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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>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
	Jonathan Corbet <corbet@lwn.net>
Cc: Aleksa Sarai <cyphar@cyphar.com>,
	Eric Biederman <ebiederm@xmission.com>,
	Andy Lutomirski <luto@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>,
	Tycho Andersen <tycho@tycho.ws>,
	David Drysdale <drysdale@google.com>,
	Chanho Min <chanho.min@lge.com>, Oleg Nesterov <oleg@redhat.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Christian Brauner <christian@brauner.io>,
	Aleksa Sarai <asarai@suse.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	dev@opencontainers.org, containers@lists.linux-foundation.org,
	bpf@vger.kernel.org, netdev@vger.kernel.org,
	linux-alpha@vger.kernel.org, linux-api@vger.kernel.org,
	libc-alpha@sourceware.org, linux-arch@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
	linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
	linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org
Subject: [PATCH RESEND v17 03/13] namei: allow nd_jump_link() to produce errors
Date: Wed, 20 Nov 2019 16:06:21 +1100
Message-ID: <20191120050631.12816-4-cyphar@cyphar.com> (raw)
In-Reply-To: <20191120050631.12816-1-cyphar@cyphar.com>

In preparation for LOOKUP_NO_MAGICLINKS, it's necessary to add the
ability for nd_jump_link() to return an error which the corresponding
get_link() caller must propogate back up to the VFS.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
---
 fs/namei.c                     |  3 ++-
 fs/proc/base.c                 |  3 +--
 fs/proc/namespaces.c           | 14 +++++++++-----
 include/linux/namei.h          |  2 +-
 security/apparmor/apparmorfs.c |  6 ++++--
 5 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 5a47d9c09581..1024a641f075 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -859,7 +859,7 @@ static int nd_jump_root(struct nameidata *nd)
  * Helper to directly jump to a known parsed path from ->get_link,
  * caller must have taken a reference to path beforehand.
  */
-void nd_jump_link(struct path *path)
+int nd_jump_link(struct path *path)
 {
 	struct nameidata *nd = current->nameidata;
 	path_put(&nd->path);
@@ -867,6 +867,7 @@ void nd_jump_link(struct path *path)
 	nd->path = *path;
 	nd->inode = nd->path.dentry->d_inode;
 	nd->flags |= LOOKUP_JUMPED;
+	return 0;
 }
 
 static inline void put_link(struct nameidata *nd)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index ebea9501afb8..ee97dd322f3e 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1626,8 +1626,7 @@ static const char *proc_pid_get_link(struct dentry *dentry,
 	if (error)
 		goto out;
 
-	nd_jump_link(&path);
-	return NULL;
+	error = nd_jump_link(&path);
 out:
 	return ERR_PTR(error);
 }
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 08dd94df1a66..a8cca516f1a9 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -51,11 +51,15 @@ static const char *proc_ns_get_link(struct dentry *dentry,
 	if (!task)
 		return ERR_PTR(-EACCES);
 
-	if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
-		error = ns_get_path(&ns_path, task, ns_ops);
-		if (!error)
-			nd_jump_link(&ns_path);
-	}
+	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
+		goto out;
+
+	error = ns_get_path(&ns_path, task, ns_ops);
+	if (error)
+		goto out;
+
+	error = nd_jump_link(&ns_path);
+out:
 	put_task_struct(task);
 	return ERR_PTR(error);
 }
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 397a08ade6a2..758e9b47db6f 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -68,7 +68,7 @@ extern int follow_up(struct path *);
 extern struct dentry *lock_rename(struct dentry *, struct dentry *);
 extern void unlock_rename(struct dentry *, struct dentry *);
 
-extern void nd_jump_link(struct path *path);
+extern int __must_check nd_jump_link(struct path *path);
 
 static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)
 {
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 45d13b6462aa..0b7d6dce6291 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -2455,16 +2455,18 @@ static const char *policy_get_link(struct dentry *dentry,
 {
 	struct aa_ns *ns;
 	struct path path;
+	int error;
 
 	if (!dentry)
 		return ERR_PTR(-ECHILD);
+
 	ns = aa_get_current_ns();
 	path.mnt = mntget(aafs_mnt);
 	path.dentry = dget(ns_dir(ns));
-	nd_jump_link(&path);
+	error = nd_jump_link(&path);
 	aa_put_ns(ns);
 
-	return NULL;
+	return ERR_PTR(error);
 }
 
 static int policy_readlink(struct dentry *dentry, char __user *buffer,
-- 
2.24.0


  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-20  5:06 [PATCH RESEND v17 00/13] open: introduce openat2(2) syscall Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 01/13] namei: only return -ECHILD from follow_dotdot_rcu() Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 02/13] nsfs: clean-up ns_get_path() signature to return int Aleksa Sarai
2019-11-20  5:06 ` Aleksa Sarai [this message]
2019-11-20  5:06 ` [PATCH RESEND v17 04/13] namei: allow set_root() to produce errors Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 05/13] namei: LOOKUP_NO_SYMLINKS: block symlink resolution Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 06/13] namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 07/13] namei: LOOKUP_NO_XDEV: block mountpoint crossing Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 08/13] namei: LOOKUP_BENEATH: O_BENEATH-like scoped resolution Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 09/13] namei: LOOKUP_IN_ROOT: chroot-like " Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 10/13] namei: LOOKUP_{IN_ROOT,BENEATH}: permit limited ".." resolution Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 11/13] open: introduce openat2(2) syscall Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 12/13] selftests: add openat2(2) selftests Aleksa Sarai
2019-11-20  5:06 ` [PATCH RESEND v17 13/13] Documentation: path-lookup: include new LOOKUP flags Aleksa Sarai

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