Posix ACL support for ext 2/3 filesystems

Posix ACL support for ext 2/3 filesystems

Post by ty.. » Fri, 18 Oct 2002 05:40:06



his patch provides converts extended attributes passed in from user
space to a generic Posix ACL representation.

                                                - Ted

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
#                  ChangeSet    1.799   -> 1.800  
#                fs/Makefile    1.43    -> 1.44  
#                      (new)            -> 1.1     include/linux/xattr_acl.h
#                      (new)            -> 1.1     fs/xattr_acl.c
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/10/16      ty...@snap.thunk.org   1.800
# Port 0.8.50 acl-xattr patch to 2.5
#
# This patch provides converts extended attributes passed in from user
# space to a generic Posix ACL representation.
# --------------------------------------------
#
diff -Nru a/fs/Makefile b/fs/Makefile
--- a/fs/Makefile       Wed Oct 16 23:02:20 2002
+++ b/fs/Makefile       Wed Oct 16 23:02:20 2002
@@ -6,7 +6,7 @@
 #

 export-objs := open.o dcache.o buffer.o bio.o inode.o dquot.o mpage.o aio.o \
-                fcntl.o read_write.o dcookies.o mbcache.o
+                fcntl.o read_write.o dcookies.o mbcache.o xattr_acl.o

 obj-y :=       open.o read_write.o devices.o file_table.o buffer.o \
                bio.o super.o block_dev.o char_dev.o stat.o exec.o pipe.o \
@@ -31,7 +31,7 @@
 obj-$(CONFIG_BINFMT_ELF)       += binfmt_elf.o

 obj-$(CONFIG_FS_MBCACHE)       += mbcache.o
-obj-$(CONFIG_FS_POSIX_ACL)     += posix_acl.o
+obj-$(CONFIG_FS_POSIX_ACL)     += posix_acl.o xattr_acl.o

 obj-$(CONFIG_QUOTA)            += dquot.o
 obj-$(CONFIG_QFMT_V1)          += quota_v1.o
diff -Nru a/fs/xattr_acl.c b/fs/xattr_acl.c
--- /dev/null   Wed Dec 31 16:00:00 1969
+++ b/fs/xattr_acl.c    Wed Oct 16 23:02:20 2002
@@ -0,0 +1,99 @@
+/*
+ * linux/fs/xattr_acl.c
+ *
+ * Almost all from linux/fs/ext2/acl.c:
+ * Copyright (C) 2001 by Andreas Gruenbacher, <a.gruenbac...@computer.org>
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/xattr_acl.h>
+
+
+/*
+ * Convert from extended attribute to in-memory representation.
+ */
+struct posix_acl *
+posix_acl_from_xattr(const void *value, size_t size)
+{
+       xattr_acl_header *header = (xattr_acl_header *)value;
+       xattr_acl_entry *entry = (xattr_acl_entry *)(header+1), *end;
+       int count;
+       struct posix_acl *acl;
+       struct posix_acl_entry *acl_e;
+
+       if (!value)
+               return NULL;
+       if (size < sizeof(xattr_acl_header))
+                return ERR_PTR(-EINVAL);
+       if (header->a_version != cpu_to_le32(XATTR_ACL_VERSION))
+               return ERR_PTR(-EINVAL);
+
+       count = xattr_acl_count(size);
+       if (count < 0)
+               return ERR_PTR(-EINVAL);
+       if (count == 0)
+               return NULL;
+      
+       acl = posix_acl_alloc(count, GFP_KERNEL);
+       if (!acl)
+               return ERR_PTR(-ENOMEM);
+       acl_e = acl->a_entries;
+      
+       for (end = entry + count; entry != end; acl_e++, entry++) {
+               acl_e->e_tag  = le16_to_cpu(entry->e_tag);
+               acl_e->e_perm = le16_to_cpu(entry->e_perm);
+
+               switch(acl_e->e_tag) {
+                       case ACL_USER_OBJ:
+                       case ACL_GROUP_OBJ:
+                       case ACL_MASK:
+                       case ACL_OTHER:
+                               acl_e->e_id = ACL_UNDEFINED_ID;
+                               break;
+
+                       case ACL_USER:
+                       case ACL_GROUP:
+                               acl_e->e_id = le32_to_cpu(entry->e_id);
+                               break;
+
+                       default:
+                               goto fail;
+               }
+       }
+       return acl;
+
+fail:
+       posix_acl_release(acl);
+       return ERR_PTR(-EINVAL);
+}
+EXPORT_SYMBOL (posix_acl_from_xattr);
+
+/*
+ * Convert from in-memory to extended attribute representation.
+ */
+int
+posix_acl_to_xattr(const struct posix_acl *acl, void *buffer, size_t size)
+{
+       xattr_acl_header *ext_acl = (xattr_acl_header *)buffer;
+       xattr_acl_entry *ext_entry = ext_acl->a_entries;
+       int real_size, n;
+
+       real_size = xattr_acl_size(acl->a_count);
+       if (!buffer)
+               return real_size;
+       if (real_size > size)
+               return -ERANGE;
+      
+       ext_acl->a_version = cpu_to_le32(XATTR_ACL_VERSION);
+
+       for (n=0; n < acl->a_count; n++, ext_entry++) {
+               ext_entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
+               ext_entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
+               ext_entry->e_id   = cpu_to_le32(acl->a_entries[n].e_id);
+       }
+       return real_size;
+}
+EXPORT_SYMBOL (posix_acl_to_xattr);
diff -Nru a/include/linux/xattr_acl.h b/include/linux/xattr_acl.h
--- /dev/null   Wed Dec 31 16:00:00 1969
+++ b/include/linux/xattr_acl.h Wed Oct 16 23:02:20 2002
@@ -0,0 +1,50 @@
+/*
+  File: linux/xattr_acl.h
+
+  (extended attribute representation of access control lists)
+
+  (C) 2000 Andreas Gruenbacher, <a.gruenbac...@computer.org>
+*/
+
+#ifndef _LINUX_XATTR_ACL_H
+#define _LINUX_XATTR_ACL_H
+
+#include <linux/posix_acl.h>
+
+#define XATTR_NAME_ACL_ACCESS  "system.posix_acl_access"
+#define XATTR_NAME_ACL_DEFAULT "system.posix_acl_default"
+
+#define XATTR_ACL_VERSION      0x0002
+
+typedef struct {
+       __u16           e_tag;
+       __u16           e_perm;
+       __u32           e_id;
+} xattr_acl_entry;
+
+typedef struct {
+       __u32           a_version;
+       xattr_acl_entry a_entries[0];
+} xattr_acl_header;
+
+static inline size_t xattr_acl_size(int count)
+{
+       return sizeof(xattr_acl_header) + count * sizeof(xattr_acl_entry);
+}
+
+static inline int xattr_acl_count(size_t size)
+{
+       if (size < sizeof(xattr_acl_header))
+               return -1;
+       size -= sizeof(xattr_acl_header);
+       if (size % sizeof(xattr_acl_entry))
+               return -1;
+       return size / sizeof(xattr_acl_entry);
+}
+
+struct posix_acl * posix_acl_from_xattr(const void *value, size_t size);
+int posix_acl_to_xattr(const struct posix_acl *acl, void *buffer, size_t size);
+
+
+
+#endif /* _LINUX_XATTR_ACL_H */
-
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