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authorJohn Johansen <john.johansen@canonical.com>2017-06-09 16:19:02 -0700
committerJohn Johansen <john.johansen@canonical.com>2017-06-10 17:11:44 -0700
commit496c93196654d3e604013d750b7047886af14506 (patch)
tree37c3a7e09e82bf37664476a371f9956d46d52bb5
parent8014370f1257619226b79cb6de8e28563fbbc070 (diff)
downloadlinux-496c93196654d3e604013d750b7047886af14506.tar.bz2
apparmor: rework file permission to cache file access in file->ctx
This is a temporary step, towards using the file->ctx for delegation, and also helps speed up file queries, until the permission lookup cache is introduced. Signed-off-by: John Johansen <john.johansen@canonical.com>
-rw-r--r--security/apparmor/file.c82
1 files changed, 76 insertions, 6 deletions
diff --git a/security/apparmor/file.c b/security/apparmor/file.c
index eb4c3006af67..b6e8e5b11e05 100644
--- a/security/apparmor/file.c
+++ b/security/apparmor/file.c
@@ -492,6 +492,80 @@ int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
return error;
}
+static void update_file_ctx(struct aa_file_ctx *fctx, struct aa_label *label,
+ u32 request)
+{
+ struct aa_label *l, *old;
+
+ /* update caching of label on file_ctx */
+ spin_lock(&fctx->lock);
+ old = rcu_dereference_protected(fctx->label,
+ spin_is_locked(&fctx->lock));
+ l = aa_label_merge(old, label, GFP_ATOMIC);
+ if (l) {
+ if (l != old) {
+ rcu_assign_pointer(fctx->label, l);
+ aa_put_label(old);
+ } else
+ aa_put_label(l);
+ fctx->allow |= request;
+ }
+ spin_unlock(&fctx->lock);
+}
+
+static int __file_path_perm(const char *op, struct aa_label *label,
+ struct aa_label *flabel, struct file *file,
+ u32 request, u32 denied)
+{
+ struct aa_profile *profile;
+ struct aa_perms perms = {};
+ struct path_cond cond = {
+ .uid = file_inode(file)->i_uid,
+ .mode = file_inode(file)->i_mode
+ };
+ char *buffer;
+ int flags, error;
+
+ /* revalidation due to label out of date. No revocation at this time */
+ if (!denied && aa_label_is_subset(flabel, label))
+ /* TODO: check for revocation on stale profiles */
+ return 0;
+
+ flags = PATH_DELEGATE_DELETED | (S_ISDIR(cond.mode) ? PATH_IS_DIR : 0);
+ get_buffers(buffer);
+
+ /* check every profile in task label not in current cache */
+ error = fn_for_each_not_in_set(flabel, label, profile,
+ profile_path_perm(op, profile, &file->f_path, buffer,
+ request, &cond, flags, &perms));
+ if (denied && !error) {
+ /*
+ * check every profile in file label that was not tested
+ * in the initial check above.
+ *
+ * TODO: cache full perms so this only happens because of
+ * conditionals
+ * TODO: don't audit here
+ */
+ if (label == flabel)
+ error = fn_for_each(label, profile,
+ profile_path_perm(op, profile, &file->f_path,
+ buffer, request, &cond, flags,
+ &perms));
+ else
+ error = fn_for_each_not_in_set(label, flabel, profile,
+ profile_path_perm(op, profile, &file->f_path,
+ buffer, request, &cond, flags,
+ &perms));
+ }
+ if (!error)
+ update_file_ctx(file_ctx(file), label, request);
+
+ put_buffers(buffer);
+
+ return error;
+}
+
/**
* aa_file_perm - do permission revalidation check & audit for @file
* @op: operation being checked
@@ -504,10 +578,6 @@ int aa_path_link(struct aa_label *label, struct dentry *old_dentry,
int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
u32 request)
{
- struct path_cond cond = {
- .uid = file_inode(file)->i_uid,
- .mode = file_inode(file)->i_mode
- };
struct aa_file_ctx *fctx;
struct aa_label *flabel;
u32 denied;
@@ -537,8 +607,8 @@ int aa_file_perm(const char *op, struct aa_label *label, struct file *file,
/* TODO: label cross check */
if (file->f_path.mnt && path_mediated_fs(file->f_path.dentry))
- error = aa_path_perm(op, label, &file->f_path,
- PATH_DELEGATE_DELETED, request, &cond);
+ error = __file_path_perm(op, label, flabel, file, request,
+ denied);
done:
rcu_read_unlock();