Re: [PATCH 1/2] ima: check xattr value length in ima_inode_setxattr()

From: Jan Kara
Date: Thu Oct 23 2014 - 11:40:19 EST


On Thu 23-10-14 16:47:17, Dmitry Kasatkin wrote:
> ima_inode_setxattr() can be called with no value. Function does not
> check the length so that following command can be used to produce
> kernel oops: setfattr -n security.ima FOO. This patch fixes it.
>
..
>
> Reported-by: Jan Kara <jack@xxxxxxx>
> Signed-off-by: Dmitry Kasatkin <d.kasatkin@xxxxxxxxxxx>
> ---
> security/integrity/ima/ima_appraise.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
> index 5b845af..f07aacd 100644
> --- a/security/integrity/ima/ima_appraise.c
> +++ b/security/integrity/ima/ima_appraise.c
> @@ -378,6 +378,8 @@ int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
> result = ima_protect_xattr(dentry, xattr_name, xattr_value,
> xattr_value_len);
> if (result == 1) {
> + if (!xattr_value_len)
> + return -EINVAL;
Wouldn't it be safer to return EINVAL whenever xattr_value_len !=
sizeof(evm_ima_xattr_data)?

Honza
> ima_reset_appraise_flags(dentry->d_inode,
> (xvalue->type == EVM_IMA_XATTR_DIGSIG) ? 1 : 0);
> result = 0;
> --
> 1.9.1
>
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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