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Commit 3ec30113 authored by Matthew Garrett's avatar Matthew Garrett Committed by Mimi Zohar
Browse files

security: Add a cred_getsecid hook 



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: default avatarMatthew Garrett <mjg59@google.com>
Acked-by: default avatarPaul Moore <paul@paul-moore.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: default avatarMimi Zohar <zohar@linux.vnet.ibm.com>
parent 5893ed18

include/linux/lsm_hooks.h

+6 −0
Original line number Diff line number Diff line
@@ -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.
@@ -1542,6 +1546,7 @@ 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);
@@ -1825,6 +1830,7 @@ 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;

include/linux/security.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

security/security.c

+7 −0
Original line number Diff line number Diff line
@@ -1005,6 +1005,13 @@ 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);

security/selinux/hooks.c

+6 −0
Original line number Diff line number Diff line
@@ -3844,6 +3844,11 @@ 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)

{

	*secid = cred_sid(c);

}



/*

 * set the security data for a kernel service

 * - all the creation contexts are set to unlabelled
@@ -6482,6 +6487,7 @@ 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),

security/smack/smack_lsm.c

+18 −0
Original line number Diff line number Diff line
@@ -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.
@@ -4733,6 +4750,7 @@ 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),