ProcFS server, by Alen Stojanov and David van Moolenbroek

2010-09-14 21:25:25 +00:00
parent 3eb65448a6
commit 2c5c5c06ea
17 changed files with 1629 additions and 2 deletions
@@ -0,0 +1,33 @@
+#ifndef _PROCFS_CONST_H
+#define _PROCFS_CONST_H
+
+/* The minimum number of inodes depends on a number of factors:
+ * - Each statically created inode (e.g., /proc/hz) needs an inode. As of
+ *   writing, this requires about a dozen inodes.
+ * - Deleted inodes that are still in use by VFS must be retained. For deleted
+ *   directories, all their containing directories up to the root must be
+ *   retained as well (to allow the user to "cd .." out). VTreeFS already takes
+ *   care of this. In the case of ProcFS, only PID-based directories can be
+ *   deleted; no other directories are dynamically created. These directories
+ *   currently do not contain subdirectories, either. Hence, for deleted open
+ *   inodes, we need to reserve at most NR_VNODES inodes in the worst case.
+ * - In order for getdents to be able to return all PID-based directories,
+ *   inodes must not be recycled while generating the list of these PID-based
+ *   directories. In the worst case, this means (NR_TASKS + NR_PROCS) extra
+ *   inodes.
+ * The sum of these is the bare minimum for correct operation in all possible
+ * circumstances. In practice, not all open files will be deleted files in
+ * ProcFS, and not all process slots will be in use either, so the average use
+ * will be a lot less. However, setting the value too low allows for a
+ * potential denial-of-service attack by a non-root user.
+ *
+ * For the moment, we simply set this value to something reasonable.
+ */
+#define NR_INODES	((NR_TASKS + NR_PROCS) * 4)
+
+/* Various file modes. */
+#define REG_ALL_MODE	(S_IFREG | 0444)	/* world-readable regular */
+#define DIR_ALL_MODE	(S_IFDIR | 0555)	/* world-accessible directory */
+#define LNK_ALL_MODE	(S_IFLNK | 0777)	/* symbolic link */
+
+#endif /* _PROCFS_CONST_H */