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426b4ca2d6
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Merge tag 'fs.setgid.v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull setgid updates from Christian Brauner:
"This contains the work to move setgid stripping out of individual
filesystems and into the VFS itself.
Creating files that have both the S_IXGRP and S_ISGID bit raised in
directories that themselves have the S_ISGID bit set requires
additional privileges to avoid security issues.
When a filesystem creates a new inode it needs to take care that the
caller is either in the group of the newly created inode or they have
CAP_FSETID in their current user namespace and are privileged over the
parent directory of the new inode. If any of these two conditions is
true then the S_ISGID bit can be raised for an S_IXGRP file and if not
it needs to be stripped.
However, there are several key issues with the current implementation:
- S_ISGID stripping logic is entangled with umask stripping.
For example, if the umask removes the S_IXGRP bit from the file
about to be created then the S_ISGID bit will be kept.
The inode_init_owner() helper is responsible for S_ISGID stripping
and is called before posix_acl_create(). So we can end up with two
different orderings:
1. FS without POSIX ACL support
First strip umask then strip S_ISGID in inode_init_owner().
In other words, if a filesystem doesn't support or enable POSIX
ACLs then umask stripping is done directly in the vfs before
calling into the filesystem:
2. FS with POSIX ACL support
First strip S_ISGID in inode_init_owner() then strip umask in
posix_acl_create().
In other words, if the filesystem does support POSIX ACLs then
unmask stripping may be done in the filesystem itself when
calling posix_acl_create().
Note that technically filesystems are free to impose their own
ordering between posix_acl_create() and inode_init_owner() meaning
that there's additional ordering issues that influence S_ISGID
inheritance.
(Note that the commit message of commit
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| .. | ||
| cluster | ||
| dlm | ||
| dlmfs | ||
| acl.c | ||
| acl.h | ||
| alloc.c | ||
| alloc.h | ||
| aops.c | ||
| aops.h | ||
| blockcheck.c | ||
| blockcheck.h | ||
| buffer_head_io.c | ||
| buffer_head_io.h | ||
| dcache.c | ||
| dcache.h | ||
| dir.c | ||
| dir.h | ||
| dlmglue.c | ||
| dlmglue.h | ||
| export.c | ||
| export.h | ||
| extent_map.c | ||
| extent_map.h | ||
| file.c | ||
| file.h | ||
| filecheck.c | ||
| filecheck.h | ||
| heartbeat.c | ||
| heartbeat.h | ||
| inode.c | ||
| inode.h | ||
| ioctl.c | ||
| ioctl.h | ||
| journal.c | ||
| journal.h | ||
| Kconfig | ||
| localalloc.c | ||
| localalloc.h | ||
| locks.c | ||
| locks.h | ||
| Makefile | ||
| mmap.c | ||
| mmap.h | ||
| move_extents.c | ||
| move_extents.h | ||
| namei.c | ||
| namei.h | ||
| ocfs1_fs_compat.h | ||
| ocfs2_fs.h | ||
| ocfs2_ioctl.h | ||
| ocfs2_lockid.h | ||
| ocfs2_lockingver.h | ||
| ocfs2_trace.h | ||
| ocfs2.h | ||
| quota_global.c | ||
| quota_local.c | ||
| quota.h | ||
| refcounttree.c | ||
| refcounttree.h | ||
| reservations.c | ||
| reservations.h | ||
| resize.c | ||
| resize.h | ||
| slot_map.c | ||
| slot_map.h | ||
| stack_o2cb.c | ||
| stack_user.c | ||
| stackglue.c | ||
| stackglue.h | ||
| suballoc.c | ||
| suballoc.h | ||
| super.c | ||
| super.h | ||
| symlink.c | ||
| symlink.h | ||
| sysfile.c | ||
| sysfile.h | ||
| uptodate.c | ||
| uptodate.h | ||
| xattr.c | ||
| xattr.h | ||