Re: [PATCH v5 06/21] security: imbed evm calls in security hooks

[Serge E. Hallyn]

Quoting Mimi Zohar (zohar@xxxxxxxxxxxxxxxxxx):
> Imbed the evm calls evm_inode_setxattr(), evm_inode_post_setxattr(),
> evm_inode_removexattr() in the security hooks.  evm_inode_setxattr()
> protects security.evm xattr.  evm_inode_post_setxattr() and
> evm_inode_removexattr() updates the hmac associated with an inode.
> 
> (Assumes an LSM module protects the setting/removing of xattr.)
> 
> Changelog:
>   - Don't define evm_verifyxattr(), unless CONFIG_INTEGRITY is enabled.
>   - xattr_name is a 'const', value is 'void *'
> 
> Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxx>
> Acked-by: Serge Hallyn <serge.hallyn@xxxxxxxxxx>

Still looks good, thanks.

> ---
>  include/linux/evm.h               |   56 +++++++++++++++++++++++++++++++++++++
>  security/integrity/evm/evm_main.c |    1 +
>  security/security.c               |   16 +++++++++-
>  3 files changed, 71 insertions(+), 2 deletions(-)
>  create mode 100644 include/linux/evm.h
> 
> diff --git a/include/linux/evm.h b/include/linux/evm.h
> new file mode 100644
> index 0000000..8b4e9e3
> --- /dev/null
> +++ b/include/linux/evm.h
> @@ -0,0 +1,56 @@
> +/*
> + * evm.h
> + *
> + * Copyright (c) 2009 IBM Corporation
> + * Author: Mimi Zohar <zohar@xxxxxxxxxx>
> + */
> +
> +#ifndef _LINUX_EVM_H
> +#define _LINUX_EVM_H
> +
> +#include <linux/integrity.h>
> +
> +#ifdef CONFIG_EVM
> +extern enum integrity_status evm_verifyxattr(struct dentry *dentry,
> +					     const char *xattr_name,
> +					     void *xattr_value,
> +					     size_t xattr_value_len);
> +extern int evm_inode_setxattr(struct dentry *dentry, const char *name,
> +			      const void *value, size_t size);
> +extern void evm_inode_post_setxattr(struct dentry *dentry,
> +				    const char *xattr_name,
> +				    const void *xattr_value,
> +				    size_t xattr_value_len);
> +extern int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name);
> +#else
> +#ifdef CONFIG_INTEGRITY
> +static inline enum integrity_status evm_verifyxattr(struct dentry *dentry,
> +						    const char *xattr_name,
> +						    void *xattr_value,
> +						    size_t xattr_value_len)
> +{
> +	return INTEGRITY_UNKNOWN;
> +}
> +#endif
> +
> +static inline int evm_inode_setxattr(struct dentry *dentry, const char *name,
> +				     const void *value, size_t size)
> +{
> +	return 0;
> +}
> +
> +static inline void evm_inode_post_setxattr(struct dentry *dentry,
> +					   const char *xattr_name,
> +					   const void *xattr_value,
> +					   size_t xattr_value_len)
> +{
> +	return;
> +}
> +
> +static inline int evm_inode_removexattr(struct dentry *dentry,
> +					const char *xattr_name)
> +{
> +	return 0;
> +}
> +#endif /* CONFIG_EVM_H */
> +#endif /* LINUX_EVM_H */
> diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
> index 42c792f..e89ceb1 100644
> --- a/security/integrity/evm/evm_main.c
> +++ b/security/integrity/evm/evm_main.c
> @@ -18,6 +18,7 @@
>  #include <linux/crypto.h>
>  #include <linux/xattr.h>
>  #include <linux/integrity.h>
> +#include <linux/evm.h>
>  #include "evm.h"
>  
>  int evm_initialized;
> diff --git a/security/security.c b/security/security.c
> index d0c6576..635bcc9 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -18,6 +18,7 @@
>  #include <linux/security.h>
>  #include <linux/integrity.h>
>  #include <linux/ima.h>
> +#include <linux/evm.h>
>  
>  /* Boot-time LSM user choice */
>  static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
> @@ -549,9 +550,14 @@ int security_inode_getattr(struct vfsmount *mnt, struct dentry *dentry)
>  int security_inode_setxattr(struct dentry *dentry, const char *name,
>  			    const void *value, size_t size, int flags)
>  {
> +	int ret;
> +
>  	if (unlikely(IS_PRIVATE(dentry->d_inode)))
>  		return 0;
> -	return security_ops->inode_setxattr(dentry, name, value, size, flags);
> +	ret = security_ops->inode_setxattr(dentry, name, value, size, flags);
> +	if (ret)
> +		return ret;
> +	return evm_inode_setxattr(dentry, name, value, size);
>  }
>  
>  void security_inode_post_setxattr(struct dentry *dentry, const char *name,
> @@ -560,6 +566,7 @@ void security_inode_post_setxattr(struct dentry *dentry, const char *name,
>  	if (unlikely(IS_PRIVATE(dentry->d_inode)))
>  		return;
>  	security_ops->inode_post_setxattr(dentry, name, value, size, flags);
> +	evm_inode_post_setxattr(dentry, name, value, size);
>  }
>  
>  int security_inode_getxattr(struct dentry *dentry, const char *name)
> @@ -578,9 +585,14 @@ int security_inode_listxattr(struct dentry *dentry)
>  
>  int security_inode_removexattr(struct dentry *dentry, const char *name)
>  {
> +	int ret;
> +
>  	if (unlikely(IS_PRIVATE(dentry->d_inode)))
>  		return 0;
> -	return security_ops->inode_removexattr(dentry, name);
> +	ret = security_ops->inode_removexattr(dentry, name);
> +	if (ret)
> +		return ret;
> +	return evm_inode_removexattr(dentry, name);
>  }
>  
>  int security_inode_need_killpriv(struct dentry *dentry)
> -- 
> 1.7.3.4
> 
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