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 | 5 +++-- fs/proc/namespaces.c | 17 ++++++++++++----- include/linux/namei.h | 2 +- security/apparmor/apparmorfs.c | 8 ++++++-- 5 files changed, 24 insertions(+), 11 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c index 671c3c1a3425..965a25b2e3df 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..fecd5b4af607 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1626,8 +1626,9 @@ 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); + if (error) + path_put(&path); out: return ERR_PTR(error); } diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index 08dd94df1a66..95e199fbad57 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -51,11 +51,18 @@ 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); + if (error) + path_put(&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..da045d0477a5 100644 --- a/security/apparmor/apparmorfs.c +++ b/security/apparmor/apparmorfs.c @@ -2455,16 +2455,20 @@ 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); + if (error) + path_put(&path); aa_put_ns(ns);
- return NULL; + return ERR_PTR(error); }
static int policy_readlink(struct dentry *dentry, char __user *buffer,