24 Mar
2021
24 Mar
'21
3:03 p.m.
On 19/03/2021 22:53, Mickaël Salaün wrote:
On 19/03/2021 20:06, Kees Cook wrote:
On Tue, Mar 16, 2021 at 09:42:48PM +0100, Mickaël Salaün wrote:
From: Mickaël Salaün mic@linux.microsoft.com
[...]
+/**
- sys_landlock_create_ruleset - Create a new ruleset
- @attr: Pointer to a &struct landlock_ruleset_attr identifying the scope of
the new ruleset.
- @size: Size of the pointed &struct landlock_ruleset_attr (needed for
backward and forward compatibility).
- @flags: Must be 0.
- This system call enables to create a new Landlock ruleset, and returns the
- related file descriptor on success.
- Possible returned errors are:
- EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
- EINVAL: @flags is not 0, or unknown access, or too small @size;
- E2BIG or EFAULT: @attr or @size inconsistencies;
- ENOMSG: empty &landlock_ruleset_attr.handled_access_fs.
- */
+SYSCALL_DEFINE3(landlock_create_ruleset,
const struct landlock_ruleset_attr __user *const, attr,const size_t, size, const __u32, flags)+{
- struct landlock_ruleset_attr ruleset_attr;
- struct landlock_ruleset *ruleset;
- int err, ruleset_fd;
- /* Build-time checks. */
- build_check_abi();
- if (!landlock_initialized)
return -EOPNOTSUPP;- /* No flag for now. */
- if (flags)
return -EINVAL;- /* Copies raw user space buffer. */
- err = copy_min_struct_from_user(&ruleset_attr, sizeof(ruleset_attr),
offsetofend(typeof(ruleset_attr), handled_access_fs),The use of offsetofend() here appears to be kind of the "V1", "V2", ... sizes used in other extensible syscall implementations?
ruleset_attr is an extensible argument.
offsetofen() is used to set the minimum size of a valid argument. This code will then not change with future extended ruleset_attr.