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![Alexey Gladkov](/assets/img/avatar_default.png)
The hidepid parameter values are becoming more and more and it becomes difficult to remember what each new magic number means. Backward compatibility is preserved since it is possible to specify numerical value for the hidepid parameter. This does not break the fsconfig since it is not possible to specify a numerical value through it. All numeric values are converted to a string. The type FSCONFIG_SET_BINARY cannot be used to indicate a numerical value. Selftest has been added to verify this behavior. Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com> Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
370 lines
8.7 KiB
C
370 lines
8.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/fs/proc/root.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* proc root directory handling functions
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*/
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#include <linux/uaccess.h>
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#include <linux/errno.h>
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#include <linux/time.h>
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#include <linux/proc_fs.h>
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#include <linux/stat.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/sched/stat.h>
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#include <linux/module.h>
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#include <linux/bitops.h>
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#include <linux/user_namespace.h>
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#include <linux/fs_context.h>
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#include <linux/mount.h>
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#include <linux/pid_namespace.h>
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#include <linux/fs_parser.h>
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#include <linux/cred.h>
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#include <linux/magic.h>
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#include <linux/slab.h>
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#include "internal.h"
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struct proc_fs_context {
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struct pid_namespace *pid_ns;
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unsigned int mask;
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int hidepid;
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int gid;
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int pidonly;
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};
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enum proc_param {
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Opt_gid,
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Opt_hidepid,
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Opt_subset,
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};
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static const struct fs_parameter_spec proc_fs_parameters[] = {
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fsparam_u32("gid", Opt_gid),
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fsparam_string("hidepid", Opt_hidepid),
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fsparam_string("subset", Opt_subset),
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{}
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};
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static inline int valid_hidepid(unsigned int value)
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{
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return (value == HIDEPID_OFF ||
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value == HIDEPID_NO_ACCESS ||
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value == HIDEPID_INVISIBLE ||
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value == HIDEPID_NOT_PTRACEABLE);
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}
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static int proc_parse_hidepid_param(struct fs_context *fc, struct fs_parameter *param)
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{
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struct proc_fs_context *ctx = fc->fs_private;
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struct fs_parameter_spec hidepid_u32_spec = fsparam_u32("hidepid", Opt_hidepid);
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struct fs_parse_result result;
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int base = (unsigned long)hidepid_u32_spec.data;
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if (param->type != fs_value_is_string)
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return invalf(fc, "proc: unexpected type of hidepid value\n");
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if (!kstrtouint(param->string, base, &result.uint_32)) {
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if (!valid_hidepid(result.uint_32))
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return invalf(fc, "proc: unknown value of hidepid - %s\n", param->string);
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ctx->hidepid = result.uint_32;
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return 0;
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}
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if (!strcmp(param->string, "off"))
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ctx->hidepid = HIDEPID_OFF;
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else if (!strcmp(param->string, "noaccess"))
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ctx->hidepid = HIDEPID_NO_ACCESS;
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else if (!strcmp(param->string, "invisible"))
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ctx->hidepid = HIDEPID_INVISIBLE;
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else if (!strcmp(param->string, "ptraceable"))
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ctx->hidepid = HIDEPID_NOT_PTRACEABLE;
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else
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return invalf(fc, "proc: unknown value of hidepid - %s\n", param->string);
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return 0;
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}
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static int proc_parse_subset_param(struct fs_context *fc, char *value)
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{
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struct proc_fs_context *ctx = fc->fs_private;
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while (value) {
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char *ptr = strchr(value, ',');
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if (ptr != NULL)
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*ptr++ = '\0';
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if (*value != '\0') {
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if (!strcmp(value, "pid")) {
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ctx->pidonly = PROC_PIDONLY_ON;
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} else {
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return invalf(fc, "proc: unsupported subset option - %s\n", value);
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}
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}
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value = ptr;
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}
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return 0;
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}
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static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param)
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{
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struct proc_fs_context *ctx = fc->fs_private;
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struct fs_parse_result result;
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int opt;
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opt = fs_parse(fc, proc_fs_parameters, param, &result);
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if (opt < 0)
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return opt;
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switch (opt) {
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case Opt_gid:
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ctx->gid = result.uint_32;
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break;
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case Opt_hidepid:
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if (proc_parse_hidepid_param(fc, param))
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return -EINVAL;
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break;
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case Opt_subset:
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if (proc_parse_subset_param(fc, param->string) < 0)
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return -EINVAL;
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break;
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default:
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return -EINVAL;
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}
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ctx->mask |= 1 << opt;
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return 0;
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}
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static void proc_apply_options(struct proc_fs_info *fs_info,
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struct fs_context *fc,
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struct user_namespace *user_ns)
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{
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struct proc_fs_context *ctx = fc->fs_private;
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if (ctx->mask & (1 << Opt_gid))
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fs_info->pid_gid = make_kgid(user_ns, ctx->gid);
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if (ctx->mask & (1 << Opt_hidepid))
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fs_info->hide_pid = ctx->hidepid;
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if (ctx->mask & (1 << Opt_subset))
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fs_info->pidonly = ctx->pidonly;
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}
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static int proc_fill_super(struct super_block *s, struct fs_context *fc)
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{
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struct proc_fs_context *ctx = fc->fs_private;
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struct inode *root_inode;
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struct proc_fs_info *fs_info;
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int ret;
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fs_info = kzalloc(sizeof(*fs_info), GFP_KERNEL);
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if (!fs_info)
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return -ENOMEM;
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fs_info->pid_ns = get_pid_ns(ctx->pid_ns);
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proc_apply_options(fs_info, fc, current_user_ns());
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/* User space would break if executables or devices appear on proc */
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s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV;
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s->s_flags |= SB_NODIRATIME | SB_NOSUID | SB_NOEXEC;
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s->s_blocksize = 1024;
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s->s_blocksize_bits = 10;
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s->s_magic = PROC_SUPER_MAGIC;
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s->s_op = &proc_sops;
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s->s_time_gran = 1;
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s->s_fs_info = fs_info;
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/*
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* procfs isn't actually a stacking filesystem; however, there is
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* too much magic going on inside it to permit stacking things on
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* top of it
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*/
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s->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
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/* procfs dentries and inodes don't require IO to create */
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s->s_shrink.seeks = 0;
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pde_get(&proc_root);
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root_inode = proc_get_inode(s, &proc_root);
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if (!root_inode) {
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pr_err("proc_fill_super: get root inode failed\n");
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return -ENOMEM;
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}
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s->s_root = d_make_root(root_inode);
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if (!s->s_root) {
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pr_err("proc_fill_super: allocate dentry failed\n");
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return -ENOMEM;
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}
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ret = proc_setup_self(s);
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if (ret) {
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return ret;
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}
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return proc_setup_thread_self(s);
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}
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static int proc_reconfigure(struct fs_context *fc)
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{
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struct super_block *sb = fc->root->d_sb;
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struct proc_fs_info *fs_info = proc_sb_info(sb);
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sync_filesystem(sb);
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proc_apply_options(fs_info, fc, current_user_ns());
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return 0;
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}
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static int proc_get_tree(struct fs_context *fc)
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{
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return get_tree_nodev(fc, proc_fill_super);
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}
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static void proc_fs_context_free(struct fs_context *fc)
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{
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struct proc_fs_context *ctx = fc->fs_private;
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put_pid_ns(ctx->pid_ns);
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kfree(ctx);
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}
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static const struct fs_context_operations proc_fs_context_ops = {
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.free = proc_fs_context_free,
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.parse_param = proc_parse_param,
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.get_tree = proc_get_tree,
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.reconfigure = proc_reconfigure,
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};
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static int proc_init_fs_context(struct fs_context *fc)
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{
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struct proc_fs_context *ctx;
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ctx = kzalloc(sizeof(struct proc_fs_context), GFP_KERNEL);
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if (!ctx)
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return -ENOMEM;
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ctx->pid_ns = get_pid_ns(task_active_pid_ns(current));
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put_user_ns(fc->user_ns);
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fc->user_ns = get_user_ns(ctx->pid_ns->user_ns);
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fc->fs_private = ctx;
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fc->ops = &proc_fs_context_ops;
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return 0;
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}
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static void proc_kill_sb(struct super_block *sb)
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{
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struct proc_fs_info *fs_info = proc_sb_info(sb);
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if (fs_info->proc_self)
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dput(fs_info->proc_self);
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if (fs_info->proc_thread_self)
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dput(fs_info->proc_thread_self);
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kill_anon_super(sb);
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put_pid_ns(fs_info->pid_ns);
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kfree(fs_info);
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}
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static struct file_system_type proc_fs_type = {
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.name = "proc",
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.init_fs_context = proc_init_fs_context,
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.parameters = proc_fs_parameters,
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.kill_sb = proc_kill_sb,
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.fs_flags = FS_USERNS_MOUNT | FS_DISALLOW_NOTIFY_PERM,
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};
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void __init proc_root_init(void)
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{
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proc_init_kmemcache();
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set_proc_pid_nlink();
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proc_self_init();
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proc_thread_self_init();
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proc_symlink("mounts", NULL, "self/mounts");
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proc_net_init();
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proc_mkdir("fs", NULL);
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proc_mkdir("driver", NULL);
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proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */
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#if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE)
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/* just give it a mountpoint */
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proc_create_mount_point("openprom");
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#endif
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proc_tty_init();
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proc_mkdir("bus", NULL);
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proc_sys_init();
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register_filesystem(&proc_fs_type);
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}
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static int proc_root_getattr(const struct path *path, struct kstat *stat,
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u32 request_mask, unsigned int query_flags)
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{
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generic_fillattr(d_inode(path->dentry), stat);
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stat->nlink = proc_root.nlink + nr_processes();
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return 0;
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}
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static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
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{
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if (!proc_pid_lookup(dentry, flags))
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return NULL;
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return proc_lookup(dir, dentry, flags);
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}
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static int proc_root_readdir(struct file *file, struct dir_context *ctx)
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{
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if (ctx->pos < FIRST_PROCESS_ENTRY) {
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int error = proc_readdir(file, ctx);
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if (unlikely(error <= 0))
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return error;
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ctx->pos = FIRST_PROCESS_ENTRY;
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}
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return proc_pid_readdir(file, ctx);
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}
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/*
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* The root /proc directory is special, as it has the
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* <pid> directories. Thus we don't use the generic
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* directory handling functions for that..
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*/
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static const struct file_operations proc_root_operations = {
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.read = generic_read_dir,
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.iterate_shared = proc_root_readdir,
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.llseek = generic_file_llseek,
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};
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/*
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* proc root can do almost nothing..
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*/
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static const struct inode_operations proc_root_inode_operations = {
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.lookup = proc_root_lookup,
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.getattr = proc_root_getattr,
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};
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/*
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* This is the root "inode" in the /proc tree..
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*/
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struct proc_dir_entry proc_root = {
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.low_ino = PROC_ROOT_INO,
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.namelen = 5,
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.mode = S_IFDIR | S_IRUGO | S_IXUGO,
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.nlink = 2,
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.refcnt = REFCOUNT_INIT(1),
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.proc_iops = &proc_root_inode_operations,
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.proc_dir_ops = &proc_root_operations,
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.parent = &proc_root,
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.subdir = RB_ROOT,
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.name = "/proc",
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};
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