From patchwork Thu Oct 29 00:32:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11864553 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 CCB30697 for ; Thu, 29 Oct 2020 00:42:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B59222076B for ; Thu, 29 Oct 2020 00:42:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388853AbgJ2AmP (ORCPT ); Wed, 28 Oct 2020 20:42:15 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:33619 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731263AbgJ2AmI (ORCPT ); Wed, 28 Oct 2020 20:42:08 -0400 Received: from ip5f5af0a0.dynamic.kabel-deutschland.de ([95.90.240.160] helo=wittgenstein.fritz.box) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1kXvvH-0008Ep-6C; Thu, 29 Oct 2020 00:36:11 +0000 From: Christian Brauner To: Alexander Viro , Christoph Hellwig , linux-fsdevel@vger.kernel.org Cc: John Johansen , James Morris , Mimi Zohar , Dmitry Kasatkin , Stephen Smalley , Casey Schaufler , Arnd Bergmann , Andreas Dilger , OGAWA Hirofumi , Geoffrey Thomas , Mrunal Patel , Josh Triplett , Andy Lutomirski , Amir Goldstein , Miklos Szeredi , Theodore Tso , Alban Crequy , Tycho Andersen , David Howells , James Bottomley , Jann Horn , Seth Forshee , =?utf-8?q?St=C3=A9phane_Graber?= , Aleksa Sarai , Lennart Poettering , "Eric W. Biederman" , smbarber@chromium.org, Phil Estes , Serge Hallyn , Kees Cook , Todd Kjos , Jonathan Corbet , containers@lists.linux-foundation.org, linux-security-module@vger.kernel.org, linux-api@vger.kernel.org, linux-ext4@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-audit@redhat.com, linux-integrity@vger.kernel.org, selinux@vger.kernel.org, Christian Brauner Subject: [PATCH 34/34] fat: handle idmapped mounts Date: Thu, 29 Oct 2020 01:32:52 +0100 Message-Id: <20201029003252.2128653-35-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.29.0 In-Reply-To: <20201029003252.2128653-1-christian.brauner@ubuntu.com> References: <20201029003252.2128653-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org Let fat handle idmapped mounts. This allows to have the same fat mount appear in multiple locations with different id mappings. This allows to expose a vfat formatted USB stick to multiple user with different ids on the host or in user namespaces: mount -o uid=1000,gid=1000 /dev/sdb /mnt u1001@f2-vm:/lower1$ ls -ln /mnt/ total 4 -rwxr-xr-x 1 1000 1000 4 Oct 28 03:44 aaa -rwxr-xr-x 1 1000 1000 0 Oct 28 01:09 bbb -rwxr-xr-x 1 1000 1000 0 Oct 28 01:10 ccc -rwxr-xr-x 1 1000 1000 0 Oct 28 03:46 ddd -rwxr-xr-x 1 1000 1000 0 Oct 28 04:01 eee mount2 --idmap both:1000:1001:1 u1001@f2-vm:/lower1$ ls -ln /lower1/ total 4 -rwxr-xr-x 1 1001 1001 4 Oct 28 03:44 aaa -rwxr-xr-x 1 1001 1001 0 Oct 28 01:09 bbb -rwxr-xr-x 1 1001 1001 0 Oct 28 01:10 ccc -rwxr-xr-x 1 1001 1001 0 Oct 28 03:46 ddd -rwxr-xr-x 1 1001 1001 0 Oct 28 04:01 eee u1001@f2-vm:/lower1$ touch /lower1/fff u1001@f2-vm:/lower1$ ls -ln /lower1/fff -rwxr-xr-x 1 1001 1001 0 Oct 28 04:03 /lower1/fff u1001@f2-vm:/lower1$ ls -ln /mnt/fff -rwxr-xr-x 1 1000 1000 0 Oct 28 04:03 /mnt/fff Signed-off-by: Christian Brauner --- fs/fat/fat.h | 2 ++ fs/fat/file.c | 27 +++++++++++++++++++-------- fs/fat/namei_msdos.c | 7 +++++++ fs/fat/namei_vfat.c | 7 +++++++ 4 files changed, 35 insertions(+), 8 deletions(-) diff --git a/fs/fat/fat.h b/fs/fat/fat.h index 922a0c6ba46c..56d661e93d2a 100644 --- a/fs/fat/fat.h +++ b/fs/fat/fat.h @@ -398,6 +398,8 @@ extern long fat_generic_ioctl(struct file *filp, unsigned int cmd, extern const struct file_operations fat_file_operations; extern const struct inode_operations fat_file_inode_operations; extern int fat_setattr(struct dentry *dentry, struct iattr *attr); +extern int fat_setattr_mapped(struct user_namespace *user_ns, + struct dentry *dentry, struct iattr *attr); extern void fat_truncate_blocks(struct inode *inode, loff_t offset); extern int fat_getattr(const struct path *path, struct kstat *stat, u32 request_mask, unsigned int flags); diff --git a/fs/fat/file.c b/fs/fat/file.c index f9ee27cf4d7c..f97d46711b37 100644 --- a/fs/fat/file.c +++ b/fs/fat/file.c @@ -398,7 +398,7 @@ int fat_getattr(const struct path *path, struct kstat *stat, u32 request_mask, unsigned int flags) { struct inode *inode = d_inode(path->dentry); - generic_fillattr(inode, stat); + mapped_generic_fillattr(mnt_user_ns(path->mnt), inode, stat); stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size; if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) { @@ -447,12 +447,13 @@ static int fat_sanitize_mode(const struct msdos_sb_info *sbi, return 0; } -static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode) +static int fat_allow_set_time(struct user_namespace *user_ns, + struct msdos_sb_info *sbi, struct inode *inode) { umode_t allow_utime = sbi->options.allow_utime; - if (!uid_eq(current_fsuid(), inode->i_uid)) { - if (in_group_p(inode->i_gid)) + if (!uid_eq(current_fsuid(), i_uid_into_mnt(user_ns, inode))) { + if (in_group_p(i_gid_into_mnt(user_ns, inode))) allow_utime >>= 3; if (allow_utime & MAY_WRITE) return 1; @@ -466,7 +467,8 @@ static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode) /* valid file mode bits */ #define FAT_VALID_MODE (S_IFREG | S_IFDIR | S_IRWXUGO) -int fat_setattr(struct dentry *dentry, struct iattr *attr) +int fat_setattr_mapped(struct user_namespace *user_ns, struct dentry *dentry, + struct iattr *attr) { struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb); struct inode *inode = d_inode(dentry); @@ -476,11 +478,11 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr) /* Check for setting the inode time. */ ia_valid = attr->ia_valid; if (ia_valid & TIMES_SET_FLAGS) { - if (fat_allow_set_time(sbi, inode)) + if (fat_allow_set_time(user_ns, sbi, inode)) attr->ia_valid &= ~TIMES_SET_FLAGS; } - error = setattr_prepare(dentry, attr); + error = setattr_mapped_prepare(user_ns, dentry, attr); attr->ia_valid = ia_valid; if (error) { if (sbi->options.quiet) @@ -550,15 +552,24 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr) fat_truncate_time(inode, &attr->ia_mtime, S_MTIME); attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME); - setattr_copy(inode, attr); + setattr_mapped_copy(user_ns, inode, attr); mark_inode_dirty(inode); out: return error; } +EXPORT_SYMBOL_GPL(fat_setattr_mapped); + +int fat_setattr(struct dentry *dentry, struct iattr *attr) +{ + return fat_setattr_mapped(&init_user_ns, dentry, attr); +} EXPORT_SYMBOL_GPL(fat_setattr); const struct inode_operations fat_file_inode_operations = { .setattr = fat_setattr, .getattr = fat_getattr, .update_time = fat_update_time, +#ifdef CONFIG_IDMAP_MOUNTS + .setattr_mapped = fat_setattr_mapped, +#endif }; diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c index 9d062886fbc1..4b89d27d128d 100644 --- a/fs/fat/namei_msdos.c +++ b/fs/fat/namei_msdos.c @@ -639,6 +639,9 @@ static const struct inode_operations msdos_dir_inode_operations = { .setattr = fat_setattr, .getattr = fat_getattr, .update_time = fat_update_time, +#ifdef CONFIG_IDMAP_MOUNTS + .setattr_mapped = fat_setattr_mapped, +#endif }; static void setup(struct super_block *sb) @@ -665,7 +668,11 @@ static struct file_system_type msdos_fs_type = { .name = "msdos", .mount = msdos_mount, .kill_sb = kill_block_super, +#ifdef CONFIG_IDMAP_MOUNTS + .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP, +#else .fs_flags = FS_REQUIRES_DEV, +#endif }; MODULE_ALIAS_FS("msdos"); diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c index 0cdd0fb9f742..11fea59e1b77 100644 --- a/fs/fat/namei_vfat.c +++ b/fs/fat/namei_vfat.c @@ -1034,6 +1034,9 @@ static const struct inode_operations vfat_dir_inode_operations = { .setattr = fat_setattr, .getattr = fat_getattr, .update_time = fat_update_time, +#ifdef CONFIG_IDMAP_MOUNTS + .setattr_mapped = fat_setattr_mapped, +#endif }; static void setup(struct super_block *sb) @@ -1062,7 +1065,11 @@ static struct file_system_type vfat_fs_type = { .name = "vfat", .mount = vfat_mount, .kill_sb = kill_block_super, +#ifdef CONFIG_IDMAP_MOUNTS + .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP, +#else .fs_flags = FS_REQUIRES_DEV, +#endif }; MODULE_ALIAS_FS("vfat");