Re: [PATCH v3 12/24] LSM: Use lsmblob in security_inode_getsecid

[Kees Cook <keescook@chromium.org>]

On Fri, Jun 21, 2019 at 11:52:21AM -0700, Casey Schaufler wrote:
> Change the security_inode_getsecid() interface to fill in a
> lsmblob structure instead of a u32 secid. This allows for its
> callers to gather data from all registered LSMs. Data is provided
> for IMA and audit.
> 
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  include/linux/security.h            | 7 ++++---
>  kernel/auditsc.c                    | 6 +++++-
>  security/integrity/ima/ima_policy.c | 4 +---
>  security/security.c                 | 8 ++++++--
>  4 files changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/security.h b/include/linux/security.h
> index c5fdaaff8806..6eb64b7f878a 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -358,7 +358,7 @@ int security_inode_killpriv(struct dentry *dentry);
>  int security_inode_getsecurity(struct inode *inode, const char *name, void **buffer, bool alloc);
>  int security_inode_setsecurity(struct inode *inode, const char *name, const void *value, size_t size, int flags);
>  int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size);
> -void security_inode_getsecid(struct inode *inode, u32 *secid);
> +void security_inode_getsecid(struct inode *inode, struct lsmblob *blob);
>  int security_inode_copy_up(struct dentry *src, struct cred **new);
>  int security_inode_copy_up_xattr(const char *name);
>  int security_file_permission(struct file *file, int mask);
> @@ -854,9 +854,10 @@ static inline int security_inode_listsecurity(struct inode *inode, char *buffer,
>  	return 0;
>  }
>  
> -static inline void security_inode_getsecid(struct inode *inode, u32 *secid)
> +static inline void security_inode_getsecid(struct inode *inode,
> +					   struct lsmblob *blob)
>  {
> -	*secid = 0;
> +	lsmblob_init(blob, 0);
>  }
>  
>  static inline int security_inode_copy_up(struct dentry *src, struct cred **new)
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index 7112fe31684d..54797c0fc3b7 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -1910,13 +1910,17 @@ static inline int audit_copy_fcaps(struct audit_names *name,
>  void audit_copy_inode(struct audit_names *name, const struct dentry *dentry,
>  		      struct inode *inode, unsigned int flags)
>  {
> +	struct lsmblob blob;
> +
>  	name->ino   = inode->i_ino;
>  	name->dev   = inode->i_sb->s_dev;
>  	name->mode  = inode->i_mode;
>  	name->uid   = inode->i_uid;
>  	name->gid   = inode->i_gid;
>  	name->rdev  = inode->i_rdev;
> -	security_inode_getsecid(inode, &name->osid);
> +	security_inode_getsecid(inode, &blob);
> +	/* scaffolding until osid is updated */
> +	name->osid = blob.secid[0];
>  	if (flags & AUDIT_INODE_NOEVAL) {
>  		name->fcap_ver = -1;
>  		return;
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index e7b8ce942950..92ee3d984c73 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -326,7 +326,6 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
>  		return false;
>  	for (i = 0; i < MAX_LSM_RULES; i++) {
>  		int rc = 0;
> -		u32 osid;
>  		struct lsmblob blob;
>  		int retried = 0;
>  
> @@ -337,8 +336,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
>  		case LSM_OBJ_USER:
>  		case LSM_OBJ_ROLE:
>  		case LSM_OBJ_TYPE:
> -			security_inode_getsecid(inode, &osid);
> -			lsmblob_init(&blob, osid);
> +			security_inode_getsecid(inode, &blob);
>  			rc = security_filter_rule_match(&blob,
>  							rule->lsm[i].type,
>  							Audit_equal,
> diff --git a/security/security.c b/security/security.c
> index 1184ef092bce..6f0635b51180 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1423,9 +1423,13 @@ int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer
>  }
>  EXPORT_SYMBOL(security_inode_listsecurity);
>  
> -void security_inode_getsecid(struct inode *inode, u32 *secid)
> +void security_inode_getsecid(struct inode *inode, struct lsmblob *blob)
>  {
> -	call_void_hook(inode_getsecid, inode, secid);
> +	struct security_hook_list *hp;
> +
> +	lsmblob_init(blob, 0);
> +	hlist_for_each_entry(hp, &security_hook_heads.inode_getsecid, list)
> +		hp->hook.inode_getsecid(inode, &blob->secid[hp->slot]);
>  }
>  
>  int security_inode_copy_up(struct dentry *src, struct cred **new)
> -- 
> 2.20.1
> 

-- 
Kees Cook