For IMA purposes, we want to be able to obtain the prepared secid in the bprm structure before the credentials are committed. Add a cred_getsecid hook that makes this possible.
Signed-off-by: Matthew Garrett <[email protected]> Cc: Paul Moore <[email protected]> Cc: Stephen Smalley <[email protected]> Cc: Eric Paris <[email protected]> Cc: [email protected] Cc: Casey Schaufler <[email protected]> Cc: [email protected] Cc: Mimi Zohar <[email protected]> Cc: Dmitry Kasatkin <[email protected]> Cc: [email protected] --- include/linux/lsm_hooks.h | 6 ++++++ include/linux/security.h | 1 + security/security.c | 7 +++++++ security/selinux/hooks.c | 8 ++++++++ security/smack/smack.h | 10 ++++++++++ security/smack/smack_lsm.c | 14 ++++++++++++++ 6 files changed, 46 insertions(+) diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index ce02f76a6188..48a929fd47e6 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -556,6 +556,10 @@ * @new points to the new credentials. * @old points to the original credentials. * Transfer data from original creds to new creds + * @cred_getsecid: + * Retrieve the security identifier of the cred structure @c + * @p contains the credentials, secid will be placed into @secid. + * In case of failure, @secid will be set to zero. * @kernel_act_as: * Set the credentials for a kernel service to act as (subjective context). * @new points to the credentials to be modified. @@ -1510,6 +1514,7 @@ union security_list_options { int (*cred_prepare)(struct cred *new, const struct cred *old, gfp_t gfp); void (*cred_transfer)(struct cred *new, const struct cred *old); + void (*cred_getsecid)(const struct cred *c, u32 *secid); int (*kernel_act_as)(struct cred *new, u32 secid); int (*kernel_create_files_as)(struct cred *new, struct inode *inode); int (*kernel_module_request)(char *kmod_name); @@ -1783,6 +1788,7 @@ struct security_hook_heads { struct list_head cred_free; struct list_head cred_prepare; struct list_head cred_transfer; + struct list_head cred_getsecid; struct list_head kernel_act_as; struct list_head kernel_create_files_as; struct list_head kernel_read_file; diff --git a/include/linux/security.h b/include/linux/security.h index 458e24bea2d4..8d969958c25e 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -324,6 +324,7 @@ int security_cred_alloc_blank(struct cred *cred, gfp_t gfp); 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_create_files_as(struct cred *new, struct inode *inode); int security_kernel_module_request(char *kmod_name); diff --git a/security/security.c b/security/security.c index 55b5997e4b72..0f5784880c94 100644 --- a/security/security.c +++ b/security/security.c @@ -1009,6 +1009,13 @@ void security_transfer_creds(struct cred *new, const struct cred *old) call_void_hook(cred_transfer, new, old); } +void security_cred_getsecid(const struct cred *c, u32 *secid) +{ + *secid = 0; + call_void_hook(cred_getsecid, c, secid); +} +EXPORT_SYMBOL(security_cred_getsecid); + int security_kernel_act_as(struct cred *new, u32 secid) { return call_int_hook(kernel_act_as, 0, new, secid); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 33fd061305c4..e0828e9130c7 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3829,6 +3829,13 @@ static void selinux_cred_transfer(struct cred *new, const struct cred *old) *tsec = *old_tsec; } +static void selinux_cred_getsecid(const struct cred *c, u32 *secid) +{ + rcu_read_lock(); + *secid = cred_sid(c); + rcu_read_unlock(); +} + /* * set the security data for a kernel service * - all the creation contexts are set to unlabelled @@ -6332,6 +6339,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(cred_free, selinux_cred_free), LSM_HOOK_INIT(cred_prepare, selinux_cred_prepare), LSM_HOOK_INIT(cred_transfer, selinux_cred_transfer), + LSM_HOOK_INIT(cred_getsecid, selinux_cred_getsecid), LSM_HOOK_INIT(kernel_act_as, selinux_kernel_act_as), LSM_HOOK_INIT(kernel_create_files_as, selinux_kernel_create_files_as), LSM_HOOK_INIT(kernel_module_request, selinux_kernel_module_request), diff --git a/security/smack/smack.h b/security/smack/smack.h index 6a71fc7831ab..5af7b7e709bc 100644 --- a/security/smack/smack.h +++ b/security/smack/smack.h @@ -391,6 +391,16 @@ static inline struct smack_known *smk_of_task_struct(const struct task_struct *t return skp; } +static inline struct smack_known *smk_of_cred(const struct cred *c) +{ + struct smack_known *skp; + + rcu_read_lock(); + skp = smk_of_task(c->security); + rcu_read_unlock(); + return skp; +} + /* * Present a pointer to the forked smack label entry in an task blob. */ diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 463af86812c7..f1710cf76f7f 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -2080,6 +2080,19 @@ static void smack_cred_transfer(struct cred *new, const struct cred *old) /* cbs copy rule list */ } +/** + * smack_cred_getsecid - get the secid corresponding to a creds structure + * @c: the object creds + * @secid: where to put the result + * + * Sets the secid to contain a u32 version of the smack label. + */ +static void smack_cred_getsecid(const struct cred *c, u32 *secid) +{ + struct smack_known *skp = smk_of_cred(c); + *secid = skp->smk_secid; +} + /** * smack_kernel_act_as - Set the subjective context in a set of credentials * @new: points to the set of credentials to be modified. @@ -4684,6 +4697,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(cred_free, smack_cred_free), LSM_HOOK_INIT(cred_prepare, smack_cred_prepare), LSM_HOOK_INIT(cred_transfer, smack_cred_transfer), + LSM_HOOK_INIT(cred_getsecid, smack_cred_getsecid), LSM_HOOK_INIT(kernel_act_as, smack_kernel_act_as), LSM_HOOK_INIT(kernel_create_files_as, smack_kernel_create_files_as), LSM_HOOK_INIT(task_setpgid, smack_task_setpgid), -- 2.15.0.rc0.271.g36b669edcc-goog
