| Message ID | 20171016203709.11199-1-mjg59@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Mon, Oct 16, 2017 at 2:58 PM, Casey Schaufler <casey@schaufler-ca.com> wrote: > On 10/16/2017 1:37 PM, Matthew Garrett 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. > > Why do you want the secid? What are you planning to do with it? See the following patch - IMA policy allows the admin to restrict appraisal to executables running in specific security contexts. However, right now the check at application execution time ends up using the current task creds before the new creds are committed.
On Mon, Oct 16, 2017 at 4:37 PM, Matthew Garrett <mjg59@google.com> 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 <mjg59@google.com> > Cc: Paul Moore <paul@paul-moore.com> > Cc: Stephen Smalley <sds@tycho.nsa.gov> > Cc: Eric Paris <eparis@parisplace.org> > Cc: selinux@tycho.nsa.gov > Cc: Casey Schaufler <casey@schaufler-ca.com> > Cc: linux-security-module@vger.kernel.org > Cc: Mimi Zohar <zohar@linux.vnet.ibm.com> > Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com> > Cc: linux-integrity@vger.kernel.org > --- > 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(+) No argument from me on the SELinux/LSM bits: Acked-by: Paul Moore <paul@paul-moore.com> > 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 >
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),
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 <mjg59@google.com> Cc: Paul Moore <paul@paul-moore.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: Eric Paris <eparis@parisplace.org> Cc: selinux@tycho.nsa.gov Cc: Casey Schaufler <casey@schaufler-ca.com> Cc: linux-security-module@vger.kernel.org Cc: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com> Cc: linux-integrity@vger.kernel.org --- 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(+)