From: Aleksa Sarai <cyphar@cyphar.com>
To: Al Viro <viro@zeniv.linux.org.uk>,
Jeff Layton <jlayton@kernel.org>,
"J. Bruce Fields" <bfields@fieldses.org>,
Arnd Bergmann <arnd@arndb.de>,
David Howells <dhowells@redhat.com>,
Shuah Khan <shuah@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>,
Eric Biederman <ebiederm@xmission.com>,
Andy Lutomirski <luto@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alexei Starovoitov <ast@kernel.org>,
Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>,
Christian Brauner <christian@brauner.io>,
Tycho Andersen <tycho@tycho.ws>,
David Drysdale <drysdale@google.com>,
Chanho Min <chanho.min@lge.com>, Oleg Nesterov <oleg@redhat.com>,
Aleksa Sarai <asarai@suse.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
containers@lists.linux-foundation.org,
linux-kselftest@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org
Subject: [PATCH RFC v8 04/10] namei: split out nd->dfd handling to dirfd_path_init
Date: Mon, 20 May 2019 23:32:59 +1000 [thread overview]
Message-ID: <20190520133305.11925-5-cyphar@cyphar.com> (raw)
In-Reply-To: <20190520133305.11925-1-cyphar@cyphar.com>
Previously, path_init's handling of *at(dfd, ...) was only done once,
but with LOOKUP_BENEATH (and LOOKUP_IN_ROOT) we have to parse the
initial nd->path at different times (before or after absolute path
handling) depending on whether we have been asked to scope resolution
within a root.
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
---
fs/namei.c | 103 ++++++++++++++++++++++++++++++-----------------------
1 file changed, 59 insertions(+), 44 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 46c5302eea4a..dc323e25d4d2 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2251,9 +2251,59 @@ static int link_path_walk(const char *name, struct nameidata *nd)
}
}
+/*
+ * Configure nd->path based on the nd->dfd. This is only used as part of
+ * path_init().
+ */
+static inline int dirfd_path_init(struct nameidata *nd)
+{
+ if (nd->dfd == AT_FDCWD) {
+ if (nd->flags & LOOKUP_RCU) {
+ struct fs_struct *fs = current->fs;
+ unsigned seq;
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->path = fs->pwd;
+ nd->inode = nd->path.dentry->d_inode;
+ nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+ } while (read_seqcount_retry(&fs->seq, seq));
+ } else {
+ get_fs_pwd(current->fs, &nd->path);
+ nd->inode = nd->path.dentry->d_inode;
+ }
+ } else {
+ /* Caller must check execute permissions on the starting path component */
+ struct fd f = fdget_raw(nd->dfd);
+ struct dentry *dentry;
+
+ if (!f.file)
+ return -EBADF;
+
+ dentry = f.file->f_path.dentry;
+
+ if (*nd->name->name && unlikely(!d_can_lookup(dentry))) {
+ fdput(f);
+ return -ENOTDIR;
+ }
+
+ nd->path = f.file->f_path;
+ if (nd->flags & LOOKUP_RCU) {
+ nd->inode = nd->path.dentry->d_inode;
+ nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
+ } else {
+ path_get(&nd->path);
+ nd->inode = nd->path.dentry->d_inode;
+ }
+ fdput(f);
+ }
+ return 0;
+}
+
/* must be paired with terminate_walk() */
static const char *path_init(struct nameidata *nd, unsigned flags)
{
+ int error;
const char *s = nd->name->name;
if (!*s)
@@ -2287,52 +2337,17 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
nd->m_seq = read_seqbegin(&mount_lock);
if (*s == '/') {
- set_root(nd);
- if (likely(!nd_jump_root(nd)))
- return s;
- return ERR_PTR(-ECHILD);
- } else if (nd->dfd == AT_FDCWD) {
- if (flags & LOOKUP_RCU) {
- struct fs_struct *fs = current->fs;
- unsigned seq;
-
- do {
- seq = read_seqcount_begin(&fs->seq);
- nd->path = fs->pwd;
- nd->inode = nd->path.dentry->d_inode;
- nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
- } while (read_seqcount_retry(&fs->seq, seq));
- } else {
- get_fs_pwd(current->fs, &nd->path);
- nd->inode = nd->path.dentry->d_inode;
- }
- return s;
- } else {
- /* Caller must check execute permissions on the starting path component */
- struct fd f = fdget_raw(nd->dfd);
- struct dentry *dentry;
-
- if (!f.file)
- return ERR_PTR(-EBADF);
-
- dentry = f.file->f_path.dentry;
-
- if (*s && unlikely(!d_can_lookup(dentry))) {
- fdput(f);
- return ERR_PTR(-ENOTDIR);
- }
-
- nd->path = f.file->f_path;
- if (flags & LOOKUP_RCU) {
- nd->inode = nd->path.dentry->d_inode;
- nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
- } else {
- path_get(&nd->path);
- nd->inode = nd->path.dentry->d_inode;
- }
- fdput(f);
+ if (likely(!nd->root.mnt))
+ set_root(nd);
+ error = nd_jump_root(nd);
+ if (unlikely(error))
+ s = ERR_PTR(error);
return s;
}
+ error = dirfd_path_init(nd);
+ if (unlikely(error))
+ return ERR_PTR(error);
+ return s;
}
static const char *trailing_symlink(struct nameidata *nd)
--
2.21.0
next prev parent reply other threads:[~2019-05-20 13:34 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-20 13:32 [PATCH RFC v8 00/10] namei: resolveat(2) path resolution restrictions Aleksa Sarai
2019-05-20 13:32 ` [PATCH RFC v8 01/10] namei: obey trailing magic-link DAC permissions Aleksa Sarai
2019-05-22 17:01 ` Andy Lutomirski
2019-05-23 2:00 ` Aleksa Sarai
2019-05-24 3:11 ` Aleksa Sarai
2019-05-29 15:10 ` Andy Lutomirski
2019-05-20 13:32 ` [PATCH RFC v8 02/10] procfs: switch magic-link modes to be more sane Aleksa Sarai
2019-05-20 13:32 ` [PATCH RFC v8 03/10] open: O_EMPTYPATH: procfs-less file descriptor re-opening Aleksa Sarai
2019-05-20 13:32 ` Aleksa Sarai [this message]
2019-05-20 13:33 ` [PATCH RFC v8 05/10] namei: O_BENEATH-style path resolution flags Aleksa Sarai
2019-05-20 13:33 ` [PATCH RFC v8 06/10] namei: LOOKUP_IN_ROOT: chroot-like path resolution Aleksa Sarai
2019-05-20 13:33 ` [PATCH RFC v8 07/10] namei: aggressively check for nd->root escape on ".." resolution Aleksa Sarai
2019-05-20 13:33 ` [PATCH RFC v8 08/10] namei: resolveat(2) syscall Aleksa Sarai
2019-05-20 13:33 ` [PATCH RFC v8 09/10] kselftest: save-and-restore errno to allow for %m formatting Aleksa Sarai
2019-05-20 13:33 ` [PATCH RFC v8 10/10] selftests: add resolveat(2) selftests Aleksa Sarai
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190520133305.11925-5-cyphar@cyphar.com \
--to=cyphar@cyphar.com \
--cc=akpm@linux-foundation.org \
--cc=arnd@arndb.de \
--cc=asarai@suse.de \
--cc=ast@kernel.org \
--cc=bfields@fieldses.org \
--cc=chanho.min@lge.com \
--cc=christian@brauner.io \
--cc=containers@lists.linux-foundation.org \
--cc=dhowells@redhat.com \
--cc=drysdale@google.com \
--cc=ebiederm@xmission.com \
--cc=jannh@google.com \
--cc=jlayton@kernel.org \
--cc=keescook@chromium.org \
--cc=linux-api@vger.kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=luto@kernel.org \
--cc=oleg@redhat.com \
--cc=shuah@kernel.org \
--cc=skhan@linuxfoundation.org \
--cc=torvalds@linux-foundation.org \
--cc=tycho@tycho.ws \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).