[PATCH] Add security.selinux XATTR support for the UBIFS. Also fix couple of bugs in UBIFS extended attribute length calculation.

Subodh Nijsure subodh.nijsure at gmail.com
Mon Apr 9 02:40:00 EDT 2012


On Sun, Apr 8, 2012 at 7:37 PM, Casey Schaufler <casey at schaufler-ca.com> 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 at grid-net.com>
>
> 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 at scahufler-ca.com>
>
>> ---
>>  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...

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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