On 11/13/19 10:19 AM, Casey Schaufler wrote:
> Change the security_kernel_act_as interface to use a lsmblob
> structure in place of the single u32 secid in support of
> module stacking. Change it's only caller, set_security_override,
> to do the same. Change that one's only caller,
> set_security_override_from_ctx, to call it with the new
> parameter type.
>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Reviewed-by: John Johansen <john.johansen@xxxxxxxxxxxxx>
> Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Acked-by: John Johansen <john.johansen@xxxxxxxxxxxxx>
> ---
> include/linux/cred.h | 3 ++-
> include/linux/security.h | 5 +++--
> kernel/cred.c | 10 ++++++----
> security/security.c | 14 ++++++++++++--
> 4 files changed, 23 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/cred.h b/include/linux/cred.h
> index 18639c069263..03ae0182cba6 100644
> --- a/include/linux/cred.h
> +++ b/include/linux/cred.h
> @@ -18,6 +18,7 @@
>
> struct cred;
> struct inode;
> +struct lsmblob;
>
> /*
> * COW Supplementary groups list
> @@ -165,7 +166,7 @@ extern const struct cred *override_creds(const struct cred *);
> extern void revert_creds(const struct cred *);
> extern struct cred *prepare_kernel_cred(struct task_struct *);
> extern int change_create_files_as(struct cred *, struct inode *);
> -extern int set_security_override(struct cred *, u32);
> +extern int set_security_override(struct cred *, struct lsmblob *);
> extern int set_security_override_from_ctx(struct cred *, const char *);
> extern int set_create_files_as(struct cred *, struct inode *);
> extern int cred_fscmp(const struct cred *, const struct cred *);
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 2df58448f1f2..2b0ab47cfb26 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -435,7 +435,7 @@ void security_cred_free(struct cred *cred);
> int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp);
> void security_transfer_creds(struct cred *new, const struct cred *old);
> void security_cred_getsecid(const struct cred *c, u32 *secid);
> -int security_kernel_act_as(struct cred *new, u32 secid);
> +int security_kernel_act_as(struct cred *new, struct lsmblob *blob);
> int security_kernel_create_files_as(struct cred *new, struct inode *inode);
> int security_kernel_module_request(char *kmod_name);
> int security_kernel_load_data(enum kernel_load_data_id id);
> @@ -1041,7 +1041,8 @@ static inline void security_transfer_creds(struct cred *new,
> {
> }
>
> -static inline int security_kernel_act_as(struct cred *cred, u32 secid)
> +static inline int security_kernel_act_as(struct cred *cred,
> + struct lsmblob *blob)
> {
> return 0;
> }
> diff --git a/kernel/cred.c b/kernel/cred.c
> index c0a4c12d38b2..846ac4b23c16 100644
> --- a/kernel/cred.c
> +++ b/kernel/cred.c
> @@ -732,14 +732,14 @@ EXPORT_SYMBOL(prepare_kernel_cred);
> /**
> * set_security_override - Set the security ID in a set of credentials
> * @new: The credentials to alter
> - * @secid: The LSM security ID to set
> + * @blob: The LSM security information to set
> *
> * Set the LSM security ID in a set of credentials so that the subjective
> * security is overridden when an alternative set of credentials is used.
> */
> -int set_security_override(struct cred *new, u32 secid)
> +int set_security_override(struct cred *new, struct lsmblob *blob)
> {
> - return security_kernel_act_as(new, secid);
> + return security_kernel_act_as(new, blob);
> }
> EXPORT_SYMBOL(set_security_override);
>
> @@ -755,6 +755,7 @@ EXPORT_SYMBOL(set_security_override);
> */
> int set_security_override_from_ctx(struct cred *new, const char *secctx)
> {
> + struct lsmblob blob;
> u32 secid;
> int ret;
>
> @@ -762,7 +763,8 @@ int set_security_override_from_ctx(struct cred *new, const char *secctx)
> if (ret < 0)
> return ret;
>
> - return set_security_override(new, secid);
> + lsmblob_init(&blob, secid);
> + return set_security_override(new, &blob);
> }
> EXPORT_SYMBOL(set_security_override_from_ctx);
>
> diff --git a/security/security.c b/security/security.c
> index 7c386cbe4cf3..dd6f212e11af 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1615,9 +1615,19 @@ void security_cred_getsecid(const struct cred *c, u32 *secid)
> }
> EXPORT_SYMBOL(security_cred_getsecid);
>
> -int security_kernel_act_as(struct cred *new, u32 secid)
> +int security_kernel_act_as(struct cred *new, struct lsmblob *blob)
> {
> - return call_int_hook(kernel_act_as, 0, new, secid);
> + struct security_hook_list *hp;
> + int rc;
> +
> + hlist_for_each_entry(hp, &security_hook_heads.kernel_act_as, list) {
> + if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
> + continue;
> + rc = hp->hook.kernel_act_as(new, blob->secid[hp->lsmid->slot]);
> + if (rc != 0)
> + return rc;
> + }
> + return 0;
> }
>
> int security_kernel_create_files_as(struct cred *new, struct inode *inode)
>
