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Message-Id: <20191225125151.1950142-8-gladkov.alexey@gmail.com> Date: Wed, 25 Dec 2019 13:51:48 +0100 From: Alexey Gladkov <gladkov.alexey@...il.com> To: LKML <linux-kernel@...r.kernel.org>, Kernel Hardening <kernel-hardening@...ts.openwall.com>, Linux API <linux-api@...r.kernel.org>, Linux FS Devel <linux-fsdevel@...r.kernel.org>, Linux Security Module <linux-security-module@...r.kernel.org> Cc: Akinobu Mita <akinobu.mita@...il.com>, Alexander Viro <viro@...iv.linux.org.uk>, Alexey Dobriyan <adobriyan@...il.com>, Alexey Gladkov <gladkov.alexey@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, Andy Lutomirski <luto@...nel.org>, Daniel Micay <danielmicay@...il.com>, Djalal Harouni <tixxdz@...il.com>, "Dmitry V . Levin" <ldv@...linux.org>, "Eric W . Biederman" <ebiederm@...ssion.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Ingo Molnar <mingo@...nel.org>, "J . Bruce Fields" <bfields@...ldses.org>, Jeff Layton <jlayton@...chiereds.net>, Jonathan Corbet <corbet@....net>, Kees Cook <keescook@...omium.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Oleg Nesterov <oleg@...hat.com>, Solar Designer <solar@...nwall.com>, Stephen Rothwell <sfr@...b.auug.org.au> Subject: [PATCH v6 07/10] proc: flush task dcache entries from all procfs instances This allows to flush dcache entries of a task on multiple procfs mounts per pid namespace. Cc: Kees Cook <keescook@...omium.org> Cc: Andy Lutomirski <luto@...nel.org> Signed-off-by: Djalal Harouni <tixxdz@...il.com> Signed-off-by: Alexey Gladkov <gladkov.alexey@...il.com> --- fs/proc/base.c | 23 ++++++++++++++----- fs/proc/root.c | 14 ++++++++++++ include/linux/pid_namespace.h | 42 +++++++++++++++++++++++++++++++++++ include/linux/proc_fs.h | 2 ++ 4 files changed, 76 insertions(+), 5 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 4ccb280a3e79..f4f1bcb28603 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -3133,7 +3133,7 @@ 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[10 + 1]; @@ -3142,7 +3142,7 @@ static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid) name.name = buf; name.len = snprintf(buf, sizeof(buf), "%u", 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); @@ -3153,7 +3153,7 @@ static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid) name.name = buf; name.len = snprintf(buf, sizeof(buf), "%u", tgid); - leader = d_hash_and_lookup(mnt->mnt_root, &name); + leader = d_hash_and_lookup(mnt_root, &name); if (!leader) goto out; @@ -3208,14 +3208,27 @@ void proc_flush_task(struct task_struct *task) int i; struct pid *pid, *tgid; struct upid *upid; + struct pid_namespace *pid_ns; + struct dentry *mnt_root; + struct proc_fs_info *fs_info; 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, &pid_ns->proc_mounts, pidns_entry) { + mnt_root = fs_info->m_super->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/root.c b/fs/proc/root.c index 5d5cba4c899b..3bb8df360cf7 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -112,6 +112,12 @@ static int proc_fill_super(struct super_block *s, struct fs_context *fc) proc_apply_options(ctx->fs_info, fc, pid_ns, current_user_ns()); + ctx->fs_info->m_super = s; + + pidns_proc_lock(pid_ns); + list_add_tail(&ctx->fs_info->pidns_entry, &pid_ns->proc_mounts); + pidns_proc_unlock(pid_ns); + /* User space would break if executables or devices appear on proc */ s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV; s->s_flags |= SB_NODIRATIME | SB_NOSUID | SB_NOEXEC; @@ -215,6 +221,11 @@ 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); + + pidns_proc_lock(fs_info->pid_ns); + list_del(&fs_info->pidns_entry); + pidns_proc_unlock(fs_info->pid_ns); + kill_anon_super(sb); put_pid_ns(fs_info->pid_ns); kfree(fs_info); @@ -336,6 +347,9 @@ int pid_ns_prepare_proc(struct pid_namespace *ns) ctx->fs_info->pid_ns = ns; } + init_rwsem(&ns->rw_proc_mounts); + INIT_LIST_HEAD(&ns->proc_mounts); + mnt = fc_mount(fc); put_fs_context(fc); if (IS_ERR(mnt)) diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h index 66f47f1afe0d..297b39604312 100644 --- a/include/linux/pid_namespace.h +++ b/include/linux/pid_namespace.h @@ -26,6 +26,8 @@ struct pid_namespace { struct pid_namespace *parent; #ifdef CONFIG_PROC_FS struct vfsmount *proc_mnt; /* Internal proc mounted during each new pidns */ + struct rw_semaphore rw_proc_mounts; + struct list_head proc_mounts; /* list of separated procfs mounts */ #endif #ifdef CONFIG_BSD_PROCESS_ACCT struct fs_pin *bacct; @@ -90,4 +92,44 @@ 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_proc_mounts); +} + +static inline void pidns_proc_unlock(struct pid_namespace *pid_ns) +{ + up_write(&pid_ns->rw_proc_mounts); +} + +static inline void pidns_proc_lock_shared(struct pid_namespace *pid_ns) +{ + down_read(&pid_ns->rw_proc_mounts); +} + +static inline void pidns_proc_unlock_shared(struct pid_namespace *pid_ns) +{ + up_read(&pid_ns->rw_proc_mounts); +} +#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 fd92bf38aa62..e349fcafd729 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -20,6 +20,8 @@ enum { }; struct proc_fs_info { + struct list_head pidns_entry; /* Node in procfs_mounts of a pidns */ + struct super_block *m_super; struct pid_namespace *pid_ns; struct dentry *proc_self; /* For /proc/self */ struct dentry *proc_thread_self; /* For /proc/thread-self */ -- 2.24.1
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