From mboxrd@z Thu Jan 1 00:00:00 1970 From: sds@tycho.nsa.gov (Stephen Smalley) Date: Thu, 26 Oct 2017 10:20:58 -0400 Subject: [PATCH V3 1/2] security: Add a cred_getsecid hook In-Reply-To: <20171026084055.25482-1-mjg59@google.com> References: <20171026084055.25482-1-mjg59@google.com> Message-ID: <1509027658.25604.4.camel@tycho.nsa.gov> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On Thu, 2017-10-26 at 01:40 -0700, Matthew Garrett via Selinux wrote: > 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 > Acked-by: Paul Moore > Cc: Paul Moore > Cc: Stephen Smalley > Cc: Eric Paris > Cc: selinux at tycho.nsa.gov > Cc: Casey Schaufler > Cc: linux-security-module at vger.kernel.org > Cc: Mimi Zohar > Cc: Dmitry Kasatkin > Cc: linux-integrity at vger.kernel.org > --- > ?V3: Fix smack_cred_getsecid() > > ?include/linux/lsm_hooks.h??|??6 ++++++ > ?include/linux/security.h???|??1 + > ?security/security.c????????|??7 +++++++ > ?security/selinux/hooks.c???|??8 ++++++++ > ?security/smack/smack_lsm.c | 18 ++++++++++++++++++ > ?5 files changed, 40 insertions(+) > > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > index c9258124e417..c28c6f8b65dc 100644 > --- a/include/linux/lsm_hooks.h > +++ b/include/linux/lsm_hooks.h > @@ -554,6 +554,10 @@ > ? * @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 > + * @c 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. > @@ -1507,6 +1511,7 @@ 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); > @@ -1779,6 +1784,7 @@ 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 ce6265960d6c..14848fef8f62 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 4bf0f571b4ef..02d217597400 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -1004,6 +1004,13 @@ 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 f5d304736852..1d11679674a6 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -3836,6 +3836,13 @@ 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(); Is rcu_read_lock() necessary here? Seems like we use cred_sid() in many places without it. > +} > + > ?/* > ? * set the security data for a kernel service > ? * - all the creation contexts are set to unlabelled > @@ -6338,6 +6345,7 @@ 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_lsm.c b/security/smack/smack_lsm.c > index 286171a16ed2..37c35aaa6955 100644 > --- a/security/smack/smack_lsm.c > +++ b/security/smack/smack_lsm.c > @@ -2049,6 +2049,23 @@ 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; > + > + rcu_read_lock(); > + skp = smk_of_task(c->security); > + *secid = skp->smk_secid; > + rcu_read_unlock(); > +} > + > ?/** > ? * smack_kernel_act_as - Set the subjective context in a set of > credentials > ? * @new: points to the set of credentials to be modified. > @@ -4651,6 +4668,7 @@ 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), -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html