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Open Source and information security mailing list archives
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Date: Sat, 7 Dec 2019 01:13:28 +1100
From: Aleksa Sarai <cyphar@...har.com>
To: Al Viro <viro@...iv.linux.org.uk>,
Jeff Layton <jlayton@...nel.org>,
"J. Bruce Fields" <bfields@...ldses.org>,
Arnd Bergmann <arnd@...db.de>,
David Howells <dhowells@...hat.com>,
Shuah Khan <shuah@...nel.org>,
Shuah Khan <skhan@...uxfoundation.org>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
Andrii Nakryiko <andriin@...com>,
Jonathan Corbet <corbet@....net>
Cc: Aleksa Sarai <cyphar@...har.com>,
Eric Biederman <ebiederm@...ssion.com>,
Andy Lutomirski <luto@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Kees Cook <keescook@...omium.org>,
Jann Horn <jannh@...gle.com>, Tycho Andersen <tycho@...ho.ws>,
David Drysdale <drysdale@...gle.com>,
Chanho Min <chanho.min@....com>,
Oleg Nesterov <oleg@...hat.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
Christian Brauner <christian@...uner.io>,
Aleksa Sarai <asarai@...e.de>,
Linus Torvalds <torvalds@...ux-foundation.org>,
dev@...ncontainers.org, containers@...ts.linux-foundation.org,
bpf@...r.kernel.org, netdev@...r.kernel.org,
linux-alpha@...r.kernel.org, linux-api@...r.kernel.org,
libc-alpha@...rceware.org, linux-arch@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-ia64@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
linux-m68k@...ts.linux-m68k.org, linux-mips@...r.kernel.org,
linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
linux-xtensa@...ux-xtensa.org, sparclinux@...r.kernel.org
Subject: [PATCH v18 03/13] namei: allow nd_jump_link() to produce errors
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@...iv.linux.org.uk>
Signed-off-by: Aleksa Sarai <cyphar@...har.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
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