From: Seth Forshee <seth.forshee@canonical.com> To: "Eric W. Biederman" <ebiederm@xmission.com>, Kent Overstreet <kent.overstreet@gmail.com>, Alasdair Kergon <agk@redhat.com>, Mike Snitzer <snitzer@redhat.com>, dm-devel@redhat.com, Shaohua Li <shli@kernel.org>, David Woodhouse <dwmw2@infradead.org>, Brian Norris <computersforpeace@gmail.com>, Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.com>, Jeff Layton <jlayton@poochiereds.net>, "J. Bruce Fields" <bfields@fieldses.org> Cc: linux-bcache@vger.kernel.org, Serge Hallyn <serge.hallyn@canonical.com>, Seth Forshee <seth.forshee@canonical.com>, Miklos Szeredi <mszeredi@redhat.com>, Richard Weinberger <richard.weinberger@gmail.com>, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, fuse-devel@lists.sourceforge.net, Austin S Hemmelgarn <ahferroin7@gmail.com>, linux-mtd@lists.infradead.org, selinux@tycho.nsa.gov, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, Pavel Tikhomirov <ptikhomirov@virtuozzo.com> Subject: [PATCH v4 04/21] block_dev: Support checking inode permissions in lookup_bdev() Date: Tue, 26 Apr 2016 14:36:17 -0500 [thread overview] Message-ID: <1461699396-33000-5-git-send-email-seth.forshee@canonical.com> (raw) In-Reply-To: <1461699396-33000-1-git-send-email-seth.forshee@canonical.com> When looking up a block device by path no permission check is done to verify that the user has access to the block device inode at the specified path. In some cases it may be necessary to check permissions towards the inode, such as allowing unprivileged users to mount block devices in user namespaces. Add an argument to lookup_bdev() to optionally perform this permission check. A value of 0 skips the permission check and behaves the same as before. A non-zero value specifies the mask of access rights required towards the inode at the specified path. The check is always skipped if the user has CAP_SYS_ADMIN. All callers of lookup_bdev() currently pass a mask of 0, so this patch results in no functional change. Subsequent patches will add permission checks where appropriate. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> --- drivers/md/bcache/super.c | 2 +- drivers/md/dm-table.c | 2 +- drivers/mtd/mtdsuper.c | 2 +- fs/block_dev.c | 13 ++++++++++--- fs/quota/quota.c | 2 +- include/linux/fs.h | 2 +- 6 files changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index a296425a7270..e169739a0253 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1950,7 +1950,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr, sb); if (IS_ERR(bdev)) { if (bdev == ERR_PTR(-EBUSY)) { - bdev = lookup_bdev(strim(path)); + bdev = lookup_bdev(strim(path), 0); mutex_lock(&bch_register_lock); if (!IS_ERR(bdev) && bch_is_open(bdev)) err = "device already registered"; diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index f9e8f0bef332..13f568d527b5 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -372,7 +372,7 @@ dev_t dm_get_dev_t(const char *path) dev_t uninitialized_var(dev); struct block_device *bdev; - bdev = lookup_bdev(path); + bdev = lookup_bdev(path, 0); if (IS_ERR(bdev)) dev = name_to_dev_t(path); else { diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c index 20c02a3b7417..b5b60e1af31c 100644 --- a/drivers/mtd/mtdsuper.c +++ b/drivers/mtd/mtdsuper.c @@ -176,7 +176,7 @@ struct dentry *mount_mtd(struct file_system_type *fs_type, int flags, /* try the old way - the hack where we allowed users to mount * /dev/mtdblock$(n) but didn't actually _use_ the blockdev */ - bdev = lookup_bdev(dev_name); + bdev = lookup_bdev(dev_name, 0); if (IS_ERR(bdev)) { ret = PTR_ERR(bdev); pr_debug("MTDSB: lookup_bdev() returned %d\n", ret); diff --git a/fs/block_dev.c b/fs/block_dev.c index 3e84d62d0a25..e9b937845bdb 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1431,7 +1431,7 @@ struct block_device *blkdev_get_by_path(const char *path, fmode_t mode, struct block_device *bdev; int err; - bdev = lookup_bdev(path); + bdev = lookup_bdev(path, 0); if (IS_ERR(bdev)) return bdev; @@ -1821,12 +1821,14 @@ EXPORT_SYMBOL(ioctl_by_bdev); /** * lookup_bdev - lookup a struct block_device by name * @pathname: special file representing the block device + * @mask: rights to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) * * Get a reference to the blockdevice at @pathname in the current * namespace if possible and return it. Return ERR_PTR(error) - * otherwise. + * otherwise. If @mask is non-zero, check for access rights to the + * inode at @pathname. */ -struct block_device *lookup_bdev(const char *pathname) +struct block_device *lookup_bdev(const char *pathname, int mask) { struct block_device *bdev; struct inode *inode; @@ -1841,6 +1843,11 @@ struct block_device *lookup_bdev(const char *pathname) return ERR_PTR(error); inode = d_backing_inode(path.dentry); + if (mask != 0 && !capable(CAP_SYS_ADMIN)) { + error = __inode_permission(inode, mask); + if (error) + goto fail; + } error = -ENOTBLK; if (!S_ISBLK(inode->i_mode)) goto fail; diff --git a/fs/quota/quota.c b/fs/quota/quota.c index 0f10ee9892ce..59223384b22e 100644 --- a/fs/quota/quota.c +++ b/fs/quota/quota.c @@ -799,7 +799,7 @@ static struct super_block *quotactl_block(const char __user *special, int cmd) if (IS_ERR(tmp)) return ERR_CAST(tmp); - bdev = lookup_bdev(tmp->name); + bdev = lookup_bdev(tmp->name, 0); putname(tmp); if (IS_ERR(bdev)) return ERR_CAST(bdev); diff --git a/include/linux/fs.h b/include/linux/fs.h index 66a639ec1bc4..173b8adc6131 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2438,7 +2438,7 @@ static inline void unregister_chrdev(unsigned int major, const char *name) #define BLKDEV_MAJOR_HASH_SIZE 255 extern const char *__bdevname(dev_t, char *buffer); extern const char *bdevname(struct block_device *bdev, char *buffer); -extern struct block_device *lookup_bdev(const char *); +extern struct block_device *lookup_bdev(const char *, int mask); extern void blkdev_show(struct seq_file *,off_t); #else -- 2.7.4 ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/
WARNING: multiple messages have this Message-ID (diff)
From: Seth Forshee <seth.forshee@canonical.com> To: "Eric W. Biederman" <ebiederm@xmission.com>, Kent Overstreet <kent.overstreet@gmail.com>, Alasdair Kergon <agk@redhat.com>, Mike Snitzer <snitzer@redhat.com>, dm-devel@redhat.com, Shaohua Li <shli@kernel.org>, David Woodhouse <dwmw2@infradead.org>, Brian Norris <computersforpeace@gmail.com>, Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.com>, Jeff Layton <jlayton@poochiereds.net>, "J. Bruce Fields" <bfields@fieldses.org> Cc: Serge Hallyn <serge.hallyn@canonical.com>, Richard Weinberger <richard.weinberger@gmail.com>, Austin S Hemmelgarn <ahferroin7@gmail.com>, Miklos Szeredi <mszeredi@redhat.com>, Pavel Tikhomirov <ptikhomirov@virtuozzo.com>, linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org, linux-raid@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, fuse-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, cgroups@vger.kernel.org, Seth Forshee <seth.forshee@canonical.com> Subject: [PATCH v4 04/21] block_dev: Support checking inode permissions in lookup_bdev() Date: Tue, 26 Apr 2016 14:36:17 -0500 [thread overview] Message-ID: <1461699396-33000-5-git-send-email-seth.forshee@canonical.com> (raw) In-Reply-To: <1461699396-33000-1-git-send-email-seth.forshee@canonical.com> When looking up a block device by path no permission check is done to verify that the user has access to the block device inode at the specified path. In some cases it may be necessary to check permissions towards the inode, such as allowing unprivileged users to mount block devices in user namespaces. Add an argument to lookup_bdev() to optionally perform this permission check. A value of 0 skips the permission check and behaves the same as before. A non-zero value specifies the mask of access rights required towards the inode at the specified path. The check is always skipped if the user has CAP_SYS_ADMIN. All callers of lookup_bdev() currently pass a mask of 0, so this patch results in no functional change. Subsequent patches will add permission checks where appropriate. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> --- drivers/md/bcache/super.c | 2 +- drivers/md/dm-table.c | 2 +- drivers/mtd/mtdsuper.c | 2 +- fs/block_dev.c | 13 ++++++++++--- fs/quota/quota.c | 2 +- include/linux/fs.h | 2 +- 6 files changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index a296425a7270..e169739a0253 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1950,7 +1950,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr, sb); if (IS_ERR(bdev)) { if (bdev == ERR_PTR(-EBUSY)) { - bdev = lookup_bdev(strim(path)); + bdev = lookup_bdev(strim(path), 0); mutex_lock(&bch_register_lock); if (!IS_ERR(bdev) && bch_is_open(bdev)) err = "device already registered"; diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index f9e8f0bef332..13f568d527b5 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -372,7 +372,7 @@ dev_t dm_get_dev_t(const char *path) dev_t uninitialized_var(dev); struct block_device *bdev; - bdev = lookup_bdev(path); + bdev = lookup_bdev(path, 0); if (IS_ERR(bdev)) dev = name_to_dev_t(path); else { diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c index 20c02a3b7417..b5b60e1af31c 100644 --- a/drivers/mtd/mtdsuper.c +++ b/drivers/mtd/mtdsuper.c @@ -176,7 +176,7 @@ struct dentry *mount_mtd(struct file_system_type *fs_type, int flags, /* try the old way - the hack where we allowed users to mount * /dev/mtdblock$(n) but didn't actually _use_ the blockdev */ - bdev = lookup_bdev(dev_name); + bdev = lookup_bdev(dev_name, 0); if (IS_ERR(bdev)) { ret = PTR_ERR(bdev); pr_debug("MTDSB: lookup_bdev() returned %d\n", ret); diff --git a/fs/block_dev.c b/fs/block_dev.c index 3e84d62d0a25..e9b937845bdb 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1431,7 +1431,7 @@ struct block_device *blkdev_get_by_path(const char *path, fmode_t mode, struct block_device *bdev; int err; - bdev = lookup_bdev(path); + bdev = lookup_bdev(path, 0); if (IS_ERR(bdev)) return bdev; @@ -1821,12 +1821,14 @@ EXPORT_SYMBOL(ioctl_by_bdev); /** * lookup_bdev - lookup a struct block_device by name * @pathname: special file representing the block device + * @mask: rights to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) * * Get a reference to the blockdevice at @pathname in the current * namespace if possible and return it. Return ERR_PTR(error) - * otherwise. + * otherwise. If @mask is non-zero, check for access rights to the + * inode at @pathname. */ -struct block_device *lookup_bdev(const char *pathname) +struct block_device *lookup_bdev(const char *pathname, int mask) { struct block_device *bdev; struct inode *inode; @@ -1841,6 +1843,11 @@ struct block_device *lookup_bdev(const char *pathname) return ERR_PTR(error); inode = d_backing_inode(path.dentry); + if (mask != 0 && !capable(CAP_SYS_ADMIN)) { + error = __inode_permission(inode, mask); + if (error) + goto fail; + } error = -ENOTBLK; if (!S_ISBLK(inode->i_mode)) goto fail; diff --git a/fs/quota/quota.c b/fs/quota/quota.c index 0f10ee9892ce..59223384b22e 100644 --- a/fs/quota/quota.c +++ b/fs/quota/quota.c @@ -799,7 +799,7 @@ static struct super_block *quotactl_block(const char __user *special, int cmd) if (IS_ERR(tmp)) return ERR_CAST(tmp); - bdev = lookup_bdev(tmp->name); + bdev = lookup_bdev(tmp->name, 0); putname(tmp); if (IS_ERR(bdev)) return ERR_CAST(bdev); diff --git a/include/linux/fs.h b/include/linux/fs.h index 66a639ec1bc4..173b8adc6131 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2438,7 +2438,7 @@ static inline void unregister_chrdev(unsigned int major, const char *name) #define BLKDEV_MAJOR_HASH_SIZE 255 extern const char *__bdevname(dev_t, char *buffer); extern const char *bdevname(struct block_device *bdev, char *buffer); -extern struct block_device *lookup_bdev(const char *); +extern struct block_device *lookup_bdev(const char *, int mask); extern void blkdev_show(struct seq_file *,off_t); #else -- 2.7.4
next prev parent reply other threads:[~2016-04-26 19:36 UTC|newest] Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-04-26 19:36 [PATCH v4 00/21] Support fuse mounts in user namespaces Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 01/21] fs: fix a posible leak of allocated superblock Seth Forshee 2016-04-26 19:36 ` Seth Forshee [this message] 2016-04-26 19:36 ` [PATCH v4 04/21] block_dev: Support checking inode permissions in lookup_bdev() Seth Forshee 2016-04-26 19:36 ` [PATCH v4 05/21] block_dev: Check permissions towards block device inode when mounting Seth Forshee 2016-04-26 19:36 ` [PATCH v4 06/21] fs: Treat foreign mounts as nosuid Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 08/21] userns: Replace in_userns with current_in_userns Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 09/21] Smack: Handle labels consistently in untrusted mounts Seth Forshee 2016-04-26 19:36 ` [PATCH v4 10/21] fs: Check for invalid i_uid in may_follow_link() Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-05-24 15:55 ` Djalal Harouni 2016-04-26 19:36 ` [PATCH v4 11/21] cred: Reject inodes with invalid ids in set_create_file_as() Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 15/21] fs: Don't remove suid for CAP_FSETID in s_user_ns Seth Forshee 2016-04-26 19:36 ` Seth Forshee [not found] ` <1461699396-33000-1-git-send-email-seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> 2016-04-26 19:36 ` [PATCH v4 02/21] fs: Remove check of s_user_ns for existing mounts in fs_fully_visible() Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 03/21] fs: Allow sysfs and cgroupfs to share super blocks between user namespaces Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 07/21] selinux: Add support for unprivileged mounts from " Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 12/21] fs: Refuse uid/gid changes which don't map into s_user_ns Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 13/21] fs: Update posix_acl support to handle user namespace mounts Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 14/21] fs: Allow superblock owner to change ownership of inodes with unmappable ids Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 16/21] fs: Allow superblock owner to access do_remount_sb() Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 17/21] capabilities: Allow privileged user in s_user_ns to set security.* xattrs Seth Forshee 2016-04-26 19:36 ` Seth Forshee [not found] ` <1461699396-33000-18-git-send-email-seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> 2016-04-27 7:22 ` James Morris 2016-04-27 7:22 ` James Morris 2016-04-26 19:36 ` [PATCH v4 18/21] fuse: Add support for pid namespaces Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-07-20 2:44 ` Sheng Yang [not found] ` <CA+2rt426_pshAauQizcxkfAq16vmEpB4sJ4genW_ucosH3j=zQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2016-07-20 12:52 ` Seth Forshee 2016-07-20 12:52 ` Seth Forshee 2016-07-20 22:28 ` Sheng Yang 2016-07-21 7:25 ` Miklos Szeredi 2016-07-21 7:25 ` Miklos Szeredi 2016-04-26 19:36 ` [PATCH v4 19/21] fuse: Support fuse filesystems outside of init_user_ns Seth Forshee 2016-04-26 19:36 ` Seth Forshee 2016-04-26 19:36 ` [PATCH v4 20/21] fuse: Restrict allow_other to the superblock's namespace or a descendant Seth Forshee 2016-04-26 19:36 ` [PATCH v4 21/21] fuse: Allow user namespace mounts Seth Forshee -- strict thread matches above, loose matches on Subject: below -- 2016-04-26 19:30 [PATCH v4 00/21] Support fuse mounts in user namespaces Seth Forshee [not found] ` <1461699046-30485-1-git-send-email-seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> 2016-04-26 19:30 ` [PATCH v4 04/21] block_dev: Support checking inode permissions in lookup_bdev() Seth Forshee 2016-04-26 19:30 ` Seth Forshee
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=1461699396-33000-5-git-send-email-seth.forshee@canonical.com \ --to=seth.forshee@canonical.com \ --cc=agk@redhat.com \ --cc=ahferroin7@gmail.com \ --cc=bfields@fieldses.org \ --cc=cgroups@vger.kernel.org \ --cc=computersforpeace@gmail.com \ --cc=dm-devel@redhat.com \ --cc=dwmw2@infradead.org \ --cc=ebiederm@xmission.com \ --cc=fuse-devel@lists.sourceforge.net \ --cc=jack@suse.com \ --cc=jlayton@poochiereds.net \ --cc=kent.overstreet@gmail.com \ --cc=linux-bcache@vger.kernel.org \ --cc=linux-fsdevel@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-mtd@lists.infradead.org \ --cc=linux-raid@vger.kernel.org \ --cc=linux-security-module@vger.kernel.org \ --cc=mszeredi@redhat.com \ --cc=ptikhomirov@virtuozzo.com \ --cc=richard.weinberger@gmail.com \ --cc=selinux@tycho.nsa.gov \ --cc=serge.hallyn@canonical.com \ --cc=shli@kernel.org \ --cc=snitzer@redhat.com \ --cc=viro@zeniv.linux.org.uk \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.