lsm: separate security_task_getsecid() into subjective and objective variants

Of the three LSMs that implement the security_task_getsecid() LSM
hook, all three LSMs provide the task's objective security
credentials.  This turns out to be unfortunate as most of the hook's
callers seem to expect the task's subjective credentials, although
a small handful of callers do correctly expect the objective
credentials.

This patch is the first step towards fixing the problem: it splits
the existing security_task_getsecid() hook into two variants, one
for the subjective creds, one for the objective creds.

  void security_task_getsecid_subj(struct task_struct *p,
				   u32 *secid);
  void security_task_getsecid_obj(struct task_struct *p,
				  u32 *secid);

While this patch does fix all of the callers to use the correct
variant, in order to keep this patch focused on the callers and to
ease review, the LSMs continue to use the same implementation for
both hooks.  The net effect is that this patch should not change
the behavior of the kernel in any way, it will be up to the latter
LSM specific patches in this series to change the hook
implementations and return the correct credentials.

Acked-by: Mimi Zohar <zohar@linux.ibm.com> (IMA)
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

6 files changed, 24 insertions, 14 deletions

diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 240a53387e6b..f72406fe1bf2 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1252,7 +1252,8 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
 
 	LSM_HOOK_INIT(task_free, apparmor_task_free),
 	LSM_HOOK_INIT(task_alloc, apparmor_task_alloc),
-	LSM_HOOK_INIT(task_getsecid, apparmor_task_getsecid),
+	LSM_HOOK_INIT(task_getsecid_subj, apparmor_task_getsecid),
+	LSM_HOOK_INIT(task_getsecid_obj, apparmor_task_getsecid),
 	LSM_HOOK_INIT(task_setrlimit, apparmor_task_setrlimit),
 	LSM_HOOK_INIT(task_kill, apparmor_task_kill),
 
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 565e33ff19d0..4e5eb0236278 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -76,7 +76,7 @@ int ima_must_appraise(struct user_namespace *mnt_userns, struct inode *inode,
 	if (!ima_appraise)
 		return 0;
 
-	security_task_getsecid(current, &secid);
+	security_task_getsecid_subj(current, &secid);
 	return ima_match_policy(mnt_userns, inode, current_cred(), secid, func,
 				mask, IMA_APPRAISE | IMA_HASH, NULL, NULL, NULL);
 }
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 9ef748ea829f..b85d9e429426 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -391,7 +391,7 @@ int ima_file_mmap(struct file *file, unsigned long prot)
 	u32 secid;
 
 	if (file && (prot & PROT_EXEC)) {
-		security_task_getsecid(current, &secid);
+		security_task_getsecid_subj(current, &secid);
 		return process_measurement(file, current_cred(), secid, NULL,
 					   0, MAY_EXEC, MMAP_CHECK);
 	}
@@ -429,7 +429,7 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
 	    !(prot & PROT_EXEC) || (vma->vm_flags & VM_EXEC))
 		return 0;
 
-	security_task_getsecid(current, &secid);
+	security_task_getsecid_subj(current, &secid);
 	inode = file_inode(vma->vm_file);
 	action = ima_get_action(file_mnt_user_ns(vma->vm_file), inode,
 				current_cred(), secid, MAY_EXEC, MMAP_CHECK,
@@ -470,7 +470,7 @@ int ima_bprm_check(struct linux_binprm *bprm)
 	int ret;
 	u32 secid;
 
-	security_task_getsecid(current, &secid);
+	security_task_getsecid_subj(current, &secid);
 	ret = process_measurement(bprm->file, current_cred(), secid, NULL, 0,
 				  MAY_EXEC, BPRM_CHECK);
 	if (ret)
@@ -495,7 +495,7 @@ int ima_file_check(struct file *file, int mask)
 {
 	u32 secid;
 
-	security_task_getsecid(current, &secid);
+	security_task_getsecid_subj(current, &secid);
 	return process_measurement(file, current_cred(), secid, NULL, 0,
 				   mask & (MAY_READ | MAY_WRITE | MAY_EXEC |
 					   MAY_APPEND), FILE_CHECK);
@@ -686,7 +686,7 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id,
 
 	/* Read entire file for all partial reads. */
 	func = read_idmap[read_id] ?: FILE_CHECK;
-	security_task_getsecid(current, &secid);
+	security_task_getsecid_subj(current, &secid);
 	return process_measurement(file, current_cred(), secid, NULL,
 				   0, MAY_READ, func);
 }
@@ -729,7 +729,7 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
 	}
 
 	func = read_idmap[read_id] ?: FILE_CHECK;
-	security_task_getsecid(current, &secid);
+	security_task_getsecid_subj(current, &secid);
 	return process_measurement(file, current_cred(), secid, buf, size,
 				   MAY_READ, func);
 }
@@ -872,7 +872,7 @@ void process_buffer_measurement(struct user_namespace *mnt_userns,
 	 * buffer measurements.
 	 */
 	if (func) {
-		security_task_getsecid(current, &secid);
+		security_task_getsecid_subj(current, &secid);
 		action = ima_get_action(mnt_userns, inode, current_cred(),
 					secid, 0, func, &pcr, &template,
 					func_data);
diff --git a/security/security.c b/security/security.c
index a4e7d50c3e39..94383f83ba42 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1769,12 +1769,19 @@ int security_task_getsid(struct task_struct *p)
 	return call_int_hook(task_getsid, 0, p);
 }
 
-void security_task_getsecid(struct task_struct *p, u32 *secid)
+void security_task_getsecid_subj(struct task_struct *p, u32 *secid)
 {
 	*secid = 0;
-	call_void_hook(task_getsecid, p, secid);
+	call_void_hook(task_getsecid_subj, p, secid);
 }
-EXPORT_SYMBOL(security_task_getsecid);
+EXPORT_SYMBOL(security_task_getsecid_subj);
+
+void security_task_getsecid_obj(struct task_struct *p, u32 *secid)
+{
+	*secid = 0;
+	call_void_hook(task_getsecid_obj, p, secid);
+}
+EXPORT_SYMBOL(security_task_getsecid_obj);
 
 int security_task_setnice(struct task_struct *p, int nice)
 {
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 07ca2ebf979e..327dbc3acefc 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -7205,7 +7205,8 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(task_setpgid, selinux_task_setpgid),
 	LSM_HOOK_INIT(task_getpgid, selinux_task_getpgid),
 	LSM_HOOK_INIT(task_getsid, selinux_task_getsid),
-	LSM_HOOK_INIT(task_getsecid, selinux_task_getsecid),
+	LSM_HOOK_INIT(task_getsecid_subj, selinux_task_getsecid),
+	LSM_HOOK_INIT(task_getsecid_obj, selinux_task_getsecid),
 	LSM_HOOK_INIT(task_setnice, selinux_task_setnice),
 	LSM_HOOK_INIT(task_setioprio, selinux_task_setioprio),
 	LSM_HOOK_INIT(task_getioprio, selinux_task_getioprio),
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 12a45e61c1a5..f546fb832f30 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4759,7 +4759,8 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(task_setpgid, smack_task_setpgid),
 	LSM_HOOK_INIT(task_getpgid, smack_task_getpgid),
 	LSM_HOOK_INIT(task_getsid, smack_task_getsid),
-	LSM_HOOK_INIT(task_getsecid, smack_task_getsecid),
+	LSM_HOOK_INIT(task_getsecid_subj, smack_task_getsecid),
+	LSM_HOOK_INIT(task_getsecid_obj, smack_task_getsecid),
 	LSM_HOOK_INIT(task_setnice, smack_task_setnice),
 	LSM_HOOK_INIT(task_setioprio, smack_task_setioprio),
 	LSM_HOOK_INIT(task_getioprio, smack_task_getioprio),