- SELinux apply a different permission to ptrace a child vs non-child

- Reenable debug

1 files changed, 162 insertions, 0 deletions

diff --git a/selinux-apply-different-permission-to-ptrace-child.patch b/selinux-apply-different-permission-to-ptrace-child.patch
new file mode 100644
index 000000000..90baad840
--- /dev/null
+++ b/selinux-apply-different-permission-to-ptrace-child.patch
@@ -0,0 +1,162 @@
+Some applications, like gdb, are able to ptrace both children or other
+completely unrelated tasks.  We would like to be able to discern these two
+things and to be able to allow gdb to ptrace it's children, but not to be
+able to ptrace unrelated tasks for security reasons.
+
+Upstream is a bit weary of this patch as it may be incomplete.  They are
+not fundamentally opposed to the patch, I was just ask to see if I could
+flush out any needed refinement in Fedora where we already had the
+problem.  We may find that we need to emulate the YAMA non-child
+registration module in order to completely deal with 'normal' ptrace on
+a system.  At the moment however, this patch will at least let us get
+gdb working for many users in Fedora (See fedora-devel-list for a
+discussion of the current issues people are complaining about in F17
+without this)
+
+---
+
+ security/selinux/hooks.c            |   38 +++++++++++++++++++++++++++++++++++
+ security/selinux/include/classmap.h |    2 +-
+ security/selinux/include/security.h |    2 ++
+ security/selinux/selinuxfs.c        |    3 ++-
+ security/selinux/ss/services.c      |    3 +++
+ 5 files changed, 46 insertions(+), 2 deletions(-)
+
+diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
+index 1a4acf4..b226f26 100644
+--- a/security/selinux/hooks.c
++++ b/security/selinux/hooks.c
+@@ -1805,6 +1805,39 @@ static inline u32 open_file_to_av(struct file *file)
+ 
+ /* Hook functions begin here. */
+ 
++/**
++ * task_is_descendant - walk up a process family tree looking for a match
++ * @parent: the process to compare against while walking up from child
++ * @child: the process to start from while looking upwards for parent
++ *
++ * Returns 1 if child is a descendant of parent, 0 if not.
++ */
++static int task_is_descendant(struct task_struct *parent,
++			      struct task_struct *child)
++{
++	int rc = 0;
++	struct task_struct *walker = child;
++
++	if (!parent || !child)
++		return 0;
++
++	rcu_read_lock();
++	if (!thread_group_leader(parent))
++		parent = rcu_dereference(parent->group_leader);
++	while (walker->pid > 0) {
++		if (!thread_group_leader(walker))
++			walker = rcu_dereference(walker->group_leader);
++		if (walker == parent) {
++			rc = 1;
++			break;
++		}
++		walker = rcu_dereference(walker->real_parent);
++	}
++	rcu_read_unlock();
++
++	return rc;
++}
++
+ static int selinux_ptrace_access_check(struct task_struct *child,
+ 				     unsigned int mode)
+ {
+@@ -1820,6 +1853,9 @@ static int selinux_ptrace_access_check(struct task_struct *child,
+ 		return avc_has_perm(sid, csid, SECCLASS_FILE, FILE__READ, NULL);
+ 	}
+ 
++
++	if (selinux_policycap_ptrace_child && task_is_descendant(current, child))
++		return current_has_perm(child, PROCESS__PTRACE_CHILD);
+ 	return current_has_perm(child, PROCESS__PTRACE);
+ }
+ 
+@@ -1831,6 +1867,8 @@ static int selinux_ptrace_traceme(struct task_struct *parent)
+ 	if (rc)
+ 		return rc;
+ 
++	if (selinux_policycap_ptrace_child && task_is_descendant(parent, current))
++		return task_has_perm(parent, current, PROCESS__PTRACE_CHILD);
+ 	return task_has_perm(parent, current, PROCESS__PTRACE);
+ }
+ 
+diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
+index 39e678c..72c08b9 100644
+--- a/security/selinux/include/classmap.h
++++ b/security/selinux/include/classmap.h
+@@ -29,7 +29,7 @@ struct security_class_mapping secclass_map[] = {
+ 	    "getattr", "setexec", "setfscreate", "noatsecure", "siginh",
+ 	    "setrlimit", "rlimitinh", "dyntransition", "setcurrent",
+ 	    "execmem", "execstack", "execheap", "setkeycreate",
+-	    "setsockcreate", NULL } },
++	    "setsockcreate", "ptrace_child", NULL } },
+ 	{ "system",
+ 	  { "ipc_info", "syslog_read", "syslog_mod",
+ 	    "syslog_console", "module_request", NULL } },
+diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
+index dde2005..ac14b0a 100644
+--- a/security/selinux/include/security.h
++++ b/security/selinux/include/security.h
+@@ -68,12 +68,14 @@ extern int selinux_enabled;
+ enum {
+ 	POLICYDB_CAPABILITY_NETPEER,
+ 	POLICYDB_CAPABILITY_OPENPERM,
++	POLICYDB_CAPABILITY_PTRACE_CHILD,
+ 	__POLICYDB_CAPABILITY_MAX
+ };
+ #define POLICYDB_CAPABILITY_MAX (__POLICYDB_CAPABILITY_MAX - 1)
+ 
+ extern int selinux_policycap_netpeer;
+ extern int selinux_policycap_openperm;
++extern int selinux_policycap_ptrace_child;
+ 
+ /*
+  * type_datum properties
+diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
+index 4e93f9e..3379765 100644
+--- a/security/selinux/selinuxfs.c
++++ b/security/selinux/selinuxfs.c
+@@ -44,7 +44,8 @@
+ /* Policy capability filenames */
+ static char *policycap_names[] = {
+ 	"network_peer_controls",
+-	"open_perms"
++	"open_perms",
++	"ptrace_child",
+ };
+ 
+ unsigned int selinux_checkreqprot = CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE;
+diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
+index 9b7e7ed..4d12a6e 100644
+--- a/security/selinux/ss/services.c
++++ b/security/selinux/ss/services.c
+@@ -72,6 +72,7 @@
+ 
+ int selinux_policycap_netpeer;
+ int selinux_policycap_openperm;
++int selinux_policycap_ptrace_child;
+ 
+ static DEFINE_RWLOCK(policy_rwlock);
+ 
+@@ -1812,6 +1813,8 @@ static void security_load_policycaps(void)
+ 						  POLICYDB_CAPABILITY_NETPEER);
+ 	selinux_policycap_openperm = ebitmap_get_bit(&policydb.policycaps,
+ 						  POLICYDB_CAPABILITY_OPENPERM);
++	selinux_policycap_ptrace_child = ebitmap_get_bit(&policydb.policycaps,
++						  POLICYDB_CAPABILITY_PTRACE_CHILD);
+ }
+ 
+ static int security_preserve_bools(struct policydb *p);
+
+
+
+
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