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Subject[PATCH 3/5] Add POSIX Access Control Lists to ext2/3
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Date

This 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
#
# fs/Makefile | 4 -
# fs/xattr_acl.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++
# include/linux/xattr_acl.h | 50 +++++++++++++++++++++++
# 3 files changed, 151 insertions(+), 2 deletions(-)
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/10/15 tytso@snap.thunk.org 1.856
# 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 Tue Oct 15 16:59:35 2002
+++ b/fs/Makefile Tue Oct 15 16:59:35 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 mbcache.o
+ fcntl.o read_write.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 Tue Oct 15 16:59:35 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.gruenbacher@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 Tue Oct 15 16:59:35 2002
@@ -0,0 +1,50 @@
+/*
+ File: linux/xattr_acl.h
+
+ (extended attribute representation of access control lists)
+
+ (C) 2000 Andreas Gruenbacher, <a.gruenbacher@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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