From: Jeff Xu jeffxu@google.com
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@google.com Reported-by: kernel test robot lkp@intel.com --- include/linux/lsm_hook_defs.h | 1 + include/linux/lsm_hooks.h | 4 ++++ include/linux/security.h | 6 ++++++ mm/memfd.c | 5 +++++ security/security.c | 5 +++++ 5 files changed, 21 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; +} + 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 92f0a5765f7c..f04ed5f0474f 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -356,6 +356,11 @@ 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, diff --git a/security/security.c b/security/security.c index 79d82cb6e469..57788cf94075 100644 --- a/security/security.c +++ b/security/security.c @@ -1010,6 +1010,11 @@ int security_sb_clone_mnt_opts(const struct super_block *oldsb, } EXPORT_SYMBOL(security_sb_clone_mnt_opts);
+int security_memfd_create(char *name, unsigned int flags) +{ + return call_int_hook(memfd_create, 0, name, flags); +} + int security_move_mount(const struct path *from_path, const struct path *to_path) { return call_int_hook(move_mount, 0, from_path, to_path);