Add a new hook guarding instantiations of programs with executable
stack. They are being warned about since commit 47a2ebb7f505 ("execve:
warn if process starts with executable stack"). Lets give LSMs the
ability to control their presence on a per application basis.
Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
---
fs/exec.c | 4 ++++
include/linux/lsm_hook_defs.h | 1 +
include/linux/security.h | 6 ++++++
security/security.c | 13 +++++++++++++
4 files changed, 24 insertions(+)
diff --git a/fs/exec.c b/fs/exec.c
index 8cdd5b2dd09c..e6f9e980c6b1 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -829,6 +829,10 @@ int setup_arg_pages(struct linux_binprm *bprm,
BUG_ON(prev != vma);
if (unlikely(vm_flags & VM_EXEC)) {
+ ret = security_vm_execstack();
+ if (ret)
+ goto out_unlock;
+
pr_warn_once("process '%pD4' started with executable stack\n",
bprm->file);
}
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 185924c56378..b31d0744e7e7 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -49,6 +49,7 @@ LSM_HOOK(int, 0, syslog, int type)
LSM_HOOK(int, 0, settime, const struct timespec64 *ts,
const struct timezone *tz)
LSM_HOOK(int, 1, vm_enough_memory, struct mm_struct *mm, long pages)
+LSM_HOOK(int, 0, vm_execstack, void)
LSM_HOOK(int, 0, bprm_creds_for_exec, struct linux_binprm *bprm)
LSM_HOOK(int, 0, bprm_creds_from_file, struct linux_binprm *bprm, const struct file *file)
LSM_HOOK(int, 0, bprm_check_security, struct linux_binprm *bprm)
diff --git a/include/linux/security.h b/include/linux/security.h
index d0eb20f90b26..084b96814970 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -294,6 +294,7 @@ int security_quota_on(struct dentry *dentry);
int security_syslog(int type);
int security_settime64(const struct timespec64 *ts, const struct timezone *tz);
int security_vm_enough_memory_mm(struct mm_struct *mm, long pages);
+int security_vm_execstack(void);
int security_bprm_creds_for_exec(struct linux_binprm *bprm);
int security_bprm_creds_from_file(struct linux_binprm *bprm, const struct file *file);
int security_bprm_check(struct linux_binprm *bprm);
@@ -624,6 +625,11 @@ static inline int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
return __vm_enough_memory(mm, pages, cap_vm_enough_memory(mm, pages));
}
+static inline int security_vm_execstack(void)
+{
+ return 0;
+}
+
static inline int security_bprm_creds_for_exec(struct linux_binprm *bprm)
{
return 0;
diff --git a/security/security.c b/security/security.c
index 0144a98d3712..f75240d0d99d 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1125,6 +1125,19 @@ int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
return __vm_enough_memory(mm, pages, cap_sys_admin);
}
+/**
+ * security_vm_execstack() - Check if starting a program with executable stack
+ * is allowed
+ *
+ * Check whether starting a program with an executable stack is allowed.
+ *
+ * Return: Returns 0 if permission is granted.
+ */
+int security_vm_execstack(void)
+{
+ return call_int_hook(vm_execstack);
+}
+
/**
* security_bprm_creds_for_exec() - Prepare the credentials for exec()
* @bprm: binary program information
--
2.43.0
