diff options
Diffstat (limited to 'fs/proc/fd.c')
| -rw-r--r-- | fs/proc/fd.c | 363 |
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, +}; |