Re: your mail

[Casey Schaufler <casey@schaufler-ca.com>]

Ingo Molnar wrote:
> * James Morris <jmorris@namei.org> wrote:
>
>   
>> On Thu, 7 May 2009, Chris Wright wrote:
>>
>>     
>>> * Ingo Molnar (mingo@elte.hu) wrote:
>>>       
>> [Added LSM list to the CC; please do so whenever making changes in this 
>> area...]
>>
>>     
>>>> They have no active connection to the core kernel 
>>>> ptrace_may_access() check in any case:
>>>>         
>>> Not sure what you mean:
>>>
>>> ptrace_may_access
>>>  __ptrace_may_access
>>>   security_ptrace_may_access
>>>
>>> Looks like your patch won't compile.
>>>
>>>       
>> Below is an updated version which fixes the bug, against 
>> git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6#next
>>
>> Boot tested with SELinux.
>>     
>
> thanks! Below are the two patches i wrote and tested.
>   

I hate to make an assumption regarding whether or not your tests
included Smack, so I'll ask. Does tested mean with Smack?

Thank you.

> 	Ingo
>
> ----- Forwarded message from Ingo Molnar <mingo@elte.hu> -----
>
> Date: Thu, 7 May 2009 11:49:47 +0200
> From: Ingo Molnar <mingo@elte.hu>
> To: Chris Wright <chrisw@sous-sol.org>
> Subject: [patch 1/2] ptrace, security: rename ptrace_may_access =>
> 	ptrace_access_check
> Cc: Oleg Nesterov <oleg@redhat.com>, Roland McGrath <roland@redhat.com>,
> 	Andrew Morton <akpm@linux-foundation.org>,
> 	linux-kernel@vger.kernel.org, Al Viro <viro@ZenIV.linux.org.uk>
>
> The ptrace_may_access() methods are named confusingly - some 
> variants return a bool, while the security subsystem methods have a 
> retval convention.
>
> Rename it to ptrace_access_check, to reduce the confusion factor. A 
> followup patch eliminates the bool usage.
>
> [ Impact: cleanup, no code changed ]
>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> Cc: Roland McGrath <roland@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Chris Wright <chrisw@sous-sol.org>
> Cc: Al Viro <viro@ZenIV.linux.org.uk>
> Cc: Oleg Nesterov <oleg@redhat.com>
> LKML-Reference: <20090507084943.GB19133@elte.hu>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
>  fs/proc/array.c            |    2 +-
>  fs/proc/base.c             |   10 +++++-----
>  fs/proc/task_mmu.c         |    2 +-
>  include/linux/ptrace.h     |    4 ++--
>  include/linux/security.h   |   14 +++++++-------
>  kernel/ptrace.c            |   10 +++++-----
>  security/capability.c      |    2 +-
>  security/commoncap.c       |    4 ++--
>  security/root_plug.c       |    2 +-
>  security/security.c        |    4 ++--
>  security/selinux/hooks.c   |    6 +++---
>  security/smack/smack_lsm.c |    8 ++++----
>  12 files changed, 34 insertions(+), 34 deletions(-)
>
> Index: linux/fs/proc/array.c
> ===================================================================
> --- linux.orig/fs/proc/array.c
> +++ linux/fs/proc/array.c
> @@ -366,7 +366,7 @@ static int do_task_stat(struct seq_file 
>  
>  	state = *get_task_state(task);
>  	vsize = eip = esp = 0;
> -	permitted = ptrace_may_access(task, PTRACE_MODE_READ);
> +	permitted = ptrace_access_check(task, PTRACE_MODE_READ);
>  	mm = get_task_mm(task);
>  	if (mm) {
>  		vsize = task_vsize(mm);
> Index: linux/fs/proc/base.c
> ===================================================================
> --- linux.orig/fs/proc/base.c
> +++ linux/fs/proc/base.c
> @@ -222,7 +222,7 @@ static int check_mem_permission(struct t
>  		rcu_read_lock();
>  		match = (tracehook_tracer_task(task) == current);
>  		rcu_read_unlock();
> -		if (match && ptrace_may_access(task, PTRACE_MODE_ATTACH))
> +		if (match && ptrace_access_check(task, PTRACE_MODE_ATTACH))
>  			return 0;
>  	}
>  
> @@ -242,7 +242,7 @@ struct mm_struct *mm_for_maps(struct tas
>  	if (task->mm != mm)
>  		goto out;
>  	if (task->mm != current->mm &&
> -	    __ptrace_may_access(task, PTRACE_MODE_READ) < 0)
> +	    __ptrace_access_check(task, PTRACE_MODE_READ) < 0)
>  		goto out;
>  	task_unlock(task);
>  	return mm;
> @@ -322,7 +322,7 @@ static int proc_pid_wchan(struct task_st
>  	wchan = get_wchan(task);
>  
>  	if (lookup_symbol_name(wchan, symname) < 0)
> -		if (!ptrace_may_access(task, PTRACE_MODE_READ))
> +		if (!ptrace_access_check(task, PTRACE_MODE_READ))
>  			return 0;
>  		else
>  			return sprintf(buffer, "%lu", wchan);
> @@ -559,7 +559,7 @@ static int proc_fd_access_allowed(struct
>  	 */
>  	task = get_proc_task(inode);
>  	if (task) {
> -		allowed = ptrace_may_access(task, PTRACE_MODE_READ);
> +		allowed = ptrace_access_check(task, PTRACE_MODE_READ);
>  		put_task_struct(task);
>  	}
>  	return allowed;
> @@ -938,7 +938,7 @@ static ssize_t environ_read(struct file 
>  	if (!task)
>  		goto out_no_task;
>  
> -	if (!ptrace_may_access(task, PTRACE_MODE_READ))
> +	if (!ptrace_access_check(task, PTRACE_MODE_READ))
>  		goto out;
>  
>  	ret = -ENOMEM;
> Index: linux/fs/proc/task_mmu.c
> ===================================================================
> --- linux.orig/fs/proc/task_mmu.c
> +++ linux/fs/proc/task_mmu.c
> @@ -656,7 +656,7 @@ static ssize_t pagemap_read(struct file 
>  		goto out;
>  
>  	ret = -EACCES;
> -	if (!ptrace_may_access(task, PTRACE_MODE_READ))
> +	if (!ptrace_access_check(task, PTRACE_MODE_READ))
>  		goto out_task;
>  
>  	ret = -EINVAL;
> Index: linux/include/linux/ptrace.h
> ===================================================================
> --- linux.orig/include/linux/ptrace.h
> +++ linux/include/linux/ptrace.h
> @@ -99,9 +99,9 @@ extern void ptrace_fork(struct task_stru
>  #define PTRACE_MODE_READ   1
>  #define PTRACE_MODE_ATTACH 2
>  /* Returns 0 on success, -errno on denial. */
> -extern int __ptrace_may_access(struct task_struct *task, unsigned int mode);
> +extern int __ptrace_access_check(struct task_struct *task, unsigned int mode);
>  /* Returns true on success, false on denial. */
> -extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
> +extern bool ptrace_access_check(struct task_struct *task, unsigned int mode);
>  
>  static inline int ptrace_reparented(struct task_struct *child)
>  {
> Index: linux/include/linux/security.h
> ===================================================================
> --- linux.orig/include/linux/security.h
> +++ linux/include/linux/security.h
> @@ -52,7 +52,7 @@ struct audit_krule;
>  extern int cap_capable(struct task_struct *tsk, const struct cred *cred,
>  		       int cap, int audit);
>  extern int cap_settime(struct timespec *ts, struct timezone *tz);
> -extern int cap_ptrace_may_access(struct task_struct *child, unsigned int mode);
> +extern int cap_ptrace_access_check(struct task_struct *child, unsigned int mode);
>  extern int cap_ptrace_traceme(struct task_struct *parent);
>  extern int cap_capget(struct task_struct *target, kernel_cap_t *effective, kernel_cap_t *inheritable, kernel_cap_t *permitted);
>  extern int cap_capset(struct cred *new, const struct cred *old,
> @@ -1209,7 +1209,7 @@ static inline void security_free_mnt_opt
>   *	@alter contains the flag indicating whether changes are to be made.
>   *	Return 0 if permission is granted.
>   *
> - * @ptrace_may_access:
> + * @ptrace_access_check:
>   *	Check permission before allowing the current process to trace the
>   *	@child process.
>   *	Security modules may also want to perform a process tracing check
> @@ -1224,7 +1224,7 @@ static inline void security_free_mnt_opt
>   *	Check that the @parent process has sufficient permission to trace the
>   *	current process before allowing the current process to present itself
>   *	to the @parent process for tracing.
> - *	The parent process will still have to undergo the ptrace_may_access
> + *	The parent process will still have to undergo the ptrace_access_check
>   *	checks before it is allowed to trace this one.
>   *	@parent contains the task_struct structure for debugger process.
>   *	Return 0 if permission is granted.
> @@ -1336,7 +1336,7 @@ static inline void security_free_mnt_opt
>  struct security_operations {
>  	char name[SECURITY_NAME_MAX + 1];
>  
> -	int (*ptrace_may_access) (struct task_struct *child, unsigned int mode);
> +	int (*ptrace_access_check) (struct task_struct *child, unsigned int mode);
>  	int (*ptrace_traceme) (struct task_struct *parent);
>  	int (*capget) (struct task_struct *target,
>  		       kernel_cap_t *effective,
> @@ -1617,7 +1617,7 @@ extern int security_module_enable(struct
>  extern int register_security(struct security_operations *ops);
>  
>  /* Security operations */
> -int security_ptrace_may_access(struct task_struct *child, unsigned int mode);
> +int security_ptrace_access_check(struct task_struct *child, unsigned int mode);
>  int security_ptrace_traceme(struct task_struct *parent);
>  int security_capget(struct task_struct *target,
>  		    kernel_cap_t *effective,
> @@ -1798,10 +1798,10 @@ static inline int security_init(void)
>  	return 0;
>  }
>  
> -static inline int security_ptrace_may_access(struct task_struct *child,
> +static inline int security_ptrace_access_check(struct task_struct *child,
>  					     unsigned int mode)
>  {
> -	return cap_ptrace_may_access(child, mode);
> +	return cap_ptrace_access_check(child, mode);
>  }
>  
>  static inline int security_ptrace_traceme(struct task_struct *parent)
> Index: linux/kernel/ptrace.c
> ===================================================================
> --- linux.orig/kernel/ptrace.c
> +++ linux/kernel/ptrace.c
> @@ -127,7 +127,7 @@ int ptrace_check_attach(struct task_stru
>  	return ret;
>  }
>  
> -int __ptrace_may_access(struct task_struct *task, unsigned int mode)
> +int __ptrace_access_check(struct task_struct *task, unsigned int mode)
>  {
>  	const struct cred *cred = current_cred(), *tcred;
>  
> @@ -162,14 +162,14 @@ int __ptrace_may_access(struct task_stru
>  	if (!dumpable && !capable(CAP_SYS_PTRACE))
>  		return -EPERM;
>  
> -	return security_ptrace_may_access(task, mode);
> +	return security_ptrace_access_check(task, mode);
>  }
>  
> -bool ptrace_may_access(struct task_struct *task, unsigned int mode)
> +bool ptrace_access_check(struct task_struct *task, unsigned int mode)
>  {
>  	int err;
>  	task_lock(task);
> -	err = __ptrace_may_access(task, mode);
> +	err = __ptrace_access_check(task, mode);
>  	task_unlock(task);
>  	return !err;
>  }
> @@ -217,7 +217,7 @@ repeat:
>  	/* the same process cannot be attached many times */
>  	if (task->ptrace & PT_PTRACED)
>  		goto bad;
> -	retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
> +	retval = __ptrace_access_check(task, PTRACE_MODE_ATTACH);
>  	if (retval)
>  		goto bad;
>  
> Index: linux/security/capability.c
> ===================================================================
> --- linux.orig/security/capability.c
> +++ linux/security/capability.c
> @@ -863,7 +863,7 @@ struct security_operations default_secur
>  
>  void security_fixup_ops(struct security_operations *ops)
>  {
> -	set_to_cap_if_null(ops, ptrace_may_access);
> +	set_to_cap_if_null(ops, ptrace_access_check);
>  	set_to_cap_if_null(ops, ptrace_traceme);
>  	set_to_cap_if_null(ops, capget);
>  	set_to_cap_if_null(ops, capset);
> Index: linux/security/commoncap.c
> ===================================================================
> --- linux.orig/security/commoncap.c
> +++ linux/security/commoncap.c
> @@ -79,7 +79,7 @@ int cap_settime(struct timespec *ts, str
>  }
>  
>  /**
> - * cap_ptrace_may_access - Determine whether the current process may access
> + * cap_ptrace_access_check - Determine whether the current process may access
>   *			   another
>   * @child: The process to be accessed
>   * @mode: The mode of attachment.
> @@ -87,7 +87,7 @@ int cap_settime(struct timespec *ts, str
>   * Determine whether a process may access another, returning 0 if permission
>   * granted, -ve if denied.
>   */
> -int cap_ptrace_may_access(struct task_struct *child, unsigned int mode)
> +int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
>  {
>  	int ret = 0;
>  
> Index: linux/security/root_plug.c
> ===================================================================
> --- linux.orig/security/root_plug.c
> +++ linux/security/root_plug.c
> @@ -72,7 +72,7 @@ static int rootplug_bprm_check_security 
>  
>  static struct security_operations rootplug_security_ops = {
>  	/* Use the capability functions for some of the hooks */
> -	.ptrace_may_access =		cap_ptrace_may_access,
> +	.ptrace_access_check =		cap_ptrace_access_check,
>  	.ptrace_traceme =		cap_ptrace_traceme,
>  	.capget =			cap_capget,
>  	.capset =			cap_capset,
> Index: linux/security/security.c
> ===================================================================
> --- linux.orig/security/security.c
> +++ linux/security/security.c
> @@ -127,9 +127,9 @@ int register_security(struct security_op
>  
>  /* Security operations */
>  
> -int security_ptrace_may_access(struct task_struct *child, unsigned int mode)
> +int security_ptrace_access_check(struct task_struct *child, unsigned int mode)
>  {
> -	return security_ops->ptrace_may_access(child, mode);
> +	return security_ops->ptrace_access_check(child, mode);
>  }
>  
>  int security_ptrace_traceme(struct task_struct *parent)
> Index: linux/security/selinux/hooks.c
> ===================================================================
> --- linux.orig/security/selinux/hooks.c
> +++ linux/security/selinux/hooks.c
> @@ -1854,12 +1854,12 @@ static inline u32 open_file_to_av(struct
>  
>  /* Hook functions begin here. */
>  
> -static int selinux_ptrace_may_access(struct task_struct *child,
> +static int selinux_ptrace_access_check(struct task_struct *child,
>  				     unsigned int mode)
>  {
>  	int rc;
>  
> -	rc = cap_ptrace_may_access(child, mode);
> +	rc = cap_ptrace_access_check(child, mode);
>  	if (rc)
>  		return rc;
>  
> @@ -5318,7 +5318,7 @@ static int selinux_key_getsecurity(struc
>  static struct security_operations selinux_ops = {
>  	.name =				"selinux",
>  
> -	.ptrace_may_access =		selinux_ptrace_may_access,
> +	.ptrace_access_check =		selinux_ptrace_access_check,
>  	.ptrace_traceme =		selinux_ptrace_traceme,
>  	.capget =			selinux_capget,
>  	.capset =			selinux_capset,
> Index: linux/security/smack/smack_lsm.c
> ===================================================================
> --- linux.orig/security/smack/smack_lsm.c
> +++ linux/security/smack/smack_lsm.c
> @@ -92,7 +92,7 @@ struct inode_smack *new_inode_smack(char
>   */
>  
>  /**
> - * smack_ptrace_may_access - Smack approval on PTRACE_ATTACH
> + * smack_ptrace_access_check - Smack approval on PTRACE_ATTACH
>   * @ctp: child task pointer
>   * @mode: ptrace attachment mode
>   *
> @@ -100,11 +100,11 @@ struct inode_smack *new_inode_smack(char
>   *
>   * Do the capability checks, and require read and write.
>   */
> -static int smack_ptrace_may_access(struct task_struct *ctp, unsigned int mode)
> +static int smack_ptrace_access_check(struct task_struct *ctp, unsigned int mode)
>  {
>  	int rc;
>  
> -	rc = cap_ptrace_may_access(ctp, mode);
> +	rc = cap_ptrace_access_check(ctp, mode);
>  	if (rc != 0)
>  		return rc;
>  
> @@ -2826,7 +2826,7 @@ static void smack_release_secctx(char *s
>  struct security_operations smack_ops = {
>  	.name =				"smack",
>  
> -	.ptrace_may_access =		smack_ptrace_may_access,
> +	.ptrace_access_check =		smack_ptrace_access_check,
>  	.ptrace_traceme =		smack_ptrace_traceme,
>  	.capget = 			cap_capget,
>  	.capset = 			cap_capset,
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>
> ----- End forwarded message -----
> ----- Forwarded message from Ingo Molnar <mingo@elte.hu> -----
>
> Date: Thu, 7 May 2009 11:50:54 +0200
> From: Ingo Molnar <mingo@elte.hu>
> To: Chris Wright <chrisw@sous-sol.org>
> Subject: [patch 2/2] ptrace: turn ptrace_access_check() into a retval
> 	function
> Cc: Oleg Nesterov <oleg@redhat.com>, Roland McGrath <roland@redhat.com>,
> 	Andrew Morton <akpm@linux-foundation.org>,
> 	linux-kernel@vger.kernel.org, Al Viro <viro@ZenIV.linux.org.uk>
>
> ptrace_access_check() returns a bool, while most of the ptrace 
> access check machinery works with Linux retvals (where 0 indicates 
> success, negative indicates an error).
>
> So eliminate the bool and invert the usage at the call sites.
>
> ( Note: "< 0" checks are used instead of !0 checks, because that's
>   the convention for retval checks and it results in similarly fast
>   assembly code. )
>
> [ Impact: cleanup ]
>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
> ---
>  fs/proc/array.c        |    2 +-
>  fs/proc/base.c         |    8 ++++----
>  fs/proc/task_mmu.c     |    2 +-
>  include/linux/ptrace.h |    2 +-
>  kernel/ptrace.c        |    6 ++++--
>  5 files changed, 11 insertions(+), 9 deletions(-)
>
> Index: linux/fs/proc/array.c
> ===================================================================
> --- linux.orig/fs/proc/array.c
> +++ linux/fs/proc/array.c
> @@ -366,7 +366,7 @@ static int do_task_stat(struct seq_file 
>  
>  	state = *get_task_state(task);
>  	vsize = eip = esp = 0;
> -	permitted = ptrace_access_check(task, PTRACE_MODE_READ);
> +	permitted = !ptrace_access_check(task, PTRACE_MODE_READ);
>  	mm = get_task_mm(task);
>  	if (mm) {
>  		vsize = task_vsize(mm);
> Index: linux/fs/proc/base.c
> ===================================================================
> --- linux.orig/fs/proc/base.c
> +++ linux/fs/proc/base.c
> @@ -222,7 +222,7 @@ static int check_mem_permission(struct t
>  		rcu_read_lock();
>  		match = (tracehook_tracer_task(task) == current);
>  		rcu_read_unlock();
> -		if (match && ptrace_access_check(task, PTRACE_MODE_ATTACH))
> +		if (match && !ptrace_access_check(task, PTRACE_MODE_ATTACH))
>  			return 0;
>  	}
>  
> @@ -322,7 +322,7 @@ static int proc_pid_wchan(struct task_st
>  	wchan = get_wchan(task);
>  
>  	if (lookup_symbol_name(wchan, symname) < 0)
> -		if (!ptrace_access_check(task, PTRACE_MODE_READ))
> +		if (ptrace_access_check(task, PTRACE_MODE_READ) < 0)
>  			return 0;
>  		else
>  			return sprintf(buffer, "%lu", wchan);
> @@ -559,7 +559,7 @@ static int proc_fd_access_allowed(struct
>  	 */
>  	task = get_proc_task(inode);
>  	if (task) {
> -		allowed = ptrace_access_check(task, PTRACE_MODE_READ);
> +		allowed = !ptrace_access_check(task, PTRACE_MODE_READ);
>  		put_task_struct(task);
>  	}
>  	return allowed;
> @@ -938,7 +938,7 @@ static ssize_t environ_read(struct file 
>  	if (!task)
>  		goto out_no_task;
>  
> -	if (!ptrace_access_check(task, PTRACE_MODE_READ))
> +	if (ptrace_access_check(task, PTRACE_MODE_READ) < 0)
>  		goto out;
>  
>  	ret = -ENOMEM;
> Index: linux/fs/proc/task_mmu.c
> ===================================================================
> --- linux.orig/fs/proc/task_mmu.c
> +++ linux/fs/proc/task_mmu.c
> @@ -656,7 +656,7 @@ static ssize_t pagemap_read(struct file 
>  		goto out;
>  
>  	ret = -EACCES;
> -	if (!ptrace_access_check(task, PTRACE_MODE_READ))
> +	if (ptrace_access_check(task, PTRACE_MODE_READ) < 0)
>  		goto out_task;
>  
>  	ret = -EINVAL;
> Index: linux/include/linux/ptrace.h
> ===================================================================
> --- linux.orig/include/linux/ptrace.h
> +++ linux/include/linux/ptrace.h
> @@ -101,7 +101,7 @@ extern void ptrace_fork(struct task_stru
>  /* Returns 0 on success, -errno on denial. */
>  extern int __ptrace_access_check(struct task_struct *task, unsigned int mode);
>  /* Returns true on success, false on denial. */
> -extern bool ptrace_access_check(struct task_struct *task, unsigned int mode);
> +extern int ptrace_access_check(struct task_struct *task, unsigned int mode);
>  
>  static inline int ptrace_reparented(struct task_struct *child)
>  {
> Index: linux/kernel/ptrace.c
> ===================================================================
> --- linux.orig/kernel/ptrace.c
> +++ linux/kernel/ptrace.c
> @@ -165,13 +165,15 @@ int __ptrace_access_check(struct task_st
>  	return security_ptrace_access_check(task, mode);
>  }
>  
> -bool ptrace_access_check(struct task_struct *task, unsigned int mode)
> +int ptrace_access_check(struct task_struct *task, unsigned int mode)
>  {
>  	int err;
> +
>  	task_lock(task);
>  	err = __ptrace_access_check(task, mode);
>  	task_unlock(task);
> -	return !err;
> +
> +	return err;
>  }
>  
>  int ptrace_attach(struct task_struct *task)
> --
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>
> ----- End forwarded message -----
> --
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>
>
>