linux/fs/debugfs/inode.c, branch v4.20

Revert "debugfs: inode: debugfs_create_dir uses mode permission from parent"

2018-06-13T03:52:16Z

This reverts commit 95cde3c59966f6371b6bcd9e4e2da2ba64ee9775. The commit had good intentions, but it breaks kvm-tool and qemu-kvm. With it in place, "lkvm run" just fails with Error: KVM_CREATE_VM ioctl Warning: Failed init: kvm__init which isn't a wonderful error message, but bisection pinpointed the problematic commit. The problem is almost certainly due to the special kvm debugfs entries created dynamically by kvm under /sys/kernel/debug/kvm/. See kvm_create_vm_debugfs() Bisected-and-reported-by: Linus Torvalds Cc: Wanpeng Li Cc: Greg Kroah-Hartman Cc: Thomas Richter Cc: Kees Cook Signed-off-by: Linus Torvalds

debugfs: inode: debugfs_create_dir uses mode permission from parent

2018-05-14T14:48:18Z

Currently function debugfs_create_dir() creates a new directory in the debugfs (usually mounted /sys/kernel/debug) with permission rwxr-xr-x. This is hard coded. Change this to use the parent directory permission. Output before the patch: root@s8360047 ~]# tree -dp -L 1 /sys/kernel/debug/ /sys/kernel/debug/ ├── [drwxr-xr-x] bdi ├── [drwxr-xr-x] block ├── [drwxr-xr-x] dasd ├── [drwxr-xr-x] device_component ├── [drwxr-xr-x] extfrag ├── [drwxr-xr-x] hid ├── [drwxr-xr-x] kprobes ├── [drwxr-xr-x] kvm ├── [drwxr-xr-x] memblock ├── [drwxr-xr-x] pm_qos ├── [drwxr-xr-x] qdio ├── [drwxr-xr-x] s390 ├── [drwxr-xr-x] s390dbf └── [drwx------] tracing 14 directories [root@s8360047 linux]# Output after the patch: [root@s8360047 ~]# tree -dp -L 1 /sys/kernel/debug/ sys/kernel/debug/ ├── [drwx------] bdi ├── [drwx------] block ├── [drwx------] dasd ├── [drwx------] device_component ├── [drwx------] extfrag ├── [drwx------] hid ├── [drwx------] kprobes ├── [drwx------] kvm ├── [drwx------] memblock ├── [drwx------] pm_qos ├── [drwx------] qdio ├── [drwx------] s390 ├── [drwx------] s390dbf └── [drwx------] tracing 14 directories [root@s8360047 linux]# Here is the full diff output done with: [root@s8360047 ~]# diff -u treefull.before treefull.after | sed 's-^- # -' > treefull.diff # --- treefull.before 2018-04-27 13:22:04.532824564 +0200 # +++ treefull.after 2018-04-27 13:24:12.106182062 +0200 # @@ -1,55 +1,55 @@ # /sys/kernel/debug/ # -├── [drwxr-xr-x] bdi # -│ ├── [drwxr-xr-x] 1:0 # -│ ├── [drwxr-xr-x] 1:1 # -│ ├── [drwxr-xr-x] 1:10 # -│ ├── [drwxr-xr-x] 1:11 # -│ ├── [drwxr-xr-x] 1:12 # -│ ├── [drwxr-xr-x] 1:13 # -│ ├── [drwxr-xr-x] 1:14 # -│ ├── [drwxr-xr-x] 1:15 # -│ ├── [drwxr-xr-x] 1:2 # -│ ├── [drwxr-xr-x] 1:3 # -│ ├── [drwxr-xr-x] 1:4 # -│ ├── [drwxr-xr-x] 1:5 # -│ ├── [drwxr-xr-x] 1:6 # -│ ├── [drwxr-xr-x] 1:7 # -│ ├── [drwxr-xr-x] 1:8 # -│ ├── [drwxr-xr-x] 1:9 # -│ └── [drwxr-xr-x] 94:0 # -├── [drwxr-xr-x] block # -├── [drwxr-xr-x] dasd # -│ ├── [drwxr-xr-x] 0.0.e18a # -│ ├── [drwxr-xr-x] dasda # -│ └── [drwxr-xr-x] global # -├── [drwxr-xr-x] device_component # -├── [drwxr-xr-x] extfrag # -├── [drwxr-xr-x] hid # -├── [drwxr-xr-x] kprobes # -├── [drwxr-xr-x] kvm # -├── [drwxr-xr-x] memblock # -├── [drwxr-xr-x] pm_qos # -├── [drwxr-xr-x] qdio # -│ └── [drwxr-xr-x] 0.0.f5f2 # -├── [drwxr-xr-x] s390 # -│ └── [drwxr-xr-x] stsi # -├── [drwxr-xr-x] s390dbf # -│ ├── [drwxr-xr-x] 0.0.e18a # -│ ├── [drwxr-xr-x] cio_crw # -│ ├── [drwxr-xr-x] cio_msg # -│ ├── [drwxr-xr-x] cio_trace # -│ ├── [drwxr-xr-x] dasd # -│ ├── [drwxr-xr-x] kvm-trace # -│ ├── [drwxr-xr-x] lgr # -│ ├── [drwxr-xr-x] qdio_0.0.f5f2 # -│ ├── [drwxr-xr-x] qdio_error # -│ ├── [drwxr-xr-x] qdio_setup # -│ ├── [drwxr-xr-x] qeth_card_0.0.f5f0 # -│ ├── [drwxr-xr-x] qeth_control # -│ ├── [drwxr-xr-x] qeth_msg # -│ ├── [drwxr-xr-x] qeth_setup # -│ ├── [drwxr-xr-x] vmcp # -│ └── [drwxr-xr-x] vmur # +├── [drwx------] bdi # +│ ├── [drwx------] 1:0 # +│ ├── [drwx------] 1:1 # +│ ├── [drwx------] 1:10 # +│ ├── [drwx------] 1:11 # +│ ├── [drwx------] 1:12 # +│ ├── [drwx------] 1:13 # +│ ├── [drwx------] 1:14 # +│ ├── [drwx------] 1:15 # +│ ├── [drwx------] 1:2 # +│ ├── [drwx------] 1:3 # +│ ├── [drwx------] 1:4 # +│ ├── [drwx------] 1:5 # +│ ├── [drwx------] 1:6 # +│ ├── [drwx------] 1:7 # +│ ├── [drwx------] 1:8 # +│ ├── [drwx------] 1:9 # +│ └── [drwx------] 94:0 # +├── [drwx------] block # +├── [drwx------] dasd # +│ ├── [drwx------] 0.0.e18a # +│ ├── [drwx------] dasda # +│ └── [drwx------] global # +├── [drwx------] device_component # +├── [drwx------] extfrag # +├── [drwx------] hid # +├── [drwx------] kprobes # +├── [drwx------] kvm # +├── [drwx------] memblock # +├── [drwx------] pm_qos # +├── [drwx------] qdio # +│ └── [drwx------] 0.0.f5f2 # +├── [drwx------] s390 # +│ └── [drwx------] stsi # +├── [drwx------] s390dbf # +│ ├── [drwx------] 0.0.e18a # +│ ├── [drwx------] cio_crw # +│ ├── [drwx------] cio_msg # +│ ├── [drwx------] cio_trace # +│ ├── [drwx------] dasd # +│ ├── [drwx------] kvm-trace # +│ ├── [drwx------] lgr # +│ ├── [drwx------] qdio_0.0.f5f2 # +│ ├── [drwx------] qdio_error # +│ ├── [drwx------] qdio_setup # +│ ├── [drwx------] qeth_card_0.0.f5f0 # +│ ├── [drwx------] qeth_control # +│ ├── [drwx------] qeth_msg # +│ ├── [drwx------] qeth_setup # +│ ├── [drwx------] vmcp # +│ └── [drwx------] vmur # └── [drwx------] tracing # ├── [drwxr-xr-x] events # │ ├── [drwxr-xr-x] alarmtimer Fixes: edac65eaf8d5c ("debugfs: take mode-dependent parts of debugfs_get_inode() into callers") Signed-off-by: Thomas Richter Reviewed-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

debugfs_lookup(): switch to lookup_one_len_unlocked()

2018-03-29T19:07:47Z

Signed-off-by: Al Viro

debugfs: Remove redundant license text

2017-11-07T19:25:03Z

Now that the SPDX tag is in all debugfs files, that identifies the license in a specific and legally-defined manner. So the extra GPL text wording can be removed as it is no longer needed at all. This is done on a quest to remove the 700+ different ways that files in the kernel describe the GPL license text. And there's unneeded stuff like the address (sometimes incorrect) for the FSF which is never needed. No copyright headers or other non-license-description text was removed. Cc: Nicolai Stange Signed-off-by: Greg Kroah-Hartman

debugfs: add SPDX identifiers to all debugfs files

2017-11-07T19:25:03Z

It's good to have SPDX identifiers in all files to make it easier to audit the kernel tree for correct licenses. Update the debugfs files files with the correct SPDX license identifier based on the license text in the file itself. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This work is based on a script and data from Thomas Gleixner, Philippe Ombredanne, and Kate Stewart. Cc: Thomas Gleixner Cc: Kate Stewart Cc: Philippe Ombredanne Cc: Nicolai Stange Signed-off-by: Greg Kroah-Hartman

debugfs: defer debugfs_fsdata allocation to first usage

2017-11-07T19:25:03Z

Currently, __debugfs_create_file allocates one struct debugfs_fsdata instance for every file created. However, there are potentially many debugfs file around, most of which are never touched by userspace. Thus, defer the allocations to the first usage, i.e. to the first debugfs_file_get(). A dentry's ->d_fsdata starts out to point to the "real", user provided fops. After a debugfs_fsdata instance has been allocated (and the real fops pointer has been moved over into its ->real_fops member), ->d_fsdata is changed to point to it from then on. The two cases are distinguished by setting BIT(0) for the real fops case. struct debugfs_fsdata's foremost purpose is to track active users and to make debugfs_remove() block until they are done. Since no debugfs_fsdata instance means no active users, make debugfs_remove() return immediately in this case. Take care of possible races between debugfs_file_get() and debugfs_remove(): either debugfs_remove() must see a debugfs_fsdata instance and thus wait for possible active users or debugfs_file_get() must see a dead dentry and return immediately. Make a dentry's ->d_release(), i.e. debugfs_release_dentry(), check whether ->d_fsdata is actually a debugfs_fsdata instance before kfree()ing it. Similarly, make debugfs_real_fops() check whether ->d_fsdata is actually a debugfs_fsdata instance before returning it, otherwise emit a warning. The set of possible error codes returned from debugfs_file_get() has grown from -EIO to -EIO and -ENOMEM. Make open_proxy_open() and full_proxy_open() pass the -ENOMEM onwards to their callers. Signed-off-by: Nicolai Stange Signed-off-by: Greg Kroah-Hartman

debugfs: purge obsolete SRCU based removal protection

2017-11-07T19:25:02Z

Purge the SRCU based file removal race protection in favour of the new, refcount based debugfs_file_get()/debugfs_file_put() API. Fixes: 49d200deaa68 ("debugfs: prevent access to removed files' private data") Signed-off-by: Nicolai Stange Signed-off-by: Greg Kroah-Hartman

debugfs: implement per-file removal protection

2017-11-07T19:25:02Z

Since commit 49d200deaa68 ("debugfs: prevent access to removed files' private data"), accesses to a file's private data are protected from concurrent removal by covering all file_operations with a SRCU read section and sychronizing with those before returning from debugfs_remove() by means of synchronize_srcu(). As pointed out by Johannes Berg, there are debugfs files with forever blocking file_operations. Their corresponding SRCU read side sections would block any debugfs_remove() forever as well, even unrelated ones. This results in a livelock. Because a remover can't cancel any indefinite blocking within foreign files, this is a problem. Resolve this by introducing support for more granular protection on a per-file basis. This is implemented by introducing an 'active_users' refcount_t to the per-file struct debugfs_fsdata state. At file creation time, it is set to one and a debugfs_remove() will drop that initial reference. The new debugfs_file_get() and debugfs_file_put(), intended to be used in place of former debugfs_use_file_start() and debugfs_use_file_finish(), increment and decrement it respectively. Once the count drops to zero, debugfs_file_put() will signal a completion which is possibly being waited for from debugfs_remove(). Thus, as long as there is a debugfs_file_get() not yet matched by a corresponding debugfs_file_put() around, debugfs_remove() will block. Actual users of debugfs_use_file_start() and -finish() will get converted to the new debugfs_file_get() and debugfs_file_put() by followup patches. Fixes: 49d200deaa68 ("debugfs: prevent access to removed files' private data") Reported-by: Johannes Berg Signed-off-by: Nicolai Stange Signed-off-by: Greg Kroah-Hartman

debugfs: add support for more elaborate ->d_fsdata

2017-11-07T19:25:02Z

Currently, the user provided fops, "real_fops", are stored directly into ->d_fsdata. In order to be able to store more per-file state and thus prepare for more granular file removal protection, wrap the real_fops into a dynamically allocated container struct, debugfs_fsdata. A struct debugfs_fsdata gets allocated at file creation and freed from the newly intoduced ->d_release(). Finally, move the implementation of debugfs_real_fops() out of the public debugfs header such that struct debugfs_fsdata's declaration can be kept private. Signed-off-by: Nicolai Stange Signed-off-by: Greg Kroah-Hartman

Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2017-07-15T19:00:42Z

Pull ->s_options removal from Al Viro: "Preparations for fsmount/fsopen stuff (coming next cycle). Everything gets moved to explicit ->show_options(), killing ->s_options off + some cosmetic bits around fs/namespace.c and friends. Basically, the stuff needed to work with fsmount series with minimum of conflicts with other work. It's not strictly required for this merge window, but it would reduce the PITA during the coming cycle, so it would be nice to have those bits and pieces out of the way" * 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: isofs: Fix isofs_show_options() VFS: Kill off s_options and helpers orangefs: Implement show_options 9p: Implement show_options isofs: Implement show_options afs: Implement show_options affs: Implement show_options befs: Implement show_options spufs: Implement show_options bpf: Implement show_options ramfs: Implement show_options pstore: Implement show_options omfs: Implement show_options hugetlbfs: Implement show_options VFS: Don't use save/replace_mount_options if not using generic_show_options VFS: Provide empty name qstr VFS: Make get_filesystem() return the affected filesystem VFS: Clean up whitespace in fs/namespace.c and fs/super.c Provide a function to create a NUL-terminated string from unterminated data