linux/security/apparmor, branch v6.16

VFS: rename lookup_one_len family to lookup_noperm and remove permission check

2025-04-08T09:24:36Z

The lookup_one_len family of functions is (now) only used internally by a filesystem on itself either - in a context where permission checking is irrelevant such as by a virtual filesystem populating itself, or xfs accessing its ORPHANAGE or dquota accessing the quota file; or - in a context where a permission check (MAY_EXEC on the parent) has just been performed such as a network filesystem finding in "silly-rename" file in the same directory. This is also the context after the _parentat() functions where currently lookup_one_qstr_excl() is used. So the permission check is pointless. The name "one_len" is unhelpful in understanding the purpose of these functions and should be changed. Most of the callers pass the len as "strlen()" so using a qstr and QSTR() can simplify the code. This patch renames these functions (include lookup_positive_unlocked() which is part of the family despite the name) to have a name based on "lookup_noperm". They are changed to receive a 'struct qstr' instead of separate name and len. In a few cases the use of QSTR() results in a new call to strlen(). try_lookup_noperm() takes a pointer to a qstr instead of the whole qstr. This is consistent with d_hash_and_lookup() (which is nearly identical) and useful for lookup_noperm_unlocked(). The new lookup_noperm_common() doesn't take a qstr yet. That will be tidied up in a subsequent patch. Signed-off-by: NeilBrown Link: https://lore.kernel.org/r/20250319031545.2999807-5-neil@brown.name Signed-off-by: Christian Brauner

Change inode_operations.mkdir to return struct dentry *

2025-02-27T19:00:17Z

Some filesystems, such as NFS, cifs, ceph, and fuse, do not have complete control of sequencing on the actual filesystem (e.g. on a different server) and may find that the inode created for a mkdir request already exists in the icache and dcache by the time the mkdir request returns. For example, if the filesystem is mounted twice the directory could be visible on the other mount before it is on the original mount, and a pair of name_to_handle_at(), open_by_handle_at() calls could instantiate the directory inode with an IS_ROOT() dentry before the first mkdir returns. This means that the dentry passed to ->mkdir() may not be the one that is associated with the inode after the ->mkdir() completes. Some callers need to interact with the inode after the ->mkdir completes and they currently need to perform a lookup in the (rare) case that the dentry is no longer hashed. This lookup-after-mkdir requires that the directory remains locked to avoid races. Planned future patches to lock the dentry rather than the directory will mean that this lookup cannot be performed atomically with the mkdir. To remove this barrier, this patch changes ->mkdir to return the resulting dentry if it is different from the one passed in. Possible returns are: NULL - the directory was created and no other dentry was used ERR_PTR() - an error occurred non-NULL - this other dentry was spliced in This patch only changes file-systems to return "ERR_PTR(err)" instead of "err" or equivalent transformations. Subsequent patches will make further changes to some file-systems to return a correct dentry. Not all filesystems reliably result in a positive hashed dentry: - NFS, cifs, hostfs will sometimes need to perform a lookup of the name to get inode information. Races could result in this returning something different. Note that this lookup is non-atomic which is what we are trying to avoid. Placing the lookup in filesystem code means it only happens when the filesystem has no other option. - kernfs and tracefs leave the dentry negative and the ->revalidate operation ensures that lookup will be called to correctly populate the dentry. This could be fixed but I don't think it is important to any of the users of vfs_mkdir() which look at the dentry. The recommendation to use d_drop();d_splice_alias() is ugly but fits with current practice. A planned future patch will change this. Reviewed-by: Jeff Layton Reviewed-by: Jan Kara Signed-off-by: NeilBrown Link: https://lore.kernel.org/r/20250227013949.536172-2-neilb@suse.de Signed-off-by: Christian Brauner

treewide: const qualify ctl_tables where applicable

2025-01-28T12:48:37Z

Add the const qualifier to all the ctl_tables in the tree except for watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls, loadpin_sysctl_table and the ones calling register_net_sysctl (./net, drivers/inifiniband dirs). These are special cases as they use a registration function with a non-const qualified ctl_table argument or modify the arrays before passing them on to the registration function. Constifying ctl_table structs will prevent the modification of proc_handler function pointers as the arrays would reside in .rodata. This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide: constify the ctl_table argument of proc_handlers") constified all the proc_handlers. Created this by running an spatch followed by a sed command: Spatch: virtual patch @ depends on !(file in "net") disable optional_qualifier @ identifier table_name != { watchdog_hardlockup_sysctl, iwcm_ctl_table, ucma_ctl_table, memory_allocation_profiling_sysctls, loadpin_sysctl_table }; @@ + const struct ctl_table table_name [] = { ... }; sed: sed --in-place \ -e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \ kernel/utsname_sysctl.c Reviewed-by: Song Liu Acked-by: Steven Rostedt (Google) # for kernel/trace/ Reviewed-by: Martin K. Petersen # SCSI Reviewed-by: Darrick J. Wong # xfs Acked-by: Jani Nikula Acked-by: Corey Minyard Acked-by: Wei Liu Acked-by: Thomas Gleixner Reviewed-by: Bill O'Donnell Acked-by: Baoquan He Acked-by: Ashutosh Dixit Acked-by: Anna Schumaker Signed-off-by: Joel Granados

Merge tag 'lsm-pr-20250121' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

2025-01-22T04:03:04Z

Pull lsm updates from Paul Moore: - Improved handling of LSM "secctx" strings through lsm_context struct The LSM secctx string interface is from an older time when only one LSM was supported, migrate over to the lsm_context struct to better support the different LSMs we now have and make it easier to support new LSMs in the future. These changes explain the Rust, VFS, and networking changes in the diffstat. - Only build lsm_audit.c if CONFIG_SECURITY and CONFIG_AUDIT are enabled Small tweak to be a bit smarter about when we build the LSM's common audit helpers. - Check for absurdly large policies from userspace in SafeSetID SafeSetID policies rules are fairly small, basically just "UID:UID", it easy to impose a limit of KMALLOC_MAX_SIZE on policy writes which helps quiet a number of syzbot related issues. While work is being done to address the syzbot issues through other mechanisms, this is a trivial and relatively safe fix that we can do now. - Various minor improvements and cleanups A collection of improvements to the kernel selftests, constification of some function parameters, removing redundant assignments, and local variable renames to improve readability. * tag 'lsm-pr-20250121' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm: lockdown: initialize local array before use to quiet static analysis safesetid: check size of policy writes net: corrections for security_secid_to_secctx returns lsm: rename variable to avoid shadowing lsm: constify function parameters security: remove redundant assignment to return variable lsm: Only build lsm_audit.c if CONFIG_SECURITY and CONFIG_AUDIT are set selftests: refactor the lsm `flags_overset_lsm_set_self_attr` test binder: initialize lsm_context structure rust: replace lsm context+len with lsm_context lsm: secctx provider check on release lsm: lsm_context in security_dentry_init_security lsm: use lsm_context in security_inode_getsecctx lsm: replace context+len with lsm_context lsm: ensure the correct LSM context releaser

Merge tag 'vfs-6.14-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-01-20T17:40:49Z

Pull misc vfs updates from Christian Brauner: "Features: - Support caching symlink lengths in inodes The size is stored in a new union utilizing the same space as i_devices, thus avoiding growing the struct or taking up any more space When utilized it dodges strlen() in vfs_readlink(), giving about 1.5% speed up when issuing readlink on /initrd.img on ext4 - Add RWF_DONTCACHE iocb and FOP_DONTCACHE file_operations flag If a file system supports uncached buffered IO, it may set FOP_DONTCACHE and enable support for RWF_DONTCACHE. If RWF_DONTCACHE is attempted without the file system supporting it, it'll get errored with -EOPNOTSUPP - Enable VBOXGUEST and VBOXSF_FS on ARM64 Now that VirtualBox is able to run as a host on arm64 (e.g. the Apple M3 processors) we can enable VBOXSF_FS (and in turn VBOXGUEST) for this architecture. Tested with various runs of bonnie++ and dbench on an Apple MacBook Pro with the latest Virtualbox 7.1.4 r165100 installed Cleanups: - Delay sysctl_nr_open check in expand_files() - Use kernel-doc includes in fiemap docbook - Use page->private instead of page->index in watch_queue - Use a consume fence in mnt_idmap() as it's heavily used in link_path_walk() - Replace magic number 7 with ARRAY_SIZE() in fc_log - Sort out a stale comment about races between fd alloc and dup2() - Fix return type of do_mount() from long to int - Various cosmetic cleanups for the lockref code Fixes: - Annotate spinning as unlikely() in __read_seqcount_begin The annotation already used to be there, but got lost in commit 52ac39e5db51 ("seqlock: seqcount_t: Implement all read APIs as statement expressions") - Fix proc_handler for sysctl_nr_open - Flush delayed work in delayed fput() - Fix grammar and spelling in propagate_umount() - Fix ESP not readable during coredump In /proc/PID/stat, there is the kstkesp field which is the stack pointer of a thread. While the thread is active, this field reads zero. But during a coredump, it should have a valid value However, at the moment, kstkesp is zero even during coredump - Don't wake up the writer if the pipe is still full - Fix unbalanced user_access_end() in select code" * tag 'vfs-6.14-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (28 commits) gfs2: use lockref_init for qd_lockref erofs: use lockref_init for pcl->lockref dcache: use lockref_init for d_lockref lockref: add a lockref_init helper lockref: drop superfluous externs lockref: use bool for false/true returns lockref: improve the lockref_get_not_zero description lockref: remove lockref_put_not_zero fs: Fix return type of do_mount() from long to int select: Fix unbalanced user_access_end() vbox: Enable VBOXGUEST and VBOXSF_FS on ARM64 pipe_read: don't wake up the writer if the pipe is still full selftests: coredump: Add stackdump test fs/proc: do_task_stat: Fix ESP not readable during coredump fs: add RWF_DONTCACHE iocb and FOP_DONTCACHE file_operations flag fs: sort out a stale comment about races between fd alloc and dup2 fs: Fix grammar and spelling in propagate_umount() fs: fc_log replace magic number 7 with ARRAY_SIZE() fs: use a consume fence in mnt_idmap() file: flush delayed work in delayed fput() ...

vfs: support caching symlink lengths in inodes

2024-12-22T10:29:50Z

When utilized it dodges strlen() in vfs_readlink(), giving about 1.5% speed up when issuing readlink on /initrd.img on ext4. Filesystems opt in by calling inode_set_cached_link() when creating an inode. The size is stored in a new union utilizing the same space as i_devices, thus avoiding growing the struct or taking up any more space. Churn-wise the current readlink_copy() helper is patched to accept the size instead of calculating it. Signed-off-by: Mateusz Guzik Link: https://lore.kernel.org/r/20241120112037.822078-2-mjguzik@gmail.com Signed-off-by: Christian Brauner

lsm: secctx provider check on release

2024-12-04T19:59:57Z

Verify that the LSM releasing the secctx is the LSM that allocated it. This was not necessary when only one LSM could create a secctx, but once there can be more than one it is. Signed-off-by: Casey Schaufler [PM: subject tweak] Signed-off-by: Paul Moore

lsm: replace context+len with lsm_context

2024-12-04T19:42:31Z

Replace the (secctx,seclen) pointer pair with a single lsm_context pointer to allow return of the LSM identifier along with the context and context length. This allows security_release_secctx() to know how to release the context. Callers have been modified to use or save the returned data from the new structure. security_secid_to_secctx() and security_lsmproc_to_secctx() will now return the length value on success instead of 0. Cc: netdev@vger.kernel.org Cc: audit@vger.kernel.org Cc: netfilter-devel@vger.kernel.org Cc: Todd Kjos Signed-off-by: Casey Schaufler [PM: subject tweak, kdoc fix, signedness fix from Dan Carpenter] Signed-off-by: Paul Moore

lsm: ensure the correct LSM context releaser

2024-12-04T15:46:26Z

Add a new lsm_context data structure to hold all the information about a "security context", including the string, its size and which LSM allocated the string. The allocation information is necessary because LSMs have different policies regarding the lifecycle of these strings. SELinux allocates and destroys them on each use, whereas Smack provides a pointer to an entry in a list that never goes away. Update security_release_secctx() to use the lsm_context instead of a (char *, len) pair. Change its callers to do likewise. The LSMs supporting this hook have had comments added to remind the developer that there is more work to be done. The BPF security module provides all LSM hooks. While there has yet to be a known instance of a BPF configuration that uses security contexts, the possibility is real. In the existing implementation there is potential for multiple frees in that case. Cc: linux-integrity@vger.kernel.org Cc: netdev@vger.kernel.org Cc: audit@vger.kernel.org Cc: netfilter-devel@vger.kernel.org To: Pablo Neira Ayuso Cc: linux-nfs@vger.kernel.org Cc: Todd Kjos Signed-off-by: Casey Schaufler [PM: subject tweak] Signed-off-by: Paul Moore

module: Convert symbol namespace to string literal

2024-12-02T19:34:44Z

Clean up the existing export namespace code along the same lines of commit 33def8498fdd ("treewide: Convert macro and uses of __section(foo) to __section("foo")") and for the same reason, it is not desired for the namespace argument to be a macro expansion itself. Scripted using git grep -l -e MODULE_IMPORT_NS -e EXPORT_SYMBOL_NS | while read file; do awk -i inplace ' /^#define EXPORT_SYMBOL_NS/ { gsub(/__stringify$ns$/, "ns"); print; next; } /^#define MODULE_IMPORT_NS/ { gsub(/__stringify$ns$/, "ns"); print; next; } /MODULE_IMPORT_NS/ { $0 = gensub(/MODULE_IMPORT_NS$([^)]*)$/, "MODULE_IMPORT_NS(\"\\1\")", "g"); } /EXPORT_SYMBOL_NS/ { if ($0 ~ /(EXPORT_SYMBOL_NS[^(]*)$([^,]+),/) { if ($0 !~ /(EXPORT_SYMBOL_NS[^(]*)\(([^,]+), ([^)]+)$/ && $0 !~ /(EXPORT_SYMBOL_NS[^(]*)/ && $0 !~ /^my/) { getline line; gsub(/[[:space:]]*\\$/, ""); gsub(/[[:space:]]/, "", line); $0 = $0 " " line; } $0 = gensub(/(EXPORT_SYMBOL_NS[^(]*)$([^,]+), ([^)]+)$/, "\\1(\\2, \"\\3\")", "g"); } } { print }' $file; done Requested-by: Masahiro Yamada Signed-off-by: Peter Zijlstra (Intel) Link: https://mail.google.com/mail/u/2/#inbox/FMfcgzQXKWgMmjdFwwdsfgxzKpVHWPlc Acked-by: Greg KH Signed-off-by: Linus Torvalds