[PATCH v2] squashfs: Add posix acl support
From: Geliang Tang
Date: Mon Apr 09 2018 - 22:24:49 EST
Add posix acl (Access Control Lists) support for squashfs, which is
marked as a todo item in squashfs' documentation. This patch implements
the squashfs_get_acl function to read file's acl information from its
xattr lists.
Signed-off-by: Geliang Tang <geliangtang@xxxxxxxxx>
---
Changes in v2:
- fix build error, set squashfs_get_acl to NULL when CONFIG_SQUASHFS_POSIX_ACL is not selected.
---
Documentation/filesystems/squashfs.txt | 2 -
fs/squashfs/Kconfig | 11 ++++++
fs/squashfs/Makefile | 1 +
fs/squashfs/acl.c | 69 ++++++++++++++++++++++++++++++++++
fs/squashfs/acl.h | 31 +++++++++++++++
fs/squashfs/inode.c | 4 +-
fs/squashfs/namei.c | 6 ++-
fs/squashfs/squashfs_fs.h | 12 +++---
fs/squashfs/super.c | 3 ++
fs/squashfs/symlink.c | 6 ++-
fs/squashfs/xattr.c | 13 ++++++-
fs/squashfs/xattr.h | 8 ++++
12 files changed, 153 insertions(+), 13 deletions(-)
create mode 100644 fs/squashfs/acl.c
create mode 100644 fs/squashfs/acl.h
diff --git a/Documentation/filesystems/squashfs.txt b/Documentation/filesystems/squashfs.txt
index e5274f84dc56..539fad6b4db0 100644
--- a/Documentation/filesystems/squashfs.txt
+++ b/Documentation/filesystems/squashfs.txt
@@ -235,8 +235,6 @@ list using a second xattr id lookup table.
4.1 Todo list
-------------
-Implement ACL support.
-
4.2 Squashfs internal cache
---------------------------
diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index 1adb3346b9d6..f9587bcf9dd9 100644
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -107,6 +107,17 @@ config SQUASHFS_XATTR
If unsure, say N.
+config SQUASHFS_POSIX_ACL
+ bool "Squashfs POSIX ACL support"
+ depends on SQUASHFS_XATTR
+ select FS_POSIX_ACL
+ help
+ Saying Y here includes support for Access Control Lists (acls).
+ Acls are used to define more fine-grained discretionary access
+ rights for files and directories (see the acl(5) manual page).
+
+ If unsure, say N.
+
config SQUASHFS_ZLIB
bool "Include support for ZLIB compressed file systems"
depends on SQUASHFS
diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index 7bd9b8b856d0..73bc1c8a8df6 100644
--- a/fs/squashfs/Makefile
+++ b/fs/squashfs/Makefile
@@ -12,6 +12,7 @@ squashfs-$(CONFIG_SQUASHFS_DECOMP_SINGLE) += decompressor_single.o
squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI) += decompressor_multi.o
squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU) += decompressor_multi_percpu.o
squashfs-$(CONFIG_SQUASHFS_XATTR) += xattr.o xattr_id.o
+squashfs-$(CONFIG_SQUASHFS_POSIX_ACL) += acl.o
squashfs-$(CONFIG_SQUASHFS_LZ4) += lz4_wrapper.o
squashfs-$(CONFIG_SQUASHFS_LZO) += lzo_wrapper.o
squashfs-$(CONFIG_SQUASHFS_XZ) += xz_wrapper.o
diff --git a/fs/squashfs/acl.c b/fs/squashfs/acl.c
new file mode 100644
index 000000000000..1c9eb2d13c2b
--- /dev/null
+++ b/fs/squashfs/acl.c
@@ -0,0 +1,69 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2018
+ * Phillip Lougher <phillip@xxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * acl.c
+ */
+
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include "squashfs_fs.h"
+#include "xattr.h"
+#include "acl.h"
+
+struct posix_acl *squashfs_get_acl(struct inode *inode, int type)
+{
+ int name_index;
+ char *name;
+ struct posix_acl *acl = NULL;
+ char *value = NULL;
+ int retval;
+
+ switch (type) {
+ case ACL_TYPE_ACCESS:
+ name_index = SQUASHFS_XATTR_POSIX_ACL_ACCESS;
+ name = XATTR_POSIX_ACL_ACCESS;
+ break;
+ case ACL_TYPE_DEFAULT:
+ name_index = SQUASHFS_XATTR_POSIX_ACL_DEFAULT;
+ name = XATTR_POSIX_ACL_DEFAULT;
+ break;
+ default:
+ BUG();
+ }
+
+ retval = squashfs_xattr_get(inode, name_index, name, NULL, 0);
+ if (retval > 0) {
+ value = kmalloc(retval, GFP_KERNEL);
+ if (!value)
+ return ERR_PTR(-ENOMEM);
+ retval = squashfs_xattr_get(inode, name_index, name, value, retval);
+ }
+ if (retval > 0)
+ acl = posix_acl_from_xattr(&init_user_ns, value, retval);
+ else if (retval == -ENODATA || retval == -ENOSYS)
+ acl = NULL;
+ else
+ acl = ERR_PTR(retval);
+
+ kfree(value);
+
+ return acl;
+}
diff --git a/fs/squashfs/acl.h b/fs/squashfs/acl.h
new file mode 100644
index 000000000000..06f704e05450
--- /dev/null
+++ b/fs/squashfs/acl.h
@@ -0,0 +1,31 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2018
+ * Phillip Lougher <phillip@xxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * acl.h
+ */
+
+#include <linux/fs.h>
+#include <linux/posix_acl_xattr.h>
+
+#ifdef CONFIG_SQUASHFS_POSIX_ACL
+extern struct posix_acl *squashfs_get_acl(struct inode *inode, int type);
+#else
+#define squashfs_get_acl NULL
+#endif
diff --git a/fs/squashfs/inode.c b/fs/squashfs/inode.c
index e9793b1e49a5..2035a1acffd7 100644
--- a/fs/squashfs/inode.c
+++ b/fs/squashfs/inode.c
@@ -48,6 +48,7 @@
#include "squashfs_fs_i.h"
#include "squashfs.h"
#include "xattr.h"
+#include "acl.h"
/*
* Initialise VFS inode with the base inode information common to all
@@ -425,6 +426,7 @@ int squashfs_read_inode(struct inode *inode, long long ino)
const struct inode_operations squashfs_inode_ops = {
- .listxattr = squashfs_listxattr
+ .listxattr = squashfs_listxattr,
+ .get_acl = squashfs_get_acl
};
diff --git a/fs/squashfs/namei.c b/fs/squashfs/namei.c
index 40c10d9974c9..33ad74780040 100644
--- a/fs/squashfs/namei.c
+++ b/fs/squashfs/namei.c
@@ -64,6 +64,7 @@
#include "squashfs_fs_i.h"
#include "squashfs.h"
#include "xattr.h"
+#include "acl.h"
/*
* Lookup name in the directory index, returning the location of the metadata
@@ -246,6 +247,7 @@ static struct dentry *squashfs_lookup(struct inode *dir, struct dentry *dentry,
const struct inode_operations squashfs_dir_inode_ops = {
- .lookup = squashfs_lookup,
- .listxattr = squashfs_listxattr
+ .lookup = squashfs_lookup,
+ .listxattr = squashfs_listxattr,
+ .get_acl = squashfs_get_acl
};
diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
index 24d12fd14177..c7ac9fc4f8f4 100644
--- a/fs/squashfs/squashfs_fs.h
+++ b/fs/squashfs/squashfs_fs.h
@@ -107,11 +107,13 @@
#define SQUASHFS_MAX_DIR_TYPE 7
/* Xattr types */
-#define SQUASHFS_XATTR_USER 0
-#define SQUASHFS_XATTR_TRUSTED 1
-#define SQUASHFS_XATTR_SECURITY 2
-#define SQUASHFS_XATTR_VALUE_OOL 256
-#define SQUASHFS_XATTR_PREFIX_MASK 0xff
+#define SQUASHFS_XATTR_USER 0
+#define SQUASHFS_XATTR_POSIX_ACL_ACCESS 1
+#define SQUASHFS_XATTR_POSIX_ACL_DEFAULT 2
+#define SQUASHFS_XATTR_TRUSTED 3
+#define SQUASHFS_XATTR_SECURITY 4
+#define SQUASHFS_XATTR_VALUE_OOL 256
+#define SQUASHFS_XATTR_PREFIX_MASK 0xff
/* Flag whether block is compressed or uncompressed, bit is set if block is
* uncompressed */
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 8a73b97217c8..beea564f1063 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -196,6 +196,9 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
sb->s_maxbytes = MAX_LFS_FILESIZE;
sb->s_flags |= SB_RDONLY;
+#ifdef CONFIG_SQUASHFS_POSIX_ACL
+ sb->s_flags |= SB_POSIXACL;
+#endif
sb->s_op = &squashfs_super_ops;
err = -ENOMEM;
diff --git a/fs/squashfs/symlink.c b/fs/squashfs/symlink.c
index befeba0fa70a..a7f30d890905 100644
--- a/fs/squashfs/symlink.c
+++ b/fs/squashfs/symlink.c
@@ -42,6 +42,7 @@
#include "squashfs_fs_i.h"
#include "squashfs.h"
#include "xattr.h"
+#include "acl.h"
static int squashfs_symlink_readpage(struct file *file, struct page *page)
{
@@ -118,7 +119,8 @@ const struct address_space_operations squashfs_symlink_aops = {
};
const struct inode_operations squashfs_symlink_inode_ops = {
- .get_link = page_get_link,
- .listxattr = squashfs_listxattr
+ .get_link = page_get_link,
+ .listxattr = squashfs_listxattr,
+ .get_acl = squashfs_get_acl
};
diff --git a/fs/squashfs/xattr.c b/fs/squashfs/xattr.c
index 1548b3784548..a1d773b5b0bc 100644
--- a/fs/squashfs/xattr.c
+++ b/fs/squashfs/xattr.c
@@ -33,6 +33,7 @@
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"
+#include "acl.h"
static const struct xattr_handler *squashfs_xattr_handler(int);
@@ -115,7 +116,7 @@ ssize_t squashfs_listxattr(struct dentry *d, char *buffer,
}
-static int squashfs_xattr_get(struct inode *inode, int name_index,
+int squashfs_xattr_get(struct inode *inode, int name_index,
const char *name, void *buffer, size_t buffer_size)
{
struct super_block *sb = inode->i_sb;
@@ -265,6 +266,12 @@ static const struct xattr_handler *squashfs_xattr_handler(int type)
switch (type & SQUASHFS_XATTR_PREFIX_MASK) {
case SQUASHFS_XATTR_USER:
return &squashfs_xattr_user_handler;
+#ifdef CONFIG_SQUASHFS_POSIX_ACL
+ case SQUASHFS_XATTR_POSIX_ACL_ACCESS:
+ return &posix_acl_access_xattr_handler;
+ case SQUASHFS_XATTR_POSIX_ACL_DEFAULT:
+ return &posix_acl_default_xattr_handler;
+#endif
case SQUASHFS_XATTR_TRUSTED:
return &squashfs_xattr_trusted_handler;
case SQUASHFS_XATTR_SECURITY:
@@ -277,6 +284,10 @@ static const struct xattr_handler *squashfs_xattr_handler(int type)
const struct xattr_handler *squashfs_xattr_handlers[] = {
&squashfs_xattr_user_handler,
+#ifdef CONFIG_SQUASHFS_POSIX_ACL
+ &posix_acl_access_xattr_handler,
+ &posix_acl_default_xattr_handler,
+#endif
&squashfs_xattr_trusted_handler,
&squashfs_xattr_security_handler,
NULL
diff --git a/fs/squashfs/xattr.h b/fs/squashfs/xattr.h
index afe70f815e3d..ac08650c08cc 100644
--- a/fs/squashfs/xattr.h
+++ b/fs/squashfs/xattr.h
@@ -26,6 +26,8 @@ extern __le64 *squashfs_read_xattr_id_table(struct super_block *, u64,
u64 *, int *);
extern int squashfs_xattr_lookup(struct super_block *, unsigned int, int *,
unsigned int *, unsigned long long *);
+extern int squashfs_xattr_get(struct inode *inode, int name_index,
+ const char *name, void *buffer, size_t buffer_size);
#else
static inline __le64 *squashfs_read_xattr_id_table(struct super_block *sb,
u64 start, u64 *xattr_table_start, int *xattr_ids)
@@ -41,6 +43,12 @@ static inline int squashfs_xattr_lookup(struct super_block *sb,
{
return 0;
}
+
+static int squashfs_xattr_get(struct inode *inode, int name_index,
+ const char *name, void *buffer, size_t buffer_size)
+{
+ return 0;
+}
#define squashfs_listxattr NULL
#define squashfs_xattr_handlers NULL
#endif
--
2.14.1