--- David Howells <[EMAIL PROTECTED]> wrote:
>
> Hi Linus, Al,
>
> Would you object greatly to functions like vfs_mkdir() gaining a security
> parameter?
Could you describe how this compares to the proposal that the
AppArmor developers suggested recently? I expect that we can
reduce the amount of discussion required, and maybe avoid some
confusion if you could do that.
Thank you.
> What I'm thinking of is this:
>
> int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode,
> struct security *security)
>
> Where the security context is the state of the context at the time the call
> was issued:
>
> struct security {
> uid_t fsuid;
> git_t fsgid;
> struct group_info *group_info;
> void *security;
> struct key *session_keyring;
> struct key *process_keyring;
> struct key *thread_keyring;
>
> And perhaps:
>
> struct audit_context *audit_context;
> seccomp_t seccomp;
> };
>
> This would, for the most part, be a temporary affair, being set up by such as
> sys_mkdir()/sys_mkdirat() from data held in task_struct.
>
> This information would then be passed into the filesystem and LSM layers so
> that files, directories, etc. can be created, opened, deleted, or otherwise
> mangled based on these security items, rather than the one in whichever
> task_struct is current.
>
>
> The reason for doing this would be to support an act-as interface, so that
> services such as nfsd and cachefiles could act with different security
> details
> to the ones attached to the task. This would have a couple of potential
> benefits:
>
> (1) nfsd threads don't have to keep changing their security contexts.
>
> (2) cachefiles can act on behalf of a process without changing its security
> context.
>
>
> Note that I/O operations such as read, write and ioctl would *not* be passed
> this data as the file struct should contain the relevant security
> information.
> Similarly, page I/O operations would also not need alteration as the VMA
> covering the region points to a file struct, which holds the appropriate
> security.
>
> David
>
>
>
Casey Schaufler
[EMAIL PROTECTED]
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