kernel: backport and enable tmpfs xattr support for 2.6.39

SVN-Revision: 27691
2011-07-19 09:00:55 +00:00 · 2011-07-19 09:00:55 +00:00 · fee32761f3
parent 9c606eb4c5
commit fee32761f3
3 changed files with 480 additions and 2 deletions
--- a/target/linux/generic/config-2.6.39
+++ b/target/linux/generic/config-2.6.39
@ -2631,6 +2631,7 @@ CONFIG_TINY_RCU=y
 # CONFIG_TLAN is not set
 # CONFIG_TMD_HERMES is not set
 CONFIG_TMPFS=y
+CONFIG_TMPFS_XATTR=y
 # CONFIG_TMPFS_POSIX_ACL is not set
 # CONFIG_TOUCHSCREEN_AD7877 is not set
 # CONFIG_TOUCHSCREEN_AD7879 is not set
--- a/target/linux/generic/patches-2.6.39/040-backport_tmpfs_xattr.patch
+++ b/target/linux/generic/patches-2.6.39/040-backport_tmpfs_xattr.patch
@ -0,0 +1,477 @@
+--- a/fs/Kconfig
+++ b/fs/Kconfig
+@@ -121,9 +121,25 @@ config TMPFS
+ 
+ 	  See <file:Documentation/filesystems/tmpfs.txt> for details.
+ 
+config TMPFS_XATTR
+	bool "Tmpfs extended attributes"
+	depends on TMPFS
+	default n
+	help
+	  Extended attributes are name:value pairs associated with inodes by
+	  the kernel or by users (see the attr(5) manual page, or visit
+	  <http://acl.bestbits.at/> for details).
+
+	  Currently this enables support for the trusted.* and
+	  security.* namespaces.
+
+	  If unsure, say N.
+
+	  You need this for POSIX ACL support on tmpfs.
+
+ config TMPFS_POSIX_ACL
+ 	bool "Tmpfs POSIX Access Control Lists"
+-	depends on TMPFS
+	depends on TMPFS_XATTR
+ 	select GENERIC_ACL
+ 	help
+ 	  POSIX Access Control Lists (ACLs) support permissions for users and
+--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
+@@ -9,6 +9,8 @@
+ 
+ #define SHMEM_NR_DIRECT 16
+ 
+#define SHMEM_SYMLINK_INLINE_LEN (SHMEM_NR_DIRECT * sizeof(swp_entry_t))
+
+ struct shmem_inode_info {
+ 	spinlock_t		lock;
+ 	unsigned long		flags;
+@@ -17,8 +19,12 @@ struct shmem_inode_info {
+ 	unsigned long		next_index;	/* highest alloced index + 1 */
+ 	struct shared_policy	policy;		/* NUMA memory alloc policy */
+ 	struct page		*i_indirect;	/* top indirect blocks page */
+-	swp_entry_t		i_direct[SHMEM_NR_DIRECT]; /* first blocks */
+	union {
+		swp_entry_t	i_direct[SHMEM_NR_DIRECT]; /* first blocks */
+		char		inline_symlink[SHMEM_SYMLINK_INLINE_LEN];
+	};
+ 	struct list_head	swaplist;	/* chain of maybes on swap */
+	struct list_head	xattr_list;	/* list of shmem_xattr */
+ 	struct inode		vfs_inode;
+ };
+ 
+--- a/mm/shmem.c
+++ b/mm/shmem.c
+@@ -99,6 +99,13 @@ static struct vfsmount *shm_mnt;
+ /* Pretend that each entry is of this size in directory's i_size */
+ #define BOGO_DIRENT_SIZE 20
+ 
+struct shmem_xattr {
+	struct list_head list;	/* anchored by shmem_inode_info->xattr_list */
+	char *name;		/* xattr name */
+	size_t size;
+	char value[0];
+};
+
+ /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
+ enum sgp_type {
+ 	SGP_READ,	/* don't exceed i_size, don't allocate page */
+@@ -822,6 +829,7 @@ static int shmem_notify_change(struct de
+ static void shmem_evict_inode(struct inode *inode)
+ {
+ 	struct shmem_inode_info *info = SHMEM_I(inode);
+	struct shmem_xattr *xattr, *nxattr;
+ 
+ 	if (inode->i_mapping->a_ops == &shmem_aops) {
+ 		truncate_inode_pages(inode->i_mapping, 0);
+@@ -834,6 +842,11 @@ static void shmem_evict_inode(struct ino
+ 			mutex_unlock(&shmem_swaplist_mutex);
+ 		}
+ 	}
+
+	list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) {
+		kfree(xattr->name);
+		kfree(xattr);
+	}
+ 	BUG_ON(inode->i_blocks);
+ 	shmem_free_inode(inode->i_sb);
+ 	end_writeback(inode);
+@@ -1615,6 +1628,7 @@ static struct inode *shmem_get_inode(str
+ 		spin_lock_init(&info->lock);
+ 		info->flags = flags & VM_NORESERVE;
+ 		INIT_LIST_HEAD(&info->swaplist);
+		INIT_LIST_HEAD(&info->xattr_list);
+ 		cache_no_acl(inode);
+ 
+ 		switch (mode & S_IFMT) {
+@@ -2014,9 +2028,9 @@ static int shmem_symlink(struct inode *d
+ 
+ 	info = SHMEM_I(inode);
+ 	inode->i_size = len-1;
+-	if (len <= (char *)inode - (char *)info) {
+	if (len <= SHMEM_SYMLINK_INLINE_LEN) {
+ 		/* do it inline */
+-		memcpy(info, symname, len);
+		memcpy(info->inline_symlink, symname, len);
+ 		inode->i_op = &shmem_symlink_inline_operations;
+ 	} else {
+ 		error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
+@@ -2042,7 +2056,7 @@ static int shmem_symlink(struct inode *d
+ 
+ static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
+ {
+-	nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
+	nd_set_link(nd, SHMEM_I(dentry->d_inode)->inline_symlink);
+ 	return NULL;
+ }
+ 
+@@ -2066,63 +2080,253 @@ static void shmem_put_link(struct dentry
+ 	}
+ }
+ 
+-static const struct inode_operations shmem_symlink_inline_operations = {
+-	.readlink	= generic_readlink,
+-	.follow_link	= shmem_follow_link_inline,
+-};
+-
+-static const struct inode_operations shmem_symlink_inode_operations = {
+-	.readlink	= generic_readlink,
+-	.follow_link	= shmem_follow_link,
+-	.put_link	= shmem_put_link,
+-};
+-
+-#ifdef CONFIG_TMPFS_POSIX_ACL
+#ifdef CONFIG_TMPFS_XATTR
+ /*
+- * Superblocks without xattr inode operations will get security.* xattr
+- * support from the VFS "for free". As soon as we have any other xattrs
+ * Superblocks without xattr inode operations may get some security.* xattr
+ * support from the LSM "for free". As soon as we have any other xattrs
+  * like ACLs, we also need to implement the security.* handlers at
+  * filesystem level, though.
+  */
+ 
+-static size_t shmem_xattr_security_list(struct dentry *dentry, char *list,
+-					size_t list_len, const char *name,
+-					size_t name_len, int handler_flags)
+static int shmem_xattr_get(struct dentry *dentry, const char *name,
+			   void *buffer, size_t size)
+ {
+-	return security_inode_listsecurity(dentry->d_inode, list, list_len);
+-}
+	struct shmem_inode_info *info;
+	struct shmem_xattr *xattr;
+	int ret = -ENODATA;
+ 
+-static int shmem_xattr_security_get(struct dentry *dentry, const char *name,
+-		void *buffer, size_t size, int handler_flags)
+-{
+-	if (strcmp(name, "") == 0)
+-		return -EINVAL;
+-	return xattr_getsecurity(dentry->d_inode, name, buffer, size);
+	info = SHMEM_I(dentry->d_inode);
+
+	spin_lock(&info->lock);
+	list_for_each_entry(xattr, &info->xattr_list, list) {
+		if (strcmp(name, xattr->name))
+			continue;
+
+		ret = xattr->size;
+		if (buffer) {
+			if (size < xattr->size)
+				ret = -ERANGE;
+			else
+				memcpy(buffer, xattr->value, xattr->size);
+		}
+		break;
+	}
+	spin_unlock(&info->lock);
+	return ret;
+ }
+ 
+-static int shmem_xattr_security_set(struct dentry *dentry, const char *name,
+-		const void *value, size_t size, int flags, int handler_flags)
+static int shmem_xattr_set(struct dentry *dentry, const char *name,
+			   const void *value, size_t size, int flags)
+ {
+-	if (strcmp(name, "") == 0)
+-		return -EINVAL;
+-	return security_inode_setsecurity(dentry->d_inode, name, value,
+-					  size, flags);
+	struct inode *inode = dentry->d_inode;
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	struct shmem_xattr *xattr;
+	struct shmem_xattr *new_xattr = NULL;
+	size_t len;
+	int err = 0;
+
+	/* value == NULL means remove */
+	if (value) {
+		/* wrap around? */
+		len = sizeof(*new_xattr) + size;
+		if (len <= sizeof(*new_xattr))
+			return -ENOMEM;
+
+		new_xattr = kmalloc(len, GFP_KERNEL);
+		if (!new_xattr)
+			return -ENOMEM;
+
+		new_xattr->name = kstrdup(name, GFP_KERNEL);
+		if (!new_xattr->name) {
+			kfree(new_xattr);
+			return -ENOMEM;
+		}
+
+		new_xattr->size = size;
+		memcpy(new_xattr->value, value, size);
+	}
+
+	spin_lock(&info->lock);
+	list_for_each_entry(xattr, &info->xattr_list, list) {
+		if (!strcmp(name, xattr->name)) {
+			if (flags & XATTR_CREATE) {
+				xattr = new_xattr;
+				err = -EEXIST;
+			} else if (new_xattr) {
+				list_replace(&xattr->list, &new_xattr->list);
+			} else {
+				list_del(&xattr->list);
+			}
+			goto out;
+		}
+	}
+	if (flags & XATTR_REPLACE) {
+		xattr = new_xattr;
+		err = -ENODATA;
+	} else {
+		list_add(&new_xattr->list, &info->xattr_list);
+		xattr = NULL;
+	}
+out:
+	spin_unlock(&info->lock);
+	if (xattr)
+		kfree(xattr->name);
+	kfree(xattr);
+	return err;
+ }
+ 
+-static const struct xattr_handler shmem_xattr_security_handler = {
+-	.prefix = XATTR_SECURITY_PREFIX,
+-	.list   = shmem_xattr_security_list,
+-	.get    = shmem_xattr_security_get,
+-	.set    = shmem_xattr_security_set,
+-};
+ 
+ static const struct xattr_handler *shmem_xattr_handlers[] = {
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ 	&generic_acl_access_handler,
+ 	&generic_acl_default_handler,
+-	&shmem_xattr_security_handler,
+#endif
+ 	NULL
+ };
+
+static int shmem_xattr_validate(const char *name)
+{
+	struct { const char *prefix; size_t len; } arr[] = {
+		{ XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
+		{ XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
+	};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(arr); i++) {
+		size_t preflen = arr[i].len;
+		if (strncmp(name, arr[i].prefix, preflen) == 0) {
+			if (!name[preflen])
+				return -EINVAL;
+			return 0;
+		}
+	}
+	return -EOPNOTSUPP;
+}
+
+static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
+			      void *buffer, size_t size)
+{
+	int err;
+
+	/*
+	 * If this is a request for a synthetic attribute in the system.*
+	 * namespace use the generic infrastructure to resolve a handler
+	 * for it via sb->s_xattr.
+	 */
+	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+		return generic_getxattr(dentry, name, buffer, size);
+
+	err = shmem_xattr_validate(name);
+	if (err)
+		return err;
+
+	return shmem_xattr_get(dentry, name, buffer, size);
+}
+
+static int shmem_setxattr(struct dentry *dentry, const char *name,
+			  const void *value, size_t size, int flags)
+{
+	int err;
+
+	/*
+	 * If this is a request for a synthetic attribute in the system.*
+	 * namespace use the generic infrastructure to resolve a handler
+	 * for it via sb->s_xattr.
+	 */
+	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+		return generic_setxattr(dentry, name, value, size, flags);
+
+	err = shmem_xattr_validate(name);
+	if (err)
+		return err;
+
+	if (size == 0)
+		value = "";  /* empty EA, do not remove */
+
+	return shmem_xattr_set(dentry, name, value, size, flags);
+
+}
+
+static int shmem_removexattr(struct dentry *dentry, const char *name)
+{
+	int err;
+
+	/*
+	 * If this is a request for a synthetic attribute in the system.*
+	 * namespace use the generic infrastructure to resolve a handler
+	 * for it via sb->s_xattr.
+	 */
+	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+		return generic_removexattr(dentry, name);
+
+	err = shmem_xattr_validate(name);
+	if (err)
+		return err;
+
+	return shmem_xattr_set(dentry, name, NULL, 0, XATTR_REPLACE);
+}
+
+static bool xattr_is_trusted(const char *name)
+{
+	return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
+}
+
+static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
+{
+	bool trusted = capable(CAP_SYS_ADMIN);
+	struct shmem_xattr *xattr;
+	struct shmem_inode_info *info;
+	size_t used = 0;
+
+	info = SHMEM_I(dentry->d_inode);
+
+	spin_lock(&info->lock);
+	list_for_each_entry(xattr, &info->xattr_list, list) {
+		size_t len;
+
+		/* skip "trusted." attributes for unprivileged callers */
+		if (!trusted && xattr_is_trusted(xattr->name))
+			continue;
+
+		len = strlen(xattr->name) + 1;
+		used += len;
+		if (buffer) {
+			if (size < used) {
+				used = -ERANGE;
+				break;
+			}
+			memcpy(buffer, xattr->name, len);
+			buffer += len;
+		}
+	}
+	spin_unlock(&info->lock);
+
+	return used;
+}
+#endif /* CONFIG_TMPFS_XATTR */
+
+static const struct inode_operations shmem_symlink_inline_operations = {
+	.readlink	= generic_readlink,
+	.follow_link	= shmem_follow_link_inline,
+#ifdef CONFIG_TMPFS_XATTR
+	.setxattr	= shmem_setxattr,
+	.getxattr	= shmem_getxattr,
+	.listxattr	= shmem_listxattr,
+	.removexattr	= shmem_removexattr,
+#endif
+};
+
+static const struct inode_operations shmem_symlink_inode_operations = {
+	.readlink	= generic_readlink,
+	.follow_link	= shmem_follow_link,
+	.put_link	= shmem_put_link,
+#ifdef CONFIG_TMPFS_XATTR
+	.setxattr	= shmem_setxattr,
+	.getxattr	= shmem_getxattr,
+	.listxattr	= shmem_listxattr,
+	.removexattr	= shmem_removexattr,
+ #endif
+};
+ 
+ static struct dentry *shmem_get_parent(struct dentry *child)
+ {
+@@ -2402,8 +2606,10 @@ int shmem_fill_super(struct super_block 
+ 	sb->s_magic = TMPFS_MAGIC;
+ 	sb->s_op = &shmem_ops;
+ 	sb->s_time_gran = 1;
+-#ifdef CONFIG_TMPFS_POSIX_ACL
+#ifdef CONFIG_TMPFS_XATTR
+ 	sb->s_xattr = shmem_xattr_handlers;
+#endif
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ 	sb->s_flags |= MS_POSIXACL;
+ #endif
+ 
+@@ -2501,11 +2707,13 @@ static const struct file_operations shme
+ static const struct inode_operations shmem_inode_operations = {
+ 	.setattr	= shmem_notify_change,
+ 	.truncate_range	= shmem_truncate_range,
+#ifdef CONFIG_TMPFS_XATTR
+	.setxattr	= shmem_setxattr,
+	.getxattr	= shmem_getxattr,
+	.listxattr	= shmem_listxattr,
+	.removexattr	= shmem_removexattr,
+#endif
+ #ifdef CONFIG_TMPFS_POSIX_ACL
+-	.setxattr	= generic_setxattr,
+-	.getxattr	= generic_getxattr,
+-	.listxattr	= generic_listxattr,
+-	.removexattr	= generic_removexattr,
+ 	.check_acl	= generic_check_acl,
+ #endif
+ 
+@@ -2523,23 +2731,27 @@ static const struct inode_operations shm
+ 	.mknod		= shmem_mknod,
+ 	.rename		= shmem_rename,
+ #endif
+#ifdef CONFIG_TMPFS_XATTR
+	.setxattr	= shmem_setxattr,
+	.getxattr	= shmem_getxattr,
+	.listxattr	= shmem_listxattr,
+	.removexattr	= shmem_removexattr,
+#endif
+ #ifdef CONFIG_TMPFS_POSIX_ACL
+ 	.setattr	= shmem_notify_change,
+-	.setxattr	= generic_setxattr,
+-	.getxattr	= generic_getxattr,
+-	.listxattr	= generic_listxattr,
+-	.removexattr	= generic_removexattr,
+ 	.check_acl	= generic_check_acl,
+ #endif
+ };
+ 
+ static const struct inode_operations shmem_special_inode_operations = {
+#ifdef CONFIG_TMPFS_XATTR
+	.setxattr	= shmem_setxattr,
+	.getxattr	= shmem_getxattr,
+	.listxattr	= shmem_listxattr,
+	.removexattr	= shmem_removexattr,
+#endif
+ #ifdef CONFIG_TMPFS_POSIX_ACL
+ 	.setattr	= shmem_notify_change,
+-	.setxattr	= generic_setxattr,
+-	.getxattr	= generic_getxattr,
+-	.listxattr	= generic_listxattr,
+-	.removexattr	= generic_removexattr,
+ 	.check_acl	= generic_check_acl,
+ #endif
+ };
--- a/target/linux/generic/patches-2.6.39/950-vm_exports.patch
+++ b/target/linux/generic/patches-2.6.39/950-vm_exports.patch
@ -1,6 +1,6 @@
 --- a/mm/shmem.c
 +++ b/mm/shmem.c
-@@ -2731,6 +2731,16 @@ out:
+@@ -2943,6 +2943,16 @@ out:
 
 /* common code */
 
@ -17,7 +17,7 @@
 /**
  * shmem_file_setup - get an unlinked file living in tmpfs
  * @name: name for dentry (to be seen in /proc/<pid>/maps
-@@ -2808,10 +2818,7 @@ int shmem_zero_setup(struct vm_area_stru
+@@ -3020,10 +3030,7 @@ int shmem_zero_setup(struct vm_area_stru
 	if (IS_ERR(file))
 		return PTR_ERR(file);