Re: [PATCH] Add security.selinux XATTR support for the UBIFS. Alsofix couple of bugs in UBIFS extended attribute length calculation.
From: Casey Schaufler
Date: Mon Apr 09 2012 - 11:15:29 EST
On 4/8/2012 11:40 PM, Subodh Nijsure wrote:
> On Sun, Apr 8, 2012 at 7:37 PM, Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote:
>> On 4/8/2012 6:47 AM, Subodh Nijsure wrote:
>>> 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.
>>> Also ran integck test on UBI filesystem.
>>>
>>> Signed-off-by: Subodh Nijsure <snijsure@xxxxxxxxxxxx>
>> There is no reason to restrict xattr support to SELinux.
>> SELinux specific behavior belongs within the SELinux LSM.
>> This code needs to support the full xattr semantics.
>>
>> Nacked-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
>>
>>> ---
>>> fs/ubifs/dir.c | 4 ++
>>> 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, 167 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
>>> index ec9f187..f4e06c4 100644
>>> --- a/fs/ubifs/dir.c
>>> +++ b/fs/ubifs/dir.c
>>> @@ -293,6 +293,7 @@ static int ubifs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
>>> ubifs_release_budget(c, &req);
>>> insert_inode_hash(inode);
>>> d_instantiate(dentry, inode);
>>> + ubifs_init_security(dir, inode, &dentry->d_name);
>>> return 0;
>>>
>>> out_cancel:
>>> @@ -754,6 +755,7 @@ static int ubifs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
>>>
>>> ubifs_release_budget(c, &req);
>>> d_instantiate(dentry, inode);
>>> + ubifs_init_security(dir, inode, &dentry->d_name);
>>> return 0;
>>>
>>> out_cancel:
>>> @@ -831,6 +833,7 @@ static int ubifs_mknod(struct inode *dir, struct dentry *dentry,
>>> ubifs_release_budget(c, &req);
>>> insert_inode_hash(inode);
>>> d_instantiate(dentry, inode);
>>> + ubifs_init_security(dir, inode, &dentry->d_name);
>>> return 0;
>>>
>>> out_cancel:
>>> @@ -907,6 +910,7 @@ static int ubifs_symlink(struct inode *dir, struct dentry *dentry,
>>> ubifs_release_budget(c, &req);
>>> insert_inode_hash(inode);
>>> d_instantiate(dentry, inode);
>>> + ubifs_init_security(dir, inode, &dentry->d_name);
>>> return 0;
>>>
>>> out_cancel:
>>> 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..a402c7d 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, XATTR_NAME_SELINUX, 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, XATTR_NAME_SELINUX, value,
>> This is silly. If you're supporting xattrs there is no reason
>> single out a particular LSM. Make this general so that Smack
>> and any other LSM that wants to use xattrs will work.
>>
>> Move the changes into the SELinux LSM if you are going to
>> hard code it.
>>
> Yup, my bad, following change fixes that specific issue and one can
> set xattr for all security.* namespace. Will submit patch v2
> shortly...
Thank you. The update looks fine, although I haven't tried it.
>
> diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c
> index a402c7d..c8be7cd 100644
> --- a/fs/ubifs/xattr.c
> +++ b/fs/ubifs/xattr.c
> @@ -625,7 +625,7 @@ int ubifs_security_getxattr(struct dentry *d,
> const char *name,
> {
> if (strcmp(name, "") == 0)
> return -EINVAL;
> - return __ubifs_getxattr(d->d_inode, XATTR_NAME_SELINUX, buffer, size);
> + return __ubifs_getxattr(d->d_inode, name, buffer, size);
> }
>
>
> @@ -635,7 +635,7 @@ int ubifs_security_setxattr(struct dentry *d,
> const char *name,
> {
> if (strcmp(name, "") == 0)
> return -EINVAL;
> - return __ubifs_setxattr(d->d_inode, XATTR_NAME_SELINUX, value,
> + return __ubifs_setxattr(d->d_inode, name, value,
> size, flags);
> }
>
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