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Commit 5e751e99 authored by David Howells's avatar David Howells Committed by James Morris
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CRED: Rename cred_exec_mutex to reflect that it's a guard against ptrace 



Rename cred_exec_mutex to reflect that it's a guard against foreign
intervention on a process's credential state, such as is made by ptrace().  The
attachment of a debugger to a process affects execve()'s calculation of the new
credential state - _and_ also setprocattr()'s calculation of that state.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent d2541170

fs/compat.c

+3 −3
Original line number Diff line number Diff line
@@ -1488,7 +1488,7 @@ int compat_do_execve(char * filename, 
	if (!bprm)

		goto out_files;



	retval = mutex_lock_interruptible(&current->cred_exec_mutex);

	retval = mutex_lock_interruptible(&current->cred_guard_mutex);

	if (retval < 0)

		goto out_free;

	current->in_execve = 1;
@@ -1550,7 +1550,7 @@ int compat_do_execve(char * filename, 
	/* execve succeeded */

	current->fs->in_exec = 0;

	current->in_execve = 0;

	mutex_unlock(&current->cred_exec_mutex);

	mutex_unlock(&current->cred_guard_mutex);

	acct_update_integrals(current);

	free_bprm(bprm);

	if (displaced)
@@ -1573,7 +1573,7 @@ int compat_do_execve(char * filename, 


out_unlock:

	current->in_execve = 0;

	mutex_unlock(&current->cred_exec_mutex);

	mutex_unlock(&current->cred_guard_mutex);



out_free:

	free_bprm(bprm);

fs/exec.c

+5 −5
Original line number Diff line number Diff line
@@ -1045,7 +1045,7 @@ void install_exec_creds(struct linux_binprm *bprm) 
	commit_creds(bprm->cred);

	bprm->cred = NULL;



	/* cred_exec_mutex must be held at least to this point to prevent

	/* cred_guard_mutex must be held at least to this point to prevent

	 * ptrace_attach() from altering our determination of the task's

	 * credentials; any time after this it may be unlocked */
@@ -1055,7 +1055,7 @@ EXPORT_SYMBOL(install_exec_creds); 


/*

 * determine how safe it is to execute the proposed program

 * - the caller must hold current->cred_exec_mutex to protect against

 * - the caller must hold current->cred_guard_mutex to protect against

 *   PTRACE_ATTACH

 */

int check_unsafe_exec(struct linux_binprm *bprm)
@@ -1297,7 +1297,7 @@ int do_execve(char * filename, 
	if (!bprm)

		goto out_files;



	retval = mutex_lock_interruptible(&current->cred_exec_mutex);

	retval = mutex_lock_interruptible(&current->cred_guard_mutex);

	if (retval < 0)

		goto out_free;

	current->in_execve = 1;
@@ -1360,7 +1360,7 @@ int do_execve(char * filename, 
	/* execve succeeded */

	current->fs->in_exec = 0;

	current->in_execve = 0;

	mutex_unlock(&current->cred_exec_mutex);

	mutex_unlock(&current->cred_guard_mutex);

	acct_update_integrals(current);

	free_bprm(bprm);

	if (displaced)
@@ -1383,7 +1383,7 @@ int do_execve(char * filename, 


out_unlock:

	current->in_execve = 0;

	mutex_unlock(&current->cred_exec_mutex);

	mutex_unlock(&current->cred_guard_mutex);



out_free:

	free_bprm(bprm);

include/linux/init_task.h

+2 −2
Original line number Diff line number Diff line
@@ -145,8 +145,8 @@ extern struct cred init_cred; 
	.group_leader	= &tsk,						\

	.real_cred	= &init_cred,					\

	.cred		= &init_cred,					\

	.cred_exec_mutex =						\

		 __MUTEX_INITIALIZER(tsk.cred_exec_mutex),		\

	.cred_guard_mutex =						\

		 __MUTEX_INITIALIZER(tsk.cred_guard_mutex),		\

	.comm		= "swapper",					\

	.thread		= INIT_THREAD,					\

	.fs		= &init_fs,					\

include/linux/sched.h

+3 −1
Original line number Diff line number Diff line
@@ -1247,7 +1247,9 @@ struct task_struct { 
					 * credentials (COW) */

	const struct cred *cred;	/* effective (overridable) subjective task

					 * credentials (COW) */

	struct mutex cred_exec_mutex;	/* execve vs ptrace cred calculation mutex */

	struct mutex cred_guard_mutex;	/* guard against foreign influences on

					 * credential calculations

					 * (notably. ptrace) */



	char comm[TASK_COMM_LEN]; /* executable name excluding path

				     - access with [gs]et_task_comm (which lock

kernel/cred.c

+2 −2
Original line number Diff line number Diff line
@@ -167,7 +167,7 @@ EXPORT_SYMBOL(prepare_creds); 


/*

 * Prepare credentials for current to perform an execve()

 * - The caller must hold current->cred_exec_mutex

 * - The caller must hold current->cred_guard_mutex

 */

struct cred *prepare_exec_creds(void)

{
@@ -276,7 +276,7 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags) 
	struct cred *new;

	int ret;



	mutex_init(&p->cred_exec_mutex);

	mutex_init(&p->cred_guard_mutex);



	if (

#ifdef CONFIG_KEYS