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move mount_capable() calls to vfs_get_tree()

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sget_fc() is called only from ->get_tree() instances and
the only instance not calling it is legacy_get_tree(),
which calls mount_capable() directly.

In all sget_fc() callers the checks could be moved to the
very beginning of ->get_tree() - ->user_ns is not changed
in between.  So lifting the checks to the only caller of
->get_tree() is OK.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2019-05-12 18:16:04 -04:00
parent d5f68d330c
commit 059338aae3
2 changed files with 6 additions and 11 deletions
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5
fs/fs_context.c
View File

@ -662,11 +662,6 @@ static int legacy_get_tree(struct fs_context *fc)
struct super_block *sb;
struct dentry *root;
if (!(fc->sb_flags & (SB_KERNMOUNT|SB_SUBMOUNT))) {
if (!mount_capable(fc))
return -EPERM;
}
root = fc->fs_type->mount(fc->fs_type, fc->sb_flags,
fc->source, ctx->legacy_data);
if (IS_ERR(root))

12
fs/super.c
View File

@ -514,12 +514,6 @@ struct super_block *sget_fc(struct fs_context *fc,
struct user_namespace *user_ns = fc->global ? &init_user_ns : fc->user_ns;
int err;
if (!(fc->sb_flags & SB_KERNMOUNT) &&
fc->purpose != FS_CONTEXT_FOR_SUBMOUNT) {
if (!mount_capable(fc))
return ERR_PTR(-EPERM);
}
retry:
spin_lock(&sb_lock);
if (test) {
@ -1421,6 +1415,12 @@ int vfs_get_tree(struct fs_context *fc)
if (fc->root)
return -EBUSY;
if (!(fc->sb_flags & SB_KERNMOUNT) &&
fc->purpose != FS_CONTEXT_FOR_SUBMOUNT) {
if (!mount_capable(fc))
return -EPERM;
}
/* Get the mountable root in fc->root, with a ref on the root and a ref
* on the superblock.
*/