btrfs: Make btrfs handle security mount options internally to avoid losing security label.

Message ID	1411450808-14988-1-git-send-email-quwenruo@cn.fujitsu.com (mailing list archive)
State	Superseded
Headers	show Return-Path: <linux-btrfs-owner@kernel.org> From: Qu Wenruo <quwenruo@cn.fujitsu.com> To: <linux-btrfs@vger.kernel.org> CC: <guaneryu@gmail.com> Subject: [PATCH] btrfs: Make btrfs handle security mount options internally to avoid losing security label. Date: Tue, 23 Sep 2014 13:40:08 +0800 Message-ID: <1411450808-14988-1-git-send-email-quwenruo@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 8e29b61..c82dd6d 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -34,6 +34,7 @@ #include <linux/pagemap.h> #include <linux/btrfs.h> #include <linux/workqueue.h> +#include <linux/security.h> #include "extent_io.h" #include "extent_map.h" #include "async-thread.h" @@ -1723,6 +1724,9 @@ struct btrfs_fs_info { /* Used to reclaim the metadata space in the background. */ struct work_struct async_reclaim_work; + + /* For btrfs to record security options */ + struct security_mnt_opts security_opts; }; struct btrfs_subvolume_writers { @@ -3604,6 +3608,7 @@ static inline void free_fs_info(struct btrfs_fs_info *fs_info) kfree(fs_info->uuid_root); kfree(fs_info->super_copy); kfree(fs_info->super_for_commit); + security_free_mnt_opts(&fs_info->security_opts); kfree(fs_info); } diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index c4124de..1eb7858 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1215,6 +1215,54 @@ static struct dentry *mount_subvol(const char *subvol_name, int flags, return root; } +static int parse_security_options(char *orig_opts, + struct security_mnt_opts *sec_opts) +{ + char *secdata = NULL; + int ret = 0; + + secdata = alloc_secdata(); + if (!secdata) + return -ENOMEM; + ret = security_sb_copy_data(orig_opts, secdata); + if (ret) { + free_secdata(secdata); + return ret; + } + ret = security_sb_parse_opts_str(secdata, sec_opts); + free_secdata(secdata); + return ret; +} + +static int setup_security_options(struct btrfs_fs_info *fs_info, + struct super_block *sb, + struct security_mnt_opts *sec_opts) +{ + int ret = 0; + + /* + * Call security_sb_set_mnt_opts() to check whether new sec_opts + * is valid. + */ + ret = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL); + if (ret) + return ret; + + if (!fs_info->security_opts.num_mnt_opts) { + /* first time security setup, copy sec_opts to fs_info */ + memcpy(&fs_info->security_opts, sec_opts, sizeof(*sec_opts)); + } else { + /* + * Since SELinux(the only one supports security_mnt_opts) does + * NOT support changing context during remount/mount same sb, + * This must be the same or part of the same security options, + * just free it. + */ + security_free_mnt_opts(sec_opts); + } + return ret; +} + /* * Find a superblock for the given device / mount point. * @@ -1229,6 +1277,7 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, struct dentry *root; struct btrfs_fs_devices *fs_devices = NULL; struct btrfs_fs_info *fs_info = NULL; + struct security_mnt_opts new_sec_opts; fmode_t mode = FMODE_READ; char *subvol_name = NULL; u64 subvol_objectid = 0; @@ -1251,9 +1300,16 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, return root; } + security_init_mnt_opts(&new_sec_opts); + if (data) { + error = parse_security_options(data, &new_sec_opts); + if (error) + return ERR_PTR(error); + } + error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices); if (error) - return ERR_PTR(error); + goto error_sec_opts; /* * Setup a dummy root and fs_info for test/set super. This is because @@ -1262,13 +1318,16 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, * then open_ctree will properly initialize everything later. */ fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS); - if (!fs_info) - return ERR_PTR(-ENOMEM); + if (!fs_info) { + error = -ENOMEM; + goto error_sec_opts; + } fs_info->fs_devices = fs_devices; fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS); fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS); + security_init_mnt_opts(&fs_info->security_opts); if (!fs_info->super_copy || !fs_info->super_for_commit) { error = -ENOMEM; goto error_fs_info; @@ -1306,8 +1365,19 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags, } root = !error ? get_default_root(s, subvol_objectid) : ERR_PTR(error); - if (IS_ERR(root)) + if (IS_ERR(root)) { + deactivate_locked_super(s); + error = PTR_ERR(root); + goto error_sec_opts; + } + + fs_info = btrfs_sb(s); + error = setup_security_options(fs_info, s, &new_sec_opts); + if (error) { + dput(root); deactivate_locked_super(s); + goto error_sec_opts; + } return root; @@ -1315,6 +1385,8 @@ error_close_devices: btrfs_close_devices(fs_devices); error_fs_info: free_fs_info(fs_info); +error_sec_opts: + security_free_mnt_opts(&new_sec_opts); return ERR_PTR(error); } @@ -1396,6 +1468,21 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data) sync_filesystem(sb); btrfs_remount_prepare(fs_info); + if (data) { + struct security_mnt_opts new_sec_opts; + + security_init_mnt_opts(&new_sec_opts); + ret = parse_security_options(data, &new_sec_opts); + if (ret) + goto restore; + ret = setup_security_options(fs_info, sb, + &new_sec_opts); + if (ret) { + security_free_mnt_opts(&new_sec_opts); + goto restore; + } + } + ret = btrfs_parse_options(root, data); if (ret) { ret = -EINVAL; @@ -1769,7 +1856,7 @@ static struct file_system_type btrfs_fs_type = { .name = "btrfs", .mount = btrfs_mount, .kill_sb = btrfs_kill_super, - .fs_flags = FS_REQUIRES_DEV, + .fs_flags = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA, }; MODULE_ALIAS_FS("btrfs");

btrfs: Make btrfs handle security mount options internally to avoid losing security label.

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