aboutsummaryrefslogtreecommitdiff
path: root/security
diff options
context:
space:
mode:
authorDavid Howells <dhowells@redhat.com>2008-08-14 11:37:28 +0100
committerJames Morris <jmorris@namei.org>2008-08-14 22:59:43 +1000
commit5cd9c58fbe9ec92b45b27e131719af4f2bd9eb40 (patch)
tree8573db001b4dc3c2ad97102dda42b841c40b5f6c /security
parent8d0968abd03ec6b407df117adc773562386702fa (diff)
downloadlinux-linaro-stable-5cd9c58fbe9ec92b45b27e131719af4f2bd9eb40.tar.gz
security: Fix setting of PF_SUPERPRIV by __capable()
Fix the setting of PF_SUPERPRIV by __capable() as it could corrupt the flags the target process if that is not the current process and it is trying to change its own flags in a different way at the same time. __capable() is using neither atomic ops nor locking to protect t->flags. This patch removes __capable() and introduces has_capability() that doesn't set PF_SUPERPRIV on the process being queried. This patch further splits security_ptrace() in two: (1) security_ptrace_may_access(). This passes judgement on whether one process may access another only (PTRACE_MODE_ATTACH for ptrace() and PTRACE_MODE_READ for /proc), and takes a pointer to the child process. current is the parent. (2) security_ptrace_traceme(). This passes judgement on PTRACE_TRACEME only, and takes only a pointer to the parent process. current is the child. In Smack and commoncap, this uses has_capability() to determine whether the parent will be permitted to use PTRACE_ATTACH if normal checks fail. This does not set PF_SUPERPRIV. Two of the instances of __capable() actually only act on current, and so have been changed to calls to capable(). Of the places that were using __capable(): (1) The OOM killer calls __capable() thrice when weighing the killability of a process. All of these now use has_capability(). (2) cap_ptrace() and smack_ptrace() were using __capable() to check to see whether the parent was allowed to trace any process. As mentioned above, these have been split. For PTRACE_ATTACH and /proc, capable() is now used, and for PTRACE_TRACEME, has_capability() is used. (3) cap_safe_nice() only ever saw current, so now uses capable(). (4) smack_setprocattr() rejected accesses to tasks other than current just after calling __capable(), so the order of these two tests have been switched and capable() is used instead. (5) In smack_file_send_sigiotask(), we need to allow privileged processes to receive SIGIO on files they're manipulating. (6) In smack_task_wait(), we let a process wait for a privileged process, whether or not the process doing the waiting is privileged. I've tested this with the LTP SELinux and syscalls testscripts. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: Andrew G. Morgan <morgan@kernel.org> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'security')
-rw-r--r--security/capability.c3
-rw-r--r--security/commoncap.c24
-rw-r--r--security/root_plug.c3
-rw-r--r--security/security.c10
-rw-r--r--security/selinux/hooks.c25
-rw-r--r--security/smack/smack_lsm.c49
6 files changed, 80 insertions, 34 deletions
diff --git a/security/capability.c b/security/capability.c
index 63d10da515a5..245874819036 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -811,7 +811,8 @@ struct security_operations default_security_ops = {
void security_fixup_ops(struct security_operations *ops)
{
- set_to_cap_if_null(ops, ptrace);
+ set_to_cap_if_null(ops, ptrace_may_access);
+ set_to_cap_if_null(ops, ptrace_traceme);
set_to_cap_if_null(ops, capget);
set_to_cap_if_null(ops, capset_check);
set_to_cap_if_null(ops, capset_set);
diff --git a/security/commoncap.c b/security/commoncap.c
index 4afbece37a08..e4c4b3fc0c04 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -63,14 +63,24 @@ int cap_settime(struct timespec *ts, struct timezone *tz)
return 0;
}
-int cap_ptrace (struct task_struct *parent, struct task_struct *child,
- unsigned int mode)
+int cap_ptrace_may_access(struct task_struct *child, unsigned int mode)
{
/* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
- if (!cap_issubset(child->cap_permitted, parent->cap_permitted) &&
- !__capable(parent, CAP_SYS_PTRACE))
- return -EPERM;
- return 0;
+ if (cap_issubset(child->cap_permitted, current->cap_permitted))
+ return 0;
+ if (capable(CAP_SYS_PTRACE))
+ return 0;
+ return -EPERM;
+}
+
+int cap_ptrace_traceme(struct task_struct *parent)
+{
+ /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
+ if (cap_issubset(current->cap_permitted, parent->cap_permitted))
+ return 0;
+ if (has_capability(parent, CAP_SYS_PTRACE))
+ return 0;
+ return -EPERM;
}
int cap_capget (struct task_struct *target, kernel_cap_t *effective,
@@ -534,7 +544,7 @@ int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
static inline int cap_safe_nice(struct task_struct *p)
{
if (!cap_issubset(p->cap_permitted, current->cap_permitted) &&
- !__capable(current, CAP_SYS_NICE))
+ !capable(CAP_SYS_NICE))
return -EPERM;
return 0;
}
diff --git a/security/root_plug.c b/security/root_plug.c
index be0ebec2580b..c3f68b5b372d 100644
--- a/security/root_plug.c
+++ b/security/root_plug.c
@@ -72,7 +72,8 @@ static int rootplug_bprm_check_security (struct linux_binprm *bprm)
static struct security_operations rootplug_security_ops = {
/* Use the capability functions for some of the hooks */
- .ptrace = cap_ptrace,
+ .ptrace_may_access = cap_ptrace_may_access,
+ .ptrace_traceme = cap_ptrace_traceme,
.capget = cap_capget,
.capset_check = cap_capset_check,
.capset_set = cap_capset_set,
diff --git a/security/security.c b/security/security.c
index ff7068727757..3a4b4f55b33f 100644
--- a/security/security.c
+++ b/security/security.c
@@ -127,10 +127,14 @@ int register_security(struct security_operations *ops)
/* Security operations */
-int security_ptrace(struct task_struct *parent, struct task_struct *child,
- unsigned int mode)
+int security_ptrace_may_access(struct task_struct *child, unsigned int mode)
{
- return security_ops->ptrace(parent, child, mode);
+ return security_ops->ptrace_may_access(child, mode);
+}
+
+int security_ptrace_traceme(struct task_struct *parent)
+{
+ return security_ops->ptrace_traceme(parent);
}
int security_capget(struct task_struct *target,
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 3ae9bec5a508..03fc6a81ae32 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1738,24 +1738,34 @@ static inline u32 file_to_av(struct file *file)
/* Hook functions begin here. */
-static int selinux_ptrace(struct task_struct *parent,
- struct task_struct *child,
- unsigned int mode)
+static int selinux_ptrace_may_access(struct task_struct *child,
+ unsigned int mode)
{
int rc;
- rc = secondary_ops->ptrace(parent, child, mode);
+ rc = secondary_ops->ptrace_may_access(child, mode);
if (rc)
return rc;
if (mode == PTRACE_MODE_READ) {
- struct task_security_struct *tsec = parent->security;
+ struct task_security_struct *tsec = current->security;
struct task_security_struct *csec = child->security;
return avc_has_perm(tsec->sid, csec->sid,
SECCLASS_FILE, FILE__READ, NULL);
}
- return task_has_perm(parent, child, PROCESS__PTRACE);
+ return task_has_perm(current, child, PROCESS__PTRACE);
+}
+
+static int selinux_ptrace_traceme(struct task_struct *parent)
+{
+ int rc;
+
+ rc = secondary_ops->ptrace_traceme(parent);
+ if (rc)
+ return rc;
+
+ return task_has_perm(parent, current, PROCESS__PTRACE);
}
static int selinux_capget(struct task_struct *target, kernel_cap_t *effective,
@@ -5346,7 +5356,8 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer)
static struct security_operations selinux_ops = {
.name = "selinux",
- .ptrace = selinux_ptrace,
+ .ptrace_may_access = selinux_ptrace_may_access,
+ .ptrace_traceme = selinux_ptrace_traceme,
.capget = selinux_capget,
.capset_check = selinux_capset_check,
.capset_set = selinux_capset_set,
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 1b40e558f983..87d75417ea93 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -87,27 +87,46 @@ struct inode_smack *new_inode_smack(char *smack)
*/
/**
- * smack_ptrace - Smack approval on ptrace
- * @ptp: parent task pointer
+ * smack_ptrace_may_access - Smack approval on PTRACE_ATTACH
* @ctp: child task pointer
*
* Returns 0 if access is OK, an error code otherwise
*
* Do the capability checks, and require read and write.
*/
-static int smack_ptrace(struct task_struct *ptp, struct task_struct *ctp,
- unsigned int mode)
+static int smack_ptrace_may_access(struct task_struct *ctp, unsigned int mode)
{
int rc;
- rc = cap_ptrace(ptp, ctp, mode);
+ rc = cap_ptrace_may_access(ctp, mode);
if (rc != 0)
return rc;
- rc = smk_access(ptp->security, ctp->security, MAY_READWRITE);
- if (rc != 0 && __capable(ptp, CAP_MAC_OVERRIDE))
+ rc = smk_access(current->security, ctp->security, MAY_READWRITE);
+ if (rc != 0 && capable(CAP_MAC_OVERRIDE))
return 0;
+ return rc;
+}
+
+/**
+ * smack_ptrace_traceme - Smack approval on PTRACE_TRACEME
+ * @ptp: parent task pointer
+ *
+ * Returns 0 if access is OK, an error code otherwise
+ *
+ * Do the capability checks, and require read and write.
+ */
+static int smack_ptrace_traceme(struct task_struct *ptp)
+{
+ int rc;
+
+ rc = cap_ptrace_traceme(ptp);
+ if (rc != 0)
+ return rc;
+ rc = smk_access(ptp->security, current->security, MAY_READWRITE);
+ if (rc != 0 && has_capability(ptp, CAP_MAC_OVERRIDE))
+ return 0;
return rc;
}
@@ -923,7 +942,7 @@ static int smack_file_send_sigiotask(struct task_struct *tsk,
*/
file = container_of(fown, struct file, f_owner);
rc = smk_access(file->f_security, tsk->security, MAY_WRITE);
- if (rc != 0 && __capable(tsk, CAP_MAC_OVERRIDE))
+ if (rc != 0 && has_capability(tsk, CAP_MAC_OVERRIDE))
return 0;
return rc;
}
@@ -1164,12 +1183,12 @@ static int smack_task_wait(struct task_struct *p)
* account for the smack labels having gotten to
* be different in the first place.
*
- * This breaks the strict subjet/object access
+ * This breaks the strict subject/object access
* control ideal, taking the object's privilege
* state into account in the decision as well as
* the smack value.
*/
- if (capable(CAP_MAC_OVERRIDE) || __capable(p, CAP_MAC_OVERRIDE))
+ if (capable(CAP_MAC_OVERRIDE) || has_capability(p, CAP_MAC_OVERRIDE))
return 0;
return rc;
@@ -2016,9 +2035,6 @@ static int smack_setprocattr(struct task_struct *p, char *name,
{
char *newsmack;
- if (!__capable(p, CAP_MAC_ADMIN))
- return -EPERM;
-
/*
* Changing another process' Smack value is too dangerous
* and supports no sane use case.
@@ -2026,6 +2042,9 @@ static int smack_setprocattr(struct task_struct *p, char *name,
if (p != current)
return -EPERM;
+ if (!capable(CAP_MAC_ADMIN))
+ return -EPERM;
+
if (value == NULL || size == 0 || size >= SMK_LABELLEN)
return -EINVAL;
@@ -2552,7 +2571,8 @@ static void smack_release_secctx(char *secdata, u32 seclen)
struct security_operations smack_ops = {
.name = "smack",
- .ptrace = smack_ptrace,
+ .ptrace_may_access = smack_ptrace_may_access,
+ .ptrace_traceme = smack_ptrace_traceme,
.capget = cap_capget,
.capset_check = cap_capset_check,
.capset_set = cap_capset_set,
@@ -2729,4 +2749,3 @@ static __init int smack_init(void)
* all processes and objects when they are created.
*/
security_initcall(smack_init);
-