From patchwork Wed Dec 25 12:51:50 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Gladkov X-Patchwork-Id: 11310249 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F0529138C for ; Wed, 25 Dec 2019 13:03:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CFD962075E for ; Wed, 25 Dec 2019 13:03:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726879AbfLYNDN (ORCPT ); Wed, 25 Dec 2019 08:03:13 -0500 Received: from monster.unsafe.ru ([5.9.28.80]:36124 "EHLO mail.unsafe.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726352AbfLYNDN (ORCPT ); Wed, 25 Dec 2019 08:03:13 -0500 Received: from localhost.localdomain (ip-89-102-33-211.net.upcbroadband.cz [89.102.33.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.unsafe.ru (Postfix) with ESMTPSA id 73932C61B16; Wed, 25 Dec 2019 12:53:24 +0000 (UTC) From: Alexey Gladkov To: LKML , Kernel Hardening , Linux API , Linux FS Devel , Linux Security Module Cc: Akinobu Mita , Alexander Viro , Alexey Dobriyan , Alexey Gladkov , Andrew Morton , Andy Lutomirski , Daniel Micay , Djalal Harouni , "Dmitry V . Levin" , "Eric W . Biederman" , Greg Kroah-Hartman , Ingo Molnar , "J . Bruce Fields" , Jeff Layton , Jonathan Corbet , Kees Cook , Linus Torvalds , Oleg Nesterov , Solar Designer , Stephen Rothwell Subject: [PATCH v6 09/10] proc: add option to mount only a pids subset Date: Wed, 25 Dec 2019 13:51:50 +0100 Message-Id: <20191225125151.1950142-10-gladkov.alexey@gmail.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191225125151.1950142-1-gladkov.alexey@gmail.com> References: <20191225125151.1950142-1-gladkov.alexey@gmail.com> MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: This allows to hide all files and directories in the procfs that are not related to tasks. Signed-off-by: Alexey Gladkov Reported-by: kbuild test robot --- fs/proc/generic.c | 20 ++++++++++++++++++++ fs/proc/inode.c | 8 ++++++++ fs/proc/root.c | 14 ++++++++++++++ include/linux/proc_fs.h | 26 ++++++++++++++++++++++++++ 4 files changed, 68 insertions(+) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 64e9ee1b129e..2fa919a5544d 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -267,6 +267,11 @@ struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry, struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { + struct proc_fs_info *fs_info = proc_sb_info(dir->i_sb); + + if (proc_fs_pidonly(fs_info) == PROC_PIDONLY_ON) + return ERR_PTR(-ENOENT); + return proc_lookup_de(dir, dentry, PDE(dir)); } @@ -323,10 +328,24 @@ int proc_readdir_de(struct file *file, struct dir_context *ctx, int proc_readdir(struct file *file, struct dir_context *ctx) { struct inode *inode = file_inode(file); + struct proc_fs_info *fs_info = proc_sb_info(inode->i_sb); + + if (proc_fs_pidonly(fs_info) == PROC_PIDONLY_ON) + return 1; return proc_readdir_de(file, ctx, PDE(inode)); } +static int proc_dir_open(struct inode *inode, struct file *file) +{ + struct proc_fs_info *fs_info = proc_sb_info(inode->i_sb); + + if (proc_fs_pidonly(fs_info) == PROC_PIDONLY_ON) + return -ENOENT; + + return 0; +} + /* * These are the generic /proc directory operations. They * use the in-memory "struct proc_dir_entry" tree to parse @@ -336,6 +355,7 @@ static const struct file_operations proc_dir_operations = { .llseek = generic_file_llseek, .read = generic_read_dir, .iterate_shared = proc_readdir, + .open = proc_dir_open, }; /* diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 70b722fb8811..fe9d20da3862 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -107,6 +107,7 @@ static int proc_show_options(struct seq_file *seq, struct dentry *root) struct proc_fs_info *fs_info = proc_sb_info(root->d_sb); int hidepid = proc_fs_hide_pid(fs_info); kgid_t gid = proc_fs_pid_gid(fs_info); + int pidonly = proc_fs_pidonly(fs_info); if (!gid_eq(gid, GLOBAL_ROOT_GID)) seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, gid)); @@ -114,6 +115,9 @@ static int proc_show_options(struct seq_file *seq, struct dentry *root) if (hidepid != HIDEPID_OFF) seq_printf(seq, ",hidepid=%u", hidepid); + if (pidonly != PROC_PIDONLY_OFF) + seq_printf(seq, ",pidonly=%u", pidonly); + return 0; } @@ -333,12 +337,16 @@ proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr, static int proc_reg_open(struct inode *inode, struct file *file) { + struct proc_fs_info *fs_info = proc_sb_info(inode->i_sb); struct proc_dir_entry *pde = PDE(inode); int rv = 0; typeof_member(struct file_operations, open) open; typeof_member(struct file_operations, release) release; struct pde_opener *pdeo; + if (proc_fs_pidonly(fs_info) == PROC_PIDONLY_ON) + return -ENOENT; + /* * Ensure that * 1) PDE's ->release hook will be called no matter what diff --git a/fs/proc/root.c b/fs/proc/root.c index 3c7b29140293..fc26c22a5906 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -34,16 +34,19 @@ struct proc_fs_context { unsigned int mask; int hidepid; int gid; + int pidonly; }; enum proc_param { Opt_gid, Opt_hidepid, + Opt_pidonly, }; static const struct fs_parameter_spec proc_param_specs[] = { fsparam_u32("gid", Opt_gid), fsparam_u32("hidepid", Opt_hidepid), + fsparam_u32("pidonly", Opt_pidonly), {} }; @@ -74,6 +77,13 @@ static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) return invalf(fc, "proc: hidepid value must be between 0 and 3.\n"); break; + case Opt_pidonly: + ctx->pidonly = result.uint_32; + if (ctx->pidonly < PROC_PIDONLY_OFF || + ctx->pidonly > PROC_PIDONLY_ON) + return invalf(fc, "proc: pidonly value must be 0 or 1.\n"); + break; + default: return -EINVAL; } @@ -94,6 +104,7 @@ static void proc_apply_options(struct proc_fs_info *fs_info, proc_fs_set_pid_gid(fs_info, proc_fs_pid_gid(pidns_fs_info)); proc_fs_set_hide_pid(fs_info, proc_fs_hide_pid(pidns_fs_info)); + proc_fs_set_pidonly(fs_info, proc_fs_pidonly(pidns_fs_info)); } if (ctx->mask & (1 << Opt_gid)) @@ -101,6 +112,9 @@ static void proc_apply_options(struct proc_fs_info *fs_info, if (ctx->mask & (1 << Opt_hidepid)) proc_fs_set_hide_pid(fs_info, ctx->hidepid); + + if (ctx->mask & (1 << Opt_pidonly)) + proc_fs_set_pidonly(fs_info, ctx->pidonly); } static int proc_fill_super(struct super_block *s, struct fs_context *fc) diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index 83c87ea65505..ef1c0d9712b0 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -20,6 +20,12 @@ enum { HIDEPID_NOT_PTRACABLE = 3, /* Limit pids to only ptracable pids */ }; +/* definitions for proc mount option pidonly */ +enum { + PROC_PIDONLY_OFF = 0, + PROC_PIDONLY_ON = 1, +}; + struct proc_fs_info { struct list_head pidns_entry; /* Node in procfs_mounts of a pidns */ struct super_block *m_super; @@ -28,6 +34,7 @@ struct proc_fs_info { struct dentry *proc_thread_self; /* For /proc/thread-self */ kgid_t pid_gid; int hide_pid; + int pidonly; }; #ifdef CONFIG_PROC_FS @@ -39,6 +46,11 @@ static inline struct proc_fs_info *proc_sb_info(struct super_block *sb) return sb->s_fs_info; } +static inline void proc_fs_set_pidonly(struct proc_fs_info *fs_info, int value) +{ + fs_info->pidonly = value; +} + static inline void proc_fs_set_hide_pid(struct proc_fs_info *fs_info, int hide_pid) { fs_info->hide_pid = hide_pid; @@ -49,6 +61,11 @@ static inline void proc_fs_set_pid_gid(struct proc_fs_info *fs_info, kgid_t gid) fs_info->pid_gid = gid; } +static inline int proc_fs_pidonly(struct proc_fs_info *fs_info) +{ + return fs_info->pidonly; +} + static inline int proc_fs_hide_pid(struct proc_fs_info *fs_info) { return fs_info->hide_pid; @@ -134,6 +151,10 @@ static inline struct proc_fs_info *proc_sb_info(struct super_block *sb) return NULL; } +static inline void proc_fs_set_pidonly(struct proc_fs_info *fs_info, int value) +{ +} + static inline void proc_fs_set_hide_pid(struct proc_fs_info *fs_info, int hide_pid) { } @@ -142,6 +163,11 @@ static inline void proc_fs_set_pid_gid(struct proc_info_fs *fs_info, kgid_t gid) { } +static inline void proc_fs_pidonly(struct proc_fs_info *fs_info) +{ + return PROC_PIDONLY_OFF; +} + static inline int proc_fs_hide_pid(struct proc_fs_info *fs_info) { return 0;