From patchwork Wed Nov 17 01:58:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Anderson X-Patchwork-Id: 12623507 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A9A8C433F5 for ; Wed, 17 Nov 2021 01:58:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5219661C12 for ; Wed, 17 Nov 2021 01:58:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232672AbhKQCB2 (ORCPT ); Tue, 16 Nov 2021 21:01:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229629AbhKQCB1 (ORCPT ); Tue, 16 Nov 2021 21:01:27 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 02330C061570 for ; Tue, 16 Nov 2021 17:58:29 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id u12-20020a25f80c000000b005dd97d128f7so1574317ybd.6 for ; Tue, 16 Nov 2021 17:58:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:cc; bh=FvEzou+fI7ey46MBiHS/yrF3RR3FO5ooWBZC3muCnCM=; b=fE89ZoI2ZYzKSziFiLMNws3++j/kp3NVux5O76sSWOLEpdfkw5DeAGp0II6c/jN6y3 XSbUqs6TMcS7V9/lAC8SIrM+SA1O/ccc6Ayo1Dm5wdtv729qxKKXrvnD2gg5cE64yjJT 3ZdZn978PM/eickcU56r9mN0aeBCfajeFiDtrsRIYFGvI18r4lBYitVavFrtujufPzjY 761pa7KOFeor+//Jct/9Pbhf0/DkjFmV4ixJCJvKVCifM45UFyNuKx8OcybRCYhLCIsD LkKAqJg6Ysxr5OEaSq/xwaFl/5TdQslSpnY5OQcbg3RkyDGJ75Fbzw889gI0sJQ3APoW fYHQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:cc; bh=FvEzou+fI7ey46MBiHS/yrF3RR3FO5ooWBZC3muCnCM=; b=nn0A8CcHMFNVFBTDXhI7BUHq/zZcVWbhsW4ADWzbTBdkF4HEtYKZiDWLwSp7zefX00 zNAaNFlrT3nMzppYniOLxLeUlAoGEGd6OoESxIn3qtL8TL+fOxXmry11CrUNrlGSdMeC Pos6iXEtT0KrMxG0luRvYnBYl1ctcaHmvdnuQE/3tKFBs6lwx7QNY97uy9GdZgcZ9Wzh y9hYmbq9ZnpZcV8QdhPMw5endAv01Fa8y4K4ZAFfLjjc2aCPNi1sXR2kx8IhcaMcl5Mf U2rLFJj5jt64nWLv97jJ8Up3lHCh1PqaxebhEOIO7jUrOF2E0w2AYDp72bRxFpnzIQDI f+1Q== X-Gm-Message-State: AOAM533SD/bbC7lfmckidthCgHaAEecHRLawpxoGrnHuAalZThvH07kv sU4MDeYci3WFzbgi1Vo3NUAwvPBCViyi X-Google-Smtp-Source: ABdhPJx958FOvMsDxCg7SdPpAPGjvhNAoTV7iHce45B/z1rPP8zVDY6vjMBMIOS1BCLmiD9ieeJuwFQLZSJ+ X-Received: from dvandertop.c.googlers.com ([fda3:e722:ac3:cc00:14:4d90:c0a8:2862]) (user=dvander job=sendgmr) by 2002:a25:d283:: with SMTP id j125mr13664794ybg.476.1637114308279; Tue, 16 Nov 2021 17:58:28 -0800 (PST) Date: Wed, 17 Nov 2021 01:58:03 +0000 In-Reply-To: <20211117015806.2192263-1-dvander@google.com> Message-Id: <20211117015806.2192263-2-dvander@google.com> Mime-Version: 1.0 References: <20211117015806.2192263-1-dvander@google.com> X-Mailer: git-send-email 2.34.0.rc1.387.gb447b232ab-goog Subject: [PATCH v19 1/4] Add flags option to get xattr method paired to __vfs_getxattr From: David Anderson Cc: David Anderson , Mark Salyzyn , Jan Kara , Jeff Layton , David Sterba , "Darrick J . Wong" , Mike Marshall , linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, Stephen Smalley , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, kernel-team@android.com, selinux@vger.kernel.org, paulmoore@microsoft.com, Luca.Boccassi@microsoft.com To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: Add a flag option to get xattr method that could have a bit flag of XATTR_NOSECURITY passed to it. XATTR_NOSECURITY is generally then set in the __vfs_getxattr path when called by security infrastructure. This handles the case of a union filesystem driver that is being requested by the security layer to report back the xattr data. For the use case where access is to be blocked by the security layer. The path then could be security(dentry) -> __vfs_getxattr(dentry...XATTR_NOSECURITY) -> handler->get(dentry...XATTR_NOSECURITY) -> __vfs_getxattr(lower_dentry...XATTR_NOSECURITY) -> lower_handler->get(lower_dentry...XATTR_NOSECURITY) which would report back through the chain data and success as expected, the logging security layer at the top would have the data to determine the access permissions and report back the target context that was blocked. Without the get handler flag, the path on a union filesystem would be the errant security(dentry) -> __vfs_getxattr(dentry) -> handler->get(dentry) -> vfs_getxattr(lower_dentry) -> nested -> security(lower_dentry, log off) -> lower_handler->get(lower_dentry) which would report back through the chain no data, and -EACCES. For selinux for both cases, this would translate to a correctly determined blocked access. In the first case with this change a correct avc log would be reported, in the second legacy case an incorrect avc log would be reported against an uninitialized u:object_r:unlabeled:s0 context making the logs cosmetically useless for audit2allow. This patch series is inert and is the wide-spread addition of the flags option for xattr functions, and a replacement of __vfs_getxattr with __vfs_getxattr(...XATTR_NOSECURITY). Signed-off-by: Mark Salyzyn Signed-off-by: David Anderson Reviewed-by: Jan Kara Acked-by: Jan Kara Acked-by: Jeff Layton Acked-by: David Sterba Acked-by: Darrick J. Wong Acked-by: Mike Marshall Cc: linux-fsdevel@vger.kernel.org Cc: linux-unionfs@vger.kernel.org Cc: Stephen Smalley Cc: linux-kernel@vger.kernel.org Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: selinux@vger.kernel.org Cc: paulmoore@microsoft.com Cc: Luca.Boccassi@microsoft.com v19 - rebase v18 - rebase v17 - rebase with additional change to fs/ext4/xattr_hurd.c v16 - rebase v15 - revert back to v4 as struct xattr_gs_args was not acceptable by the wider audience. Incorporate any relevant fixes on the way. v14 (new series): - Reincorporate back into the bugfix series for overlayfs v8: - Documentation reported 'struct xattr_gs_flags' rather than 'struct xattr_gs_flags *args' as argument to get and set methods. v7: - missed spots in fs/9p/acl.c, fs/afs/xattr.c, fs/ecryptfs/crypto.c, fs/ubifs/xattr.c, fs/xfs/libxfs/xfs_attr.c, security/integrity/evm/evm_main.c and security/smack/smack_lsm.c. v6: - kernfs missed a spot v5: - introduce struct xattr_gs_args for get and set methods, __vfs_getxattr and __vfs_setxattr functions. - cover a missing spot in ext2. - switch from snprintf to scnprintf for correctness. v4: - ifdef __KERNEL__ around XATTR_NOSECURITY to keep it colocated in uapi headers. v3: - poor aim on ubifs not ubifs_xattr_get, but static xattr_get v2: - Missed a spot: ubifs, erofs and afs. v1: - Removed from an overlayfs patch set, and made independent. Expect this to be the basis of some security improvements. --- Documentation/filesystems/locking.rst | 2 +- fs/9p/acl.c | 3 +- fs/9p/xattr.c | 3 +- fs/afs/xattr.c | 10 +++---- fs/attr.c | 2 +- fs/btrfs/xattr.c | 3 +- fs/ceph/xattr.c | 3 +- fs/cifs/xattr.c | 2 +- fs/ecryptfs/inode.c | 6 ++-- fs/ecryptfs/mmap.c | 5 ++-- fs/erofs/xattr.c | 3 +- fs/ext2/xattr_security.c | 2 +- fs/ext2/xattr_trusted.c | 2 +- fs/ext2/xattr_user.c | 2 +- fs/ext4/xattr_hurd.c | 2 +- fs/ext4/xattr_security.c | 2 +- fs/ext4/xattr_trusted.c | 2 +- fs/ext4/xattr_user.c | 2 +- fs/f2fs/xattr.c | 4 +-- fs/fuse/xattr.c | 4 +-- fs/gfs2/xattr.c | 3 +- fs/hfs/attr.c | 2 +- fs/hfsplus/xattr.c | 3 +- fs/hfsplus/xattr_security.c | 3 +- fs/hfsplus/xattr_trusted.c | 3 +- fs/hfsplus/xattr_user.c | 3 +- fs/inode.c | 7 +++-- fs/internal.h | 3 +- fs/jffs2/security.c | 3 +- fs/jffs2/xattr_trusted.c | 3 +- fs/jffs2/xattr_user.c | 3 +- fs/jfs/xattr.c | 5 ++-- fs/kernfs/inode.c | 3 +- fs/nfs/nfs4proc.c | 9 ++++-- fs/ntfs3/xattr.c | 2 +- fs/ocfs2/xattr.c | 9 ++++-- fs/open.c | 2 +- fs/orangefs/xattr.c | 3 +- fs/overlayfs/super.c | 8 +++-- fs/posix_acl.c | 2 +- fs/reiserfs/xattr_security.c | 3 +- fs/reiserfs/xattr_trusted.c | 3 +- fs/reiserfs/xattr_user.c | 3 +- fs/squashfs/xattr.c | 2 +- fs/ubifs/xattr.c | 3 +- fs/xattr.c | 42 ++++++++++++++------------- fs/xfs/xfs_xattr.c | 3 +- include/linux/lsm_hook_defs.h | 3 +- include/linux/security.h | 6 ++-- include/linux/xattr.h | 6 ++-- include/uapi/linux/xattr.h | 7 +++-- mm/shmem.c | 3 +- net/socket.c | 3 +- security/commoncap.c | 11 ++++--- security/integrity/evm/evm_main.c | 13 +++++---- security/security.c | 5 ++-- security/selinux/hooks.c | 19 +++++++----- security/smack/smack_lsm.c | 18 +++++++----- 58 files changed, 178 insertions(+), 118 deletions(-) diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst index d36fe79167b3..322466cbb650 100644 --- a/Documentation/filesystems/locking.rst +++ b/Documentation/filesystems/locking.rst @@ -130,7 +130,7 @@ prototypes:: bool (*list)(struct dentry *dentry); int (*get)(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, void *buffer, - size_t size); + size_t size, int flags); int (*set)(const struct xattr_handler *handler, struct user_namespace *mnt_userns, struct dentry *dentry, struct inode *inode, const char *name, diff --git a/fs/9p/acl.c b/fs/9p/acl.c index 4dac4a0dc5f4..66389aaa2385 100644 --- a/fs/9p/acl.c +++ b/fs/9p/acl.c @@ -210,7 +210,8 @@ int v9fs_acl_mode(struct inode *dir, umode_t *modep, static int v9fs_xattr_get_acl(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { struct v9fs_session_info *v9ses; struct posix_acl *acl; diff --git a/fs/9p/xattr.c b/fs/9p/xattr.c index a824441b95a2..213ca59b1c35 100644 --- a/fs/9p/xattr.c +++ b/fs/9p/xattr.c @@ -141,7 +141,8 @@ ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) static int v9fs_xattr_handler_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { const char *full_name = xattr_full_name(handler, name); diff --git a/fs/afs/xattr.c b/fs/afs/xattr.c index 7751b0b3f81d..172013d3e0dd 100644 --- a/fs/afs/xattr.c +++ b/fs/afs/xattr.c @@ -36,7 +36,7 @@ static const struct afs_operation_ops afs_fetch_acl_operation = { static int afs_xattr_get_acl(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, - void *buffer, size_t size) + void *buffer, size_t size, int flags) { struct afs_operation *op; struct afs_vnode *vnode = AFS_FS_I(inode); @@ -138,7 +138,7 @@ static const struct afs_operation_ops yfs_fetch_opaque_acl_operation = { static int afs_xattr_get_yfs(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, - void *buffer, size_t size) + void *buffer, size_t size, int flags) { struct afs_operation *op; struct afs_vnode *vnode = AFS_FS_I(inode); @@ -268,7 +268,7 @@ static const struct xattr_handler afs_xattr_yfs_handler = { static int afs_xattr_get_cell(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, - void *buffer, size_t size) + void *buffer, size_t size, int flags) { struct afs_vnode *vnode = AFS_FS_I(inode); struct afs_cell *cell = vnode->volume->cell; @@ -295,7 +295,7 @@ static const struct xattr_handler afs_xattr_afs_cell_handler = { static int afs_xattr_get_fid(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, - void *buffer, size_t size) + void *buffer, size_t size, int flags) { struct afs_vnode *vnode = AFS_FS_I(inode); char text[16 + 1 + 24 + 1 + 8 + 1]; @@ -333,7 +333,7 @@ static const struct xattr_handler afs_xattr_afs_fid_handler = { static int afs_xattr_get_volume(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, - void *buffer, size_t size) + void *buffer, size_t size, int flags) { struct afs_vnode *vnode = AFS_FS_I(inode); const char *volname = vnode->volume->name; diff --git a/fs/attr.c b/fs/attr.c index 473d21b3a86d..caa6662cb14a 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -342,7 +342,7 @@ int notify_change(struct user_namespace *mnt_userns, struct dentry *dentry, attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode); if (ia_valid & ATTR_KILL_PRIV) { - error = security_inode_need_killpriv(dentry); + error = security_inode_need_killpriv(mnt_userns, dentry); if (error < 0) return error; if (error == 0) diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c index 2837b4c8424d..7d9f7a56e7c0 100644 --- a/fs/btrfs/xattr.c +++ b/fs/btrfs/xattr.c @@ -378,7 +378,8 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) static int btrfs_xattr_handler_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { name = xattr_full_name(handler, name); return btrfs_getxattr(inode, name, buffer, size); diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c index fcf7dfdecf96..0f4971025387 100644 --- a/fs/ceph/xattr.c +++ b/fs/ceph/xattr.c @@ -1256,7 +1256,8 @@ int __ceph_setxattr(struct inode *inode, const char *name, static int ceph_get_xattr_handler(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *value, size_t size) + const char *name, void *value, size_t size, + int flags) { if (!ceph_is_valid_xattr(name)) return -EOPNOTSUPP; diff --git a/fs/cifs/xattr.c b/fs/cifs/xattr.c index 7d8b72d67c80..e55bb399916f 100644 --- a/fs/cifs/xattr.c +++ b/fs/cifs/xattr.c @@ -279,7 +279,7 @@ static int cifs_creation_time_get(struct dentry *dentry, struct inode *inode, static int cifs_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *value, size_t size) + const char *name, void *value, size_t size, int flags) { ssize_t rc = -EOPNOTSUPP; unsigned int xid; diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c index 16d50dface59..f3a20a14dd8b 100644 --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -1050,7 +1050,8 @@ ecryptfs_getxattr_lower(struct dentry *lower_dentry, struct inode *lower_inode, goto out; } inode_lock(lower_inode); - rc = __vfs_getxattr(lower_dentry, lower_inode, name, value, size); + rc = __vfs_getxattr(&init_user_ns, lower_dentry, lower_inode, name, + value, size, XATTR_NOSECURITY); inode_unlock(lower_inode); out: return rc; @@ -1156,7 +1157,8 @@ const struct inode_operations ecryptfs_main_iops = { static int ecryptfs_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { return ecryptfs_getxattr(dentry, inode, name, buffer, size); } diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c index 7d85e64ea62f..8635390f2bcb 100644 --- a/fs/ecryptfs/mmap.c +++ b/fs/ecryptfs/mmap.c @@ -422,8 +422,9 @@ static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode) goto out; } inode_lock(lower_inode); - size = __vfs_getxattr(lower_dentry, lower_inode, ECRYPTFS_XATTR_NAME, - xattr_virt, PAGE_SIZE); + size = __vfs_getxattr(&init_user_ns, lower_dentry, lower_inode, + ECRYPTFS_XATTR_NAME, xattr_virt, PAGE_SIZE, + XATTR_NOSECURITY); if (size < 0) size = 8; put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt); diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c index 01c581e93c5f..a900976b0f77 100644 --- a/fs/erofs/xattr.c +++ b/fs/erofs/xattr.c @@ -470,7 +470,8 @@ int erofs_getxattr(struct inode *inode, int index, static int erofs_xattr_generic_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { struct erofs_sb_info *const sbi = EROFS_I_SB(inode); diff --git a/fs/ext2/xattr_security.c b/fs/ext2/xattr_security.c index ebade1f52451..91c716ec140f 100644 --- a/fs/ext2/xattr_security.c +++ b/fs/ext2/xattr_security.c @@ -11,7 +11,7 @@ static int ext2_xattr_security_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, int flags) { return ext2_xattr_get(inode, EXT2_XATTR_INDEX_SECURITY, name, buffer, size); diff --git a/fs/ext2/xattr_trusted.c b/fs/ext2/xattr_trusted.c index 18a87d5dd1ab..362f83e43c4c 100644 --- a/fs/ext2/xattr_trusted.c +++ b/fs/ext2/xattr_trusted.c @@ -18,7 +18,7 @@ ext2_xattr_trusted_list(struct dentry *dentry) static int ext2_xattr_trusted_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, int flags) { return ext2_xattr_get(inode, EXT2_XATTR_INDEX_TRUSTED, name, buffer, size); diff --git a/fs/ext2/xattr_user.c b/fs/ext2/xattr_user.c index 58092449f8ff..37936d5979c8 100644 --- a/fs/ext2/xattr_user.c +++ b/fs/ext2/xattr_user.c @@ -20,7 +20,7 @@ ext2_xattr_user_list(struct dentry *dentry) static int ext2_xattr_user_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, int flags) { if (!test_opt(inode->i_sb, XATTR_USER)) return -EOPNOTSUPP; diff --git a/fs/ext4/xattr_hurd.c b/fs/ext4/xattr_hurd.c index c78df5790377..7cce47e56a10 100644 --- a/fs/ext4/xattr_hurd.c +++ b/fs/ext4/xattr_hurd.c @@ -21,7 +21,7 @@ ext4_xattr_hurd_list(struct dentry *dentry) static int ext4_xattr_hurd_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, int flags) { if (!test_opt(inode->i_sb, XATTR_USER)) return -EOPNOTSUPP; diff --git a/fs/ext4/xattr_security.c b/fs/ext4/xattr_security.c index 8213f66f7b2d..f85699f6ad17 100644 --- a/fs/ext4/xattr_security.c +++ b/fs/ext4/xattr_security.c @@ -15,7 +15,7 @@ static int ext4_xattr_security_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, int flags) { return ext4_xattr_get(inode, EXT4_XATTR_INDEX_SECURITY, name, buffer, size); diff --git a/fs/ext4/xattr_trusted.c b/fs/ext4/xattr_trusted.c index 7c21ffb26d25..9b550a8a5c0b 100644 --- a/fs/ext4/xattr_trusted.c +++ b/fs/ext4/xattr_trusted.c @@ -22,7 +22,7 @@ ext4_xattr_trusted_list(struct dentry *dentry) static int ext4_xattr_trusted_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, int flags) { return ext4_xattr_get(inode, EXT4_XATTR_INDEX_TRUSTED, name, buffer, size); diff --git a/fs/ext4/xattr_user.c b/fs/ext4/xattr_user.c index 2fe7ff0a479c..5483b158c5b5 100644 --- a/fs/ext4/xattr_user.c +++ b/fs/ext4/xattr_user.c @@ -21,7 +21,7 @@ ext4_xattr_user_list(struct dentry *dentry) static int ext4_xattr_user_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, int flags) { if (!test_opt(inode->i_sb, XATTR_USER)) return -EOPNOTSUPP; diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c index e348f33bcb2b..a73a3d0510f1 100644 --- a/fs/f2fs/xattr.c +++ b/fs/f2fs/xattr.c @@ -45,7 +45,7 @@ static void xattr_free(struct f2fs_sb_info *sbi, void *xattr_addr, static int f2fs_xattr_generic_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, int flags) { struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb); @@ -101,7 +101,7 @@ static bool f2fs_xattr_trusted_list(struct dentry *dentry) static int f2fs_xattr_advise_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, int flags) { if (buffer) *((char *)buffer) = F2FS_I(inode)->i_advise; diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c index 0d3e7177fce0..d77d5844e6c2 100644 --- a/fs/fuse/xattr.c +++ b/fs/fuse/xattr.c @@ -180,7 +180,7 @@ int fuse_removexattr(struct inode *inode, const char *name) static int fuse_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *value, size_t size) + const char *name, void *value, size_t size, int flags) { if (fuse_is_bad(inode)) return -EIO; @@ -210,7 +210,7 @@ static bool no_xattr_list(struct dentry *dentry) static int no_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *value, size_t size) + const char *name, void *value, size_t size, int flags) { return -EOPNOTSUPP; } diff --git a/fs/gfs2/xattr.c b/fs/gfs2/xattr.c index 0c5650fe1fd1..d4e8fb14b18e 100644 --- a/fs/gfs2/xattr.c +++ b/fs/gfs2/xattr.c @@ -602,7 +602,8 @@ static int __gfs2_xattr_get(struct inode *inode, const char *name, static int gfs2_xattr_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { struct gfs2_inode *ip = GFS2_I(inode); struct gfs2_holder gh; diff --git a/fs/hfs/attr.c b/fs/hfs/attr.c index 2bd54efaf416..c42385c33d2a 100644 --- a/fs/hfs/attr.c +++ b/fs/hfs/attr.c @@ -115,7 +115,7 @@ static ssize_t __hfs_getxattr(struct inode *inode, enum hfs_xattr_type type, static int hfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *value, size_t size) + const char *name, void *value, size_t size, int flags) { return __hfs_getxattr(inode, handler->flags, value, size); } diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c index e2855ceefd39..65e625aa4fa9 100644 --- a/fs/hfsplus/xattr.c +++ b/fs/hfsplus/xattr.c @@ -838,7 +838,8 @@ static int hfsplus_removexattr(struct inode *inode, const char *name) static int hfsplus_osx_getxattr(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { /* * Don't allow retrieving properly prefixed attributes diff --git a/fs/hfsplus/xattr_security.c b/fs/hfsplus/xattr_security.c index c1c7a16cbf21..1b28b83c201e 100644 --- a/fs/hfsplus/xattr_security.c +++ b/fs/hfsplus/xattr_security.c @@ -15,7 +15,8 @@ static int hfsplus_security_getxattr(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, + size_t size, int flags) { return hfsplus_getxattr(inode, name, buffer, size, XATTR_SECURITY_PREFIX, diff --git a/fs/hfsplus/xattr_trusted.c b/fs/hfsplus/xattr_trusted.c index e150372ec564..7caeff6243d7 100644 --- a/fs/hfsplus/xattr_trusted.c +++ b/fs/hfsplus/xattr_trusted.c @@ -14,7 +14,8 @@ static int hfsplus_trusted_getxattr(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, + size_t size, int flags) { return hfsplus_getxattr(inode, name, buffer, size, XATTR_TRUSTED_PREFIX, diff --git a/fs/hfsplus/xattr_user.c b/fs/hfsplus/xattr_user.c index a6b60b153916..ca74443eb123 100644 --- a/fs/hfsplus/xattr_user.c +++ b/fs/hfsplus/xattr_user.c @@ -14,7 +14,8 @@ static int hfsplus_user_getxattr(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { return hfsplus_getxattr(inode, name, buffer, size, diff --git a/fs/inode.c b/fs/inode.c index 3eba0940ffcf..a8234909ca5a 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1907,7 +1907,8 @@ EXPORT_SYMBOL(should_remove_suid); * response to write or truncate. Return 0 if nothing has to be changed. * Negative value on error (change should be denied). */ -int dentry_needs_remove_privs(struct dentry *dentry) +int dentry_needs_remove_privs(struct user_namespace *mnt_userns, + struct dentry *dentry) { struct inode *inode = d_inode(dentry); int mask = 0; @@ -1917,7 +1918,7 @@ int dentry_needs_remove_privs(struct dentry *dentry) return 0; mask = should_remove_suid(dentry); - ret = security_inode_need_killpriv(dentry); + ret = security_inode_need_killpriv(mnt_userns, dentry); if (ret < 0) return ret; if (ret) @@ -1958,7 +1959,7 @@ int file_remove_privs(struct file *file) if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode)) return 0; - kill = dentry_needs_remove_privs(dentry); + kill = dentry_needs_remove_privs(file_mnt_user_ns(file), dentry); if (kill < 0) return kill; if (kill) diff --git a/fs/internal.h b/fs/internal.h index 7979ff8d168c..2ed729447c4d 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -138,7 +138,8 @@ extern int vfs_open(const struct path *, struct file *); * inode.c */ extern long prune_icache_sb(struct super_block *sb, struct shrink_control *sc); -extern int dentry_needs_remove_privs(struct dentry *dentry); +extern int dentry_needs_remove_privs(struct user_namespace *mnt_userns, + struct dentry *dentry); /* * fs-writeback.c diff --git a/fs/jffs2/security.c b/fs/jffs2/security.c index aef5522551db..c443c4e47208 100644 --- a/fs/jffs2/security.c +++ b/fs/jffs2/security.c @@ -50,7 +50,8 @@ int jffs2_init_security(struct inode *inode, struct inode *dir, /* ---- XATTR Handler for "security.*" ----------------- */ static int jffs2_security_getxattr(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { return do_jffs2_getxattr(inode, JFFS2_XPREFIX_SECURITY, name, buffer, size); diff --git a/fs/jffs2/xattr_trusted.c b/fs/jffs2/xattr_trusted.c index cc3f24883e7d..95ed9ce1eaaf 100644 --- a/fs/jffs2/xattr_trusted.c +++ b/fs/jffs2/xattr_trusted.c @@ -18,7 +18,8 @@ static int jffs2_trusted_getxattr(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { return do_jffs2_getxattr(inode, JFFS2_XPREFIX_TRUSTED, name, buffer, size); diff --git a/fs/jffs2/xattr_user.c b/fs/jffs2/xattr_user.c index fb945977c013..418bb8d2758f 100644 --- a/fs/jffs2/xattr_user.c +++ b/fs/jffs2/xattr_user.c @@ -18,7 +18,8 @@ static int jffs2_user_getxattr(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { return do_jffs2_getxattr(inode, JFFS2_XPREFIX_USER, name, buffer, size); diff --git a/fs/jfs/xattr.c b/fs/jfs/xattr.c index f9273f6901c8..8728df337090 100644 --- a/fs/jfs/xattr.c +++ b/fs/jfs/xattr.c @@ -925,7 +925,7 @@ static int __jfs_xattr_set(struct inode *inode, const char *name, static int jfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *value, size_t size) + const char *name, void *value, size_t size, int flags) { name = xattr_full_name(handler, name); return __jfs_getxattr(inode, name, value, size); @@ -943,7 +943,8 @@ static int jfs_xattr_set(const struct xattr_handler *handler, static int jfs_xattr_get_os2(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *value, size_t size) + const char *name, void *value, size_t size, + int flags) { if (is_known_namespace(name)) return -EOPNOTSUPP; diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c index c0eae1725435..d56210c657f0 100644 --- a/fs/kernfs/inode.c +++ b/fs/kernfs/inode.c @@ -313,7 +313,8 @@ int kernfs_xattr_set(struct kernfs_node *kn, const char *name, static int kernfs_vfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *suffix, void *value, size_t size) + const char *suffix, void *value, size_t size, + int flags) { const char *name = xattr_full_name(handler, suffix); struct kernfs_node *kn = inode->i_private; diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index ee3bc79f6ca3..4e5f66623cda 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -7542,7 +7542,8 @@ static int nfs4_xattr_set_nfs4_acl(const struct xattr_handler *handler, static int nfs4_xattr_get_nfs4_acl(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *key, void *buf, size_t buflen) + const char *key, void *buf, size_t buflen, + int flags) { return nfs4_proc_get_acl(inode, buf, buflen); } @@ -7568,7 +7569,8 @@ static int nfs4_xattr_set_nfs4_label(const struct xattr_handler *handler, static int nfs4_xattr_get_nfs4_label(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *key, void *buf, size_t buflen) + const char *key, void *buf, size_t buflen, + int flags) { if (security_ismaclabel(key)) return nfs4_get_security_label(inode, buf, buflen); @@ -7646,7 +7648,8 @@ static int nfs4_xattr_set_nfs4_user(const struct xattr_handler *handler, static int nfs4_xattr_get_nfs4_user(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *key, void *buf, size_t buflen) + const char *key, void *buf, size_t buflen, + int flags) { struct nfs_access_entry cache; ssize_t ret; diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c index afd0ddad826f..fdc54f7573d5 100644 --- a/fs/ntfs3/xattr.c +++ b/fs/ntfs3/xattr.c @@ -710,7 +710,7 @@ ssize_t ntfs_listxattr(struct dentry *dentry, char *buffer, size_t size) static int ntfs_getxattr(const struct xattr_handler *handler, struct dentry *de, struct inode *inode, const char *name, void *buffer, - size_t size) + size_t size, int flags) { int err; struct ntfs_inode *ni = ntfs_i(inode); diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c index dd784eb0cd7c..bd019ed56555 100644 --- a/fs/ocfs2/xattr.c +++ b/fs/ocfs2/xattr.c @@ -7240,7 +7240,8 @@ int ocfs2_init_security_and_acl(struct inode *dir, */ static int ocfs2_xattr_security_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { return ocfs2_xattr_get(inode, OCFS2_XATTR_INDEX_SECURITY, name, buffer, size); @@ -7313,7 +7314,8 @@ const struct xattr_handler ocfs2_xattr_security_handler = { */ static int ocfs2_xattr_trusted_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { return ocfs2_xattr_get(inode, OCFS2_XATTR_INDEX_TRUSTED, name, buffer, size); @@ -7340,7 +7342,8 @@ const struct xattr_handler ocfs2_xattr_trusted_handler = { */ static int ocfs2_xattr_user_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); diff --git a/fs/open.c b/fs/open.c index f732fb94600c..0591189a169a 100644 --- a/fs/open.c +++ b/fs/open.c @@ -53,7 +53,7 @@ int do_truncate(struct user_namespace *mnt_userns, struct dentry *dentry, } /* Remove suid, sgid, and file capabilities on truncate too */ - ret = dentry_needs_remove_privs(dentry); + ret = dentry_needs_remove_privs(mnt_userns, dentry); if (ret < 0) return ret; if (ret) diff --git a/fs/orangefs/xattr.c b/fs/orangefs/xattr.c index 9a5b757fbd2f..2cc3bc61235b 100644 --- a/fs/orangefs/xattr.c +++ b/fs/orangefs/xattr.c @@ -542,7 +542,8 @@ static int orangefs_xattr_get_default(const struct xattr_handler *handler, struct inode *inode, const char *name, void *buffer, - size_t size) + size_t size, + int flags) { return orangefs_inode_getxattr(inode, name, buffer, size); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 265181c110ae..359aa5772cb7 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1004,7 +1004,7 @@ static unsigned int ovl_split_lowerdirs(char *str) static int __maybe_unused ovl_posix_acl_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, int flags) { return ovl_xattr_get(dentry, inode, handler->name, buffer, size); } @@ -1067,7 +1067,8 @@ ovl_posix_acl_xattr_set(const struct xattr_handler *handler, static int ovl_own_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { return -EOPNOTSUPP; } @@ -1083,7 +1084,8 @@ static int ovl_own_xattr_set(const struct xattr_handler *handler, static int ovl_other_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { return ovl_xattr_get(dentry, inode, name, buffer, size); } diff --git a/fs/posix_acl.c b/fs/posix_acl.c index 9323a854a60a..e6cd6065ddd0 100644 --- a/fs/posix_acl.c +++ b/fs/posix_acl.c @@ -887,7 +887,7 @@ EXPORT_SYMBOL (posix_acl_to_xattr); static int posix_acl_xattr_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *value, size_t size) + const char *name, void *value, size_t size, int flags) { struct posix_acl *acl; int error; diff --git a/fs/reiserfs/xattr_security.c b/fs/reiserfs/xattr_security.c index 8965c8e5e172..1fd1359a98ba 100644 --- a/fs/reiserfs/xattr_security.c +++ b/fs/reiserfs/xattr_security.c @@ -11,7 +11,8 @@ static int security_get(const struct xattr_handler *handler, struct dentry *unused, - struct inode *inode, const char *name, void *buffer, size_t size) + struct inode *inode, const char *name, void *buffer, size_t size, + int flags) { if (IS_PRIVATE(inode)) return -EPERM; diff --git a/fs/reiserfs/xattr_trusted.c b/fs/reiserfs/xattr_trusted.c index d853cea2afcd..f54b848e9504 100644 --- a/fs/reiserfs/xattr_trusted.c +++ b/fs/reiserfs/xattr_trusted.c @@ -10,7 +10,8 @@ static int trusted_get(const struct xattr_handler *handler, struct dentry *unused, - struct inode *inode, const char *name, void *buffer, size_t size) + struct inode *inode, const char *name, void *buffer, size_t size, + int flags) { if (!capable(CAP_SYS_ADMIN) || IS_PRIVATE(inode)) return -EPERM; diff --git a/fs/reiserfs/xattr_user.c b/fs/reiserfs/xattr_user.c index 65d9cd10a5ea..ddd98cdab24d 100644 --- a/fs/reiserfs/xattr_user.c +++ b/fs/reiserfs/xattr_user.c @@ -9,7 +9,8 @@ static int user_get(const struct xattr_handler *handler, struct dentry *unused, - struct inode *inode, const char *name, void *buffer, size_t size) + struct inode *inode, const char *name, void *buffer, size_t size, + int flags) { if (!reiserfs_xattrs_user(inode->i_sb)) return -EOPNOTSUPP; diff --git a/fs/squashfs/xattr.c b/fs/squashfs/xattr.c index e1e3f3dd5a06..d8d58c990652 100644 --- a/fs/squashfs/xattr.c +++ b/fs/squashfs/xattr.c @@ -204,7 +204,7 @@ static int squashfs_xattr_handler_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, const char *name, - void *buffer, size_t size) + void *buffer, size_t size, int flags) { return squashfs_xattr_get(inode, handler->flags, name, buffer, size); diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c index e4f193eae4b2..681663f5bfa1 100644 --- a/fs/ubifs/xattr.c +++ b/fs/ubifs/xattr.c @@ -689,7 +689,8 @@ int ubifs_init_security(struct inode *dentry, struct inode *inode, static int xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { dbg_gen("xattr '%s', ino %lu ('%pd'), buf size %zd", name, inode->i_ino, dentry, size); diff --git a/fs/xattr.c b/fs/xattr.c index 5c8c5175b385..4c36ddd6ac3c 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -369,7 +369,7 @@ vfs_getxattr_alloc(struct user_namespace *mnt_userns, struct dentry *dentry, return PTR_ERR(handler); if (!handler->get) return -EOPNOTSUPP; - error = handler->get(handler, dentry, inode, name, NULL, 0); + error = handler->get(handler, dentry, inode, name, NULL, 0, 0); if (error < 0) return error; @@ -380,33 +380,22 @@ vfs_getxattr_alloc(struct user_namespace *mnt_userns, struct dentry *dentry, memset(value, 0, error + 1); } - error = handler->get(handler, dentry, inode, name, value, error); + error = handler->get(handler, dentry, inode, name, value, error, 0); *xattr_value = value; return error; } ssize_t -__vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name, - void *value, size_t size) +__vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry, + struct inode *inode, const char *name, void *value, + size_t size, int flags) { const struct xattr_handler *handler; - - handler = xattr_resolve_name(inode, &name); - if (IS_ERR(handler)) - return PTR_ERR(handler); - if (!handler->get) - return -EOPNOTSUPP; - return handler->get(handler, dentry, inode, name, value, size); -} -EXPORT_SYMBOL(__vfs_getxattr); - -ssize_t -vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry, - const char *name, void *value, size_t size) -{ - struct inode *inode = dentry->d_inode; int error; + if (flags & XATTR_NOSECURITY) + goto nolsm; + error = xattr_permission(mnt_userns, inode, name, MAY_READ); if (error) return error; @@ -429,7 +418,20 @@ vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry, return ret; } nolsm: - return __vfs_getxattr(dentry, inode, name, value, size); + handler = xattr_resolve_name(inode, &name); + if (IS_ERR(handler)) + return PTR_ERR(handler); + if (!handler->get) + return -EOPNOTSUPP; + return handler->get(handler, dentry, inode, name, value, size, flags); +} +EXPORT_SYMBOL(__vfs_getxattr); + +ssize_t +vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry, + const char *name, void *value, size_t size) +{ + return __vfs_getxattr(mnt_userns, dentry, dentry->d_inode, name, value, size, 0); } EXPORT_SYMBOL_GPL(vfs_getxattr); diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c index 0d050f8829ef..296b494e67c6 100644 --- a/fs/xfs/xfs_xattr.c +++ b/fs/xfs/xfs_xattr.c @@ -21,7 +21,8 @@ static int xfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused, - struct inode *inode, const char *name, void *value, size_t size) + struct inode *inode, const char *name, void *value, size_t size, + int flags) { struct xfs_da_args args = { .dp = XFS_I(inode), diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index df8de62f4710..999375766635 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -147,7 +147,8 @@ LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name) LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry) LSM_HOOK(int, 0, inode_removexattr, struct user_namespace *mnt_userns, struct dentry *dentry, const char *name) -LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry) +LSM_HOOK(int, 0, inode_need_killpriv, struct user_namespace *mnt_userns, + struct dentry *dentry) LSM_HOOK(int, 0, inode_killpriv, struct user_namespace *mnt_userns, struct dentry *dentry) LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct user_namespace *mnt_userns, diff --git a/include/linux/security.h b/include/linux/security.h index bbf44a466832..c48992c71295 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -150,7 +150,8 @@ int cap_inode_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags); int cap_inode_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry, const char *name); -int cap_inode_need_killpriv(struct dentry *dentry); +int cap_inode_need_killpriv(struct user_namespace *mnt_userns, + struct dentry *dentry); int cap_inode_killpriv(struct user_namespace *mnt_userns, struct dentry *dentry); int cap_inode_getsecurity(struct user_namespace *mnt_userns, @@ -364,7 +365,8 @@ int security_inode_getxattr(struct dentry *dentry, const char *name); int security_inode_listxattr(struct dentry *dentry); int security_inode_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry, const char *name); -int security_inode_need_killpriv(struct dentry *dentry); +int security_inode_need_killpriv(struct user_namespace *mnt_userns, + struct dentry *dentry); int security_inode_killpriv(struct user_namespace *mnt_userns, struct dentry *dentry); int security_inode_getsecurity(struct user_namespace *mnt_userns, diff --git a/include/linux/xattr.h b/include/linux/xattr.h index 4c379d23ec6e..663a04ae6223 100644 --- a/include/linux/xattr.h +++ b/include/linux/xattr.h @@ -34,7 +34,7 @@ struct xattr_handler { bool (*list)(struct dentry *dentry); int (*get)(const struct xattr_handler *, struct dentry *dentry, struct inode *inode, const char *name, void *buffer, - size_t size); + size_t size, int flags); int (*set)(const struct xattr_handler *, struct user_namespace *mnt_userns, struct dentry *dentry, struct inode *inode, const char *name, const void *buffer, @@ -49,7 +49,9 @@ struct xattr { size_t value_len; }; -ssize_t __vfs_getxattr(struct dentry *, struct inode *, const char *, void *, size_t); +ssize_t __vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry, + struct inode *inode, const char *name, void *buffer, + size_t size, int flags); ssize_t vfs_getxattr(struct user_namespace *, struct dentry *, const char *, void *, size_t); ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size); diff --git a/include/uapi/linux/xattr.h b/include/uapi/linux/xattr.h index 9463db2dfa9d..d22191a3cf09 100644 --- a/include/uapi/linux/xattr.h +++ b/include/uapi/linux/xattr.h @@ -18,8 +18,11 @@ #if __UAPI_DEF_XATTR #define __USE_KERNEL_XATTR_DEFS -#define XATTR_CREATE 0x1 /* set value, fail if attr already exists */ -#define XATTR_REPLACE 0x2 /* set value, fail if attr does not exist */ +#define XATTR_CREATE 0x1 /* set value, fail if attr already exists */ +#define XATTR_REPLACE 0x2 /* set value, fail if attr does not exist */ +#ifdef __KERNEL__ /* following is kernel internal, colocated for maintenance */ +#define XATTR_NOSECURITY 0x4 /* get value, do not involve security check */ +#endif #endif /* Namespaces */ diff --git a/mm/shmem.c b/mm/shmem.c index dc038ce78700..ece9a84c7701 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3152,7 +3152,8 @@ static int shmem_initxattrs(struct inode *inode, static int shmem_xattr_handler_get(const struct xattr_handler *handler, struct dentry *unused, struct inode *inode, - const char *name, void *buffer, size_t size) + const char *name, void *buffer, size_t size, + int flags) { struct shmem_inode_info *info = SHMEM_I(inode); diff --git a/net/socket.c b/net/socket.c index 7f64a6eccf63..8704bbf55eda 100644 --- a/net/socket.c +++ b/net/socket.c @@ -364,7 +364,8 @@ static const struct dentry_operations sockfs_dentry_operations = { static int sockfs_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, - const char *suffix, void *value, size_t size) + const char *suffix, void *value, size_t size, + int flags) { if (value) { if (dentry->d_name.len + 1 > size) diff --git a/security/commoncap.c b/security/commoncap.c index 3f810d37b71b..05a5bc2c0db9 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -292,12 +292,14 @@ int cap_capset(struct cred *new, * Return: 1 if security.capability has a value, meaning inode_killpriv() * is required, 0 otherwise, meaning inode_killpriv() is not required. */ -int cap_inode_need_killpriv(struct dentry *dentry) +int cap_inode_need_killpriv(struct user_namespace *mnt_userns, + struct dentry *dentry) { struct inode *inode = d_backing_inode(dentry); int error; - error = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); + error = __vfs_getxattr(mnt_userns, dentry, inode, XATTR_NAME_CAPS, + NULL, 0, XATTR_NOSECURITY); return error > 0; } @@ -660,8 +662,9 @@ int get_vfs_caps_from_disk(struct user_namespace *mnt_userns, return -ENODATA; fs_ns = inode->i_sb->s_user_ns; - size = __vfs_getxattr((struct dentry *)dentry, inode, - XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ); + size = __vfs_getxattr(mnt_userns, (struct dentry *)dentry, inode, + XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ, + XATTR_NOSECURITY); if (size == -ENODATA || size == -EOPNOTSUPP) /* no data, that's ok */ return -ENODATA; diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 08f907382c61..e8335fb04c7a 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -145,7 +145,8 @@ static int evm_find_protected_xattrs(struct dentry *dentry) return -EOPNOTSUPP; list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) { - error = __vfs_getxattr(dentry, inode, xattr->name, NULL, 0); + error = __vfs_getxattr(&init_user_ns, dentry, inode, + xattr->name, NULL, 0, XATTR_NOSECURITY); if (error < 0) { if (error == -ENODATA) continue; @@ -343,8 +344,9 @@ int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer, int rc, size, total_size = 0; list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) { - rc = __vfs_getxattr(dentry, d_backing_inode(dentry), - xattr->name, NULL, 0); + rc = __vfs_getxattr(&init_user_ns, dentry, + d_backing_inode(dentry), xattr->name, NULL, + 0, XATTR_NOSECURITY); if (rc < 0 && rc == -ENODATA) continue; else if (rc < 0) @@ -372,10 +374,11 @@ int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer, case 'v': size = rc; if (buffer) { - rc = __vfs_getxattr(dentry, + rc = __vfs_getxattr(&init_user_ns, dentry, d_backing_inode(dentry), xattr->name, buffer + total_size, - buffer_size - total_size); + buffer_size - total_size, + XATTR_NOSECURITY); if (rc < 0) return rc; } diff --git a/security/security.c b/security/security.c index c88167a414b4..cc75b37dedc0 100644 --- a/security/security.c +++ b/security/security.c @@ -1404,9 +1404,10 @@ int security_inode_removexattr(struct user_namespace *mnt_userns, return evm_inode_removexattr(mnt_userns, dentry, name); } -int security_inode_need_killpriv(struct dentry *dentry) +int security_inode_need_killpriv(struct user_namespace *mnt_userns, + struct dentry *dentry) { - return call_int_hook(inode_need_killpriv, 0, dentry); + return call_int_hook(inode_need_killpriv, 0, mnt_userns, dentry); } int security_inode_killpriv(struct user_namespace *mnt_userns, diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 62d30c0a30c2..84c12072e38a 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -490,7 +490,7 @@ static int selinux_is_sblabel_mnt(struct super_block *sb) } } -static int sb_check_xattr_support(struct super_block *sb) +static int sb_check_xattr_support(struct user_namespace *mnt_userns, struct super_block *sb) { struct superblock_security_struct *sbsec = sb->s_security; struct dentry *root = sb->s_root; @@ -511,7 +511,8 @@ static int sb_check_xattr_support(struct super_block *sb) goto fallback; } - rc = __vfs_getxattr(root, root_inode, XATTR_NAME_SELINUX, NULL, 0); + rc = __vfs_getxattr(mnt_userns, root, root_inode, XATTR_NAME_SELINUX, NULL, 0, + XATTR_NOSECURITY); if (rc < 0 && rc != -ENODATA) { if (rc == -EOPNOTSUPP) { pr_warn("SELinux: (dev %s, type %s) has no security xattr handler\n", @@ -547,7 +548,7 @@ static int sb_finish_set_opts(struct super_block *sb) int rc = 0; if (sbsec->behavior == SECURITY_FS_USE_XATTR) { - rc = sb_check_xattr_support(sb); + rc = sb_check_xattr_support(sb->s_user_ns, sb); if (rc) return rc; } @@ -1371,12 +1372,15 @@ static int inode_doinit_use_xattr(struct inode *inode, struct dentry *dentry, return -ENOMEM; context[len] = '\0'; - rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, context, len); + rc = __vfs_getxattr(&init_user_ns, dentry, inode, XATTR_NAME_SELINUX, + context, len, XATTR_NOSECURITY); if (rc == -ERANGE) { kfree(context); /* Need a larger buffer. Query for the right size. */ - rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, NULL, 0); + rc = __vfs_getxattr(&init_user_ns, dentry, inode, + XATTR_NAME_SELINUX, NULL, 0, + XATTR_NOSECURITY); if (rc < 0) return rc; @@ -1386,8 +1390,9 @@ static int inode_doinit_use_xattr(struct inode *inode, struct dentry *dentry, return -ENOMEM; context[len] = '\0'; - rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, - context, len); + rc = __vfs_getxattr(&init_user_ns, dentry, inode, + XATTR_NAME_SELINUX, context, len, + XATTR_NOSECURITY); } if (rc < 0) { kfree(context); diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index efd35b07c7f8..5ea91eae1054 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -277,8 +277,9 @@ static int smk_bu_credfile(const struct cred *cred, struct file *file, * Returns a pointer to the master list entry for the Smack label, * NULL if there was no label to fetch, or an error code. */ -static struct smack_known *smk_fetch(const char *name, struct inode *ip, - struct dentry *dp) +static struct smack_known *smk_fetch(struct user_namespace *mnt_userns, + const char *name, struct inode *ip, + struct dentry *dp) { int rc; char *buffer; @@ -291,7 +292,8 @@ static struct smack_known *smk_fetch(const char *name, struct inode *ip, if (buffer == NULL) return ERR_PTR(-ENOMEM); - rc = __vfs_getxattr(dp, ip, name, buffer, SMK_LONGLABEL); + rc = __vfs_getxattr(mnt_userns, dp, ip, name, buffer, SMK_LONGLABEL, + XATTR_NOSECURITY); if (rc < 0) skp = ERR_PTR(rc); else if (rc == 0) @@ -3414,7 +3416,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode) * Get the dentry for xattr. */ dp = dget(opt_dentry); - skp = smk_fetch(XATTR_NAME_SMACK, inode, dp); + skp = smk_fetch(&init_user_ns, XATTR_NAME_SMACK, inode, dp); if (!IS_ERR_OR_NULL(skp)) final = skp; @@ -3438,9 +3440,9 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode) TRANS_TRUE, TRANS_TRUE_SIZE, 0); } else { - rc = __vfs_getxattr(dp, inode, + rc = __vfs_getxattr(&init_user_ns, dp, inode, XATTR_NAME_SMACKTRANSMUTE, trattr, - TRANS_TRUE_SIZE); + TRANS_TRUE_SIZE, XATTR_NOSECURITY); if (rc >= 0 && strncmp(trattr, TRANS_TRUE, TRANS_TRUE_SIZE) != 0) rc = -EINVAL; @@ -3451,13 +3453,13 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode) /* * Don't let the exec or mmap label be "*" or "@". */ - skp = smk_fetch(XATTR_NAME_SMACKEXEC, inode, dp); + skp = smk_fetch(&init_user_ns, XATTR_NAME_SMACKEXEC, inode, dp); if (IS_ERR(skp) || skp == &smack_known_star || skp == &smack_known_web) skp = NULL; isp->smk_task = skp; - skp = smk_fetch(XATTR_NAME_SMACKMMAP, inode, dp); + skp = smk_fetch(&init_user_ns, XATTR_NAME_SMACKMMAP, inode, dp); if (IS_ERR(skp) || skp == &smack_known_star || skp == &smack_known_web) skp = NULL; From patchwork Wed Nov 17 01:58:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Anderson X-Patchwork-Id: 12623509 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51B80C4167B for ; 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Tue, 16 Nov 2021 17:58:30 -0800 (PST) Date: Wed, 17 Nov 2021 01:58:04 +0000 In-Reply-To: <20211117015806.2192263-1-dvander@google.com> Message-Id: <20211117015806.2192263-3-dvander@google.com> Mime-Version: 1.0 References: <20211117015806.2192263-1-dvander@google.com> X-Mailer: git-send-email 2.34.0.rc1.387.gb447b232ab-goog Subject: [PATCH v19 2/4] overlayfs: handle XATTR_NOSECURITY flag for get xattr method From: David Anderson Cc: David Anderson , Mark Salyzyn , linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, Stephen Smalley , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, kernel-team@android.com, Miklos Szeredi , Jonathan Corbet , Vivek Goyal , "Eric W . Biederman" , Amir Goldstein , linux-doc@vger.kernel.org, selinux@vger.kernel.org, paulmoore@microsoft.com, Luca.Boccassi@microsoft.com To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: Because of the overlayfs getxattr recursion, the incoming inode fails to update the selinux sid resulting in avc denials being reported against a target context of u:object_r:unlabeled:s0. Solution is to respond to the XATTR_NOSECURITY flag in get xattr method that calls the __vfs_getxattr handler instead so that the context can be read in, rather than being denied with an -EACCES when vfs_getxattr handler is called. For the use case where access is to be blocked by the security layer. The path then would be security(dentry) -> __vfs_getxattr({dentry...XATTR_NOSECURITY}) -> handler->get({dentry...XATTR_NOSECURITY}) -> __vfs_getxattr({realdentry...XATTR_NOSECURITY}) -> lower_handler->get({realdentry...XATTR_NOSECURITY}) which would report back through the chain data and success as expected, the logging security layer at the top would have the data to determine the access permissions and report back to the logs and the caller that the target context was blocked. For selinux this would solve the cosmetic issue of the selinux log and allow audit2allow to correctly report the rule needed to address the access problem. Check impure, opaque, origin & meta xattr with no sepolicy audit (using __vfs_getxattr) since these operations are internal to overlayfs operations and do not disclose any data. This became an issue for credential override off since sys_admin would have been required by the caller; whereas would have been inherently present for the creator since it performed the mount. This is a change in operations since we do not check in the new ovl_do_getxattr function if the credential override is off or not. Reasoning is that the sepolicy check is unnecessary overhead, especially since the check can be expensive. Because for override credentials off, this affects _everyone_ that underneath performs private xattr calls without the appropriate sepolicy permissions and sys_admin capability. Providing blanket support for sys_admin would be bad for all possible callers. For the override credentials on, this will affect only the mounter, should it lack sepolicy permissions. Not considered a security problem since mounting by definition has sys_admin capabilities, but sepolicy contexts would still need to be crafted. It should be noted that there is precedence, __vfs_getxattr is used in other filesystems for their own internal trusted xattr management. Signed-off-by: Mark Salyzyn Signed-off-by: David Anderson Cc: linux-fsdevel@vger.kernel.org Cc: linux-unionfs@vger.kernel.org Cc: Stephen Smalley Cc: linux-kernel@vger.kernel.org Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: Miklos Szeredi Cc: Jonathan Corbet Cc: Vivek Goyal Cc: Eric W. Biederman Cc: Amir Goldstein Cc: Stephen Smalley Cc: linux-doc@vger.kernel.org Cc: selinux@vger.kernel.org Cc: paulmoore@microsoft.com Cc: Luca.Boccassi@microsoft.com v19 - rebase v18 - correct inode argument to __vfs_getxattr v17 - rebase and add inode argument to __vfs_getxattr v16 - rebase and merge internal getxattr operations patch v15 - revert to v13 because xattr_gs_args rejected. v14 - rebase to use xattr_gs_args. v13 - rebase to use __vfs_getxattr flags option. v12 - Added back to patch series as get xattr with flag option. v11 - Squashed out of patch series and replaced with per-thread flag solution. v10 - Added to patch series as __get xattr method. --- fs/overlayfs/inode.c | 5 +++-- fs/overlayfs/overlayfs.h | 6 ++++-- fs/overlayfs/super.c | 4 ++-- 3 files changed, 9 insertions(+), 6 deletions(-) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 1f36158c7dbe..49bfa33bb682 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -386,7 +386,7 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name, } int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name, - void *value, size_t size) + void *value, size_t size, int flags) { ssize_t res; const struct cred *old_cred; @@ -394,7 +394,8 @@ int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name, ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry); old_cred = ovl_override_creds(dentry->d_sb); - res = vfs_getxattr(&init_user_ns, realdentry, name, value, size); + res = __vfs_getxattr(&init_user_ns, realdentry, d_inode(realdentry), + name, value, size, flags); revert_creds(old_cred); return res; } diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 2cd5741c873b..3fcd62e72aad 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -187,7 +187,9 @@ static inline ssize_t ovl_do_getxattr(struct ovl_fs *ofs, struct dentry *dentry, size_t size) { const char *name = ovl_xattr(ofs, ox); - int err = vfs_getxattr(&init_user_ns, dentry, name, value, size); + struct inode *ip = d_inode(dentry); + int err = __vfs_getxattr(&init_user_ns, dentry, ip, name, value, size, + XATTR_NOSECURITY); int len = (value && err > 0) ? err : 0; pr_debug("getxattr(%pd2, \"%s\", \"%*pE\", %zu, 0) = %i\n", @@ -496,7 +498,7 @@ int ovl_permission(struct user_namespace *mnt_userns, struct inode *inode, int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name, const void *value, size_t size, int flags); int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name, - void *value, size_t size); + void *value, size_t size, int flags); ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size); struct posix_acl *ovl_get_acl(struct inode *inode, int type, bool rcu); int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 359aa5772cb7..973644af1288 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1006,7 +1006,7 @@ ovl_posix_acl_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, void *buffer, size_t size, int flags) { - return ovl_xattr_get(dentry, inode, handler->name, buffer, size); + return ovl_xattr_get(dentry, inode, handler->name, buffer, size, flags); } static int __maybe_unused @@ -1087,7 +1087,7 @@ static int ovl_other_xattr_get(const struct xattr_handler *handler, const char *name, void *buffer, size_t size, int flags) { - return ovl_xattr_get(dentry, inode, name, buffer, size); + return ovl_xattr_get(dentry, inode, name, buffer, size, flags); } static int ovl_other_xattr_set(const struct xattr_handler *handler, From patchwork Wed Nov 17 01:58:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Anderson X-Patchwork-Id: 12623511 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC4EBC433FE for ; Wed, 17 Nov 2021 01:58:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6DED61507 for ; Wed, 17 Nov 2021 01:58:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232805AbhKQCBj (ORCPT ); Tue, 16 Nov 2021 21:01:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232727AbhKQCBb (ORCPT ); Tue, 16 Nov 2021 21:01:31 -0500 Received: from mail-vk1-xa4a.google.com (mail-vk1-xa4a.google.com [IPv6:2607:f8b0:4864:20::a4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 98095C061200 for ; Tue, 16 Nov 2021 17:58:33 -0800 (PST) Received: by mail-vk1-xa4a.google.com with SMTP id j20-20020a056122217400b002facf017a12so569681vkr.10 for ; Tue, 16 Nov 2021 17:58:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:cc; bh=QIjKXLTRjvfWUxFUWwuhm7GQFs9wHbpNZr/P8Fm90e4=; b=lF1VG1awJjmK9HHEojHUaUnv8Hu0VRNS68XMx+KkMY0JmJGBOw+HqFimP9wdbKAZmd zogMLNYpt4WmM/FCRSVIhrHDlHkW9IRh1tB3RrEsDqBvwMyXGytSn8ZkWApNkfV3Yim4 rciF2VPTcd5z+lgeWXpG9u8ZIPurEelK1/9WkARovQNIlvqJi/p1uSpFa382SMc9wLzE Pcwu28QzRHyQjNGRt0HW2T1PmtckNao7p450Xs5Je4erW/6TS8sLciZCp/PnvP9unAh6 v+ySxDg4AqygQCHw5i/JOKHVV6REpoukn7pXG0JWRZ9neFn3BqfbdWqD7MeIR+r9CUFA 0lDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:cc; bh=QIjKXLTRjvfWUxFUWwuhm7GQFs9wHbpNZr/P8Fm90e4=; b=5KbGubhCMiAGCMvoGsYiHXCyHEhZr/0KfW5joCXd2s/nxy4cqckwOZnPVDdAGv1ytx a7O6IB2lBFCHQZc0mRJ3vi0Xf+2e0GL5GQ6+yMBL0oWJjYkkromz+X2sHv/FXLhBD+P1 U3Mk2WcVGaFQD/ifEo4g3e+Uf3AdmvR5TdvdGb5C2Ht9Mz2UgHQDCJgbo0EM1ZN8ev02 XUU1i6QLgS5H7X2H7aKXkcM57JA+15w+OCKSOOq2w5yIt5/R6u3HhBuodsQdFY4VGqEe 9+kGG427p4DJkRZtdlkY0p5rDzPWd2+lIu8l/B0UTMEF+hqzHQr0JErtKoijxUVAPgo2 7jvQ== X-Gm-Message-State: AOAM5326JKwquWdXrwOGFMqAS05dGSw+y90BIjl3TYfppkPgka2GyeRt gC1xJgUwhrioLn6Kh8hjIoqAD07Lb8Gt X-Google-Smtp-Source: ABdhPJyi7pTakD9nPX3PByWnb98KtPu3ExwhWdw3fC4z7533pQ8vjSVfTAgIcCgh9hIKlp1RbVWJPNTYeVpE X-Received: from dvandertop.c.googlers.com ([fda3:e722:ac3:cc00:14:4d90:c0a8:2862]) (user=dvander job=sendgmr) by 2002:a05:6122:894:: with SMTP id 20mr26286532vkf.23.1637114312772; Tue, 16 Nov 2021 17:58:32 -0800 (PST) Date: Wed, 17 Nov 2021 01:58:05 +0000 In-Reply-To: <20211117015806.2192263-1-dvander@google.com> Message-Id: <20211117015806.2192263-4-dvander@google.com> Mime-Version: 1.0 References: <20211117015806.2192263-1-dvander@google.com> X-Mailer: git-send-email 2.34.0.rc1.387.gb447b232ab-goog Subject: [PATCH v19 3/4] overlayfs: override_creds=off option bypass creator_cred From: David Anderson Cc: David Anderson , Mark Salyzyn , linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, Miklos Szeredi , Jonathan Corbet , Vivek Goyal , "Eric W . Biederman" , Amir Goldstein , Randy Dunlap , Stephen Smalley , linux-security-module@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, selinux@vger.kernel.org, paulmoore@microsoft.com, Luca.Boccassi@microsoft.com To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: By default, all access to the upper, lower and work directories is the recorded mounter's MAC and DAC credentials. The incoming accesses are checked against the caller's credentials. If the principles of least privilege are applied, the mounter's credentials might not overlap the credentials of the caller's when accessing the overlayfs filesystem. For example, a file that a lower DAC privileged caller can execute, is MAC denied to the generally higher DAC privileged mounter, to prevent an attack vector. We add the option to turn off override_creds in the mount options; all subsequent operations after mount on the filesystem will be only the caller's credentials. The module boolean parameter and mount option override_creds is also added as a presence check for this "feature", existence of /sys/module/overlay/parameters/override_creds. It was not always this way. Circa 4.6 there was no recorded mounter's credentials, instead privileged access to upper or work directories were temporarily increased to perform the operations. The MAC (selinux) policies were caller's in all cases. override_creds=off partially returns us to this older access model minus the insecure temporary credential increases. This is to permit use in a system with non-overlapping security models for each executable including the agent that mounts the overlayfs filesystem. In Android this is the case since init, which performs the mount operations, has a minimal MAC set of privileges to reduce any attack surface, and services that use the content have a different set of MAC privileges (eg: read, for vendor labelled configuration, execute for vendor libraries and modules). The caveats are not a problem in the Android usage model, however they should be fixed for completeness and for general use in time. Signed-off-by: Mark Salyzyn Signed-off-by: David Anderson Cc: linux-fsdevel@vger.kernel.org Cc: linux-unionfs@vger.kernel.org Cc: Miklos Szeredi Cc: Jonathan Corbet Cc: Vivek Goyal Cc: Eric W. Biederman Cc: Amir Goldstein Cc: Randy Dunlap Cc: Stephen Smalley Cc: linux-security-module@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: kernel-team@android.com Cc: selinux@vger.kernel.org Cc: paulmoore@microsoft.com Cc: Luca.Boccassi@microsoft.com v19 - rebase v18 - rebase v17 - move credential section for override_creds=off as a level 3 heading subsection of the permissions section. v16 - Rebase, cover a few more new ovl_revert_creds callpoints. v15 - Rebase v14: - fix an issue in ovl_create_or_link which leaks credentials. v12 + v13 - Rebase v11: - add sb argument to ovl_revert_creds to match future work in progress in other commiter's hands. v10: - Rebase (and expand because of increased revert_cred usage) v9: - Add to the caveats v8: - drop pr_warn message after straw poll to remove it. - added a use case in the commit message v7: - change name of internal parameter to ovl_override_creds_def - report override_creds only if different than default v6: - Drop CONFIG_OVERLAY_FS_OVERRIDE_CREDS. - Do better with the documentation. - pr_warn message adjusted to report consequences. v5: - beefed up the caveats in the Documentation - Is dependent on "overlayfs: check CAP_DAC_READ_SEARCH before issuing exportfs_decode_fh" "overlayfs: check CAP_MKNOD before issuing vfs_whiteout" - Added prwarn when override_creds=off v4: - spelling and grammar errors in text v3: - Change name from caller_credentials / creator_credentials to the boolean override_creds. - Changed from creator to mounter credentials. - Updated and fortified the documentation. - Added CONFIG_OVERLAY_FS_OVERRIDE_CREDS v2: - Forward port changed attr to stat, resulting in a build error. - altered commit message. --- Documentation/filesystems/overlayfs.rst | 26 ++++++++++++++++++++++++- fs/overlayfs/copy_up.c | 2 +- fs/overlayfs/dir.c | 17 +++++++++------- fs/overlayfs/file.c | 22 ++++++++++----------- fs/overlayfs/inode.c | 24 +++++++++++------------ fs/overlayfs/namei.c | 6 +++--- fs/overlayfs/overlayfs.h | 1 + fs/overlayfs/ovl_entry.h | 1 + fs/overlayfs/readdir.c | 8 ++++---- fs/overlayfs/super.c | 22 ++++++++++++++++++++- fs/overlayfs/util.c | 13 +++++++++++-- 11 files changed, 100 insertions(+), 42 deletions(-) diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst index 7da6c30ed596..d7cd4032134a 100644 --- a/Documentation/filesystems/overlayfs.rst +++ b/Documentation/filesystems/overlayfs.rst @@ -195,7 +195,7 @@ handle it in two different ways: 1. return EXDEV error: this error is returned by rename(2) when trying to move a file or directory across filesystem boundaries. Hence - applications are usually prepared to hande this error (mv(1) for example + applications are usually prepared to handle this error (mv(1) for example recursively copies the directory tree). This is the default behavior. 2. If the "redirect_dir" feature is enabled, then the directory will be @@ -324,6 +324,30 @@ and The resulting access permissions should be the same. The difference is in the time of copy (on-demand vs. up-front). +### Non overlapping credentials + +As noted above, all access to the upper, lower and work directories is the +recorded mounter's MAC and DAC credentials. The incoming accesses are +checked against the caller's credentials. + +In the case where caller MAC or DAC credentials do not overlap the mounter, a +use case available in older versions of the driver, the override_creds mount +flag can be turned off. For when the use pattern has caller with legitimate +credentials where the mounter does not. For example init may have been the +mounter, but the caller would have execute or read MAC permissions where +init would not. override_creds off means all access, incoming, upper, lower +or working, will be tested against the caller. + +Several unintended side effects will occur though. The caller without certain +key capabilities or lower privilege will not always be able to delete files or +directories, create nodes, or search some restricted directories. The ability +to search and read a directory entry is spotty as a result of the cache +mechanism not re-testing the credentials because of the assumption, a +privileged caller can fill cache, then a lower privilege can read the directory +cache. The uneven security model where cache, upperdir and workdir are opened +at privilege, but accessed without creating a form of privilege escalation, +should only be used with strict understanding of the side effects and of the +security policies. Multiple lower layers --------------------- diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index b193d08a3dc3..de7fdcb3eb6c 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -1032,7 +1032,7 @@ static int ovl_copy_up_flags(struct dentry *dentry, int flags) dput(parent); dput(next); } - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); return err; } diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index f18490813170..7449825b6cbd 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -569,7 +569,7 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, struct ovl_cattr *attr, bool origin) { int err; - const struct cred *old_cred; + const struct cred *old_cred, *hold_cred = NULL; struct cred *override_cred; struct dentry *parent = dentry->d_parent; @@ -596,14 +596,15 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, override_cred->fsgid = inode->i_gid; if (!attr->hardlink) { err = security_dentry_create_files_as(dentry, - attr->mode, &dentry->d_name, old_cred, + attr->mode, &dentry->d_name, + old_cred ? old_cred : current_cred(), override_cred); if (err) { put_cred(override_cred); goto out_revert_creds; } } - put_cred(override_creds(override_cred)); + hold_cred = override_creds(override_cred); put_cred(override_cred); if (!ovl_dentry_is_whiteout(dentry)) @@ -612,7 +613,9 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, err = ovl_create_over_whiteout(dentry, inode, attr); } out_revert_creds: - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred ?: hold_cred); + if (old_cred && hold_cred) + put_cred(hold_cred); return err; } @@ -689,7 +692,7 @@ static int ovl_set_link_redirect(struct dentry *dentry) old_cred = ovl_override_creds(dentry->d_sb); err = ovl_set_redirect(dentry, false); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); return err; } @@ -908,7 +911,7 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir) err = ovl_remove_upper(dentry, is_dir, &list); else err = ovl_remove_and_whiteout(dentry, &list); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); if (!err) { if (is_dir) clear_nlink(dentry->d_inode); @@ -1283,7 +1286,7 @@ static int ovl_rename(struct user_namespace *mnt_userns, struct inode *olddir, out_unlock: unlock_rename(new_upperdir, old_upperdir); out_revert_creds: - revert_creds(old_cred); + ovl_revert_creds(old->d_sb, old_cred); if (update_nlink) ovl_nlink_end(new); out_drop_write: diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index fa125feed0ff..11d8277c94cd 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -61,7 +61,7 @@ static struct file *ovl_open_realfile(const struct file *file, realfile = open_with_fake_path(&file->f_path, flags, realinode, current_cred()); } - revert_creds(old_cred); + ovl_revert_creds(inode->i_sb, old_cred); pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n", file, file, ovl_whatisit(inode, realinode), file->f_flags, @@ -205,7 +205,7 @@ static loff_t ovl_llseek(struct file *file, loff_t offset, int whence) old_cred = ovl_override_creds(inode->i_sb); ret = vfs_llseek(real.file, offset, whence); - revert_creds(old_cred); + ovl_revert_creds(inode->i_sb, old_cred); file->f_pos = real.file->f_pos; ovl_inode_unlock(inode); @@ -334,7 +334,7 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter) ovl_aio_cleanup_handler(aio_req); } out: - revert_creds(old_cred); + ovl_revert_creds(file_inode(file)->i_sb, old_cred); ovl_file_accessed(file); out_fdput: fdput(real); @@ -407,7 +407,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) ovl_aio_cleanup_handler(aio_req); } out: - revert_creds(old_cred); + ovl_revert_creds(file_inode(file)->i_sb, old_cred); out_fdput: fdput(real); @@ -453,7 +453,7 @@ static ssize_t ovl_splice_write(struct pipe_inode_info *pipe, struct file *out, file_end_write(real.file); /* Update size */ ovl_copyattr(realinode, inode); - revert_creds(old_cred); + ovl_revert_creds(inode->i_sb, old_cred); fdput(real); out_unlock: @@ -480,7 +480,7 @@ static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync) if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) { old_cred = ovl_override_creds(file_inode(file)->i_sb); ret = vfs_fsync_range(real.file, start, end, datasync); - revert_creds(old_cred); + ovl_revert_creds(file_inode(file)->i_sb, old_cred); } fdput(real); @@ -504,7 +504,7 @@ static int ovl_mmap(struct file *file, struct vm_area_struct *vma) old_cred = ovl_override_creds(file_inode(file)->i_sb); ret = call_mmap(vma->vm_file, vma); - revert_creds(old_cred); + ovl_revert_creds(file_inode(file)->i_sb, old_cred); ovl_file_accessed(file); return ret; @@ -523,7 +523,7 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len old_cred = ovl_override_creds(file_inode(file)->i_sb); ret = vfs_fallocate(real.file, mode, offset, len); - revert_creds(old_cred); + ovl_revert_creds(file_inode(file)->i_sb, old_cred); /* Update size */ ovl_copyattr(ovl_inode_real(inode), inode); @@ -545,7 +545,7 @@ static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice) old_cred = ovl_override_creds(file_inode(file)->i_sb); ret = vfs_fadvise(real.file, offset, len, advice); - revert_creds(old_cred); + ovl_revert_creds(file_inode(file)->i_sb, old_cred); fdput(real); @@ -595,7 +595,7 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in, flags); break; } - revert_creds(old_cred); + ovl_revert_creds(file_inode(file_out)->i_sb, old_cred); /* Update size */ ovl_copyattr(ovl_inode_real(inode_out), inode_out); @@ -654,7 +654,7 @@ static int ovl_flush(struct file *file, fl_owner_t id) if (real.file->f_op->flush) { old_cred = ovl_override_creds(file_inode(file)->i_sb); err = real.file->f_op->flush(real.file, id); - revert_creds(old_cred); + ovl_revert_creds(file_inode(file)->i_sb, old_cred); } fdput(real); diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 49bfa33bb682..0123270e295f 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -78,7 +78,7 @@ int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, inode_lock(upperdentry->d_inode); old_cred = ovl_override_creds(dentry->d_sb); err = notify_change(&init_user_ns, upperdentry, attr, NULL); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); if (!err) ovl_copyattr(upperdentry->d_inode, dentry->d_inode); inode_unlock(upperdentry->d_inode); @@ -270,7 +270,7 @@ int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path, stat->nlink = dentry->d_inode->i_nlink; out: - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); return err; } @@ -305,7 +305,7 @@ int ovl_permission(struct user_namespace *mnt_userns, mask |= MAY_READ; } err = inode_permission(&init_user_ns, realinode, mask); - revert_creds(old_cred); + ovl_revert_creds(inode->i_sb, old_cred); return err; } @@ -322,7 +322,7 @@ static const char *ovl_get_link(struct dentry *dentry, old_cred = ovl_override_creds(dentry->d_sb); p = vfs_get_link(ovl_dentry_real(dentry), done); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); return p; } @@ -353,7 +353,7 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name, if (!value && !upperdentry) { old_cred = ovl_override_creds(dentry->d_sb); err = vfs_getxattr(&init_user_ns, realdentry, name, NULL, 0); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); if (err < 0) goto out_drop_write; } @@ -374,7 +374,7 @@ int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name, WARN_ON(flags != XATTR_REPLACE); err = vfs_removexattr(&init_user_ns, realdentry, name); } - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); /* copy c/mtime */ ovl_copyattr(d_inode(realdentry), inode); @@ -396,7 +396,7 @@ int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name, old_cred = ovl_override_creds(dentry->d_sb); res = __vfs_getxattr(&init_user_ns, realdentry, d_inode(realdentry), name, value, size, flags); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); return res; } @@ -424,7 +424,7 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) old_cred = ovl_override_creds(dentry->d_sb); res = vfs_listxattr(realdentry, list, size); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); if (res <= 0 || size == 0) return res; @@ -462,7 +462,7 @@ struct posix_acl *ovl_get_acl(struct inode *inode, int type, bool rcu) old_cred = ovl_override_creds(inode->i_sb); acl = get_acl(realinode, type); - revert_creds(old_cred); + ovl_revert_creds(inode->i_sb, old_cred); return acl; } @@ -496,7 +496,7 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, old_cred = ovl_override_creds(inode->i_sb); err = realinode->i_op->fiemap(realinode, fieinfo, start, len); - revert_creds(old_cred); + ovl_revert_creds(inode->i_sb, old_cred); return err; } @@ -567,7 +567,7 @@ int ovl_fileattr_set(struct user_namespace *mnt_userns, err = ovl_set_protattr(inode, upperpath.dentry, fa); if (!err) err = ovl_real_fileattr_set(&upperpath, fa); - revert_creds(old_cred); + ovl_revert_creds(inode->i_sb, old_cred); /* * Merge real inode flags with inode flags read from @@ -629,7 +629,7 @@ int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa) old_cred = ovl_override_creds(inode->i_sb); err = ovl_real_fileattr_get(&realpath, fa); ovl_fileattr_prot_flags(inode, fa); - revert_creds(old_cred); + ovl_revert_creds(inode->i_sb, old_cred); return err; } diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index 1a9b515fc45d..0ecb6bab0f2a 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -1106,7 +1106,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, ovl_dentry_update_reval(dentry, upperdentry, DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); if (origin_path) { dput(origin_path->dentry); kfree(origin_path); @@ -1133,7 +1133,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, kfree(upperredirect); out: kfree(d.redirect); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); return ERR_PTR(err); } @@ -1185,7 +1185,7 @@ bool ovl_lower_positive(struct dentry *dentry) dput(this); } } - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); return positive; } diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index 3fcd62e72aad..16c6280d8201 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -282,6 +282,7 @@ int ovl_want_write(struct dentry *dentry); void ovl_drop_write(struct dentry *dentry); struct dentry *ovl_workdir(struct dentry *dentry); const struct cred *ovl_override_creds(struct super_block *sb); +void ovl_revert_creds(struct super_block *sb, const struct cred *oldcred); int ovl_can_decode_fh(struct super_block *sb); struct dentry *ovl_indexdir(struct super_block *sb); bool ovl_index_all(struct super_block *sb); diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 63efee554f69..31aebf6d2ea4 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -20,6 +20,7 @@ struct ovl_config { bool metacopy; bool userxattr; bool ovl_volatile; + bool override_creds; }; struct ovl_sb { diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 150fdf3bc68d..c6038e6ad753 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -286,7 +286,7 @@ static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd) } inode_unlock(dir->d_inode); } - revert_creds(old_cred); + ovl_revert_creds(rdd->dentry->d_sb, old_cred); return err; } @@ -789,7 +789,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx) } err = 0; out: - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); return err; } @@ -841,7 +841,7 @@ static struct file *ovl_dir_open_realfile(const struct file *file, old_cred = ovl_override_creds(file_inode(file)->i_sb); res = ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE)); - revert_creds(old_cred); + ovl_revert_creds(file_inode(file)->i_sb, old_cred); return res; } @@ -967,7 +967,7 @@ int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list) old_cred = ovl_override_creds(dentry->d_sb); err = ovl_dir_read_merged(dentry, list, &root); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); if (err) return err; diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 973644af1288..d1c6e883790d 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -53,6 +53,11 @@ module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644); MODULE_PARM_DESC(xino_auto, "Auto enable xino feature"); +static bool __read_mostly ovl_override_creds_def = true; +module_param_named(override_creds, ovl_override_creds_def, bool, 0644); +MODULE_PARM_DESC(ovl_override_creds_def, + "Use mounter's credentials for accesses"); + static void ovl_entry_stack_free(struct ovl_entry *oe) { unsigned int i; @@ -382,6 +387,9 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) seq_puts(m, ",volatile"); if (ofs->config.userxattr) seq_puts(m, ",userxattr"); + if (ofs->config.override_creds != ovl_override_creds_def) + seq_show_option(m, "override_creds", + ofs->config.override_creds ? "on" : "off"); return 0; } @@ -437,6 +445,8 @@ enum { OPT_METACOPY_ON, OPT_METACOPY_OFF, OPT_VOLATILE, + OPT_OVERRIDE_CREDS_ON, + OPT_OVERRIDE_CREDS_OFF, OPT_ERR, }; @@ -459,6 +469,8 @@ static const match_table_t ovl_tokens = { {OPT_METACOPY_ON, "metacopy=on"}, {OPT_METACOPY_OFF, "metacopy=off"}, {OPT_VOLATILE, "volatile"}, + {OPT_OVERRIDE_CREDS_ON, "override_creds=on"}, + {OPT_OVERRIDE_CREDS_OFF, "override_creds=off"}, {OPT_ERR, NULL} }; @@ -518,6 +530,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); if (!config->redirect_mode) return -ENOMEM; + config->override_creds = ovl_override_creds_def; while ((p = ovl_next_opt(&opt)) != NULL) { int token; @@ -619,6 +632,14 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) config->userxattr = true; break; + case OPT_OVERRIDE_CREDS_ON: + config->override_creds = true; + break; + + case OPT_OVERRIDE_CREDS_OFF: + config->override_creds = false; + break; + default: pr_err("unrecognized mount option \"%s\" or missing value\n", p); @@ -2144,7 +2165,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) kfree(splitlower); sb->s_root = root_dentry; - return 0; out_free_oe: diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c index f48284a2a896..32eceb495202 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -38,9 +38,18 @@ const struct cred *ovl_override_creds(struct super_block *sb) { struct ovl_fs *ofs = sb->s_fs_info; + if (!ofs->config.override_creds) + return NULL; return override_creds(ofs->creator_cred); } +void ovl_revert_creds(struct super_block *sb, const struct cred *old_cred) +{ + if (old_cred) + revert_creds(old_cred); +} + + /* * Check if underlying fs supports file handles and try to determine encoding * type, in order to deduce maximum inode number used by fs. @@ -899,7 +908,7 @@ int ovl_nlink_start(struct dentry *dentry) * value relative to the upper inode nlink in an upper inode xattr. */ err = ovl_set_nlink_upper(dentry); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); out: if (err) @@ -917,7 +926,7 @@ void ovl_nlink_end(struct dentry *dentry) old_cred = ovl_override_creds(dentry->d_sb); ovl_cleanup_index(dentry); - revert_creds(old_cred); + ovl_revert_creds(dentry->d_sb, old_cred); } ovl_inode_unlock(inode); From patchwork Wed Nov 17 01:58:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Anderson X-Patchwork-Id: 12623513 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B12A3C433F5 for ; Wed, 17 Nov 2021 01:58:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AE5561041 for ; Wed, 17 Nov 2021 01:58:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232784AbhKQCBn (ORCPT ); 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(no To-header on input) Precedence: bulk List-ID: From: John Stultz Using old_creds as an indication that we are not overriding the credentials, bypass call to inode_owner_or_capable. This solves a problem with all execv calls being blocked when using the caller's credentials. Signed-off-by: John Stultz Signed-off-by: Mark Salyzyn Signed-off-by: David Anderson Fixes: 05acefb4872da ("ovl: check permission to open real file") Cc: linux-fsdevel@vger.kernel.org Cc: linux-unionfs@vger.kernel.org Cc: Stephen Smalley Cc: linux-kernel@vger.kernel.org Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com Cc: selinux@vger.kernel.org Cc: paulmoore@microsoft.com Cc: Luca.Boccassi@microsoft.com v19 - rebase v18 - rebase v17 - rebase v16 - introduced fix over rebased series --- fs/overlayfs/file.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 11d8277c94cd..586de55bba79 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -55,7 +55,8 @@ static struct file *ovl_open_realfile(const struct file *file, if (err) { realfile = ERR_PTR(err); } else { - if (!inode_owner_or_capable(&init_user_ns, realinode)) + if (old_cred && !inode_owner_or_capable(&init_user_ns, + realinode)) flags &= ~O_NOATIME; realfile = open_with_fake_path(&file->f_path, flags, realinode,