Re: [PATCH v9 05/10] namei: O_BENEATH-style path resolution flags
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2019-07-12 04:34:14
Also in:
linux-alpha, linux-api, linux-arch, linux-arm-kernel, linux-fsdevel, linux-kselftest, linux-mips, linux-s390, linux-sh, lkml, sparclinux
On Sun, Jul 07, 2019 at 12:57:32AM +1000, Aleksa Sarai wrote:
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@@ -1442,8 +1464,11 @@ static int follow_dotdot_rcu(struct nameidata *nd) struct inode *inode = nd->inode; while (1) { - if (path_equal(&nd->path, &nd->root)) + if (path_equal(&nd->path, &nd->root)) { + if (unlikely(nd->flags & LOOKUP_BENEATH)) + return -EXDEV;
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@@ -1468,6 +1493,8 @@ static int follow_dotdot_rcu(struct nameidata *nd) return -ECHILD; if (&mparent->mnt == nd->path.mnt) break; + if (unlikely(nd->flags & LOOKUP_XDEV)) + return -EXDEV; /* we know that mountpoint was pinned */ nd->path.dentry = mountpoint; nd->path.mnt = &mparent->mnt;@@ -1482,6 +1509,8 @@ static int follow_dotdot_rcu(struct nameidata *nd) return -ECHILD; if (!mounted) break; + if (unlikely(nd->flags & LOOKUP_XDEV)) + return -EXDEV;
Are you sure these failure exits in follow_dotdot_rcu() won't give suprious hard errors?
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+ if (unlikely(nd->flags & LOOKUP_BENEATH)) { + error = dirfd_path_init(nd); + if (unlikely(error)) + return ERR_PTR(error); + nd->root = nd->path; + if (!(nd->flags & LOOKUP_RCU)) + path_get(&nd->root); + } if (*s == '/') { if (likely(!nd->root.mnt)) set_root(nd);@@ -2350,9 +2400,11 @@ static const char *path_init(struct nameidata *nd, unsigned flags) s = ERR_PTR(error); return s; } - error = dirfd_path_init(nd); - if (unlikely(error)) - return ERR_PTR(error); + if (likely(!nd->path.mnt)) {
Is that a weird way of saying "if we hadn't already called dirfd_path_init()"?