[PATCH] ubifs: implement POSIX Access Control Lists (ACLs)

[Pascal Eberhard <pascal.eberhard@gmail.com>]

This patch implements POSIX Access Control Lists (ACLs) in UBIFS.
It uses posix_acl_(access|default)_xattr_handler ACL generic handlers
as xattr handlers are now used in UBIFS.

Signed-off-by: Pascal Eberhard <pascal.eberhard@gmail.com>
---
 fs/ubifs/Kconfig  |  13 +++++
 fs/ubifs/Makefile |   1 +
 fs/ubifs/acl.c    | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/ubifs/dir.c    |  22 +++++++++
 fs/ubifs/file.c   |   9 ++++
 fs/ubifs/super.c  |  15 ++++++
 fs/ubifs/ubifs.h  |  18 +++++++
 fs/ubifs/xattr.c  |  11 +++--
 8 files changed, 229 insertions(+), 3 deletions(-)
 create mode 100644 fs/ubifs/acl.c

diff --git a/fs/ubifs/Kconfig b/fs/ubifs/Kconfig
index 7ff7712..39119e5 100644
--- a/fs/ubifs/Kconfig
+++ b/fs/ubifs/Kconfig
@@ -50,3 +50,16 @@ config UBIFS_ATIME_SUPPORT
 	  strictatime is the "heavy", relatime is "lighter", etc.
 
 	  If unsure, say 'N'
+
+config UBIFS_FS_POSIX_ACL
+	bool "UBIFS POSIX Access Control Lists"
+	depends on UBIFS_FS
+	select FS_POSIX_ACL
+	help
+	  POSIX Access Control Lists (ACLs) support permissions for users and
+	  groups beyond the owner/group/world scheme.
+
+	  To learn more about Access Control Lists, visit the POSIX ACLs for
+	  Linux website <http://acl.bestbits.at/>.
+
+	  If you don't know what Access Control Lists are, say N
diff --git a/fs/ubifs/Makefile b/fs/ubifs/Makefile
index c54a243..af7a83f 100644
--- a/fs/ubifs/Makefile
+++ b/fs/ubifs/Makefile
@@ -5,3 +5,4 @@ ubifs-y += tnc.o master.o scan.o replay.o log.o commit.o gc.o orphan.o
 ubifs-y += budget.o find.o tnc_commit.o compress.o lpt.o lprops.o
 ubifs-y += recovery.o ioctl.o lpt_commit.o tnc_misc.o xattr.o debug.o
 ubifs-y += misc.o
+ubifs-$(CONFIG_UBIFS_FS_POSIX_ACL) += acl.o
\ No newline at end of file
diff --git a/fs/ubifs/acl.c b/fs/ubifs/acl.c
new file mode 100644
index 0000000..a4d4734
--- /dev/null
+++ b/fs/ubifs/acl.c
@@ -0,0 +1,143 @@
+/*
+ * This file is part of UBIFS.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#include <linux/fs.h>
+#include <linux/xattr.h>
+#include <linux/posix_acl_xattr.h>
+
+#include "ubifs.h"
+
+struct posix_acl *ubifs_get_acl(struct inode *inode, int type)
+{
+	int size;
+	const char *name;
+	char *value = NULL;
+	struct posix_acl *acl;
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		name = XATTR_NAME_POSIX_ACL_ACCESS;
+		break;
+	case ACL_TYPE_DEFAULT:
+		name = XATTR_NAME_POSIX_ACL_DEFAULT;
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+
+	size = __ubifs_getxattr(inode, name, NULL, 0);
+	if (size > 0) {
+		value = kzalloc(size, GFP_KERNEL);
+		if (!value)
+			return ERR_PTR(-ENOMEM);
+		size = __ubifs_getxattr(inode, name, value, size);
+	}
+	if (size > 0)
+		acl = posix_acl_from_xattr(&init_user_ns, value, size);
+	else if (size == -ERANGE || size == -ENODATA || size == 0)
+		acl = NULL;
+	else
+		acl = ERR_PTR(size);
+
+	kfree(value);
+	if (!IS_ERR(acl))
+		set_cached_acl(inode, type, acl);
+
+	return acl;
+}
+
+int ubifs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
+{
+	int ret;
+	int size = 0;
+	const char *name;
+	char *value = NULL;
+	int flags = 0;
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		name = XATTR_NAME_POSIX_ACL_ACCESS;
+		if (acl) {
+			ret = posix_acl_equiv_mode(acl, &inode->i_mode);
+			if (ret < 0)
+				return ret;
+			if (ret == 0)
+				acl = NULL;
+		}
+		ret = 0;
+		break;
+	case ACL_TYPE_DEFAULT:
+		if (!S_ISDIR(inode->i_mode))
+			return acl ? -EINVAL : 0;
+		name = XATTR_NAME_POSIX_ACL_DEFAULT;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (acl) {
+		size = posix_acl_xattr_size(acl->a_count);
+		value = kmalloc(size, GFP_KERNEL);
+		if (!value)
+			return -ENOMEM;
+
+		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
+		if (ret < 0)
+			goto out;
+	}
+
+	if (size == 0)
+		flags = XATTR_REPLACE;
+	ret = __ubifs_setxattr(inode, name, value, size, flags);
+
+out:
+	kfree(value);
+	if (!ret)
+		set_cached_acl(inode, type, acl);
+
+	return ret;
+}
+
+/*
+ * Initialize the ACLs of a new inode.
+ */
+int ubifs_init_acl(struct inode *dir, struct inode *inode)
+{
+	struct posix_acl *default_acl, *acl;
+	int ret = 0;
+
+	ret = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
+	if (ret)
+		return ret;
+
+	if (default_acl) {
+		inode_lock(inode);
+		ret = ubifs_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
+		inode_unlock(inode);
+		posix_acl_release(default_acl);
+	}
+
+	if (acl) {
+		if (!ret) {
+			inode_lock(inode);
+			ret = ubifs_set_acl(inode, acl, ACL_TYPE_ACCESS);
+			inode_unlock(inode);
+		}
+		posix_acl_release(acl);
+	}
+
+	if (!default_acl && !acl)
+		cache_no_acl(inode);
+	return ret;
+}
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index ccd9128..a2e5609 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -270,6 +270,10 @@ static int ubifs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 		goto out_budg;
 	}
 
+	err = ubifs_init_acl(dir, inode);
+	if (err)
+		goto out_inode;
+
 	err = ubifs_init_security(dir, inode, &dentry->d_name);
 	if (err)
 		goto out_inode;
@@ -341,6 +345,10 @@ static int do_tmpfile(struct inode *dir, struct dentry *dentry,
 		ubifs_assert(inode->i_op == &ubifs_file_inode_operations);
 	}
 
+	err = ubifs_init_acl(dir, inode);
+	if (err)
+		goto out_inode;
+
 	err = ubifs_init_security(dir, inode, &dentry->d_name);
 	if (err)
 		goto out_inode;
@@ -821,6 +829,10 @@ static int ubifs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 		goto out_budg;
 	}
 
+	err = ubifs_init_acl(dir, inode);
+	if (err)
+		goto out_inode;
+
 	err = ubifs_init_security(dir, inode, &dentry->d_name);
 	if (err)
 		goto out_inode;
@@ -903,6 +915,10 @@ static int ubifs_mknod(struct inode *dir, struct dentry *dentry,
 	ui->data = dev;
 	ui->data_len = devlen;
 
+	err = ubifs_init_acl(dir, inode);
+	if (err)
+		goto out_inode;
+
 	err = ubifs_init_security(dir, inode, &dentry->d_name);
 	if (err)
 		goto out_inode;
@@ -985,6 +1001,10 @@ static int ubifs_symlink(struct inode *dir, struct dentry *dentry,
 	ui->data_len = len;
 	inode->i_size = ubifs_inode(inode)->ui_size = len;
 
+	err = ubifs_init_acl(dir, inode);
+	if (err)
+		goto out_inode;
+
 	err = ubifs_init_security(dir, inode, &dentry->d_name);
 	if (err)
 		goto out_inode;
@@ -1395,6 +1415,8 @@ const struct inode_operations ubifs_dir_inode_operations = {
 	.update_time = ubifs_update_time,
 #endif
 	.tmpfile     = ubifs_tmpfile,
+	.get_acl     = ubifs_get_acl,
+	.set_acl     = ubifs_set_acl,
 };
 
 const struct file_operations ubifs_dir_operations = {
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 4ed270b..17f6098 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -53,6 +53,7 @@
 #include <linux/mount.h>
 #include <linux/slab.h>
 #include <linux/migrate.h>
+#include <linux/posix_acl.h>
 
 static int read_block(struct inode *inode, void *addr, unsigned int block,
 		      struct ubifs_data_node *dn)
@@ -1251,6 +1252,10 @@ static int do_setattr(struct ubifs_info *c, struct inode *inode,
 		ubifs_release_budget(c, &req);
 	if (IS_SYNC(inode))
 		err = inode->i_sb->s_op->write_inode(inode, NULL);
+
+	if (!err && (attr->ia_valid & ATTR_MODE))
+		err = posix_acl_chmod(inode, inode->i_mode);
+
 	return err;
 }
 
@@ -1628,6 +1633,8 @@ const struct inode_operations ubifs_file_inode_operations = {
 #ifdef CONFIG_UBIFS_ATIME_SUPPORT
 	.update_time = ubifs_update_time,
 #endif
+	.get_acl     = ubifs_get_acl,
+	.set_acl     = ubifs_set_acl,
 };
 
 const struct inode_operations ubifs_symlink_inode_operations = {
@@ -1642,6 +1649,8 @@ const struct inode_operations ubifs_symlink_inode_operations = {
 #ifdef CONFIG_UBIFS_ATIME_SUPPORT
 	.update_time = ubifs_update_time,
 #endif
+	.get_acl     = ubifs_get_acl,
+	.set_acl     = ubifs_set_acl,
 };
 
 const struct file_operations ubifs_file_operations = {
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 4ec0510..8239dfd 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -444,6 +444,9 @@ static int ubifs_show_options(struct seq_file *s, struct dentry *root)
 			   ubifs_compr_name(c->mount_opts.compr_type));
 	}
 
+	if (c->vfs_sb->s_flags & MS_POSIXACL)
+		seq_puts(s, ",acl");
+
 	return 0;
 }
 
@@ -929,6 +932,8 @@ enum {
 	Opt_chk_data_crc,
 	Opt_no_chk_data_crc,
 	Opt_override_compr,
+	Opt_acl,
+	Opt_noacl,
 	Opt_err,
 };
 
@@ -940,6 +945,8 @@ static const match_table_t tokens = {
 	{Opt_chk_data_crc, "chk_data_crc"},
 	{Opt_no_chk_data_crc, "no_chk_data_crc"},
 	{Opt_override_compr, "compr=%s"},
+	{Opt_acl, "acl"},
+	{Opt_noacl, "noacl"},
 	{Opt_err, NULL},
 };
 
@@ -1040,6 +1047,14 @@ static int ubifs_parse_options(struct ubifs_info *c, char *options,
 			c->default_compr = c->mount_opts.compr_type;
 			break;
 		}
+#ifdef CONFIG_UBIFS_FS_POSIX_ACL
+		case Opt_acl:
+			c->vfs_sb->s_flags |= MS_POSIXACL;
+			break;
+		case Opt_noacl:
+			c->vfs_sb->s_flags &= ~MS_POSIXACL;
+			break;
+#endif
 		default:
 		{
 			unsigned long flag;
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 096035e..7935449 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1743,6 +1743,24 @@ extern const struct xattr_handler *ubifs_xattr_handlers[];
 ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size);
 int ubifs_init_security(struct inode *dentry, struct inode *inode,
 			const struct qstr *qstr);
+ssize_t __ubifs_getxattr(struct inode *host, const char *name,
+				void *buf, size_t size);
+int __ubifs_setxattr(struct inode *host, const char *name,
+			    const void *value, size_t size, int flags);
+
+/* acl.c */
+#ifdef CONFIG_UBIFS_FS_POSIX_ACL
+int ubifs_init_acl(struct inode *dir, struct inode *inode);
+int ubifs_set_acl(struct inode *inode, struct posix_acl *acl, int type);
+struct posix_acl *ubifs_get_acl(struct inode *inode, int type);
+#else
+static inline int ubifs_init_acl(struct inode *inode, struct inode *dir)
+{
+	return 0;
+}
+#define ubifs_get_acl NULL
+#define ubifs_set_acl NULL
+#endif
 
 /* super.c */
 struct inode *ubifs_iget(struct super_block *sb, unsigned long inum);
diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c
index 6c2f4d4..0a596a1 100644
--- a/fs/ubifs/xattr.c
+++ b/fs/ubifs/xattr.c
@@ -52,13 +52,14 @@
  * in the VFS inode cache. The xentries are cached in the LNC cache (see
  * tnc.c).
  *
- * ACL support is not implemented.
+ * ACL support is now implemented.
  */
 
 #include "ubifs.h"
 #include <linux/fs.h>
 #include <linux/slab.h>
 #include <linux/xattr.h>
+#include <linux/posix_acl_xattr.h>
 
 /*
  * Limit the number of extended attributes per inode so that the total size
@@ -268,7 +269,7 @@ static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
 	return ERR_PTR(-EINVAL);
 }
 
-static int __ubifs_setxattr(struct inode *host, const char *name,
+int __ubifs_setxattr(struct inode *host, const char *name,
 			    const void *value, size_t size, int flags)
 {
 	struct inode *inode;
@@ -328,7 +329,7 @@ out_free:
 	return err;
 }
 
-static ssize_t __ubifs_getxattr(struct inode *host, const char *name,
+ssize_t __ubifs_getxattr(struct inode *host, const char *name,
 				void *buf, size_t size)
 {
 	struct inode *inode;
@@ -619,5 +620,9 @@ const struct xattr_handler *ubifs_xattr_handlers[] = {
 	&ubifs_user_xattr_handler,
 	&ubifs_trusted_xattr_handler,
 	&ubifs_security_xattr_handler,
+#ifdef CONFIG_UBIFS_FS_POSIX_ACL
+	&posix_acl_access_xattr_handler,
+	&posix_acl_default_xattr_handler,
+#endif
 	NULL
 };
-- 
2.7.4