Re: [PATCH v3 02/15] exec: Rename bprm->cred_prepared to called_set_creds

[John Johansen <john.johansen@canonical.com>]

On 07/18/2017 03:25 PM, Kees Cook wrote:
> The cred_prepared bprm flag has a misleading name. It has nothing to do
> with the bprm_prepare_cred hook, and actually tracks if bprm_set_creds has
> been called. Rename this flag and improve its comment.
> 
> Cc: David Howells <dhowells@redhat.com>
> Cc: John Johansen <john.johansen@canonical.com>
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: Stephen Smalley <sds@tycho.nsa.gov>
> Cc: Casey Schaufler <casey@schaufler-ca.com>
> Cc: James Morris <james.l.morris@oracle.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>

looks good

Acked-by: John Johansen <john.johansen@canonical.com>

> ---
>  fs/binfmt_flat.c           | 2 +-
>  fs/exec.c                  | 2 +-
>  include/linux/binfmts.h    | 8 ++++++--
>  security/apparmor/domain.c | 2 +-
>  security/selinux/hooks.c   | 2 +-
>  security/smack/smack_lsm.c | 2 +-
>  security/tomoyo/tomoyo.c   | 2 +-
>  7 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
> index 2edcefc0a294..a722530cc468 100644
> --- a/fs/binfmt_flat.c
> +++ b/fs/binfmt_flat.c
> @@ -885,7 +885,7 @@ static int load_flat_shared_library(int id, struct lib_info *libs)
>  	 * as we're past the point of no return and are dealing with shared
>  	 * libraries.
>  	 */
> -	bprm.cred_prepared = 1;
> +	bprm.called_set_creds = 1;
>  
>  	res = prepare_binprm(&bprm);
>  
> diff --git a/fs/exec.c b/fs/exec.c
> index 904199086490..925c85a45d97 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -1547,7 +1547,7 @@ int prepare_binprm(struct linux_binprm *bprm)
>  	retval = security_bprm_set_creds(bprm);
>  	if (retval)
>  		return retval;
> -	bprm->cred_prepared = 1;
> +	bprm->called_set_creds = 1;
>  
>  	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
>  	return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
> diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
> index 9508b5f83c7e..36be5a67517a 100644
> --- a/include/linux/binfmts.h
> +++ b/include/linux/binfmts.h
> @@ -25,8 +25,12 @@ struct linux_binprm {
>  	struct mm_struct *mm;
>  	unsigned long p; /* current top of mem */
>  	unsigned int
> -		cred_prepared:1,/* true if creds already prepared (multiple
> -				 * preps happen for interpreters) */
> +		/*
> +		 * True after the bprm_set_creds hook has been called once
> +		 * (multiple calls can be made via prepare_binprm() for
> +		 * binfmt_script/misc).
> +		 */
> +		called_set_creds:1,
>  		cap_effective:1,/* true if has elevated effective capabilities,
>  				 * false if not; except for init which inherits
>  				 * its parent's caps anyway */
> diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
> index 001e133a3c8c..878407e023e3 100644
> --- a/security/apparmor/domain.c
> +++ b/security/apparmor/domain.c
> @@ -350,7 +350,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
>  	const char *name = NULL, *info = NULL;
>  	int error = 0;
>  
> -	if (bprm->cred_prepared)
> +	if (bprm->called_set_creds)
>  		return 0;
>  
>  	ctx = cred_ctx(bprm->cred);
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 819fd6858b49..0f1450a06b02 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -2327,7 +2327,7 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
>  
>  	/* SELinux context only depends on initial program or script and not
>  	 * the script interpreter */
> -	if (bprm->cred_prepared)
> +	if (bprm->called_set_creds)
>  		return 0;
>  
>  	old_tsec = current_security();
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 658f5d8c7e76..7d4b2e221124 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -917,7 +917,7 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)
>  	struct superblock_smack *sbsp;
>  	int rc;
>  
> -	if (bprm->cred_prepared)
> +	if (bprm->called_set_creds)
>  		return 0;
>  
>  	isp = inode->i_security;
> diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
> index 130b4fa4f65f..d25b705360e0 100644
> --- a/security/tomoyo/tomoyo.c
> +++ b/security/tomoyo/tomoyo.c
> @@ -76,7 +76,7 @@ static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
>  	 * Do only if this function is called for the first time of an execve
>  	 * operation.
>  	 */
> -	if (bprm->cred_prepared)
> +	if (bprm->called_set_creds)
>  		return 0;
>  #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
>  	/*
>