Re: [PATCH] tmpfs: security xattr setting on inode creation

["Sakkinen, Jarkko" <jarkko.sakkinen@intel.com>]

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Hi

Noticed some style issues that I need to fix.

On Wed, Feb 22, 2012 at 9:48 AM, Jarkko Sakkinen
<jarkko.sakkinen@intel.com> wrote:
> Adds to generic xattr support introduced in Linux 3.0 by
> implementing initxattrs callback. This enables consulting
> of security attributes from LSM and EVM when inode originally
> created.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
> ---
>  mm/shmem.c |   77 +++++++++++++++++++++++++++++++++++++++++++++++------------
>  1 files changed, 61 insertions(+), 16 deletions(-)
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 7a45ad0..72addf1 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1480,6 +1480,59 @@ static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
>  /*
>  * File creation. Allocate an inode, and we're done..
>  */

Oops. Have to move these new functions before this
comment.

> +
> +static int shmem_xattr_alloc(size_t size, struct shmem_xattr **new_xattr)
> +{
> +       /* wrap around? */
> +       size_t len = sizeof(**new_xattr) + size;
> +       if (len <= sizeof(**new_xattr))
> +               return -ENOMEM;
> +
> +       *new_xattr = kmalloc(len, GFP_KERNEL);
> +       if (*new_xattr == NULL)
> +               return -ENOMEM;
> +
> +       (*new_xattr)->size = size;
> +       return 0;
> +}
> +
> +static int shmem_initxattrs(struct inode *inode,
> +                           const struct xattr *xattr_array,
> +                           void *fs_info)
> +{
> +       const struct xattr *xattr;
> +       struct shmem_inode_info *info = SHMEM_I(inode);
> +       struct shmem_xattr *new_xattr = NULL;
> +       size_t len;
> +       int err = 0;
> +
> +       for (xattr = xattr_array; xattr->name != NULL; xattr++) {
> +               err = shmem_xattr_alloc(xattr->value_len, &new_xattr);
> +               if (err < 0)
> +                       break;

Should be "return err;" (consistency).

> +
> +               len = strlen(xattr->name) + 1;
> +               new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
> +                                         GFP_KERNEL);
> +               if (new_xattr->name == NULL) {
> +                       kfree(new_xattr);
> +                       return -ENOMEM;
> +               }
> +
> +               memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
> +                      XATTR_SECURITY_PREFIX_LEN);
> +               memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
> +                      xattr->name, len);
> +               memcpy(new_xattr->value, xattr->value, xattr->value_len);
> +
> +               spin_lock(&info->lock);
> +               list_add(&new_xattr->list, &info->xattr_list);
> +               spin_unlock(&info->lock);
> +       }
> +
> +       return err;

Should be "return 0;" (consistency).

> +}
> +
>  static int
>  shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
>  {
> @@ -1490,7 +1543,7 @@ shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
>        if (inode) {
>                error = security_inode_init_security(inode, dir,
>                                                     &dentry->d_name,
> -                                                    NULL, NULL);
> +                                                    &shmem_initxattrs, NULL);
>                if (error) {
>                        if (error != -EOPNOTSUPP) {
>                                iput(inode);
> @@ -1630,7 +1683,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
>                return -ENOSPC;
>
>        error = security_inode_init_security(inode, dir, &dentry->d_name,
> -                                            NULL, NULL);
> +                                            &shmem_initxattrs, NULL);
>        if (error) {
>                if (error != -EOPNOTSUPP) {
>                        iput(inode);
> @@ -1731,26 +1784,19 @@ static int shmem_xattr_get(struct dentry *dentry, const char *name,
>        return ret;
>  }
>
> -static int shmem_xattr_set(struct dentry *dentry, const char *name,
> +static int shmem_xattr_set(struct inode *inode, const char *name,
>                           const void *value, size_t size, int 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;
> +               err = shmem_xattr_alloc(size, &new_xattr);
> +               if (err < 0)
> +                       return err;
>
>                new_xattr->name = kstrdup(name, GFP_KERNEL);
>                if (!new_xattr->name) {
> @@ -1758,7 +1804,6 @@ static int shmem_xattr_set(struct dentry *dentry, const char *name,
>                        return -ENOMEM;
>                }
>
> -               new_xattr->size = size;
>                memcpy(new_xattr->value, value, size);
>        }
>
> @@ -1858,7 +1903,7 @@ static int shmem_setxattr(struct dentry *dentry, const char *name,
>        if (size == 0)
>                value = "";  /* empty EA, do not remove */
>
> -       return shmem_xattr_set(dentry, name, value, size, flags);
> +       return shmem_xattr_set(dentry->d_inode, name, value, size, flags);
>
>  }
>
> @@ -1878,7 +1923,7 @@ static int shmem_removexattr(struct dentry *dentry, const char *name)
>        if (err)
>                return err;
>
> -       return shmem_xattr_set(dentry, name, NULL, 0, XATTR_REPLACE);
> +       return shmem_xattr_set(dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
>  }
>
>  static bool xattr_is_trusted(const char *name)
> --
> 1.7.5.4
>

/Jarkko
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