[JFFS2][XATTR] XATTR support on JFFS2 (version. 5)

This attached patches provide xattr support including POSIX-ACL and
SELinux support on JFFS2 (version.5).

There are some significant differences from previous version posted
at last December.
The biggest change is addition of EBS(Erase Block Summary) support.
Currently, both kernel and usermode utility (sumtool) can recognize
xattr nodes which have JFFS2_NODETYPE_XATTR/_XREF nodetype.

In addition, some bugs are fixed.
- A potential race condition was fixed.
- Unexpected fail when updating a xattr by same name/value pair was fixed.
- A bug when removing xattr name/value pair was fixed.

The fundamental structures (such as using two new nodetypes and exclusion
mechanism by rwsem) are unchanged. But most of implementation were reviewed
and updated if necessary.
Espacially, we had to change several internal implementations related to
load_xattr_datum() to avoid a potential race condition.

[1/2] xattr_on_jffs2.kernel.version-5.patch
[2/2] xattr_on_jffs2.utils.version-5.patch

Signed-off-by: KaiGai Kohei <kaigai@ak.jp.nec.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 483 insertions, 0 deletions

diff --git a/fs/jffs2/acl.c b/fs/jffs2/acl.c
new file mode 100644
index 00000000000..080bb51e4b6
--- /dev/null
+++ b/fs/jffs2/acl.c
@@ -0,0 +1,483 @@
+/*-------------------------------------------------------------------------*
+ *  File: fs/jffs2/acl.c
+ *  POSIX ACL support on JFFS2 FileSystem
+ *
+ *  Implemented by KaiGai Kohei <kaigai@ak.jp.nec.com>
+ *  Copyright (C) 2006 NEC Corporation
+ *
+ *  For licensing information, see the file 'LICENCE' in the jffs2 directory.
+ *-------------------------------------------------------------------------*/
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/time.h>
+#include <linux/crc32.h>
+#include <linux/jffs2.h>
+#include <linux/xattr.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/mtd/mtd.h>
+#include "nodelist.h"
+
+static size_t jffs2_acl_size(int count)
+{
+	if (count <= 4) {
+		return sizeof(jffs2_acl_header)
+		       + count * sizeof(jffs2_acl_entry_short);
+	} else {
+		return sizeof(jffs2_acl_header)
+		       + 4 * sizeof(jffs2_acl_entry_short)
+		       + (count - 4) * sizeof(jffs2_acl_entry);
+	}
+}
+
+static int jffs2_acl_count(size_t size)
+{
+	size_t s;
+
+	size -= sizeof(jffs2_acl_header);
+	s = size - 4 * sizeof(jffs2_acl_entry_short);
+	if (s < 0) {
+		if (size % sizeof(jffs2_acl_entry_short))
+			return -1;
+		return size / sizeof(jffs2_acl_entry_short);
+	} else {
+		if (s % sizeof(jffs2_acl_entry))
+			return -1;
+		return s / sizeof(jffs2_acl_entry) + 4;
+	}
+}
+
+static struct posix_acl *jffs2_acl_from_medium(const void *value, size_t size)
+{
+	const char *end = (char *)value + size;
+	struct posix_acl *acl;
+	uint32_t ver;
+	int i, count;
+
+	if (!value)
+		return NULL;
+	if (size < sizeof(jffs2_acl_header))
+		return ERR_PTR(-EINVAL);
+	ver = je32_to_cpu(((jffs2_acl_header *)value)->a_version);
+	if (ver != JFFS2_ACL_VERSION) {
+		JFFS2_WARNING("Invalid ACL version. (=%u)\n", ver);
+		return ERR_PTR(-EINVAL);
+	}
+
+	value = (char *)value + sizeof(jffs2_acl_header);
+	count = jffs2_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);
+
+	for (i=0; i < count; i++) {
+		jffs2_acl_entry *entry = (jffs2_acl_entry *)value;
+		if ((char *)value + sizeof(jffs2_acl_entry_short) > end)
+			goto fail;
+		acl->a_entries[i].e_tag = je16_to_cpu(entry->e_tag);
+		acl->a_entries[i].e_perm = je16_to_cpu(entry->e_perm);
+		switch (acl->a_entries[i].e_tag) {
+			case ACL_USER_OBJ:
+			case ACL_GROUP_OBJ:
+			case ACL_MASK:
+			case ACL_OTHER:
+				value = (char *)value + sizeof(jffs2_acl_entry_short);
+				acl->a_entries[i].e_id = ACL_UNDEFINED_ID;
+				break;
+
+			case ACL_USER:
+			case ACL_GROUP:
+				value = (char *)value + sizeof(jffs2_acl_entry);
+				if ((char *)value > end)
+					goto fail;
+				acl->a_entries[i].e_id = je32_to_cpu(entry->e_id);
+				break;
+
+			default:
+				goto fail;
+		}
+	}
+	if (value != end)
+		goto fail;
+	return acl;
+ fail:
+	posix_acl_release(acl);
+	return ERR_PTR(-EINVAL);
+}
+
+static void *jffs2_acl_to_medium(const struct posix_acl *acl, size_t *size)
+{
+	jffs2_acl_header *jffs2_acl;
+	char *e;
+	size_t i;
+
+	*size = jffs2_acl_size(acl->a_count);
+	jffs2_acl = (jffs2_acl_header *)kmalloc(sizeof(jffs2_acl_header)
+						+ acl->a_count * sizeof(jffs2_acl_entry),
+						GFP_KERNEL);
+	if (!jffs2_acl)
+		return ERR_PTR(-ENOMEM);
+	jffs2_acl->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
+	e = (char *)jffs2_acl + sizeof(jffs2_acl_header);
+	for (i=0; i < acl->a_count; i++) {
+		jffs2_acl_entry *entry = (jffs2_acl_entry *)e;
+		entry->e_tag = cpu_to_je16(acl->a_entries[i].e_tag);
+		entry->e_perm = cpu_to_je16(acl->a_entries[i].e_perm);
+		switch(acl->a_entries[i].e_tag) {
+			case ACL_USER:
+			case ACL_GROUP:
+				entry->e_id = cpu_to_je32(acl->a_entries[i].e_id);
+				e += sizeof(jffs2_acl_entry);
+				break;
+
+			case ACL_USER_OBJ:
+			case ACL_GROUP_OBJ:
+			case ACL_MASK:
+			case ACL_OTHER:
+				e += sizeof(jffs2_acl_entry_short);
+				break;
+
+			default:
+				goto fail;
+		}
+	}
+	return (char *)jffs2_acl;
+ fail:
+	kfree(jffs2_acl);
+	return ERR_PTR(-EINVAL);
+}
+
+static struct posix_acl *jffs2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
+{
+	struct posix_acl *acl = JFFS2_ACL_NOT_CACHED;
+
+	spin_lock(&inode->i_lock);
+	if (*i_acl != JFFS2_ACL_NOT_CACHED)
+		acl = posix_acl_dup(*i_acl);
+	spin_unlock(&inode->i_lock);
+	return acl;
+}
+
+static void jffs2_iset_acl(struct inode *inode, struct posix_acl **i_acl, struct posix_acl *acl)
+{
+	spin_lock(&inode->i_lock);
+	if (*i_acl != JFFS2_ACL_NOT_CACHED)
+		posix_acl_release(*i_acl);
+	*i_acl = posix_acl_dup(acl);
+	spin_unlock(&inode->i_lock);
+}
+
+static struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
+{
+	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
+	struct posix_acl *acl;
+	char *value = NULL;
+	int rc, xprefix;
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		acl = jffs2_iget_acl(inode, &f->i_acl_access);
+		if (acl != JFFS2_ACL_NOT_CACHED)
+			return acl;
+		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
+		break;
+	case ACL_TYPE_DEFAULT:
+		acl = jffs2_iget_acl(inode, &f->i_acl_default);
+		if (acl != JFFS2_ACL_NOT_CACHED)
+			return acl;
+		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+	rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
+	if (rc > 0) {
+		value = kmalloc(rc, GFP_KERNEL);
+		if (!value)
+			return ERR_PTR(-ENOMEM);
+		rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
+	}
+	if (rc > 0) {
+		acl = jffs2_acl_from_medium(value, rc);
+	} else if (rc == -ENODATA || rc == -ENOSYS) {
+		acl = NULL;
+	} else {
+		acl = ERR_PTR(rc);
+	}
+	if (value)
+		kfree(value);
+	if (!IS_ERR(acl)) {
+		switch (type) {
+		case ACL_TYPE_ACCESS:
+			jffs2_iset_acl(inode, &f->i_acl_access, acl);
+			break;
+		case ACL_TYPE_DEFAULT:
+			jffs2_iset_acl(inode, &f->i_acl_default, acl);
+			break;
+		}
+	}
+	return acl;
+}
+
+static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
+{
+	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
+	size_t size = 0;
+	char *value = NULL;
+	int rc, xprefix;
+
+	if (S_ISLNK(inode->i_mode))
+		return -EOPNOTSUPP;
+
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
+		if (acl) {
+			mode_t mode = inode->i_mode;
+			rc = posix_acl_equiv_mode(acl, &mode);
+			if (rc < 0)
+				return rc;
+			if (inode->i_mode != mode) {
+				inode->i_mode = mode;
+				jffs2_dirty_inode(inode);
+			}
+			if (rc == 0)
+				acl = NULL;
+		}
+		break;
+	case ACL_TYPE_DEFAULT:
+		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
+		if (!S_ISDIR(inode->i_mode))
+			return acl ? -EACCES : 0;
+		break;
+	default:
+		return -EINVAL;
+	}
+	if (acl) {
+		value = jffs2_acl_to_medium(acl, &size);
+		if (IS_ERR(value))
+			return PTR_ERR(value);
+	}
+
+	rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
+	if (value)
+		kfree(value);
+	if (!rc) {
+		switch(type) {
+		case ACL_TYPE_ACCESS:
+			jffs2_iset_acl(inode, &f->i_acl_access, acl);
+			break;
+		case ACL_TYPE_DEFAULT:
+			jffs2_iset_acl(inode, &f->i_acl_default, acl);
+			break;
+		}
+	}
+	return rc;
+}
+
+static int jffs2_check_acl(struct inode *inode, int mask)
+{
+	struct posix_acl *acl;
+	int rc;
+
+	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
+	if (IS_ERR(acl))
+		return PTR_ERR(acl);
+	if (acl) {
+		rc = posix_acl_permission(inode, acl, mask);
+		posix_acl_release(acl);
+		return rc;
+	}
+	return -EAGAIN;
+}
+
+int jffs2_permission(struct inode *inode, int mask, struct nameidata *nd)
+{
+	return generic_permission(inode, mask, jffs2_check_acl);
+}
+
+int jffs2_init_acl(struct inode *inode, struct inode *dir)
+{
+	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
+	struct posix_acl *acl = NULL, *clone;
+	mode_t mode;
+	int rc = 0;
+
+	f->i_acl_access = JFFS2_ACL_NOT_CACHED;
+	f->i_acl_default = JFFS2_ACL_NOT_CACHED;
+	if (!S_ISLNK(inode->i_mode)) {
+		acl = jffs2_get_acl(dir, ACL_TYPE_DEFAULT);
+		if (IS_ERR(acl))
+			return PTR_ERR(acl);
+		if (!acl)
+			inode->i_mode &= ~current->fs->umask;
+	}
+	if (acl) {
+		if (S_ISDIR(inode->i_mode)) {
+			rc = jffs2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
+			if (rc)
+				goto cleanup;
+		}
+		clone = posix_acl_clone(acl, GFP_KERNEL);
+		rc = -ENOMEM;
+		if (!clone)
+			goto cleanup;
+		mode = inode->i_mode;
+		rc = posix_acl_create_masq(clone, &mode);
+		if (rc >= 0) {
+			inode->i_mode = mode;
+			if (rc > 0)
+				rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
+		}
+		posix_acl_release(clone);
+	}
+ cleanup:
+	posix_acl_release(acl);
+	return rc;
+}
+
+void jffs2_clear_acl(struct inode *inode)
+{
+	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
+
+	if (f->i_acl_access && f->i_acl_access != JFFS2_ACL_NOT_CACHED) {
+		posix_acl_release(f->i_acl_access);
+		f->i_acl_access = JFFS2_ACL_NOT_CACHED;
+	}
+	if (f->i_acl_default && f->i_acl_default != JFFS2_ACL_NOT_CACHED) {
+		posix_acl_release(f->i_acl_default);
+		f->i_acl_default = JFFS2_ACL_NOT_CACHED;
+	}
+}
+
+int jffs2_acl_chmod(struct inode *inode)
+{
+	struct posix_acl *acl, *clone;
+	int rc;
+
+	if (S_ISLNK(inode->i_mode))
+		return -EOPNOTSUPP;
+	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
+	if (IS_ERR(acl) || !acl)
+		return PTR_ERR(acl);
+	clone = posix_acl_clone(acl, GFP_KERNEL);
+	posix_acl_release(acl);
+	if (!clone)
+		return -ENOMEM;
+	rc = posix_acl_chmod_masq(clone, inode->i_mode);
+	if (!rc)
+		rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
+	posix_acl_release(clone);
+	return rc;
+}
+
+static size_t jffs2_acl_access_listxattr(struct inode *inode, char *list, size_t list_size,
+					 const char *name, size_t name_len)
+{
+	const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
+
+	if (list && retlen <= list_size)
+		strcpy(list, POSIX_ACL_XATTR_ACCESS);
+	return retlen;
+}
+
+static size_t jffs2_acl_default_listxattr(struct inode *inode, char *list, size_t list_size,
+					  const char *name, size_t name_len)
+{
+	const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
+
+	if (list && retlen <= list_size)
+		strcpy(list, POSIX_ACL_XATTR_DEFAULT);
+	return retlen;
+}
+
+static int jffs2_acl_getxattr(struct inode *inode, int type, void *buffer, size_t size)
+{
+	struct posix_acl *acl;
+	int rc;
+
+	acl = jffs2_get_acl(inode, type);
+	if (IS_ERR(acl))
+		return PTR_ERR(acl);
+	if (!acl)
+		return -ENODATA;
+	rc = posix_acl_to_xattr(acl, buffer, size);
+	posix_acl_release(acl);
+
+	return rc;
+}
+
+static int jffs2_acl_access_getxattr(struct inode *inode, const char *name, void *buffer, size_t size)
+{
+	if (name[0] != '\0')
+		return -EINVAL;
+	return jffs2_acl_getxattr(inode, ACL_TYPE_ACCESS, buffer, size);
+}
+
+static int jffs2_acl_default_getxattr(struct inode *inode, const char *name, void *buffer, size_t size)
+{
+	if (name[0] != '\0')
+		return -EINVAL;
+	return jffs2_acl_getxattr(inode, ACL_TYPE_DEFAULT, buffer, size);
+}
+
+static int jffs2_acl_setxattr(struct inode *inode, int type, const void *value, size_t size)
+{
+	struct posix_acl *acl;
+	int rc;
+
+	if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
+		return -EPERM;
+
+	if (value) {
+		acl = posix_acl_from_xattr(value, size);
+		if (IS_ERR(acl))
+			return PTR_ERR(acl);
+		if (acl) {
+			rc = posix_acl_valid(acl);
+			if (rc)
+				goto out;
+		}
+	} else {
+		acl = NULL;
+	}
+	rc = jffs2_set_acl(inode, type, acl);
+ out:
+	posix_acl_release(acl);
+	return rc;
+}
+
+static int jffs2_acl_access_setxattr(struct inode *inode, const char *name,
+				     const void *buffer, size_t size, int flags)
+{
+	if (name[0] != '\0')
+		return -EINVAL;
+	return jffs2_acl_setxattr(inode, ACL_TYPE_ACCESS, buffer, size);
+}
+
+static int jffs2_acl_default_setxattr(struct inode *inode, const char *name,
+				      const void *buffer, size_t size, int flags)
+{
+	if (name[0] != '\0')
+		return -EINVAL;
+	return jffs2_acl_setxattr(inode, ACL_TYPE_DEFAULT, buffer, size);
+}
+
+struct xattr_handler jffs2_acl_access_xattr_handler = {
+	.prefix	= POSIX_ACL_XATTR_ACCESS,
+	.list	= jffs2_acl_access_listxattr,
+	.get	= jffs2_acl_access_getxattr,
+	.set	= jffs2_acl_access_setxattr,
+};
+
+struct xattr_handler jffs2_acl_default_xattr_handler = {
+	.prefix	= POSIX_ACL_XATTR_DEFAULT,
+	.list	= jffs2_acl_default_listxattr,
+	.get	= jffs2_acl_default_getxattr,
+	.set	= jffs2_acl_default_setxattr,
+};