From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- fs/proc_namespace.c | 337 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 337 insertions(+) create mode 100644 fs/proc_namespace.c (limited to 'fs/proc_namespace.c') diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c new file mode 100644 index 000000000..036356c0a --- /dev/null +++ b/fs/proc_namespace.c @@ -0,0 +1,337 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/proc_namespace.c - handling of /proc//{mounts,mountinfo,mountstats} + * + * In fact, that's a piece of procfs; it's *almost* isolated from + * the rest of fs/proc, but has rather close relationships with + * fs/namespace.c, thus here instead of fs/proc + * + */ +#include +#include +#include +#include +#include + +#include "proc/internal.h" /* only for get_proc_task() in ->open() */ + +#include "pnode.h" +#include "internal.h" + +static __poll_t mounts_poll(struct file *file, poll_table *wait) +{ + struct seq_file *m = file->private_data; + struct proc_mounts *p = m->private; + struct mnt_namespace *ns = p->ns; + __poll_t res = EPOLLIN | EPOLLRDNORM; + int event; + + poll_wait(file, &p->ns->poll, wait); + + event = READ_ONCE(ns->event); + if (m->poll_event != event) { + m->poll_event = event; + res |= EPOLLERR | EPOLLPRI; + } + + return res; +} + +struct proc_fs_opts { + int flag; + const char *str; +}; + +static int show_sb_opts(struct seq_file *m, struct super_block *sb) +{ + static const struct proc_fs_opts fs_opts[] = { + { SB_SYNCHRONOUS, ",sync" }, + { SB_DIRSYNC, ",dirsync" }, + { SB_MANDLOCK, ",mand" }, + { SB_LAZYTIME, ",lazytime" }, + { 0, NULL } + }; + const struct proc_fs_opts *fs_infop; + + for (fs_infop = fs_opts; fs_infop->flag; fs_infop++) { + if (sb->s_flags & fs_infop->flag) + seq_puts(m, fs_infop->str); + } + + return security_sb_show_options(m, sb); +} + +static void show_vfsmnt_opts(struct seq_file *m, struct vfsmount *mnt) +{ + static const struct proc_fs_opts mnt_opts[] = { + { MNT_NOSUID, ",nosuid" }, + { MNT_NODEV, ",nodev" }, + { MNT_NOEXEC, ",noexec" }, + { MNT_NOATIME, ",noatime" }, + { MNT_NODIRATIME, ",nodiratime" }, + { MNT_RELATIME, ",relatime" }, + { MNT_NOSYMFOLLOW, ",nosymfollow" }, + { 0, NULL } + }; + const struct proc_fs_opts *fs_infop; + + for (fs_infop = mnt_opts; fs_infop->flag; fs_infop++) { + if (mnt->mnt_flags & fs_infop->flag) + seq_puts(m, fs_infop->str); + } + + if (is_idmapped_mnt(mnt)) + seq_puts(m, ",idmapped"); +} + +static inline void mangle(struct seq_file *m, const char *s) +{ + seq_escape(m, s, " \t\n\\#"); +} + +static void show_type(struct seq_file *m, struct super_block *sb) +{ + mangle(m, sb->s_type->name); + if (sb->s_subtype) { + seq_putc(m, '.'); + mangle(m, sb->s_subtype); + } +} + +static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt) +{ + struct proc_mounts *p = m->private; + struct mount *r = real_mount(mnt); + struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; + struct super_block *sb = mnt_path.dentry->d_sb; + int err; + + if (sb->s_op->show_devname) { + err = sb->s_op->show_devname(m, mnt_path.dentry); + if (err) + goto out; + } else { + mangle(m, r->mnt_devname); + } + seq_putc(m, ' '); + /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ + err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\"); + if (err) + goto out; + seq_putc(m, ' '); + show_type(m, sb); + seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); + err = show_sb_opts(m, sb); + if (err) + goto out; + show_vfsmnt_opts(m, mnt); + if (sb->s_op->show_options) + err = sb->s_op->show_options(m, mnt_path.dentry); + seq_puts(m, " 0 0\n"); +out: + return err; +} + +static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt) +{ + struct proc_mounts *p = m->private; + struct mount *r = real_mount(mnt); + struct super_block *sb = mnt->mnt_sb; + struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; + int err; + + seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id, + MAJOR(sb->s_dev), MINOR(sb->s_dev)); + err = show_path(m, mnt->mnt_root); + if (err) + goto out; + seq_putc(m, ' '); + + /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ + err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\"); + if (err) + goto out; + + seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); + show_vfsmnt_opts(m, mnt); + + /* Tagged fields ("foo:X" or "bar") */ + if (IS_MNT_SHARED(r)) + seq_printf(m, " shared:%i", r->mnt_group_id); + if (IS_MNT_SLAVE(r)) { + int master = r->mnt_master->mnt_group_id; + int dom = get_dominating_id(r, &p->root); + seq_printf(m, " master:%i", master); + if (dom && dom != master) + seq_printf(m, " propagate_from:%i", dom); + } + if (IS_MNT_UNBINDABLE(r)) + seq_puts(m, " unbindable"); + + /* Filesystem specific data */ + seq_puts(m, " - "); + show_type(m, sb); + seq_putc(m, ' '); + if (sb->s_op->show_devname) { + err = sb->s_op->show_devname(m, mnt->mnt_root); + if (err) + goto out; + } else { + mangle(m, r->mnt_devname); + } + seq_puts(m, sb_rdonly(sb) ? " ro" : " rw"); + err = show_sb_opts(m, sb); + if (err) + goto out; + if (sb->s_op->show_options) + err = sb->s_op->show_options(m, mnt->mnt_root); + seq_putc(m, '\n'); +out: + return err; +} + +static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt) +{ + struct proc_mounts *p = m->private; + struct mount *r = real_mount(mnt); + struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; + struct super_block *sb = mnt_path.dentry->d_sb; + int err; + + /* device */ + seq_puts(m, "device "); + if (sb->s_op->show_devname) { + err = sb->s_op->show_devname(m, mnt_path.dentry); + if (err) + goto out; + } else { + mangle(m, r->mnt_devname); + } + + /* mount point */ + seq_puts(m, " mounted on "); + /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ + err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\"); + if (err) + goto out; + seq_putc(m, ' '); + + /* file system type */ + seq_puts(m, "with fstype "); + show_type(m, sb); + + /* optional statistics */ + if (sb->s_op->show_stats) { + seq_putc(m, ' '); + err = sb->s_op->show_stats(m, mnt_path.dentry); + } + + seq_putc(m, '\n'); +out: + return err; +} + +static int mounts_open_common(struct inode *inode, struct file *file, + int (*show)(struct seq_file *, struct vfsmount *)) +{ + struct task_struct *task = get_proc_task(inode); + struct nsproxy *nsp; + struct mnt_namespace *ns = NULL; + struct path root; + struct proc_mounts *p; + struct seq_file *m; + int ret = -EINVAL; + + if (!task) + goto err; + + task_lock(task); + nsp = task->nsproxy; + if (!nsp || !nsp->mnt_ns) { + task_unlock(task); + put_task_struct(task); + goto err; + } + ns = nsp->mnt_ns; + get_mnt_ns(ns); + if (!task->real_fs) { + task_unlock(task); + put_task_struct(task); + ret = -ENOENT; + goto err_put_ns; + } + get_fs_root(task->real_fs, &root); + task_unlock(task); + put_task_struct(task); + + ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts)); + if (ret) + goto err_put_path; + + m = file->private_data; + m->poll_event = ns->event; + + p = m->private; + p->ns = ns; + p->root = root; + p->show = show; + + return 0; + + err_put_path: + path_put(&root); + err_put_ns: + put_mnt_ns(ns); + err: + return ret; +} + +static int mounts_release(struct inode *inode, struct file *file) +{ + struct seq_file *m = file->private_data; + struct proc_mounts *p = m->private; + path_put(&p->root); + put_mnt_ns(p->ns); + return seq_release_private(inode, file); +} + +static int mounts_open(struct inode *inode, struct file *file) +{ + return mounts_open_common(inode, file, show_vfsmnt); +} + +static int mountinfo_open(struct inode *inode, struct file *file) +{ + return mounts_open_common(inode, file, show_mountinfo); +} + +static int mountstats_open(struct inode *inode, struct file *file) +{ + return mounts_open_common(inode, file, show_vfsstat); +} + +const struct file_operations proc_mounts_operations = { + .open = mounts_open, + .read_iter = seq_read_iter, + .splice_read = copy_splice_read, + .llseek = seq_lseek, + .release = mounts_release, + .poll = mounts_poll, +}; + +const struct file_operations proc_mountinfo_operations = { + .open = mountinfo_open, + .read_iter = seq_read_iter, + .splice_read = copy_splice_read, + .llseek = seq_lseek, + .release = mounts_release, + .poll = mounts_poll, +}; + +const struct file_operations proc_mountstats_operations = { + .open = mountstats_open, + .read_iter = seq_read_iter, + .splice_read = copy_splice_read, + .llseek = seq_lseek, + .release = mounts_release, +}; -- cgit v1.3.1