Thread (30 messages) 30 messages, 4 authors, 2019-11-14

Re: [PATCH v15 5/9] namei: LOOKUP_IN_ROOT: chroot-like scoped resolution

From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2019-11-13 02:03:45
Also in: linux-alpha, linux-api, linux-arch, linux-arm-kernel, linux-fsdevel, linux-kselftest, linux-mips, linux-s390, linux-sh, lkml, sparclinux

On Tue, Nov 05, 2019 at 08:05:49PM +1100, Aleksa Sarai wrote:
quoted hunk ↗ jump to hunk
@@ -2277,12 +2277,20 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
 
 	nd->m_seq = read_seqbegin(&mount_lock);
 
-	/* Figure out the starting path and root (if needed). */
-	if (*s == '/') {
+	/* Absolute pathname -- fetch the root. */
+	if (flags & LOOKUP_IN_ROOT) {
+		/* With LOOKUP_IN_ROOT, act as a relative path. */
+		while (*s == '/')
+			s++;
Er...  Why bother skipping slashes?  I mean, not only link_path_walk()
will skip them just fine, you are actually risking breakage in this:
                if (*s && unlikely(!d_can_lookup(dentry))) {
                        fdput(f);
                        return ERR_PTR(-ENOTDIR);
                }
which is downstream from there with you patch, AFAICS.
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