * Universite Pierre et Marie Curie (Paris VI)
  16  */
  17
  18 /*
  19  * This file will contain the Access Control Lists management for UFS
  20  */
  21
  22 #include <linux/errno.h>
  23 #include <linux/fs.h>
  24 #include <linux/ufs_fs.h>
  25 #include <linux/sched.h>
  26 #include <linux/stat.h>
  27
  28 /*
  29  * ufs_permission ()
  30  *
  31  * Check for access rights
  32  */
  33 int ufs_permission (struct inode * inode, int mask)
  34 {
  35         unsigned short mode = inode->i_mode;
  36
  37         /*
  38          * Nobody gets write access to a file on a readonly-fs
  39          */
  40         if ((mask & S_IWOTH) &&
  41             (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)) &&
  42             IS_RDONLY(inode))
  43                 return -EROFS;
  44         /*
  45          * Nobody gets write access to an immutable file
  46          */
  47         if ((mask & S_IWOTH) && IS_IMMUTABLE(inode))
  48                 return -EACCES;
  49
  50         /*
  51          * If no ACL, checks using the file mode
  52          */
  53         else if (current->fsuid == inode->i_uid)
  54                 mode >>= 6;
  55         else if (in_group_p (inode->i_gid))
  56                 mode >>= 3;
  57         /*
  58          * Access is always granted for root. We now check last,
  59          * though, for BSD process accounting correctness
  60          */
  61         if (((mode & mask & S_IRWXO) == mask) || capable(CAP_DAC_OVERRIDE))
  62                 return 0;
  63         if ((mask == S_IROTH) ||
  64             (S_ISDIR(mode)  && !(mask & ~(S_IROTH | S_IXOTH))))
  65                 if (capable(CAP_DAC_READ_SEARCH))
  66                         return 0;
  67         return -EACCES;
  68 }