// SPDX-License-Identifier: GPL-2.0 /* * linux/fs/proc/root.c * * Copyright (C) 1991, 1992 Linus Torvalds * * proc root directory handling functions */ #include <linux/uaccess.h> #include <linux/errno.h> #include <linux/time.h> #include <linux/proc_fs.h> #include <linux/stat.h> #include <linux/init.h> #include <linux/sched.h> #include <linux/sched/stat.h> #include <linux/module.h> #include <linux/bitops.h> #include <linux/user_namespace.h> #include <linux/fs_context.h> #include <linux/mount.h> #include <linux/pid_namespace.h> #include <linux/fs_parser.h> #include <linux/cred.h> #include <linux/magic.h> #include <linux/slab.h> #include "internal.h" struct proc_fs_context { struct pid_namespace *pid_ns; unsigned int mask; enum proc_hidepid hidepid; int gid; enum proc_pidonly pidonly; }; enum proc_param { Opt_gid, Opt_hidepid, Opt_subset, }; static const struct fs_parameter_spec proc_fs_parameters[] = { fsparam_u32("gid", Opt_gid), fsparam_string("hidepid", Opt_hidepid), fsparam_string("subset", Opt_subset), {} }; static inline int valid_hidepid(unsigned int value) { return (value == HIDEPID_OFF || value == HIDEPID_NO_ACCESS || value == HIDEPID_INVISIBLE || value == HIDEPID_NOT_PTRACEABLE); } static int proc_parse_hidepid_param(struct fs_context *fc, struct fs_parameter *param) { struct proc_fs_context *ctx = fc->fs_private; struct fs_parameter_spec hidepid_u32_spec = fsparam_u32("hidepid", Opt_hidepid); struct fs_parse_result result; int base = (unsigned long)hidepid_u32_spec.data; if (param->type != fs_value_is_string) return invalf(fc, "proc: unexpected type of hidepid value\n"); if (!kstrtouint(param->string, base, &result.uint_32)) { if (!valid_hidepid(result.uint_32)) return invalf(fc, "proc: unknown value of hidepid - %s\n", param->string); ctx->hidepid = result.uint_32; return 0; } if (!strcmp(param->string, "off")) ctx->hidepid = HIDEPID_OFF; else if (!strcmp(param->string, "noaccess")) ctx->hidepid = HIDEPID_NO_ACCESS; else if (!strcmp(param->string, "invisible")) ctx->hidepid = HIDEPID_INVISIBLE; else if (!strcmp(param->string, "ptraceable")) ctx->hidepid = HIDEPID_NOT_PTRACEABLE; else return invalf(fc, "proc: unknown value of hidepid - %s\n", param->string); return 0; } static int proc_parse_subset_param(struct fs_context *fc, char *value) { struct proc_fs_context *ctx = fc->fs_private; while (value) { char *ptr = strchr(value, ','); if (ptr != NULL) *ptr++ = '\0'; if (*value != '\0') { if (!strcmp(value, "pid")) { ctx->pidonly = PROC_PIDONLY_ON; } else { return invalf(fc, "proc: unsupported subset option - %s\n", value); } } value = ptr; } return 0; } static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) { struct proc_fs_context *ctx = fc->fs_private; struct fs_parse_result result; int opt; opt = fs_parse(fc, proc_fs_parameters, param, &result); if (opt < 0) return opt; switch (opt) { case Opt_gid: ctx->gid = result.uint_32; break; case Opt_hidepid: if (proc_parse_hidepid_param(fc, param)) return -EINVAL; break; case Opt_subset: if (proc_parse_subset_param(fc, param->string) < 0) return -EINVAL; break; default: return -EINVAL; } ctx->mask |= 1 << opt; return 0; } static void proc_apply_options(struct proc_fs_info *fs_info, struct fs_context *fc, struct user_namespace *user_ns) { struct proc_fs_context *ctx = fc->fs_private; if (ctx->mask & (1 << Opt_gid)) fs_info->pid_gid = make_kgid(user_ns, ctx->gid); if (ctx->mask & (1 << Opt_hidepid)) fs_info->hide_pid = ctx->hidepid; if (ctx->mask & (1 << Opt_subset)) fs_info->pidonly = ctx->pidonly; } static int proc_fill_super(struct super_block *s, struct fs_context *fc) { struct proc_fs_context *ctx = fc->fs_private; struct inode *root_inode; struct proc_fs_info *fs_info; int ret; fs_info = kzalloc(sizeof(*fs_info), GFP_KERNEL); if (!fs_info) return -ENOMEM; fs_info->pid_ns = get_pid_ns(ctx->pid_ns); proc_apply_options(fs_info, fc, current_user_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; s->s_blocksize = 1024; s->s_blocksize_bits = 10; s->s_magic = PROC_SUPER_MAGIC; s->s_op = &proc_sops; s->s_time_gran = 1; s->s_fs_info = fs_info; /* * procfs isn't actually a stacking filesystem; however, there is * too much magic going on inside it to permit stacking things on * top of it */ s->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH; /* procfs dentries and inodes don't require IO to create */ s->s_shrink.seeks = 0; pde_get(&proc_root); root_inode = proc_get_inode(s, &proc_root); if (!root_inode) { pr_err("proc_fill_super: get root inode failed\n"); return -ENOMEM; } s->s_root = d_make_root(root_inode); if (!s->s_root) { pr_err("proc_fill_super: allocate dentry failed\n"); return -ENOMEM; } ret = proc_setup_self(s); if (ret) { return ret; } return proc_setup_thread_self(s); } static int proc_reconfigure(struct fs_context *fc) { struct super_block *sb = fc->root->d_sb; struct proc_fs_info *fs_info = proc_sb_info(sb); sync_filesystem(sb); proc_apply_options(fs_info, fc, current_user_ns()); return 0; } static int proc_get_tree(struct fs_context *fc) { return get_tree_nodev(fc, proc_fill_super); } static void proc_fs_context_free(struct fs_context *fc) { struct proc_fs_context *ctx = fc->fs_private; put_pid_ns(ctx->pid_ns); kfree(ctx); } static const struct fs_context_operations proc_fs_context_ops = { .free = proc_fs_context_free, .parse_param = proc_parse_param, .get_tree = proc_get_tree, .reconfigure = proc_reconfigure, }; static int proc_init_fs_context(struct fs_context *fc) { struct proc_fs_context *ctx; ctx = kzalloc(sizeof(struct proc_fs_context), GFP_KERNEL); if (!ctx) return -ENOMEM; ctx->pid_ns = get_pid_ns(task_active_pid_ns(current)); put_user_ns(fc->user_ns); fc->user_ns = get_user_ns(ctx->pid_ns->user_ns); fc->fs_private = ctx; fc->ops = &proc_fs_context_ops; return 0; } static void proc_kill_sb(struct super_block *sb) { struct proc_fs_info *fs_info = proc_sb_info(sb); if (!fs_info) { kill_anon_super(sb); return; } dput(fs_info->proc_self); dput(fs_info->proc_thread_self); kill_anon_super(sb); put_pid_ns(fs_info->pid_ns); kfree(fs_info); } static struct file_system_type proc_fs_type = { .name = "proc", .init_fs_context = proc_init_fs_context, .parameters = proc_fs_parameters, .kill_sb = proc_kill_sb, .fs_flags = FS_USERNS_MOUNT | FS_DISALLOW_NOTIFY_PERM, }; void __init proc_root_init(void) { proc_init_kmemcache(); set_proc_pid_nlink(); proc_self_init(); proc_thread_self_init(); proc_symlink("mounts", NULL, "self/mounts"); proc_net_init(); proc_mkdir("fs", NULL); proc_mkdir("driver", NULL); proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */ #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE) /* just give it a mountpoint */ proc_create_mount_point("openprom"); #endif proc_tty_init(); proc_mkdir("bus", NULL); proc_sys_init(); register_filesystem(&proc_fs_type); } static int proc_root_getattr(struct user_namespace *mnt_userns, const struct path *path, struct kstat *stat, u32 request_mask, unsigned int query_flags) { generic_fillattr(&init_user_ns, d_inode(path->dentry), stat); stat->nlink = proc_root.nlink + nr_processes(); return 0; } static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags) { if (!proc_pid_lookup(dentry, flags)) return NULL; return proc_lookup(dir, dentry, flags); } static int proc_root_readdir(struct file *file, struct dir_context *ctx) { if (ctx->pos < FIRST_PROCESS_ENTRY) { int error = proc_readdir(file, ctx); if (unlikely(error <= 0)) return error; ctx->pos = FIRST_PROCESS_ENTRY; } return proc_pid_readdir(file, ctx); } /* * The root /proc directory is special, as it has the * <pid> directories. Thus we don't use the generic * directory handling functions for that.. */ static const struct file_operations proc_root_operations = { .read = generic_read_dir, .iterate_shared = proc_root_readdir, .llseek = generic_file_llseek, }; /* * proc root can do almost nothing.. */ static const struct inode_operations proc_root_inode_operations = { .lookup = proc_root_lookup, .getattr = proc_root_getattr, }; /* * This is the root "inode" in the /proc tree.. */ struct proc_dir_entry proc_root = { .low_ino = PROC_ROOT_INO, .namelen = 5, .mode = S_IFDIR | S_IRUGO | S_IXUGO, .nlink = 2, .refcnt = REFCOUNT_INIT(1), .proc_iops = &proc_root_inode_operations, .proc_dir_ops = &proc_root_operations, .parent = &proc_root, .subdir = RB_ROOT, .name = "/proc", };