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Date: Mon, 20 Jun 2011 23:11:03 +0400
From: Vasiliy Kulikov <segoon@...nwall.com>
To: linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org,
apparmor@...ts.ubuntu.com,
"selinux@...ho.nsa.gov Stephen Smalley" <sds@...ho.nsa.gov>,
James Morris <jmorris@...ei.org>,
Eric Paris <eparis@...isplace.org>,
John Johansen <john.johansen@...onical.com>,
kernel-hardening@...ts.openwall.com, serge@...lyn.com
Subject: [RFC v3 2/2] security: add ptrace_task_may_access_current()
ptrace_task_may_access_current() is needed to check whether another
process may ptrace current. LSM hook and related functions now have
"tracer" as the first argument instead of implicit "current".
Signed-off-by: Vasiliy Kulikov <segoon@...nwall.com>
---
include/linux/ptrace.h | 6 +++++-
include/linux/security.h | 22 +++++++++++++++-------
kernel/ptrace.c | 30 ++++++++++++++++++++++--------
security/apparmor/lsm.c | 7 ++++---
security/commoncap.c | 8 +++++---
security/security.c | 6 ++++--
security/selinux/hooks.c | 11 ++++++-----
security/smack/smack.h | 1 +
security/smack/smack_access.c | 15 +++++++++++----
security/smack/smack_lsm.c | 9 ++++++---
10 files changed, 79 insertions(+), 36 deletions(-)
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index 9178d5c..e68ff58 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -116,9 +116,13 @@ extern void exit_ptrace(struct task_struct *tracer);
#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_may_access(struct task_struct *tracer,
+ 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_task_may_access_current(struct task_struct *task,
+ unsigned int mode);
static inline int ptrace_reparented(struct task_struct *child)
{
diff --git a/include/linux/security.h b/include/linux/security.h
index 8509dbf..8998fd6 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -56,7 +56,9 @@ struct user_namespace;
extern int cap_capable(struct task_struct *tsk, const struct cred *cred,
struct user_namespace *ns, int cap, int audit);
extern int cap_settime(const struct timespec *ts, const struct timezone *tz);
-extern int cap_ptrace_access_check(struct task_struct *child, unsigned int mode);
+extern int cap_ptrace_access_check(struct task_struct *tracer,
+ 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,
@@ -1221,13 +1223,14 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
* Return 0 if permission is granted.
*
* @ptrace_access_check:
- * Check permission before allowing the current process to trace the
+ * Check permission before allowing the @tracer process to trace the
* @child process.
* Security modules may also want to perform a process tracing check
* during an execve in the set_security or apply_creds hooks of
* tracing check during an execve in the bprm_set_creds hook of
* binprm_security_ops if the process is being traced and its security
* attributes would be changed by the execve.
+ * @tracer contains the task_struct structure for the tracer process.
* @child contains the task_struct structure for the target process.
* @mode contains the PTRACE_MODE flags indicating the form of access.
* Return 0 if permission is granted.
@@ -1375,7 +1378,9 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
struct security_operations {
char name[SECURITY_NAME_MAX + 1];
- int (*ptrace_access_check) (struct task_struct *child, unsigned int mode);
+ int (*ptrace_access_check) (struct task_struct *tracer,
+ struct task_struct *child,
+ unsigned int mode);
int (*ptrace_traceme) (struct task_struct *parent);
int (*capget) (struct task_struct *target,
kernel_cap_t *effective,
@@ -1657,7 +1662,9 @@ extern int security_module_enable(struct security_operations *ops);
extern int register_security(struct security_operations *ops);
/* Security operations */
-int security_ptrace_access_check(struct task_struct *child, unsigned int mode);
+int security_ptrace_access_check(struct task_struct *tracer,
+ 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,
@@ -1837,10 +1844,11 @@ static inline int security_init(void)
return 0;
}
-static inline int security_ptrace_access_check(struct task_struct *child,
- unsigned int mode)
+static inline int security_ptrace_access_check(struct task_struct *tracer,
+ struct task_struct *child,
+ unsigned int mode)
{
- return cap_ptrace_access_check(child, mode);
+ return cap_ptrace_access_check(tracer, child, mode);
}
static inline int security_ptrace_traceme(struct task_struct *parent)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 2df1157..7b40b24 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -132,9 +132,11 @@ int ptrace_check_attach(struct task_struct *child, int kill)
return ret;
}
-int __ptrace_may_access(struct task_struct *task, unsigned int mode)
+int __ptrace_may_access(struct task_struct *tracer,
+ struct task_struct *task,
+ unsigned int mode)
{
- const struct cred *cred = current_cred(), *tcred;
+ const struct cred *cred, *tcred;
/* May we inspect the given task?
* This check is used both for attaching with ptrace
@@ -146,9 +148,10 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode)
*/
int dumpable = 0;
/* Don't let security modules deny introspection */
- if (task == current)
+ if (task == tracer)
return 0;
rcu_read_lock();
+ cred = __task_cred(tracer);
tcred = __task_cred(task);
if (cred->user->user_ns == tcred->user->user_ns &&
(cred->uid == tcred->euid &&
@@ -158,7 +161,7 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode)
cred->gid == tcred->sgid &&
cred->gid == tcred->gid))
goto ok;
- if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
+ if (has_ns_capability(tracer, tcred->user->user_ns, CAP_SYS_PTRACE))
goto ok;
rcu_read_unlock();
return -EPERM;
@@ -167,17 +170,28 @@ ok:
smp_rmb();
if (task->mm)
dumpable = get_dumpable(task->mm);
- if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE))
+ if (!dumpable && !has_ns_capability(tracer,
+ task_cred_xxx(task, user)->user_ns,
+ CAP_SYS_PTRACE))
return -EPERM;
- return security_ptrace_access_check(task, mode);
+ return security_ptrace_access_check(tracer, task, mode);
}
bool ptrace_may_access(struct task_struct *task, unsigned int mode)
{
int err;
task_lock(task);
- err = __ptrace_may_access(task, mode);
+ err = __ptrace_may_access(current, task, mode);
+ task_unlock(task);
+ return !err;
+}
+
+bool ptrace_task_may_access_current(struct task_struct *task, unsigned int mode)
+{
+ int err;
+ task_lock(task);
+ err = __ptrace_may_access(task, current, mode);
task_unlock(task);
return !err;
}
@@ -205,7 +219,7 @@ static int ptrace_attach(struct task_struct *task)
goto out;
task_lock(task);
- retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
+ retval = __ptrace_may_access(current, task, PTRACE_MODE_ATTACH);
task_unlock(task);
if (retval)
goto unlock_creds;
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index ec1bcec..e78112a 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -93,14 +93,15 @@ static void apparmor_cred_transfer(struct cred *new, const struct cred *old)
aa_dup_task_context(new_cxt, old_cxt);
}
-static int apparmor_ptrace_access_check(struct task_struct *child,
+static int apparmor_ptrace_access_check(struct task_struct *tracer,
+ struct task_struct *child,
unsigned int mode)
{
- int error = cap_ptrace_access_check(child, mode);
+ int error = cap_ptrace_access_check(tracer, child, mode);
if (error)
return error;
- return aa_ptrace(current, child, mode);
+ return aa_ptrace(tracer, child, mode);
}
static int apparmor_ptrace_traceme(struct task_struct *parent)
diff --git a/security/commoncap.c b/security/commoncap.c
index a93b3b7..d02eb58 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -136,18 +136,20 @@ int cap_settime(const struct timespec *ts, const struct timezone *tz)
* Determine whether a process may access another, returning 0 if permission
* granted, -ve if denied.
*/
-int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
+int cap_ptrace_access_check(struct task_struct *tracer,
+ struct task_struct *child,
+ unsigned int mode)
{
int ret = 0;
const struct cred *cred, *child_cred;
rcu_read_lock();
- cred = current_cred();
+ cred = __task_cred(tracer);
child_cred = __task_cred(child);
if (cred->user->user_ns == child_cred->user->user_ns &&
cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
goto out;
- if (ns_capable(child_cred->user->user_ns, CAP_SYS_PTRACE))
+ if (has_ns_capability(tracer, child_cred->user->user_ns, CAP_SYS_PTRACE))
goto out;
ret = -EPERM;
out:
diff --git a/security/security.c b/security/security.c
index dd16397..4ec7e04 100644
--- a/security/security.c
+++ b/security/security.c
@@ -127,9 +127,11 @@ int __init register_security(struct security_operations *ops)
/* Security operations */
-int security_ptrace_access_check(struct task_struct *child, unsigned int mode)
+int security_ptrace_access_check(struct task_struct *tracer,
+ struct task_struct *child,
+ unsigned int mode)
{
- return security_ops->ptrace_access_check(child, mode);
+ return security_ops->ptrace_access_check(tracer, child, mode);
}
int security_ptrace_traceme(struct task_struct *parent)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index a0d3845..eb46b15 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1800,22 +1800,23 @@ static inline u32 open_file_to_av(struct file *file)
/* Hook functions begin here. */
-static int selinux_ptrace_access_check(struct task_struct *child,
- unsigned int mode)
+static int selinux_ptrace_access_check(struct task_struct *tracer,
+ struct task_struct *child,
+ unsigned int mode)
{
int rc;
- rc = cap_ptrace_access_check(child, mode);
+ rc = cap_ptrace_access_check(tracer, child, mode);
if (rc)
return rc;
if (mode == PTRACE_MODE_READ) {
- u32 sid = current_sid();
+ u32 sid = task_sid(tracer);
u32 csid = task_sid(child);
return avc_has_perm(sid, csid, SECCLASS_FILE, FILE__READ, NULL);
}
- return current_has_perm(child, PROCESS__PTRACE);
+ return task_has_perm(tracer, child, PROCESS__PTRACE);
}
static int selinux_ptrace_traceme(struct task_struct *parent)
diff --git a/security/smack/smack.h b/security/smack/smack.h
index 2b6c6a5..0170b24 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -200,6 +200,7 @@ struct inode_smack *new_inode_smack(char *);
int smk_access_entry(char *, char *, struct list_head *);
int smk_access(char *, char *, int, struct smk_audit_info *);
int smk_curacc(char *, u32, struct smk_audit_info *);
+int smk_taskacc(struct task_struct *task, char *, u32, struct smk_audit_info *);
int smack_to_cipso(const char *, struct smack_cipso *);
void smack_from_cipso(u32, char *, char *);
char *smack_from_secid(const u32);
diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index 9637e10..4075755 100644
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -201,7 +201,8 @@ out_audit:
}
/**
- * smk_curacc - determine if current has a specific access to an object
+ * smk_taskacc - determine if task has a specific access to an object
+ * @task: a pointer to the subject's task struct
* @obj_label: a pointer to the object's Smack label
* @mode: the access requested, in "MAY" format
* @a : common audit data
@@ -211,9 +212,10 @@ out_audit:
* non zero otherwise. It allows that current may have the capability
* to override the rules.
*/
-int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
+int smk_taskacc(struct task_struct *task, char *obj_label,
+ u32 mode, struct smk_audit_info *a)
{
- struct task_smack *tsp = current_security();
+ struct task_smack *tsp = task_cred_xxx(task, security);
char *sp = smk_of_task(tsp);
int may;
int rc;
@@ -243,7 +245,7 @@ int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
if (smack_onlycap != NULL && smack_onlycap != sp)
goto out_audit;
- if (capable(CAP_MAC_OVERRIDE))
+ if (has_capability(task, CAP_MAC_OVERRIDE))
rc = 0;
out_audit:
@@ -254,6 +256,11 @@ out_audit:
return rc;
}
+int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
+{
+ return smk_taskacc(current, obj_label, mode, a);
+}
+
#ifdef CONFIG_AUDIT
/**
* smack_str_from_perm : helper to transalate an int to a
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 9831a39..bb18fda 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -142,6 +142,7 @@ static int smk_copy_rules(struct list_head *nhead, struct list_head *ohead,
/**
* smack_ptrace_access_check - Smack approval on PTRACE_ATTACH
+ * @ttp: tracer task pointer
* @ctp: child task pointer
* @mode: ptrace attachment mode
*
@@ -149,13 +150,15 @@ static int smk_copy_rules(struct list_head *nhead, struct list_head *ohead,
*
* Do the capability checks, and require read and write.
*/
-static int smack_ptrace_access_check(struct task_struct *ctp, unsigned int mode)
+static int smack_ptrace_access_check(struct task_struct *ttp,
+ struct task_struct *ctp,
+ unsigned int mode)
{
int rc;
struct smk_audit_info ad;
char *tsp;
- rc = cap_ptrace_access_check(ctp, mode);
+ rc = cap_ptrace_access_check(ttp, ctp, mode);
if (rc != 0)
return rc;
@@ -163,7 +166,7 @@ static int smack_ptrace_access_check(struct task_struct *ctp, unsigned int mode)
smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
smk_ad_setfield_u_tsk(&ad, ctp);
- rc = smk_curacc(tsp, MAY_READWRITE, &ad);
+ rc = smk_taskacc(ttp, tsp, MAY_READWRITE, &ad);
return rc;
}
---
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