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[PATCH v17 03/13] namei: allow nd_jump_link() to produce errors
- From: Aleksa Sarai <cyphar at cyphar dot com>
- To: Al Viro <viro at zeniv dot linux dot org dot uk>, Jeff Layton <jlayton at kernel dot org>, "J. Bruce Fields" <bfields at fieldses dot org>, Arnd Bergmann <arnd at arndb dot de>, David Howells <dhowells at redhat dot com>, Shuah Khan <shuah at kernel dot org>, Shuah Khan <skhan at linuxfoundation dot org>, Ingo Molnar <mingo at redhat dot com>, Peter Zijlstra <peterz at infradead dot org>, Alexei Starovoitov <ast at kernel dot org>, Daniel Borkmann <daniel at iogearbox dot net>, Martin KaFai Lau <kafai at fb dot com>, Song Liu <songliubraving at fb dot com>, Yonghong Song <yhs at fb dot com>, Andrii Nakryiko <andriin at fb dot com>, Jonathan Corbet <corbet at lwn dot net>
- Cc: Aleksa Sarai <cyphar at cyphar dot com>, Eric Biederman <ebiederm at xmission dot com>, Andy Lutomirski <luto at kernel dot org>, Andrew Morton <akpm at linux-foundation dot org>, Kees Cook <keescook at chromium dot org>, Jann Horn <jannh at google dot com>, Tycho Andersen <tycho at tycho dot ws>, David Drysdale <drysdale at google dot com>, Chanho Min <chanho dot min at lge dot com>, Oleg Nesterov <oleg at redhat dot com>, Rasmus Villemoes <linux at rasmusvillemoes dot dk>, Alexander Shishkin <alexander dot shishkin at linux dot intel dot com>, Jiri Olsa <jolsa at redhat dot com>, Namhyung Kim <namhyung at kernel dot org>, Christian Brauner <christian at brauner dot io>, Aleksa Sarai <asarai at suse dot de>, Linus Torvalds <torvalds at linux-foundation dot org>, dev at opencontainers dot org, containers at lists dot linux-foundation dot org, bpf at vger dot kernel dot org, netdev at vger dot kernel dot org, linux-alpha at vger dot kernel dot org, linux-api at vger dot kernel dot org, libc-alpha at sourceware dot org, linux-arch at vger dot kernel dot org, linux-arm-kernel at lists dot infradead dot org, linux-doc at vger dot kernel dot org, linux-fsdevel at vger dot kernel dot org, linux-ia64 at vger dot kernel dot org, linux-kernel at vger dot kernel dot org, linux-kselftest at vger dot kernel dot org, linux-m68k at lists dot linux-m68k dot org, linux-mips at vger dot kernel dot org, linux-parisc at vger dot kernel dot org, linuxppc-dev at lists dot ozlabs dot org, linux-s390 at vger dot kernel dot org, linux-sh at vger dot kernel dot org, linux-xtensa at linux-xtensa dot org, sparclinux at vger dot kernel dot org
- Date: Sun, 17 Nov 2019 12:17:03 +1100
- Subject: [PATCH v17 03/13] namei: allow nd_jump_link() to produce errors
- References: <20191117011713.13032-1-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