Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:51272 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753312AbdECQFp (ORCPT ); Wed, 3 May 2017 12:05:45 -0400 Subject: [PATCH 8/9] proc: Support the mount context in procfs From: David Howells To: viro@zeniv.linux.org.uk Cc: linux-fsdevel@vger.kernel.org, dhowells@redhat.com, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, mszeredi@redhat.com Date: Wed, 03 May 2017 17:05:38 +0100 Message-ID: <149382753822.30481.10825924363079302327.stgit@warthog.procyon.org.uk> In-Reply-To: <149382747487.30481.15428192741961545429.stgit@warthog.procyon.org.uk> References: <149382747487.30481.15428192741961545429.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: --- fs/proc/inode.c | 2 - fs/proc/internal.h | 2 - fs/proc/root.c | 158 ++++++++++++++++++++++++++++++++-------------------- 3 files changed, 100 insertions(+), 62 deletions(-) diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 194fa2d13b7e..9ddaf60c6f93 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -118,7 +118,7 @@ const struct super_operations proc_sops = { .drop_inode = generic_delete_inode, .evict_inode = proc_evict_inode, .statfs = simple_statfs, - .remount_fs = proc_remount, + .remount_fs_mc = proc_remount, .show_options = proc_show_options, }; diff --git a/fs/proc/internal.h b/fs/proc/internal.h index b681533f59dd..68b693478e7e 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -262,7 +262,7 @@ static inline void proc_tty_init(void) {} extern struct proc_dir_entry proc_root; extern void proc_self_init(void); -extern int proc_remount(struct super_block *, int *, char *); +extern int proc_remount(struct super_block *, struct mount_context *); /* * task_[no]mmu.c diff --git a/fs/proc/root.c b/fs/proc/root.c index ff2e810e9e64..132529a5e896 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -23,9 +23,17 @@ #include #include #include +#include #include "internal.h" +struct proc_mount_context { + struct mount_context mc; + unsigned long mask; + int hidepid; + int gid; +}; + enum { Opt_gid, Opt_hidepid, Opt_err, }; @@ -36,56 +44,68 @@ static const match_table_t tokens = { {Opt_err, NULL}, }; -static int proc_parse_options(char *options, struct pid_namespace *pid) +static int proc_mount_option(struct mount_context *mc, char *p) { - char *p; + struct proc_mount_context *ctx = + container_of(mc, struct proc_mount_context, mc); substring_t args[MAX_OPT_ARGS]; - int option; - - if (!options) - return 1; - - while ((p = strsep(&options, ",")) != NULL) { - int token; - if (!*p) - continue; - - args[0].to = args[0].from = NULL; - token = match_token(p, tokens, args); - switch (token) { - case Opt_gid: - if (match_int(&args[0], &option)) - return 0; - pid->pid_gid = make_kgid(current_user_ns(), option); - break; - case Opt_hidepid: - if (match_int(&args[0], &option)) - return 0; - if (option < HIDEPID_OFF || - option > HIDEPID_INVISIBLE) { - pr_err("proc: hidepid value must be between 0 and 2.\n"); - return 0; - } - pid->hide_pid = option; - break; - default: - pr_err("proc: unrecognized mount option \"%s\" " - "or missing value\n", p); - return 0; + int token; + + args[0].to = args[0].from = NULL; + token = match_token(p, tokens, args); + switch (token) { + case Opt_gid: + if (match_int(&args[0], &ctx->gid)) { + mc->error = "procfs: Unparseable gid= argument"; + return -EINVAL; + } + break; + + case Opt_hidepid: + if (match_int(&args[0], &ctx->hidepid)) { + mc->error = "procfs: Unparseable hidepid= argument"; + return -EINVAL; } + if (ctx->hidepid < HIDEPID_OFF || + ctx->hidepid > HIDEPID_INVISIBLE) { + mc->error = "procfs: Invalid hidepid= argument"; + pr_err("proc: hidepid value must be between 0 and 2.\n"); + return -EINVAL; + } + break; + + default: + pr_err("proc: unrecognized mount option \"%s\" " + "or missing value\n", p); + mc->error = "procfs: Invalid mount option or missing value"; + return -EINVAL; } - return 1; + ctx->mask |= 1 << token; + return 0; } -static int proc_fill_super(struct super_block *s, void *data, int silent) +static void proc_set_options(struct super_block *s, + struct mount_context *mc, + struct pid_namespace *pid_ns, + struct user_namespace *user_ns) { - struct pid_namespace *ns = get_pid_ns(s->s_fs_info); + struct proc_mount_context *ctx = + container_of(mc, struct proc_mount_context, mc); + + if (ctx->mask & (1 << Opt_gid)) + pid_ns->pid_gid = make_kgid(user_ns, ctx->gid); + if (ctx->mask & (1 << Opt_hidepid)) + pid_ns->hide_pid = ctx->hidepid; +} + +static int proc_fill_super(struct super_block *s, struct mount_context *mc) +{ + struct pid_namespace *pid_ns = get_pid_ns(s->s_fs_info); struct inode *root_inode; int ret; - if (!proc_parse_options(data, ns)) - return -EINVAL; + proc_set_options(s, mc, pid_ns, 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; @@ -102,7 +122,7 @@ static int proc_fill_super(struct super_block *s, void *data, int silent) * top of it */ s->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH; - + pde_get(&proc_root); root_inode = proc_get_inode(s, &proc_root); if (!root_inode) { @@ -123,27 +143,32 @@ static int proc_fill_super(struct super_block *s, void *data, int silent) return proc_setup_thread_self(s); } -int proc_remount(struct super_block *sb, int *flags, char *data) +int proc_remount(struct super_block *sb, struct mount_context *mc) { struct pid_namespace *pid = sb->s_fs_info; sync_filesystem(sb); - return !proc_parse_options(data, pid); + + if (mc) + proc_set_options(sb, mc, pid, current_user_ns()); + return 0; } -static struct dentry *proc_mount(struct file_system_type *fs_type, - int flags, const char *dev_name, void *data) +static struct dentry *proc_mount(struct mount_context *mc) { - struct pid_namespace *ns; + return mount_ns_mc(mc, mc->pid_ns); +} - if (flags & MS_KERNMOUNT) { - ns = data; - data = NULL; - } else { - ns = task_active_pid_ns(current); - } +static const struct mount_context_operations proc_mount_ctx_ops = { + .option = proc_mount_option, + .mount = proc_mount, + .fill_super = proc_fill_super, +}; - return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super); +static int proc_fsopen(struct mount_context *mc, struct super_block *src_sb) +{ + mc->ops = &proc_mount_ctx_ops; + return 0; } static void proc_kill_sb(struct super_block *sb) @@ -161,7 +186,8 @@ static void proc_kill_sb(struct super_block *sb) static struct file_system_type proc_fs_type = { .name = "proc", - .mount = proc_mount, + .fsopen = proc_fsopen, + .mc_size = sizeof(struct proc_mount_context), .kill_sb = proc_kill_sb, .fs_flags = FS_USERNS_MOUNT, }; @@ -209,7 +235,7 @@ static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentr { if (!proc_pid_lookup(dir, dentry, flags)) return NULL; - + return proc_lookup(dir, dentry, flags); } @@ -248,12 +274,12 @@ static const struct inode_operations proc_root_inode_operations = { * 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, + .low_ino = PROC_ROOT_INO, + .namelen = 5, + .mode = S_IFDIR | S_IRUGO | S_IXUGO, + .nlink = 2, .count = ATOMIC_INIT(1), - .proc_iops = &proc_root_inode_operations, + .proc_iops = &proc_root_inode_operations, .proc_fops = &proc_root_operations, .parent = &proc_root, .subdir = RB_ROOT, @@ -262,9 +288,21 @@ struct proc_dir_entry proc_root = { int pid_ns_prepare_proc(struct pid_namespace *ns) { + struct mount_context *mc; struct vfsmount *mnt; - mnt = kern_mount_data(&proc_fs_type, ns); + mc = __vfs_fsopen(&proc_fs_type, NULL, 0, 0, MOUNT_TYPE_NEW); + if (IS_ERR(mc)) + return PTR_ERR(mc); + + if (mc->pid_ns != ns) { + put_pid_ns(mc->pid_ns); + get_pid_ns(ns); + mc->pid_ns = ns; + } + + mnt = kern_mount_data_mc(mc); + put_mount_context(mc); if (IS_ERR(mnt)) return PTR_ERR(mnt);