kernel/linux.git/fs/tracefs, branch v5.10.257

tracefs: Add missing lockdown check to tracefs_create_dir()

2023-09-23T09:01:10+00:00

commit 51aab5ffceb43e05119eb059048fd75765d2bc21 upstream. The function tracefs_create_dir() was missing a lockdown check and was called by the RV code. This gave an inconsistent behavior of this function returning success while other tracefs functions failed. This caused the inode being freed by the wrong kmem_cache. Link: https://lkml.kernel.org/r/20230905182711.692687042@goodmis.org Link: https://lore.kernel.org/all/202309050916.58201dc6-oliver.sang@intel.com/ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Andrew Morton Cc: Ajay Kaher Cc: Ching-lin Yu Fixes: bf8e602186ec4 ("tracing: Do not create tracefs files if tracefs lockdown is in effect") Reported-by: kernel test robot Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

tracefs: Only clobber mode/uid/gid on remount if asked

2022-09-20T10:38:31+00:00

[ Upstream commit 47311db8e8f33011d90dee76b39c8886120cdda4 ] Users may have explicitly configured their tracefs permissions; we shouldn't overwrite those just because a second mount appeared. Only clobber if the options were provided at mount time. Note: the previous behavior was especially surprising in the presence of automounted /sys/kernel/debug/tracing/. Existing behavior: ## Pre-existing status: tracefs is 0755. # stat -c '%A' /sys/kernel/tracing/ drwxr-xr-x ## (Re)trigger the automount. # umount /sys/kernel/debug/tracing # stat -c '%A' /sys/kernel/debug/tracing/. drwx------ ## Unexpected: the automount changed mode for other mount instances. # stat -c '%A' /sys/kernel/tracing/ drwx------ New behavior (after this change): ## Pre-existing status: tracefs is 0755. # stat -c '%A' /sys/kernel/tracing/ drwxr-xr-x ## (Re)trigger the automount. # umount /sys/kernel/debug/tracing # stat -c '%A' /sys/kernel/debug/tracing/. drwxr-xr-x ## Expected: the automount does not change other mount instances. # stat -c '%A' /sys/kernel/tracing/ drwxr-xr-x Link: https://lkml.kernel.org/r/20220826174353.2.Iab6e5ea57963d6deca5311b27fb7226790d44406@changeid Cc: stable@vger.kernel.org Fixes: 4282d60689d4f ("tracefs: Add new tracefs file system") Signed-off-by: Brian Norris Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin

tracefs: Set the group ownership in apply_options() not parse_options()

2022-03-02T10:42:54+00:00

commit 851e99ebeec3f4a672bb5010cf1ece095acee447 upstream. Al Viro brought it to my attention that the dentries may not be filled when the parse_options() is called, causing the call to set_gid() to possibly crash. It should only be called if parse_options() succeeds totally anyway. He suggested the logical place to do the update is in apply_options(). Link: https://lore.kernel.org/all/20220225165219.737025658@goodmis.org/ Link: https://lkml.kernel.org/r/20220225153426.1c4cab6b@gandalf.local.home Cc: stable@vger.kernel.org Acked-by: Al Viro Reported-by: Al Viro Fixes: 48b27b6b5191 ("tracefs: Set all files to the same group ownership as the mount option") Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

tracefs: Set all files to the same group ownership as the mount option

2021-12-14T10:32:40+00:00

commit 48b27b6b5191e2e1f2798cd80877b6e4ef47c351 upstream. As people have been asking to allow non-root processes to have access to the tracefs directory, it was considered best to only allow groups to have access to the directory, where it is easier to just set the tracefs file system to a specific group (as other would be too dangerous), and that way the admins could pick which processes would have access to tracefs. Unfortunately, this broke tooling on Android that expected the other bit to be set. For some special cases, for non-root tools to trace the system, tracefs would be mounted and change the permissions of the top level directory which gave access to all running tasks permission to the tracing directory. Even though this would be dangerous to do in a production environment, for testing environments this can be useful. Now with the new changes to not allow other (which is still the proper thing to do), it breaks the testing tooling. Now more code needs to be loaded on the system to change ownership of the tracing directory. The real solution is to have tracefs honor the gid=xxx option when mounting. That is, (tracing group tracing has value 1003) mount -t tracefs -o gid=1003 tracefs /sys/kernel/tracing should have it that all files in the tracing directory should be of the given group. Copy the logic from d_walk() from dcache.c and simplify it for the mount case of tracefs if gid is set. All the files in tracefs will be walked and their group will be set to the value passed in. Link: https://lkml.kernel.org/r/20211207171729.2a54e1b3@gandalf.local.home Cc: Ingo Molnar Cc: Kees Cook Cc: Andrew Morton Cc: Linus Torvalds Cc: linux-fsdevel@vger.kernel.org Cc: Al Viro Cc: Greg Kroah-Hartman Reported-by: Kalesh Singh Reported-by: Yabin Cui Fixes: 49d67e445742 ("tracefs: Have tracefs directories not set OTH permission bits by default") Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman

tracefs: Have new files inherit the ownership of their parent

2021-12-14T10:32:39+00:00

commit ee7f3666995d8537dec17b1d35425f28877671a9 upstream. If directories in tracefs have their ownership changed, then any new files and directories that are created under those directories should inherit the ownership of the director they are created in. Link: https://lkml.kernel.org/r/20211208075720.4855d180@gandalf.local.home Cc: Kees Cook Cc: Ingo Molnar Cc: Andrew Morton Cc: Linus Torvalds Cc: Al Viro Cc: Greg Kroah-Hartman Cc: Yabin Cui Cc: Christian Brauner Cc: stable@vger.kernel.org Fixes: 4282d60689d4f ("tracefs: Add new tracefs file system") Reported-by: Kalesh Singh Reported: https://lore.kernel.org/all/CAC_TJve8MMAv+H_NdLSJXZUSoxOEq2zB_pVaJ9p=7H6Bu3X76g@mail.gmail.com/ Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman

tracefs: Have tracefs directories not set OTH permission bits by default

2021-11-18T13:03:56+00:00

[ Upstream commit 49d67e445742bbcb03106b735b2ab39f6e5c56bc ] The tracefs file system is by default mounted such that only root user can access it. But there are legitimate reasons to create a group and allow those added to the group to have access to tracing. By changing the permissions of the tracefs mount point to allow access, it will allow group access to the tracefs directory. There should not be any real reason to allow all access to the tracefs directory as it contains sensitive information. Have the default permission of directories being created not have any OTH (other) bits set, such that an admin that wants to give permission to a group has to first disable all OTH bits in the file system. Link: https://lkml.kernel.org/r/20210818153038.664127804@goodmis.org Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin

simple_recursive_removal(): kernel-side rm -rf for ramfs-style filesystems

2019-12-11T03:29:58+00:00

two requirements: no file creations in IS_DEADDIR and no cross-directory renames whatsoever. Signed-off-by: Al Viro

tracing: Do not create tracefs files if tracefs lockdown is in effect

2019-10-13T00:49:07+00:00

If on boot up, lockdown is activated for tracefs, don't even bother creating the files. This can also prevent instances from being created if lockdown is in effect. Link: http://lkml.kernel.org/r/CAHk-=whC6Ji=fWnjh2+eS4b15TnbsS4VPVtvBOwCy1jjEG_JHQ@mail.gmail.com Suggested-by: Linus Torvalds Signed-off-by: Steven Rostedt (VMware)

tracefs: Revert ccbd54ff54e8 ("tracefs: Restrict tracefs when the kernel is locked down")

2019-10-13T00:36:50+00:00

Running the latest kernel through my "make instances" stress tests, I triggered the following bug (with KASAN and kmemleak enabled): mkdir invoked oom-killer: gfp_mask=0x40cd0(GFP_KERNEL|__GFP_COMP|__GFP_RECLAIMABLE), order=0, oom_score_adj=0 CPU: 1 PID: 2229 Comm: mkdir Not tainted 5.4.0-rc2-test #325 Hardware name: MSI MS-7823/CSM-H87M-G43 (MS-7823), BIOS V1.6 02/22/2014 Call Trace: dump_stack+0x64/0x8c dump_header+0x43/0x3b7 ? trace_hardirqs_on+0x48/0x4a oom_kill_process+0x68/0x2d5 out_of_memory+0x2aa/0x2d0 __alloc_pages_nodemask+0x96d/0xb67 __alloc_pages_node+0x19/0x1e alloc_slab_page+0x17/0x45 new_slab+0xd0/0x234 ___slab_alloc.constprop.86+0x18f/0x336 ? alloc_inode+0x2c/0x74 ? irq_trace+0x12/0x1e ? tracer_hardirqs_off+0x1d/0xd7 ? __slab_alloc.constprop.85+0x21/0x53 __slab_alloc.constprop.85+0x31/0x53 ? __slab_alloc.constprop.85+0x31/0x53 ? alloc_inode+0x2c/0x74 kmem_cache_alloc+0x50/0x179 ? alloc_inode+0x2c/0x74 alloc_inode+0x2c/0x74 new_inode_pseudo+0xf/0x48 new_inode+0x15/0x25 tracefs_get_inode+0x23/0x7c ? lookup_one_len+0x54/0x6c tracefs_create_file+0x53/0x11d trace_create_file+0x15/0x33 event_create_dir+0x2a3/0x34b __trace_add_new_event+0x1c/0x26 event_trace_add_tracer+0x56/0x86 trace_array_create+0x13e/0x1e1 instance_mkdir+0x8/0x17 tracefs_syscall_mkdir+0x39/0x50 ? get_dname+0x31/0x31 vfs_mkdir+0x78/0xa3 do_mkdirat+0x71/0xb0 sys_mkdir+0x19/0x1b do_fast_syscall_32+0xb0/0xed I bisected this down to the addition of the proxy_ops into tracefs for lockdown. It appears that the allocation of the proxy_ops and then freeing it in the destroy_inode callback, is causing havoc with the memory system. Reading the documentation about destroy_inode and talking with Linus about this, this is buggy and wrong. When defining the destroy_inode() method, it is expected that the destroy_inode() will also free the inode, and not just the extra allocations done in the creation of the inode. The faulty commit causes a memory leak of the inode data structure when they are deleted. Instead of allocating the proxy_ops (and then having to free it) the checks should be done by the open functions themselves, and not hack into the tracefs directory. First revert the tracefs updates for locked_down and then later we can add the locked_down checks in the kernel/trace files. Link: http://lkml.kernel.org/r/20191011135458.7399da44@gandalf.local.home Fixes: ccbd54ff54e8 ("tracefs: Restrict tracefs when the kernel is locked down") Suggested-by: Linus Torvalds Signed-off-by: Steven Rostedt (VMware)

Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

2019-09-28T15:14:15+00:00

Pull kernel lockdown mode from James Morris: "This is the latest iteration of the kernel lockdown patchset, from Matthew Garrett, David Howells and others. From the original description: This patchset introduces an optional kernel lockdown feature, intended to strengthen the boundary between UID 0 and the kernel. When enabled, various pieces of kernel functionality are restricted. Applications that rely on low-level access to either hardware or the kernel may cease working as a result - therefore this should not be enabled without appropriate evaluation beforehand. The majority of mainstream distributions have been carrying variants of this patchset for many years now, so there's value in providing a doesn't meet every distribution requirement, but gets us much closer to not requiring external patches. There are two major changes since this was last proposed for mainline: - Separating lockdown from EFI secure boot. Background discussion is covered here: https://lwn.net/Articles/751061/ - Implementation as an LSM, with a default stackable lockdown LSM module. This allows the lockdown feature to be policy-driven, rather than encoding an implicit policy within the mechanism. The new locked_down LSM hook is provided to allow LSMs to make a policy decision around whether kernel functionality that would allow tampering with or examining the runtime state of the kernel should be permitted. The included lockdown LSM provides an implementation with a simple policy intended for general purpose use. This policy provides a coarse level of granularity, controllable via the kernel command line: lockdown={integrity|confidentiality} Enable the kernel lockdown feature. If set to integrity, kernel features that allow userland to modify the running kernel are disabled. If set to confidentiality, kernel features that allow userland to extract confidential information from the kernel are also disabled. This may also be controlled via /sys/kernel/security/lockdown and overriden by kernel configuration. New or existing LSMs may implement finer-grained controls of the lockdown features. Refer to the lockdown_reason documentation in include/linux/security.h for details. The lockdown feature has had signficant design feedback and review across many subsystems. This code has been in linux-next for some weeks, with a few fixes applied along the way. Stephen Rothwell noted that commit 9d1f8be5cf42 ("bpf: Restrict bpf when kernel lockdown is in confidentiality mode") is missing a Signed-off-by from its author. Matthew responded that he is providing this under category (c) of the DCO" * 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (31 commits) kexec: Fix file verification on S390 security: constify some arrays in lockdown LSM lockdown: Print current->comm in restriction messages efi: Restrict efivar_ssdt_load when the kernel is locked down tracefs: Restrict tracefs when the kernel is locked down debugfs: Restrict debugfs when the kernel is locked down kexec: Allow kexec_file() with appropriate IMA policy when locked down lockdown: Lock down perf when in confidentiality mode bpf: Restrict bpf when kernel lockdown is in confidentiality mode lockdown: Lock down tracing and perf kprobes when in confidentiality mode lockdown: Lock down /proc/kcore x86/mmiotrace: Lock down the testmmiotrace module lockdown: Lock down module params that specify hardware parameters (eg. ioport) lockdown: Lock down TIOCSSERIAL lockdown: Prohibit PCMCIA CIS storage when the kernel is locked down acpi: Disable ACPI table override if the kernel is locked down acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down ACPI: Limit access to custom_method when the kernel is locked down x86/msr: Restrict MSR access when the kernel is locked down x86: Lock down IO port access when the kernel is locked down ...