On Fri, Dec 02, 2022 at 01:34:03AM +0000, jeffxu@chromium.org wrote:
From: Jeff Xu jeffxu@chromium.org
The new security_memfd_create allows lsm to check flags of memfd_create.
The security by default system (such as chromeos) can use this to implement system wide lsm to allow only non-executable memfd being created.
Signed-off-by: Jeff Xu jeffxu@chromium.org
include/linux/lsm_hook_defs.h | 1 + include/linux/lsm_hooks.h | 4 ++++ include/linux/security.h | 6 ++++++ mm/memfd.c | 5 +++++ 4 files changed, 16 insertions(+)
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index ec119da1d89b..fd40840927c8 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -164,6 +164,7 @@ LSM_HOOK(int, 0, file_alloc_security, struct file *file) LSM_HOOK(void, LSM_RET_VOID, file_free_security, struct file *file) LSM_HOOK(int, 0, file_ioctl, struct file *file, unsigned int cmd, unsigned long arg) +LSM_HOOK(int, 0, memfd_create, char *name, unsigned int flags) LSM_HOOK(int, 0, mmap_addr, unsigned long addr) LSM_HOOK(int, 0, mmap_file, struct file *file, unsigned long reqprot, unsigned long prot, unsigned long flags) diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 4ec80b96c22e..5a18a6552278 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -543,6 +543,10 @@
- simple integer value. When @arg represents a user space pointer, it
- should never be used by the security module.
- Return 0 if permission is granted.
- @memfd_create:
- @name is the name of memfd file.
- @flags is the flags used in memfd_create.
- Return 0 if permission is granted.
- @mmap_addr :
- Check permissions for a mmap operation at @addr.
- @addr contains virtual address that will be used for the operation.
diff --git a/include/linux/security.h b/include/linux/security.h index ca1b7109c0db..5b87a780822a 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -384,6 +384,7 @@ int security_file_permission(struct file *file, int mask); int security_file_alloc(struct file *file); void security_file_free(struct file *file); int security_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg); +int security_memfd_create(char *name, unsigned int flags); int security_mmap_file(struct file *file, unsigned long prot, unsigned long flags); int security_mmap_addr(unsigned long addr); @@ -963,6 +964,11 @@ static inline int security_file_ioctl(struct file *file, unsigned int cmd, return 0; } +static inline int security_memfd_create(char *name, unsigned int flags) +{
- return 0;
+}
I think this is missing the security/security.c changes for the non-inline version?
-Kees
static inline int security_mmap_file(struct file *file, unsigned long prot, unsigned long flags) { diff --git a/mm/memfd.c b/mm/memfd.c index 69e897dea6d5..96dcfbfed09e 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -346,6 +346,11 @@ SYSCALL_DEFINE2(memfd_create, goto err_name; }
- /* security hook for memfd_create */
- error = security_memfd_create(name, flags);
- if (error)
return error;- if (flags & MFD_HUGETLB) { file = hugetlb_file_setup(name, 0, VM_NORESERVE, HUGETLB_ANONHUGE_INODE,
-- 2.39.0.rc0.267.gcb52ba06e7-goog