Re: [PATCH v19 04/23] LSM: Use lsmblob in security_kernel_act_as

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 its 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. The security module hook is unchanged, still taking a secid. The infrastructure passes the correct entry from the lsmblob. lsmblob_init() is used to fill the lsmblob structure, however this will be removed later in the series when security_secctx_to_secid() is undated to provide a lsmblob instead of a secid.

Reviewed-by: Kees Cook <keescook(a)chromium.org&gt; Reviewed-by: John Johansen <john.johansen(a)canonical.com&gt; Acked-by: Stephen Smalley <sds(a)tycho.nsa.gov&gt; Signed-off-by: Casey Schaufler <casey(a)schaufler-ca.com&gt; --- 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 294410533b51..6d403a522918 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -441,7 +441,7 @@ 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); @@ -1055,7 +1055,8 @@ 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 421b1149c651..22e0e7cbefde 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -733,14 +733,14 @@ 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); @@ -756,6 +756,7 @@ EXPORT_SYMBOL(set_security_override); */ int set_security_override_from_ctx(struct cred *new, const char *secctx) { + struct lsmblob blob; u32 secid; int ret; @@ -763,7 +764,8 @@ 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 f9a249a93215..d6d882b1f7d5 100644 --- a/security/security.c +++ b/security/security.c @@ -1692,9 +1692,19 @@ 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)