Merge branch 'exec-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull execve updates from Eric Biederman:
 "Last cycle for the Nth time I ran into bugs and quality of
  implementation issues related to exec that could not be easily be
  fixed because of the way exec is implemented. So I have been digging
  into exec and cleanup up what I can.

  I don't think I have exec sorted out enough to fix the issues I
  started with but I have made some headway this cycle with 4 sets of
  changes.

   - promised cleanups after introducing exec_update_mutex

   - trivial cleanups for exec

   - control flow simplifications

   - remove the recomputation of bprm->cred

  The net result is code that is a bit easier to understand and work
  with and a decrease in the number of lines of code (if you don't count
  the added tests)"

* 'exec-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (24 commits)
  exec: Compute file based creds only once
  exec: Add a per bprm->file version of per_clear
  binfmt_elf_fdpic: fix execfd build regression
  selftests/exec: Add binfmt_script regression test
  exec: Remove recursion from search_binary_handler
  exec: Generic execfd support
  exec/binfmt_script: Don't modify bprm->buf and then return -ENOEXEC
  exec: Move the call of prepare_binprm into search_binary_handler
  exec: Allow load_misc_binary to call prepare_binprm unconditionally
  exec: Convert security_bprm_set_creds into security_bprm_repopulate_creds
  exec: Factor security_bprm_creds_for_exec out of security_bprm_set_creds
  exec: Teach prepare_exec_creds how exec treats uids & gids
  exec: Set the point of no return sooner
  exec: Move handling of the point of no return to the top level
  exec: Run sync_mm_rss before taking exec_update_mutex
  exec: Fix spelling of search_binary_handler in a comment
  exec: Move the comment from above de_thread to above unshare_sighand
  exec: Rename flush_old_exec begin_new_exec
  exec: Move most of setup_new_exec into flush_old_exec
  exec: In setup_new_exec cache current in the local variable me
  ...

8 files changed, 32 insertions, 40 deletions

diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index a84ef030fbd7d1..745a1cf490031a 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -854,14 +854,14 @@ static struct aa_label *handle_onexec(struct aa_label *label,
 }
 
 /**
- * apparmor_bprm_set_creds - set the new creds on the bprm struct
+ * apparmor_bprm_creds_for_exec - Update the new creds on the bprm struct
  * @bprm: binprm for the exec  (NOT NULL)
  *
  * Returns: %0 or error on failure
  *
  * TODO: once the other paths are done see if we can't refactor into a fn
  */
-int apparmor_bprm_set_creds(struct linux_binprm *bprm)
+int apparmor_bprm_creds_for_exec(struct linux_binprm *bprm)
 {
 	struct aa_task_ctx *ctx;
 	struct aa_label *label, *new = NULL;
@@ -875,9 +875,6 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 		file_inode(bprm->file)->i_mode
 	};
 
-	if (bprm->called_set_creds)
-		return 0;
-
 	ctx = task_ctx(current);
 	AA_BUG(!cred_label(bprm->cred));
 	AA_BUG(!ctx);
diff --git a/security/apparmor/include/domain.h b/security/apparmor/include/domain.h
index 21b875fe2d3756..d14928fe1c6f16 100644
--- a/security/apparmor/include/domain.h
+++ b/security/apparmor/include/domain.h
@@ -30,7 +30,7 @@ struct aa_domain {
 struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
 				const char **name);
 
-int apparmor_bprm_set_creds(struct linux_binprm *bprm);
+int apparmor_bprm_creds_for_exec(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/lsm.c b/security/apparmor/lsm.c
index 27e371b44dad8f..ef6f7002af2896 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1232,7 +1232,7 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(cred_prepare, apparmor_cred_prepare),
 	LSM_HOOK_INIT(cred_transfer, apparmor_cred_transfer),
 
-	LSM_HOOK_INIT(bprm_set_creds, apparmor_bprm_set_creds),
+	LSM_HOOK_INIT(bprm_creds_for_exec, apparmor_bprm_creds_for_exec),
 	LSM_HOOK_INIT(bprm_committing_creds, apparmor_bprm_committing_creds),
 	LSM_HOOK_INIT(bprm_committed_creds, apparmor_bprm_committed_creds),
 
diff --git a/security/commoncap.c b/security/commoncap.c
index 0ca31c8bc0b13b..59bf3c1674c8b4 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -647,7 +647,8 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data
  * its xattrs and, if present, apply them to the proposed credentials being
  * constructed by execve().
  */
-static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_fcap)
+static int get_file_caps(struct linux_binprm *bprm, struct file *file,
+			 bool *effective, bool *has_fcap)
 {
 	int rc = 0;
 	struct cpu_vfs_cap_data vcaps;
@@ -657,7 +658,7 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_f
 	if (!file_caps_enabled)
 		return 0;
 
-	if (!mnt_may_suid(bprm->file->f_path.mnt))
+	if (!mnt_may_suid(file->f_path.mnt))
 		return 0;
 
 	/*
@@ -665,10 +666,10 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_f
 	 * explicit that capability bits are limited to s_user_ns and its
 	 * descendants.
 	 */
-	if (!current_in_userns(bprm->file->f_path.mnt->mnt_sb->s_user_ns))
+	if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns))
 		return 0;
 
-	rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps);
+	rc = get_vfs_caps_from_disk(file->f_path.dentry, &vcaps);
 	if (rc < 0) {
 		if (rc == -EINVAL)
 			printk(KERN_NOTICE "Invalid argument reading file caps for %s\n",
@@ -797,26 +798,27 @@ static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old,
 }
 
 /**
- * cap_bprm_set_creds - Set up the proposed credentials for execve().
+ * cap_bprm_creds_from_file - Set up the proposed credentials for execve().
  * @bprm: The execution parameters, including the proposed creds
+ * @file: The file to pull the credentials from
  *
  * Set up the proposed credentials for a new execution context being
  * constructed by execve().  The proposed creds in @bprm->cred is altered,
  * which won't take effect immediately.  Returns 0 if successful, -ve on error.
  */
-int cap_bprm_set_creds(struct linux_binprm *bprm)
+int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file)
 {
+	/* Process setpcap binaries and capabilities for uid 0 */
 	const struct cred *old = current_cred();
 	struct cred *new = bprm->cred;
 	bool effective = false, has_fcap = false, is_setid;
 	int ret;
 	kuid_t root_uid;
 
-	new->cap_ambient = old->cap_ambient;
 	if (WARN_ON(!cap_ambient_invariant_ok(old)))
 		return -EPERM;
 
-	ret = get_file_caps(bprm, &effective, &has_fcap);
+	ret = get_file_caps(bprm, file, &effective, &has_fcap);
 	if (ret < 0)
 		return ret;
 
@@ -885,12 +887,11 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
 		return -EPERM;
 
 	/* Check for privilege-elevated exec. */
-	bprm->cap_elevated = 0;
 	if (is_setid ||
 	    (!__is_real(root_uid, new) &&
 	     (effective ||
 	      __cap_grew(permitted, ambient, new))))
-		bprm->cap_elevated = 1;
+		bprm->secureexec = 1;
 
 	return 0;
 }
@@ -1347,7 +1348,7 @@ static struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
 	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_creds_from_file, cap_bprm_creds_from_file),
 	LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
 	LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
 	LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity),
diff --git a/security/security.c b/security/security.c
index 51de970fbb1edf..11c1a7da4fd1f8 100644
--- a/security/security.c
+++ b/security/security.c
@@ -823,9 +823,14 @@ int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
 	return __vm_enough_memory(mm, pages, cap_sys_admin);
 }
 
-int security_bprm_set_creds(struct linux_binprm *bprm)
+int security_bprm_creds_for_exec(struct linux_binprm *bprm)
 {
-	return call_int_hook(bprm_set_creds, 0, bprm);
+	return call_int_hook(bprm_creds_for_exec, 0, bprm);
+}
+
+int security_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file)
+{
+	return call_int_hook(bprm_creds_from_file, 0, bprm, file);
 }
 
 int security_bprm_check(struct linux_binprm *bprm)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 4c037c2545c161..7e954b555be687 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2286,7 +2286,7 @@ static int check_nnp_nosuid(const struct linux_binprm *bprm,
 	return -EACCES;
 }
 
-static int selinux_bprm_set_creds(struct linux_binprm *bprm)
+static int selinux_bprm_creds_for_exec(struct linux_binprm *bprm)
 {
 	const struct task_security_struct *old_tsec;
 	struct task_security_struct *new_tsec;
@@ -2297,8 +2297,6 @@ 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->called_set_creds)
-		return 0;
 
 	old_tsec = selinux_cred(current_cred());
 	new_tsec = selinux_cred(bprm->cred);
@@ -6405,7 +6403,7 @@ static int selinux_setprocattr(const char *name, void *value, size_t size)
 	/* Permission checking based on the specified context is
 	   performed during the actual operation (execve,
 	   open/mkdir/...), when we know the full context of the
-	   operation.  See selinux_bprm_set_creds for the execve
+	   operation.  See selinux_bprm_creds_for_exec for the execve
 	   checks and may_create for the file creation checks. The
 	   operation will then fail if the context is not permitted. */
 	tsec = selinux_cred(new);
@@ -6934,7 +6932,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 
 	LSM_HOOK_INIT(netlink_send, selinux_netlink_send),
 
-	LSM_HOOK_INIT(bprm_set_creds, selinux_bprm_set_creds),
+	LSM_HOOK_INIT(bprm_creds_for_exec, selinux_bprm_creds_for_exec),
 	LSM_HOOK_INIT(bprm_committing_creds, selinux_bprm_committing_creds),
 	LSM_HOOK_INIT(bprm_committed_creds, selinux_bprm_committed_creds),
 
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 6d4883a43fffe8..cd44b79bf1f577 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -887,12 +887,12 @@ static int smack_sb_statfs(struct dentry *dentry)
  */
 
 /**
- * smack_bprm_set_creds - set creds for exec
+ * smack_bprm_creds_for_exec - Update bprm->cred if needed for exec
  * @bprm: the exec information
  *
  * Returns 0 if it gets a blob, -EPERM if exec forbidden and -ENOMEM otherwise
  */
-static int smack_bprm_set_creds(struct linux_binprm *bprm)
+static int smack_bprm_creds_for_exec(struct linux_binprm *bprm)
 {
 	struct inode *inode = file_inode(bprm->file);
 	struct task_smack *bsp = smack_cred(bprm->cred);
@@ -900,9 +900,6 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)
 	struct superblock_smack *sbsp;
 	int rc;
 
-	if (bprm->called_set_creds)
-		return 0;
-
 	isp = smack_inode(inode);
 	if (isp->smk_task == NULL || isp->smk_task == bsp->smk_task)
 		return 0;
@@ -4584,7 +4581,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(sb_statfs, smack_sb_statfs),
 	LSM_HOOK_INIT(sb_set_mnt_opts, smack_set_mnt_opts),
 
-	LSM_HOOK_INIT(bprm_set_creds, smack_bprm_set_creds),
+	LSM_HOOK_INIT(bprm_creds_for_exec, smack_bprm_creds_for_exec),
 
 	LSM_HOOK_INIT(inode_alloc_security, smack_inode_alloc_security),
 	LSM_HOOK_INIT(inode_init_security, smack_inode_init_security),
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index 716c92ec941adc..f9adddc42ac8de 100644
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -63,21 +63,15 @@ static void tomoyo_bprm_committed_creds(struct linux_binprm *bprm)
 
 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
 /**
- * tomoyo_bprm_set_creds - Target for security_bprm_set_creds().
+ * tomoyo_bprm_for_exec - Target for security_bprm_creds_for_exec().
  *
  * @bprm: Pointer to "struct linux_binprm".
  *
  * Returns 0.
  */
-static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
+static int tomoyo_bprm_creds_for_exec(struct linux_binprm *bprm)
 {
 	/*
-	 * Do only if this function is called for the first time of an execve
-	 * operation.
-	 */
-	if (bprm->called_set_creds)
-		return 0;
-	/*
 	 * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
 	 * for the first time.
 	 */
@@ -539,7 +533,7 @@ static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(task_alloc, tomoyo_task_alloc),
 	LSM_HOOK_INIT(task_free, tomoyo_task_free),
 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
-	LSM_HOOK_INIT(bprm_set_creds, tomoyo_bprm_set_creds),
+	LSM_HOOK_INIT(bprm_creds_for_exec, tomoyo_bprm_creds_for_exec),
 #endif
 	LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
 	LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),