Re: [PATCH v2] fs,security: Fix file_set_fowner LSM hook inconsistencies
flat view
From: Mateusz Guzik <hidden>
Date: 2024-08-12 21:45:42
Also in:
linux-fsdevel, lkml, selinux
On Mon, Aug 12, 2024 at 07:44:17PM +0200, Mickaël Salaün wrote: No opinion about the core idea, I'll note though that this conflicts with a patch to move f_owner out of the struct: https://lore.kernel.org/linux-fsdevel/20240809-koriander-biobauer-6237cbc106f3@brauner/ (local) Presumably nothing which can't get sorted out with some shoveling. I do have actionable remark concerning creds though: both get_cred and put_cred are slow. Sorting that out is on my todo list. In the meantime adding more calls can be avoided:
quoted hunk ↗ jump to hunk
diff --git a/fs/file_table.c b/fs/file_table.c index 4f03beed4737..d28b76aef4f3 100644 --- a/fs/file_table.c +++ b/fs/file_table.c@@ -66,6 +66,7 @@ static inline void file_free(struct file *f) if (likely(!(f->f_mode & FMODE_NOACCOUNT))) percpu_counter_dec(&nr_files); put_cred(f->f_cred); + put_cred(f->f_owner.cred);
if (likely(f->f_cred == f->f_owner.cred)) {
put_cred_many(f->f_cred, 2);
} else {
put_cred(f->f_cred);
put_cred(f->f_owner.cred);
}
quoted hunk ↗ jump to hunk
if (unlikely(f->f_mode & FMODE_BACKING)) { path_put(backing_file_user_path(f)); kfree(backing_file(f));@@ -149,9 +150,11 @@ static int init_file(struct file *f, int flags, const struct cred *cred) int error; f->f_cred = get_cred(cred); + f->f_owner.cred = get_cred(cred);
f->f_cred = f->f_owner.cred = get_cred_many(cred, 2);
quoted hunk ↗ jump to hunk
error = security_file_alloc(f); if (unlikely(error)) { put_cred(f->f_cred); + put_cred(f->f_owner.cred);
put_cred_many(cred, 2);
return error; }