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[109.45.0.227]) by smtp.gmail.com with ESMTPSA id d3sm5826085edd.41.2017.11.09.08.14.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 09 Nov 2017 08:14:38 -0800 (PST) From: Djalal Harouni To: Kees Cook , Alexey Gladkov , Andy Lutomirski , Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-security-module@vger.kernel.org, linux-api@vger.kernel.org Cc: Greg Kroah-Hartman , Alexander Viro , Akinobu Mita , me@tobin.cc, Oleg Nesterov , Jeff Layton , Ingo Molnar , Alexey Dobriyan , ebiederm@xmission.com, Linus Torvalds , Daniel Micay , Jonathan Corbet , bfields@fieldses.org, Stephen Rothwell , solar@openwall.com, Djalal Harouni Subject: [PATCH RFC v3 7/7] proc: flush dcache entries from all procfs instances Date: Thu, 9 Nov 2017 17:14:06 +0100 Message-Id: <1510244046-3256-8-git-send-email-tixxdz@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1510244046-3256-1-git-send-email-tixxdz@gmail.com> References: <1510244046-3256-1-git-send-email-tixxdz@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Flush dcache entries of a task when it terminates. The task may have showed up in multiple procfs mounts per pid namespace, and we need to walk the mounts and invalidate any left entires. Cc: Kees Cook Cc: Greg Kroah-Hartman Cc: Andy Lutomirski Cc: Alexey Gladkov Signed-off-by: Djalal Harouni --- fs/proc/base.c | 27 +++++++++++++++++++----- fs/proc/inode.c | 9 +++++++- fs/proc/root.c | 10 +++++++++ include/linux/pid_namespace.h | 49 +++++++++++++++++++++++++++++++++++++++++++ include/linux/proc_fs.h | 2 ++ 5 files changed, 91 insertions(+), 6 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 88b92bc..27e52aa 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -3034,7 +3034,8 @@ static const struct inode_operations proc_tgid_base_inode_operations = { .permission = proc_pid_permission, }; -static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid) +static void proc_flush_task_mnt_root(struct dentry *mnt_root, + pid_t pid, pid_t tgid) { struct dentry *dentry, *leader, *dir; char buf[PROC_NUMBUF]; @@ -3043,7 +3044,7 @@ static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid) name.name = buf; name.len = snprintf(buf, sizeof(buf), "%d", pid); /* no ->d_hash() rejects on procfs */ - dentry = d_hash_and_lookup(mnt->mnt_root, &name); + dentry = d_hash_and_lookup(mnt_root, &name); if (dentry) { d_invalidate(dentry); dput(dentry); @@ -3054,7 +3055,7 @@ static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid) name.name = buf; name.len = snprintf(buf, sizeof(buf), "%d", tgid); - leader = d_hash_and_lookup(mnt->mnt_root, &name); + leader = d_hash_and_lookup(mnt_root, &name); if (!leader) goto out; @@ -3109,14 +3110,30 @@ void proc_flush_task(struct task_struct *task) int i; struct pid *pid, *tgid; struct upid *upid; + struct proc_fs_info *fs_info_entry; + struct pid_namespace *pid_ns; + struct dentry *mnt_root; pid = task_pid(task); tgid = task_tgid(task); for (i = 0; i <= pid->level; i++) { upid = &pid->numbers[i]; - proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr, - tgid->numbers[i].nr); + pid_ns = upid->ns; + + pidns_proc_lock_shared(pid_ns); + list_for_each_entry(fs_info_entry, &pid_ns->procfs_mounts, + pidns_entry) { + if (proc_fs_newinstance(fs_info_entry)) { + mnt_root = fs_info_entry->sb->s_root; + proc_flush_task_mnt_root(mnt_root, upid->nr, + tgid->numbers[i].nr); + } + } + pidns_proc_unlock_shared(pid_ns); + + mnt_root = pid_ns->proc_mnt->mnt_root; + proc_flush_task_mnt_root(mnt_root, upid->nr, tgid->numbers[i].nr); } } diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 2707d5f..8fcf0d7 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -484,10 +484,17 @@ struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) int proc_fill_super(struct super_block *s, void *data, int silent) { struct proc_fs_info *fs_info = proc_sb(s); + struct pid_namespace *ns = get_pid_ns(fs_info->pid_ns); struct inode *root_inode; int ret; - get_pid_ns(fs_info->pid_ns); + fs_info->sb = s; + + if (proc_fs_newinstance(fs_info)) { + pidns_proc_lock(ns); + list_add_tail(&fs_info->pidns_entry, &ns->procfs_mounts); + pidns_proc_unlock(ns); + } if (!proc_parse_options(data, fs_info)) return -EINVAL; diff --git a/fs/proc/root.c b/fs/proc/root.c index 5cdff69..5503799 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -259,6 +259,13 @@ static void proc_kill_sb(struct super_block *sb) dput(fs_info->proc_self); if (fs_info->proc_thread_self) dput(fs_info->proc_thread_self); + + if (proc_fs_newinstance(fs_info)) { + pidns_proc_lock(ns); + list_del(&fs_info->pidns_entry); + pidns_proc_unlock(ns); + } + kill_anon_super(sb); put_pid_ns(ns); kfree(fs_info); @@ -374,6 +381,9 @@ int pid_ns_prepare_proc(struct pid_namespace *ns) return PTR_ERR(mnt); ns->proc_mnt = mnt; + init_rwsem(&ns->rw_procfs_mnts); + INIT_LIST_HEAD(&ns->procfs_mounts); + return 0; } diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h index 66f47f1..9a7a28d 100644 --- a/include/linux/pid_namespace.h +++ b/include/linux/pid_namespace.h @@ -26,6 +26,15 @@ struct pid_namespace { struct pid_namespace *parent; #ifdef CONFIG_PROC_FS struct vfsmount *proc_mnt; /* Internal proc mounted during each new pidns */ + + /* Serialize separated procfs access from super block create/destory */ + struct rw_semaphore rw_procfs_mnts; + + /* + * List of separated procfs mounts, used to invalidate task dentry + * from all the related procfs mounts. + */ + struct list_head procfs_mounts; #endif #ifdef CONFIG_BSD_PROCESS_ACCT struct fs_pin *bacct; @@ -90,4 +99,44 @@ extern struct pid_namespace *task_active_pid_ns(struct task_struct *tsk); void pidhash_init(void); void pid_idr_init(void); +#ifdef CONFIG_PROC_FS +static inline void pidns_proc_lock(struct pid_namespace *pid_ns) +{ + down_write(&pid_ns->rw_procfs_mnts); +} + +static inline void pidns_proc_unlock(struct pid_namespace *pid_ns) +{ + up_write(&pid_ns->rw_procfs_mnts); +} + +static inline void pidns_proc_lock_shared(struct pid_namespace *pid_ns) +{ + down_read(&pid_ns->rw_procfs_mnts); +} + +static inline void pidns_proc_unlock_shared(struct pid_namespace *pid_ns) +{ + up_read(&pid_ns->rw_procfs_mnts); +} +#else /* !CONFIG_PROC_FS */ + +static inline void pidns_proc_lock(struct pid_namespace *pid_ns) +{ +} + +static inline void pidns_proc_unlock(struct pid_namespace *pid_ns) +{ +} + +static inline void pidns_proc_lock_shared(struct pid_namespace *pid_ns) +{ +} + +static inline void pidns_proc_unlock_shared(struct pid_namespace *pid_ns) +{ +} + +#endif /* CONFIG_PROC_FS */ + #endif /* _LINUX_PID_NS_H */ diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index 0730f52..e56fbab 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -24,7 +24,9 @@ enum { /* definitions for 'pids' mount option */ }; struct proc_fs_info { + struct super_block *sb; struct pid_namespace *pid_ns; + struct list_head pidns_entry; /* Node in procfs_mounts of pidns */ struct dentry *proc_self; /* For /proc/self/ */ struct dentry *proc_thread_self; /* For /proc/thread-self/ */ bool newinstance; /* Flag for new separated instances */