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Message-ID: <1334186854.2153.12.camel@falcor>
Date:	Wed, 11 Apr 2012 19:27:33 -0400
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	subodh.nijsure@...il.com
Cc:	linux-mtd@...ts.infradead.org,
	Artem Bityutskiy <dedekind1@...il.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	Subodh Nijsure <snijsure@...d-net.com>
Subject: Re: [PATCH v3] Add security.* XATTR support for the UBIFS

On Wed, 2012-04-11 at 14:28 -0700, subodh.nijsure@...il.com wrote:
> From: Subodh Nijsure <snijsure@...d-net.com>
> 
> Also fix couple of bugs in UBIFS extended attribute length calculation.
> 
> Changes in v3:
>          Invoke ubifs_init_security only if CONFIG_UBIFS_FS_XATTR is defined. 
>          Invoke it before d_instantiate and check ubifs_init_security return 
>          code.

> Changes in v2:
>          Instead of just handling security.selinux extended attribute handle
>          all security.* attributes.
> 
> TESTING: Tested on  MX28 based platforms using Micron MT29F2G08ABAEAH4 NAND
>          With these change we are able to label UBIFS filesystem with
>          security.selinux and run system with selinux enabled.
>          This change also allows one to set other security.* extended
>          attributes, such as security.smack security.evm, security.ima
>          Ran integck test on UBI filesystem.
> 
> Signed-off-by: Subodh Nijsure <snijsure@...d-net.com>
> ---
>  fs/ubifs/dir.c     |   47 +++++++++++++++++
>  fs/ubifs/file.c    |    6 ++
>  fs/ubifs/journal.c |   12 +++-
>  fs/ubifs/super.c   |    3 +
>  fs/ubifs/ubifs.h   |    9 +++
>  fs/ubifs/xattr.c   |  147 ++++++++++++++++++++++++++++++++++++++++++++++++----
>  6 files changed, 210 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
> index ec9f187..422bcec 100644
> --- a/fs/ubifs/dir.c
> +++ b/fs/ubifs/dir.c
> @@ -292,6 +292,18 @@ static int ubifs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
> 
>  	ubifs_release_budget(c, &req);
>  	insert_inode_hash(inode);
> +
> +#ifdef CONFIG_UBIFS_FS_XATTR
> +
> +	err = ubifs_init_security(dir, inode, &dentry->d_name);
> +	if (err) {
> +		ubifs_err("cannot initialize extended attribute, error %d",
> +			  err);
> +		goto out_cancel;
> +	}
> +
> +#endif
> +

The preferred method for including code based on CONFIG options is to
define a stub function in an include file.  #ifdef's in C code is
frowned upon (refer to section 2.2 of Documentation/SubmittingPatches).

thanks,

Mimi

>  	d_instantiate(dentry, inode);
>  	return 0;
> 
> @@ -753,6 +765,17 @@ static int ubifs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
>  	mutex_unlock(&dir_ui->ui_mutex);
> 
>  	ubifs_release_budget(c, &req);
> +
> +#ifdef CONFIG_UBIFS_FS_XATTR
> +
> +	err = ubifs_init_security(dir, inode, &dentry->d_name);
> +	if (err) {
> +		ubifs_err("cannot initialize extended attribute, error %d",
> +			  err);
> +		goto out_cancel;
> +	}
> +
> +#endif
>  	d_instantiate(dentry, inode);
>  	return 0;
> 
> @@ -830,6 +853,18 @@ static int ubifs_mknod(struct inode *dir, struct dentry *dentry,
> 
>  	ubifs_release_budget(c, &req);
>  	insert_inode_hash(inode);
> +
> +#ifdef CONFIG_UBIFS_FS_XATTR
> +
> +	err = ubifs_init_security(dir, inode, &dentry->d_name);
> +	if (err) {
> +		ubifs_err("cannot initialize extended attribute, error %d",
> +			  err);
> +		goto out_cancel;
> +	}
> +
> +#endif
> +
>  	d_instantiate(dentry, inode);
>  	return 0;
> 
> @@ -906,6 +941,18 @@ static int ubifs_symlink(struct inode *dir, struct dentry *dentry,
> 
>  	ubifs_release_budget(c, &req);
>  	insert_inode_hash(inode);
> +
> +#ifdef CONFIG_UBIFS_FS_XATTR
> +
> +	err = ubifs_init_security(dir, inode, &dentry->d_name);
> +	if (err) {
> +		ubifs_err("cannot initialize extended attribute, error %d",
> +			  err);
> +		goto out_cancel;
> +	}
> +
> +#endif
> +
>  	d_instantiate(dentry, inode);
>  	return 0;
> 
> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
> index 5c8f6dc..b8e9d66 100644
> --- a/fs/ubifs/file.c
> +++ b/fs/ubifs/file.c
> @@ -1575,6 +1575,12 @@ const struct inode_operations ubifs_symlink_inode_operations = {
>  	.follow_link = ubifs_follow_link,
>  	.setattr     = ubifs_setattr,
>  	.getattr     = ubifs_getattr,
> +#ifdef CONFIG_UBIFS_FS_XATTR
> +	.setxattr    = ubifs_symlink_setxattr,
> +	.getxattr    = ubifs_symlink_getxattr,
> +	.listxattr   = ubifs_listxattr,
> +	.removexattr = ubifs_removexattr,
> +#endif
>  };
> 
>  const struct file_operations ubifs_file_operations = {
> diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
> index 2f438ab..725dc17 100644
> --- a/fs/ubifs/journal.c
> +++ b/fs/ubifs/journal.c
> @@ -553,7 +553,8 @@ int ubifs_jnl_update(struct ubifs_info *c, const struct inode *dir,
> 
>  	dbg_jnl("ino %lu, dent '%.*s', data len %d in dir ino %lu",
>  		inode->i_ino, nm->len, nm->name, ui->data_len, dir->i_ino);
> -	ubifs_assert(dir_ui->data_len == 0);
> +	if (!xent)
> +		ubifs_assert(dir_ui->data_len == 0);
>  	ubifs_assert(mutex_is_locked(&dir_ui->ui_mutex));
> 
>  	dlen = UBIFS_DENT_NODE_SZ + nm->len + 1;
> @@ -572,7 +573,11 @@ int ubifs_jnl_update(struct ubifs_info *c, const struct inode *dir,
> 
>  	aligned_dlen = ALIGN(dlen, 8);
>  	aligned_ilen = ALIGN(ilen, 8);
> -	len = aligned_dlen + aligned_ilen + UBIFS_INO_NODE_SZ;
> +	/* Make sure to account for dir_ui+data_len in length calculation
> +	 * in case there is extended attribute.
> +	 */
> +	len = aligned_dlen + aligned_ilen +
> +	      UBIFS_INO_NODE_SZ + dir_ui->data_len;
>  	dent = kmalloc(len, GFP_NOFS);
>  	if (!dent)
>  		return -ENOMEM;
> @@ -649,7 +654,8 @@ int ubifs_jnl_update(struct ubifs_info *c, const struct inode *dir,
> 
>  	ino_key_init(c, &ino_key, dir->i_ino);
>  	ino_offs += aligned_ilen;
> -	err = ubifs_tnc_add(c, &ino_key, lnum, ino_offs, UBIFS_INO_NODE_SZ);
> +	err = ubifs_tnc_add(c, &ino_key, lnum, ino_offs,
> +			    UBIFS_INO_NODE_SZ + dir_ui->data_len);
>  	if (err)
>  		goto out_ro;
> 
> diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
> index 76e4e05..c28ac04 100644
> --- a/fs/ubifs/super.c
> +++ b/fs/ubifs/super.c
> @@ -2061,6 +2061,9 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
>  	if (c->max_inode_sz > MAX_LFS_FILESIZE)
>  		sb->s_maxbytes = c->max_inode_sz = MAX_LFS_FILESIZE;
>  	sb->s_op = &ubifs_super_operations;
> +#ifdef CONFIG_UBIFS_FS_XATTR
> +	sb->s_xattr = ubifs_xattr_handlers;
> +#endif
> 
>  	mutex_lock(&c->umount_mutex);
>  	err = mount_ubifs(c);
> diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
> index 93d59ac..60b57f7 100644
> --- a/fs/ubifs/ubifs.h
> +++ b/fs/ubifs/ubifs.h
> @@ -36,6 +36,7 @@
>  #include <linux/mtd/ubi.h>
>  #include <linux/pagemap.h>
>  #include <linux/backing-dev.h>
> +#include <linux/security.h>
>  #include "ubifs-media.h"
> 
>  /* Version of this UBIFS implementation */
> @@ -1454,6 +1455,7 @@ extern spinlock_t ubifs_infos_lock;
>  extern atomic_long_t ubifs_clean_zn_cnt;
>  extern struct kmem_cache *ubifs_inode_slab;
>  extern const struct super_operations ubifs_super_operations;
> +extern const struct xattr_handler *ubifs_xattr_handlers[];
>  extern const struct address_space_operations ubifs_file_address_operations;
>  extern const struct file_operations ubifs_file_operations;
>  extern const struct inode_operations ubifs_file_inode_operations;
> @@ -1736,10 +1738,17 @@ int ubifs_getattr(struct vfsmount *mnt, struct dentry *dentry,
>  		  struct kstat *stat);
> 
>  /* xattr.c */
> +
>  int ubifs_setxattr(struct dentry *dentry, const char *name,
>  		   const void *value, size_t size, int flags);
> +int ubifs_init_security(struct inode *dentry, struct inode *inode,
> +			const struct qstr *qstr);
> +int ubifs_symlink_setxattr(struct dentry *dentry, const char *name,
> +			   const void *value, size_t size, int flags);
>  ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
>  		       size_t size);
> +ssize_t ubifs_symlink_getxattr(struct dentry *dentry, const char *name,
> +			       void *buf, size_t size);
>  ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size);
>  int ubifs_removexattr(struct dentry *dentry, const char *name);
> 
> diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c
> index 85b2722..c8be7cd 100644
> --- a/fs/ubifs/xattr.c
> +++ b/fs/ubifs/xattr.c
> @@ -209,11 +209,11 @@ static int change_xattr(struct ubifs_info *c, struct inode *host,
>  		goto out_free;
>  	}
>  	inode->i_size = ui->ui_size = size;
> -	ui->data_len = size;
> 
>  	mutex_lock(&host_ui->ui_mutex);
>  	host->i_ctime = ubifs_current_time(host);
>  	host_ui->xattr_size -= CALC_XATTR_BYTES(ui->data_len);
> +	ui->data_len = size;
>  	host_ui->xattr_size += CALC_XATTR_BYTES(size);
> 
>  	/*
> @@ -293,18 +293,16 @@ static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
>  	return ERR_PTR(-EINVAL);
>  }
> 
> -int ubifs_setxattr(struct dentry *dentry, const char *name,
> -		   const void *value, size_t size, int flags)
> +static int __ubifs_setxattr(struct inode *host, const char *name,
> +			    const void *value, size_t size, int flags)
>  {
> -	struct inode *inode, *host = dentry->d_inode;
> +	struct inode *inode;
>  	struct ubifs_info *c = host->i_sb->s_fs_info;
>  	struct qstr nm = { .name = name, .len = strlen(name) };
>  	struct ubifs_dent_node *xent;
>  	union ubifs_key key;
>  	int err, type;
> 
> -	dbg_gen("xattr '%s', host ino %lu ('%.*s'), size %zd", name,
> -		host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
>  	ubifs_assert(mutex_is_locked(&host->i_mutex));
> 
>  	if (size > UBIFS_MAX_INO_DATA)
> @@ -356,10 +354,29 @@ out_free:
>  	return err;
>  }
> 
> -ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
> -		       size_t size)
> +int ubifs_symlink_setxattr(struct dentry *dentry, const char *name,
> +			   const void *value, size_t size, int flags)
>  {
> -	struct inode *inode, *host = dentry->d_inode;
> +	struct inode *host = dentry->d_inode;
> +	dbg_gen("xattr '%s', host ino %lu ('%.*s'), size %zd", name,
> +		host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
> +	return __ubifs_setxattr(host, name, value, size, flags);
> +}
> +
> +int ubifs_setxattr(struct dentry *dentry, const char *name,
> +		   const void *value, size_t size, int flags)
> +{
> +	struct inode *host = dentry->d_inode;
> +	dbg_gen("xattr '%s', host ino %lu ('%.*s'), size %zd", name,
> +		host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
> +	return __ubifs_setxattr(host, name, value, size, flags);
> +}
> +
> +static
> +ssize_t __ubifs_getxattr(struct inode *host, const char *name, void *buf,
> +			 size_t size)
> +{
> +	struct inode *inode;
>  	struct ubifs_info *c = host->i_sb->s_fs_info;
>  	struct qstr nm = { .name = name, .len = strlen(name) };
>  	struct ubifs_inode *ui;
> @@ -367,8 +384,8 @@ ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
>  	union ubifs_key key;
>  	int err;
> 
> -	dbg_gen("xattr '%s', ino %lu ('%.*s'), buf size %zd", name,
> -		host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
> +	dbg_gen("xattr '%s', ino %lu  buf size %zd", name,
> +		host->i_ino, size);
> 
>  	err = check_namespace(&nm);
>  	if (err < 0)
> @@ -416,6 +433,25 @@ out_unlock:
>  	return err;
>  }
> 
> +ssize_t ubifs_symlink_getxattr(struct dentry *dentry, const char *name,
> +			       void *buf, size_t size)
> +{
> +	struct inode *host = dentry->d_inode;
> +	dbg_gen("xattr '%s', ino %lu ('%.*s'), buf size %zd", name,
> +		host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
> +	return __ubifs_getxattr(host, name, buf, size);
> +}
> +
> +ssize_t ubifs_getxattr(struct dentry *dentry, const char *name, void *buf,
> +		       size_t size)
> +{
> +	struct inode *host = dentry->d_inode;
> +	dbg_gen("xattr '%s', ino %lu ('%.*s'), buf size %zd", name,
> +		host->i_ino, dentry->d_name.len, dentry->d_name.name, size);
> +	return __ubifs_getxattr(host, name, buf, size);
> +}
> +
> +
>  ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
>  {
>  	union ubifs_key key;
> @@ -568,3 +604,92 @@ out_free:
>  	kfree(xent);
>  	return err;
>  }
> +
> +size_t
> +ubifs_security_listxattr(struct dentry *d, char *list, size_t list_size,
> +			 const char *name, size_t name_len, int flags)
> +{
> +	const int prefix_len = XATTR_SECURITY_PREFIX_LEN;
> +	const size_t total_len = prefix_len + name_len + 1;
> +	if (list && total_len <= list_size) {
> +		memcpy(list, XATTR_SECURITY_PREFIX, prefix_len);
> +		memcpy(list+prefix_len, name, name_len);
> +		list[prefix_len + name_len] = '\0';
> +	}
> +	return total_len;
> +}
> +
> +
> +int ubifs_security_getxattr(struct dentry *d, const char *name,
> +			    void *buffer, size_t size, int flags)
> +{
> +	if (strcmp(name, "") == 0)
> +		return -EINVAL;
> +	return __ubifs_getxattr(d->d_inode, name, buffer, size);
> +}
> +
> +
> +int ubifs_security_setxattr(struct dentry *d, const char *name,
> +			    const void *value, size_t size,
> +			    int flags, int handler_flags)
> +{
> +	if (strcmp(name, "") == 0)
> +		return -EINVAL;
> +	return __ubifs_setxattr(d->d_inode, name, value,
> +				size, flags);
> +}
> +
> +struct xattr_handler ubifs_xattr_security_handler = {
> +	.prefix = XATTR_SECURITY_PREFIX,
> +	.list   = ubifs_security_listxattr,
> +	.get    = ubifs_security_getxattr,
> +	.set    = ubifs_security_setxattr,
> +};
> +
> +const struct xattr_handler *ubifs_xattr_handlers[] = {
> +	&ubifs_xattr_security_handler,
> +	NULL
> +};
> +
> +static int ubifs_initxattrs(struct inode *inode,
> +			    const struct xattr *xattr_array, void *fs_info)
> +{
> +	const struct xattr *xattr;
> +	char *name;
> +	int err = 0;
> +
> +	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
> +		name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
> +			       strlen(xattr->name) + 1, GFP_NOFS);
> +		if (!name) {
> +			err = -ENOMEM;
> +			break;
> +		}
> +		strcpy(name, XATTR_SECURITY_PREFIX);
> +		strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
> +
> +		err = __ubifs_setxattr(inode, xattr->name, xattr->value,
> +			       xattr->value_len, 0);
> +		kfree(name);
> +		if (err < 0)
> +			break;
> +	}
> +	return err;
> +}
> +
> +int
> +ubifs_init_security(struct inode *dentry, struct inode *inode,
> +		   const struct qstr *qstr)
> +{
> +	struct ubifs_inode *dir_ui = ubifs_inode(inode);
> +	int err = 0;
> +
> +	mutex_lock(&dir_ui->ui_mutex);
> +	mutex_lock(&inode->i_mutex);
> +
> +	err = security_inode_init_security(inode, dentry, qstr,
> +					   &ubifs_initxattrs, 0);
> +	mutex_unlock(&inode->i_mutex);
> +	mutex_unlock(&dir_ui->ui_mutex);
> +	return err;
> +}


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