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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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