Merge tag 'secureexec-v4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull secureexec update from Kees Cook:
 "This series has the ultimate goal of providing a sane stack rlimit
  when running set*id processes.

  To do this, the bprm_secureexec LSM hook is collapsed into the
  bprm_set_creds hook so the secureexec-ness of an exec can be
  determined early enough to make decisions about rlimits and the
  resulting memory layouts. Other logic acting on the secureexec-ness of
  an exec is similarly consolidated. Capabilities needed some special
  handling, but the refactoring removed other special handling, so that
  was a wash"

* tag 'secureexec-v4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  exec: Consolidate pdeath_signal clearing
  exec: Use sane stack rlimit under secureexec
  exec: Consolidate dumpability logic
  smack: Remove redundant pdeath_signal clearing
  exec: Use secureexec for clearing pdeath_signal
  exec: Use secureexec for setting dumpability
  LSM: drop bprm_secureexec hook
  commoncap: Move cap_elevated calculation into bprm_set_creds
  commoncap: Refactor to remove bprm_secureexec hook
  smack: Refactor to remove bprm_secureexec hook
  selinux: Refactor to remove bprm_secureexec hook
  apparmor: Refactor to remove bprm_secureexec hook
  binfmt: Introduce secureexec flag
  exec: Correct comments about "point of no return"
  exec: Rename bprm->cred_prepared to called_set_creds

9 files changed, 23 insertions, 120 deletions

diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index d0594446ae3f..17a601c67b62 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -758,7 +758,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 		file_inode(bprm->file)->i_mode
 	};
 
-	if (bprm->cred_prepared)
+	if (bprm->called_set_creds)
 		return 0;
 
 	ctx = cred_ctx(bprm->cred);
@@ -807,7 +807,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 			aa_label_printk(new, GFP_ATOMIC);
 			dbg_printk("\n");
 		}
-		bprm->unsafe |= AA_SECURE_X_NEEDED;
+		bprm->secureexec = 1;
 	}
 
 	if (label->proxy != new->proxy) {
@@ -843,23 +843,6 @@ audit:
 	goto done;
 }
 
-/**
- * apparmor_bprm_secureexec - determine if secureexec is needed
- * @bprm: binprm for exec  (NOT NULL)
- *
- * Returns: %1 if secureexec is needed else %0
- */
-int apparmor_bprm_secureexec(struct linux_binprm *bprm)
-{
-	/* the decision to use secure exec is computed in set_creds
-	 * and stored in bprm->unsafe.
-	 */
-	if (bprm->unsafe & AA_SECURE_X_NEEDED)
-		return 1;
-
-	return 0;
-}
-
 /*
  * Functions for self directed profile change
  */
diff --git a/security/apparmor/include/domain.h b/security/apparmor/include/domain.h
index bab5810b6e9a..24c5976d6143 100644
--- a/security/apparmor/include/domain.h
+++ b/security/apparmor/include/domain.h
@@ -30,7 +30,6 @@ struct aa_domain {
 #define AA_CHANGE_STACK 8
 
 int apparmor_bprm_set_creds(struct linux_binprm *bprm);
-int apparmor_bprm_secureexec(struct linux_binprm *bprm);
 
 void aa_free_domain_entries(struct aa_domain *domain);
 int aa_change_hat(const char *hats[], int count, u64 token, int flags);
diff --git a/security/apparmor/include/file.h b/security/apparmor/include/file.h
index 001e40073ff9..4c2c8ac8842f 100644
--- a/security/apparmor/include/file.h
+++ b/security/apparmor/include/file.h
@@ -101,9 +101,6 @@ static inline struct aa_label *aa_get_file_label(struct aa_file_ctx *ctx)
 #define AA_X_INHERIT		0x4000
 #define AA_X_UNCONFINED		0x8000
 
-/* AA_SECURE_X_NEEDED - is passed in the bprm->unsafe field */
-#define AA_SECURE_X_NEEDED	0x8000
-
 /* need to make conditional which ones are being set */
 struct path_cond {
 	kuid_t uid;
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 867bcd154c7e..7a82c0f61452 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -694,7 +694,6 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(bprm_set_creds, apparmor_bprm_set_creds),
 	LSM_HOOK_INIT(bprm_committing_creds, apparmor_bprm_committing_creds),
 	LSM_HOOK_INIT(bprm_committed_creds, apparmor_bprm_committed_creds),
-	LSM_HOOK_INIT(bprm_secureexec, apparmor_bprm_secureexec),
 
 	LSM_HOOK_INIT(task_setrlimit, apparmor_task_setrlimit),
 };
diff --git a/security/commoncap.c b/security/commoncap.c
index 7abebd782d5e..d8e26fb9781d 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -285,15 +285,6 @@ int cap_capset(struct cred *new,
 	return 0;
 }
 
-/*
- * Clear proposed capability sets for execve().
- */
-static inline void bprm_clear_caps(struct linux_binprm *bprm)
-{
-	cap_clear(bprm->cred->cap_permitted);
-	bprm->cap_effective = false;
-}
-
 /**
  * cap_inode_need_killpriv - Determine if inode change affects privileges
  * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
@@ -443,7 +434,7 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_c
 	int rc = 0;
 	struct cpu_vfs_cap_data vcaps;
 
-	bprm_clear_caps(bprm);
+	cap_clear(bprm->cred->cap_permitted);
 
 	if (!file_caps_enabled)
 		return 0;
@@ -476,7 +467,7 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_c
 
 out:
 	if (rc)
-		bprm_clear_caps(bprm);
+		cap_clear(bprm->cred->cap_permitted);
 
 	return rc;
 }
@@ -585,8 +576,6 @@ skip:
 	if (WARN_ON(!cap_ambient_invariant_ok(new)))
 		return -EPERM;
 
-	bprm->cap_effective = effective;
-
 	/*
 	 * Audit candidate if current->cap_effective is set
 	 *
@@ -614,33 +603,17 @@ skip:
 	if (WARN_ON(!cap_ambient_invariant_ok(new)))
 		return -EPERM;
 
-	return 0;
-}
-
-/**
- * cap_bprm_secureexec - Determine whether a secure execution is required
- * @bprm: The execution parameters
- *
- * Determine whether a secure execution is required, return 1 if it is, and 0
- * if it is not.
- *
- * The credentials have been committed by this point, and so are no longer
- * available through @bprm->cred.
- */
-int cap_bprm_secureexec(struct linux_binprm *bprm)
-{
-	const struct cred *cred = current_cred();
-	kuid_t root_uid = make_kuid(cred->user_ns, 0);
-
-	if (!uid_eq(cred->uid, root_uid)) {
-		if (bprm->cap_effective)
-			return 1;
-		if (!cap_issubset(cred->cap_permitted, cred->cap_ambient))
-			return 1;
+	/* Check for privilege-elevated exec. */
+	bprm->cap_elevated = 0;
+	if (is_setid) {
+		bprm->cap_elevated = 1;
+	} else if (!uid_eq(new->uid, root_uid)) {
+		if (effective ||
+		    !cap_issubset(new->cap_permitted, new->cap_ambient))
+			bprm->cap_elevated = 1;
 	}
 
-	return (!uid_eq(cred->euid, cred->uid) ||
-		!gid_eq(cred->egid, cred->gid));
+	return 0;
 }
 
 /**
@@ -1079,7 +1052,6 @@ struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(capget, cap_capget),
 	LSM_HOOK_INIT(capset, cap_capset),
 	LSM_HOOK_INIT(bprm_set_creds, cap_bprm_set_creds),
-	LSM_HOOK_INIT(bprm_secureexec, cap_bprm_secureexec),
 	LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
 	LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
 	LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
diff --git a/security/security.c b/security/security.c
index 30132378d103..afc34f46c6c5 100644
--- a/security/security.c
+++ b/security/security.c
@@ -351,11 +351,6 @@ void security_bprm_committed_creds(struct linux_binprm *bprm)
 	call_void_hook(bprm_committed_creds, bprm);
 }
 
-int security_bprm_secureexec(struct linux_binprm *bprm)
-{
-	return call_int_hook(bprm_secureexec, 0, bprm);
-}
-
 int security_sb_alloc(struct super_block *sb)
 {
 	return call_int_hook(sb_alloc_security, 0, sb);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 2f2e1338cd3d..ad3b0f53ede0 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2356,7 +2356,7 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
 
 	/* SELinux context only depends on initial program or script and not
 	 * the script interpreter */
-	if (bprm->cred_prepared)
+	if (bprm->called_set_creds)
 		return 0;
 
 	old_tsec = current_security();
@@ -2442,30 +2442,17 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
 
 		/* Clear any possibly unsafe personality bits on exec: */
 		bprm->per_clear |= PER_CLEAR_ON_SETID;
-	}
-
-	return 0;
-}
-
-static int selinux_bprm_secureexec(struct linux_binprm *bprm)
-{
-	const struct task_security_struct *tsec = current_security();
-	u32 sid, osid;
-	int atsecure = 0;
-
-	sid = tsec->sid;
-	osid = tsec->osid;
 
-	if (osid != sid) {
 		/* Enable secure mode for SIDs transitions unless
 		   the noatsecure permission is granted between
 		   the two SIDs, i.e. ahp returns 0. */
-		atsecure = avc_has_perm(osid, sid,
-					SECCLASS_PROCESS,
-					PROCESS__NOATSECURE, NULL);
+		rc = avc_has_perm(old_tsec->sid, new_tsec->sid,
+				  SECCLASS_PROCESS, PROCESS__NOATSECURE,
+				  NULL);
+		bprm->secureexec |= !!rc;
 	}
 
-	return !!atsecure;
+	return 0;
 }
 
 static int match_file(const void *p, struct file *file, unsigned fd)
@@ -6266,7 +6253,6 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(bprm_set_creds, selinux_bprm_set_creds),
 	LSM_HOOK_INIT(bprm_committing_creds, selinux_bprm_committing_creds),
 	LSM_HOOK_INIT(bprm_committed_creds, selinux_bprm_committed_creds),
-	LSM_HOOK_INIT(bprm_secureexec, selinux_bprm_secureexec),
 
 	LSM_HOOK_INIT(sb_alloc_security, selinux_sb_alloc_security),
 	LSM_HOOK_INIT(sb_free_security, selinux_sb_free_security),
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 463af86812c7..319add31b4a4 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -917,7 +917,7 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)
 	struct superblock_smack *sbsp;
 	int rc;
 
-	if (bprm->cred_prepared)
+	if (bprm->called_set_creds)
 		return 0;
 
 	isp = inode->i_security;
@@ -950,35 +950,9 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)
 	bsp->smk_task = isp->smk_task;
 	bprm->per_clear |= PER_CLEAR_ON_SETID;
 
-	return 0;
-}
-
-/**
- * smack_bprm_committing_creds - Prepare to install the new credentials
- * from bprm.
- *
- * @bprm: binprm for exec
- */
-static void smack_bprm_committing_creds(struct linux_binprm *bprm)
-{
-	struct task_smack *bsp = bprm->cred->security;
-
+	/* Decide if this is a secure exec. */
 	if (bsp->smk_task != bsp->smk_forked)
-		current->pdeath_signal = 0;
-}
-
-/**
- * smack_bprm_secureexec - Return the decision to use secureexec.
- * @bprm: binprm for exec
- *
- * Returns 0 on success.
- */
-static int smack_bprm_secureexec(struct linux_binprm *bprm)
-{
-	struct task_smack *tsp = current_security();
-
-	if (tsp->smk_task != tsp->smk_forked)
-		return 1;
+		bprm->secureexec = 1;
 
 	return 0;
 }
@@ -4645,8 +4619,6 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(sb_parse_opts_str, smack_parse_opts_str),
 
 	LSM_HOOK_INIT(bprm_set_creds, smack_bprm_set_creds),
-	LSM_HOOK_INIT(bprm_committing_creds, smack_bprm_committing_creds),
-	LSM_HOOK_INIT(bprm_secureexec, smack_bprm_secureexec),
 
 	LSM_HOOK_INIT(inode_alloc_security, smack_inode_alloc_security),
 	LSM_HOOK_INIT(inode_free_security, smack_inode_free_security),
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index 130b4fa4f65f..d25b705360e0 100644
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -76,7 +76,7 @@ static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
 	 * Do only if this function is called for the first time of an execve
 	 * operation.
 	 */
-	if (bprm->cred_prepared)
+	if (bprm->called_set_creds)
 		return 0;
 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
 	/*