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-rw-r--r--fs/proc/fd.c363
1 files changed, 363 insertions, 0 deletions
diff --git a/fs/proc/fd.c b/fs/proc/fd.c
new file mode 100644
index 000000000..81882a132
--- /dev/null
+++ b/fs/proc/fd.c
@@ -0,0 +1,363 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/sched/signal.h>
+#include <linux/errno.h>
+#include <linux/dcache.h>
+#include <linux/path.h>
+#include <linux/fdtable.h>
+#include <linux/namei.h>
+#include <linux/pid.h>
+#include <linux/security.h>
+#include <linux/file.h>
+#include <linux/seq_file.h>
+#include <linux/fs.h>
+
+#include <linux/proc_fs.h>
+
+#include "../mount.h"
+#include "internal.h"
+#include "fd.h"
+
+static int seq_show(struct seq_file *m, void *v)
+{
+ struct files_struct *files = NULL;
+ int f_flags = 0, ret = -ENOENT;
+ struct file *file = NULL;
+ struct task_struct *task;
+
+ task = get_proc_task(m->private);
+ if (!task)
+ return -ENOENT;
+
+ files = get_files_struct(task);
+ put_task_struct(task);
+
+ if (files) {
+ unsigned int fd = proc_fd(m->private);
+
+ spin_lock(&files->file_lock);
+ file = fcheck_files(files, fd);
+ if (file) {
+ struct fdtable *fdt = files_fdtable(files);
+
+ f_flags = file->f_flags;
+ if (close_on_exec(fd, fdt))
+ f_flags |= O_CLOEXEC;
+
+ get_file(file);
+ ret = 0;
+ }
+ spin_unlock(&files->file_lock);
+ put_files_struct(files);
+ }
+
+ if (ret)
+ return ret;
+
+ seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n",
+ (long long)file->f_pos, f_flags,
+ real_mount(file->f_path.mnt)->mnt_id);
+
+ show_fd_locks(m, file, files);
+ if (seq_has_overflowed(m))
+ goto out;
+
+ if (file->f_op->show_fdinfo)
+ file->f_op->show_fdinfo(m, file);
+
+out:
+ fput(file);
+ return 0;
+}
+
+static int seq_fdinfo_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, seq_show, inode);
+}
+
+static const struct file_operations proc_fdinfo_file_operations = {
+ .open = seq_fdinfo_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
+{
+ struct files_struct *files = get_files_struct(task);
+ struct file *file;
+
+ if (!files)
+ return false;
+
+ rcu_read_lock();
+ file = fcheck_files(files, fd);
+ if (file)
+ *mode = file->f_mode;
+ rcu_read_unlock();
+ put_files_struct(files);
+ return !!file;
+}
+
+static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
+ fmode_t f_mode)
+{
+ task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
+
+ if (S_ISLNK(inode->i_mode)) {
+ unsigned i_mode = S_IFLNK;
+ if (f_mode & FMODE_READ)
+ i_mode |= S_IRUSR | S_IXUSR;
+ if (f_mode & FMODE_WRITE)
+ i_mode |= S_IWUSR | S_IXUSR;
+ inode->i_mode = i_mode;
+ }
+ security_task_to_inode(task, inode);
+}
+
+static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ struct task_struct *task;
+ struct inode *inode;
+ unsigned int fd;
+
+ if (flags & LOOKUP_RCU)
+ return -ECHILD;
+
+ inode = d_inode(dentry);
+ task = get_proc_task(inode);
+ fd = proc_fd(inode);
+
+ if (task) {
+ fmode_t f_mode;
+ if (tid_fd_mode(task, fd, &f_mode)) {
+ tid_fd_update_inode(task, inode, f_mode);
+ put_task_struct(task);
+ return 1;
+ }
+ put_task_struct(task);
+ }
+ return 0;
+}
+
+static const struct dentry_operations tid_fd_dentry_operations = {
+ .d_revalidate = tid_fd_revalidate,
+ .d_delete = pid_delete_dentry,
+};
+
+static int proc_fd_link(struct dentry *dentry, struct path *path)
+{
+ struct files_struct *files = NULL;
+ struct task_struct *task;
+ int ret = -ENOENT;
+
+ task = get_proc_task(d_inode(dentry));
+ if (task) {
+ files = get_files_struct(task);
+ put_task_struct(task);
+ }
+
+ if (files) {
+ unsigned int fd = proc_fd(d_inode(dentry));
+ struct file *fd_file;
+
+ spin_lock(&files->file_lock);
+ fd_file = fcheck_files(files, fd);
+ if (fd_file) {
+ *path = fd_file->f_path;
+ path_get(&fd_file->f_path);
+ ret = 0;
+ }
+ spin_unlock(&files->file_lock);
+ put_files_struct(files);
+ }
+
+ return ret;
+}
+
+struct fd_data {
+ fmode_t mode;
+ unsigned fd;
+};
+
+static struct dentry *proc_fd_instantiate(struct dentry *dentry,
+ struct task_struct *task, const void *ptr)
+{
+ const struct fd_data *data = ptr;
+ struct proc_inode *ei;
+ struct inode *inode;
+
+ inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
+ if (!inode)
+ return ERR_PTR(-ENOENT);
+
+ ei = PROC_I(inode);
+ ei->fd = data->fd;
+
+ inode->i_op = &proc_pid_link_inode_operations;
+ inode->i_size = 64;
+
+ ei->op.proc_get_link = proc_fd_link;
+ tid_fd_update_inode(task, inode, data->mode);
+
+ d_set_d_op(dentry, &tid_fd_dentry_operations);
+ return d_splice_alias(inode, dentry);
+}
+
+static struct dentry *proc_lookupfd_common(struct inode *dir,
+ struct dentry *dentry,
+ instantiate_t instantiate)
+{
+ struct task_struct *task = get_proc_task(dir);
+ struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
+ struct dentry *result = ERR_PTR(-ENOENT);
+
+ if (!task)
+ goto out_no_task;
+ if (data.fd == ~0U)
+ goto out;
+ if (!tid_fd_mode(task, data.fd, &data.mode))
+ goto out;
+
+ result = instantiate(dentry, task, &data);
+out:
+ put_task_struct(task);
+out_no_task:
+ return result;
+}
+
+static int proc_readfd_common(struct file *file, struct dir_context *ctx,
+ instantiate_t instantiate)
+{
+ struct task_struct *p = get_proc_task(file_inode(file));
+ struct files_struct *files;
+ unsigned int fd;
+
+ if (!p)
+ return -ENOENT;
+
+ if (!dir_emit_dots(file, ctx))
+ goto out;
+ files = get_files_struct(p);
+ if (!files)
+ goto out;
+
+ rcu_read_lock();
+ for (fd = ctx->pos - 2;
+ fd < files_fdtable(files)->max_fds;
+ fd++, ctx->pos++) {
+ struct file *f;
+ struct fd_data data;
+ char name[10 + 1];
+ unsigned int len;
+
+ f = fcheck_files(files, fd);
+ if (!f)
+ continue;
+ data.mode = f->f_mode;
+ rcu_read_unlock();
+ data.fd = fd;
+
+ len = snprintf(name, sizeof(name), "%u", fd);
+ if (!proc_fill_cache(file, ctx,
+ name, len, instantiate, p,
+ &data))
+ goto out_fd_loop;
+ cond_resched();
+ rcu_read_lock();
+ }
+ rcu_read_unlock();
+out_fd_loop:
+ put_files_struct(files);
+out:
+ put_task_struct(p);
+ return 0;
+}
+
+static int proc_readfd(struct file *file, struct dir_context *ctx)
+{
+ return proc_readfd_common(file, ctx, proc_fd_instantiate);
+}
+
+const struct file_operations proc_fd_operations = {
+ .read = generic_read_dir,
+ .iterate_shared = proc_readfd,
+ .llseek = generic_file_llseek,
+};
+
+static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
+ unsigned int flags)
+{
+ return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
+}
+
+/*
+ * /proc/pid/fd needs a special permission handler so that a process can still
+ * access /proc/self/fd after it has executed a setuid().
+ */
+int proc_fd_permission(struct inode *inode, int mask)
+{
+ struct task_struct *p;
+ int rv;
+
+ rv = generic_permission(inode, mask);
+ if (rv == 0)
+ return rv;
+
+ rcu_read_lock();
+ p = pid_task(proc_pid(inode), PIDTYPE_PID);
+ if (p && same_thread_group(p, current))
+ rv = 0;
+ rcu_read_unlock();
+
+ return rv;
+}
+
+const struct inode_operations proc_fd_inode_operations = {
+ .lookup = proc_lookupfd,
+ .permission = proc_fd_permission,
+ .setattr = proc_setattr,
+};
+
+static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
+ struct task_struct *task, const void *ptr)
+{
+ const struct fd_data *data = ptr;
+ struct proc_inode *ei;
+ struct inode *inode;
+
+ inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUSR);
+ if (!inode)
+ return ERR_PTR(-ENOENT);
+
+ ei = PROC_I(inode);
+ ei->fd = data->fd;
+
+ inode->i_fop = &proc_fdinfo_file_operations;
+ tid_fd_update_inode(task, inode, 0);
+
+ d_set_d_op(dentry, &tid_fd_dentry_operations);
+ return d_splice_alias(inode, dentry);
+}
+
+static struct dentry *
+proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags)
+{
+ return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
+}
+
+static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
+{
+ return proc_readfd_common(file, ctx,
+ proc_fdinfo_instantiate);
+}
+
+const struct inode_operations proc_fdinfo_inode_operations = {
+ .lookup = proc_lookupfdinfo,
+ .setattr = proc_setattr,
+};
+
+const struct file_operations proc_fdinfo_operations = {
+ .read = generic_read_dir,
+ .iterate_shared = proc_readfdinfo,
+ .llseek = generic_file_llseek,
+};