- 17 Feb, 2022 1 commit
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Eric W. Biederman authored
Michal Koutný <mkoutny@suse.com> wrote: > Tasks are associated to multiple users at once. Historically and as per > setrlimit(2) RLIMIT_NPROC is enforce based on real user ID. > > The commit 21d1c5e3 ("Reimplement RLIMIT_NPROC on top of ucounts") > made the accounting structure "indexed" by euid and hence potentially > account tasks differently. > > The effective user ID may be different e.g. for setuid programs but > those are exec'd into already existing task (i.e. below limit), so > different accounting is moot. > > Some special setresuid(2) users may notice the difference, justifying > this fix. I looked at cred->ucount and it is only used for rlimit operations that were previously stored in cred->user. Making the fact cred->ucount can refer to a different user from cred->user a bug, affecting all uses of cred->ulimit not just RLIMIT_NPROC. Fix set_cred_ucounts to always use the real uid not the effective uid. Further simplify set_cred_ucounts by noticing that set_cred_ucounts somehow retained a draft version of the check to see if alloc_ucounts was needed that checks the new->user and new->user_ns against the current_real_cred(). Remove that draft version of the check. All that matters for setting the cred->ucounts are the user_ns and uid fields in the cred. Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20220207121800.5079-4-mkoutny@suse.com Link: https://lkml.kernel.org/r/20220216155832.680775-3-ebiederm@xmission.com Reported-by:
Michal Koutný <mkoutny@suse.com> Reviewed-by:
"Eric W. Biederman" <ebiederm@xmission.com>
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- 20 Oct, 2021 2 commits
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Eric W. Biederman authored
Any cred that is destined for use by commit_creds must have a non-NULL cred->ucounts field. Only curing credential construction is a NULL cred->ucounts valid. Only abort_creds, put_cred, and put_cred_rcu needs to deal with a cred with a NULL ucount. As set_cred_ucounts is non of those case don't confuse people by handling something that can not happen. Link: https://lkml.kernel.org/r/871r4irzds.fsf_-_@disp2133 Tested-by:
Yu Zhao <yuzhao@google.com> Reviewed-by:
Alexey Gladkov <legion@kernel.org> Signed-off-by:
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Eric W. Biederman authored
Setting cred->ucounts in cred_alloc_blank does not make sense. The uid and user_ns are deliberately not set in cred_alloc_blank but instead the setting is delayed until key_change_session_keyring. So move dealing with ucounts into key_change_session_keyring as well. Unfortunately that movement of get_ucounts adds a new failure mode to key_change_session_keyring. I do not see anything stopping the parent process from calling setuid and changing the relevant part of it's cred while keyctl_session_to_parent is running making it fundamentally necessary to call get_ucounts in key_change_session_keyring. Which means that the new failure mode cannot be avoided. A failure of key_change_session_keyring results in a single threaded parent keeping it's existing credentials. Which results in the parent process not being able to access the session keyring and whichever keys are in the new keyring. Further get_ucounts is only expected to fail if the number of bits in the refernece count for the structure is too few. Since the code has no other way to report the failure of get_ucounts and because such failures are not expected to be common add a WARN_ONCE to report this problem to userspace. Between the WARN_ONCE and the parent process not having access to the keys in the new session keyring I expect any failure of get_ucounts will be noticed and reported and we can find another way to handle this condition. (Possibly by just making ucounts->count an atomic_long_t). Cc: stable@vger.kernel.org Fixes: 905ae01c ("Add a reference to ucounts for each cred") Link: https://lkml.kernel.org/r/7k0ias0uf.fsf_-_@disp2133 Tested-by:
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- 19 Oct, 2021 2 commits
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Eric W. Biederman authored
Instead of leaking the ucounts in new if alloc_ucounts fails, store the result of alloc_ucounts into a temporary variable, which is later assigned to new->ucounts. Cc: stable@vger.kernel.org Fixes: 905ae01c ("Add a reference to ucounts for each cred") Link: https://lkml.kernel.org/r/87pms2s0v8.fsf_-_@disp2133 Tested-by:
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Eric W. Biederman authored
The purpose of inc_rlimit_ucounts and dec_rlimit_ucounts in commit_creds is to change which rlimit counter is used to track a process when the credentials changes. Use the same test for both to guarantee the tracking is correct. Cc: stable@vger.kernel.org Fixes: 21d1c5e3 ("Reimplement RLIMIT_NPROC on top of ucounts") Link: https://lkml.kernel.org/r/87v91us0w4.fsf_-_@disp2133 Tested-by:
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- 23 Aug, 2021 1 commit
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Alexey Gladkov authored
We need to increment the ucounts reference counter befor security_prepare_creds() because this function may fail and abort_creds() will try to decrement this reference. [ 96.465056][ T8641] FAULT_INJECTION: forcing a failure. [ 96.465056][ T8641] name fail_page_alloc, interval 1, probability 0, space 0, times 0 [ 96.478453][ T8641] CPU: 1 PID: 8641 Comm: syz-executor668 Not tainted 5.14.0-rc6-syzkaller #0 [ 96.487215][ T8641] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 96.497254][ T8641] Call Trace: [ 96.500517][ T8641] dump_stack_lvl+0x1d3/0x29f [ 96.505758][ T8641] ? show_regs_print_info+0x12/0x12 [ 96.510944][ T8641] ? log_buf_vmcoreinfo_setup+0x498/0x498 [ 96.516652][ T8641] should_fail+0x384/0x4b0 [ 96.521141][ T8641] prepare_alloc_pages+0x1d1/0x5a0 [ 96.526236][ T8641] __alloc_pages+0x14d/0x5f0 [ 96.530808][ T8641] ? __rmqueue_pcplist+0x2030/0x2030 [ 96.536073][ T8641] ? lockdep_hardirqs_on_prepare+0x3e2/0x750 [ 96.542056][ T8641] ? alloc_pages+0x3f3/0x500 [ 96.546635][ T8641] allocate_slab+0xf1/0x540 [ 96.551120][ T8641] ___slab_alloc+0x1cf/0x350 [ 96.555689][ T8641] ? kzalloc+0x1d/0x30 [ 96.559740][ T8641] __kmalloc+0x2e7/0x390 [ 96.563980][ T8641] ? kzalloc+0x1d/0x30 [ 96.568029][ T8641] kzalloc+0x1d/0x30 [ 96.571903][ T8641] security_prepare_creds+0x46/0x220 [ 96.577174][ T8641] prepare_creds+0x411/0x640 [ 96.581747][ T8641] __sys_setfsuid+0xe2/0x3a0 [ 96.586333][ T8641] do_syscall_64+0x3d/0xb0 [ 96.590739][ T8641] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 96.596611][ T8641] RIP: 0033:0x445a69 [ 96.600483][ T8641] Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 [ 96.620152][ T8641] RSP: 002b:00007f1054173318 EFLAGS: 00000246 ORIG_RAX: 000000000000007a [ 96.628543][ T8641] RAX: ffffffffffffffda RBX: 00000000004ca4c8 RCX: 0000000000445a69 [ 96.636600][ T8641] RDX: 0000000000000010 RSI: 00007f10541732f0 RDI: 0000000000000000 [ 96.644550][ T8641] RBP: 00000000004ca4c0 R08: 0000000000000001 R09: 0000000000000000 [ 96.652500][ T8641] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004ca4cc [ 96.660631][ T8641] R13: 00007fffffe0b62f R14: 00007f1054173400 R15: 0000000000022000 Fixes: 905ae01c ("Add a reference to ucounts for each cred") Reported-by: syzbot+01985d7909f9468f013c@syzkaller.appspotmail.com Signed-off-by:
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- 28 May, 2021 1 commit
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Yang Yingliang authored
If set_cred_ucounts() failed, we need return the error code. Fixes: 905ae01c ("Add a reference to ucounts for each cred") Reported-by:
Hulk Robot <hulkci@huawei.com> Signed-off-by:
Yang Yingliang <yangyingliang@huawei.com> Link: https://lkml.kernel.org/r/20210526143805.2549649-1-yangyingliang@huawei.com Reviewed-by:
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- 07 May, 2021 1 commit
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Rasmus Villemoes authored
init_groups is declared in both cred.h and init_task.h, but it is not actually referenced anywhere outside of cred.c where it is defined. So make it static and remove the declarations. Link: https://lkml.kernel.org/r/20210310220102.2484201-1-linux@rasmusvillemoes.dk Signed-off-by:
Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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- 30 Apr, 2021 2 commits
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Alexey Gladkov authored
The rlimit counter is tied to uid in the user_namespace. This allows rlimit values to be specified in userns even if they are already globally exceeded by the user. However, the value of the previous user_namespaces cannot be exceeded. To illustrate the impact of rlimits, let's say there is a program that does not fork. Some service-A wants to run this program as user X in multiple containers. Since the program never fork the service wants to set RLIMIT_NPROC=1. service-A \- program (uid=1000, container1, rlimit_nproc=1) \- program (uid=1000, container2, rlimit_nproc=1) The service-A sets RLIMIT_NPROC=1 and runs the program in container1. When the service-A tries to run a program with RLIMIT_NPROC=1 in container2 it fails since user X already has one running process. We cannot use existing inc_ucounts / dec_ucounts because they do not allow us to exceed the maximum for the counter. Some rlimits can be overlimited by root or if the user has the appropriate capability. Changelog v11: * Change inc_rlimit_ucounts() which now returns top value of ucounts. * Drop inc_rlimit_ucounts_and_test() because the return code of inc_rlimit_ucounts() can be checked. Signed-off-by:
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Alexey Gladkov authored
For RLIMIT_NPROC and some other rlimits the user_struct that holds the global limit is kept alive for the lifetime of a process by keeping it in struct cred. Adding a pointer to ucounts in the struct cred will allow to track RLIMIT_NPROC not only for user in the system, but for user in the user_namespace. Updating ucounts may require memory allocation which may fail. So, we cannot change cred.ucounts in the commit_creds() because this function cannot fail and it should always return 0. For this reason, we modify cred.ucounts before calling the commit_creds(). Changelog v6: * Fix null-ptr-deref in is_ucounts_overlimit() detected by trinity. This error was caused by the fact that cred_alloc_blank() left the ucounts pointer empty. Reported-by:
kernel test robot <oliver.sang@intel.com> Signed-off-by:
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- 20 May, 2020 1 commit
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Eric W. Biederman authored
It is almost possible to use the result of prepare_exec_creds with no modifications during exec. Update prepare_exec_creds to initialize the suid and the fsuid to the euid, and the sgid and the fsgid to the egid. This is all that is needed to handle the common case of exec when nothing special like a setuid exec is happening. That this preserves the existing behavior of exec can be verified by examing bprm_fill_uid and cap_bprm_set_creds. This change makes it clear that the later parts of exec that update bprm->cred are just need to handle special cases such as setuid exec and change of domains. Link: https://lkml.kernel.org/r/871rng22dm.fsf_-_@x220.int.ebiederm.org Acked-by:
Kees Cook <keescook@chromium.org> Signed-off-by:
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- 25 Mar, 2020 1 commit
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Bernd Edlinger authored
This removes an outdated comment in prepare_kernel_cred. There is no "cred_replace_mutex" any more, so the comment must go away. Signed-off-by:
Bernd Edlinger <bernd.edlinger@hotmail.de> Reviewed-by:
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- 14 Jan, 2020 1 commit
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David Howells authored
When the key cached by request_key() and co. is cleaned up on exit(), the code looks in the wrong task_struct, and so clears the wrong cache. This leads to anomalies in key refcounting when doing, say, a kernel build on an afs volume, that then trigger kasan to report a use-after-free when the key is viewed in /proc/keys. Fix this by making exit_creds() look in the passed-in task_struct rather than in current (the task_struct cleanup code is deferred by RCU and potentially run in another task). Fixes: 7743c48e ("keys: Cache result of request_key*() temporarily in task_struct") Signed-off-by:
David Howells <dhowells@redhat.com> Signed-off-by:
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- 04 Jan, 2020 1 commit
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Shakeel Butt authored
The cred_jar kmem_cache is already memcg accounted in the current kernel but cred->security is not. Account cred->security to kmemcg. Recently we saw high root slab usage on our production and on further inspection, we found a buggy application leaking processes. Though that buggy application was contained within its memcg but we observe much more system memory overhead, couple of GiBs, during that period. This overhead can adversely impact the isolation on the system. One source of high overhead we found was cred->security objects, which have a lifetime of at least the life of the process which allocated them. Link: http://lkml.kernel.org/r/20191205223721.40034-1-shakeelb@google.com Signed-off-by:
Shakeel Butt <shakeelb@google.com> Acked-by:
Chris Down <chris@chrisdown.name> Reviewed-by:
Roman Gushchin <guro@fb.com> Acked-by:
Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> Signed-off-by:
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- 24 Jul, 2019 1 commit
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Linus Torvalds authored
It turns out that 'access()' (and 'faccessat()') can cause a lot of RCU work because it installs a temporary credential that gets allocated and freed for each system call. The allocation and freeing overhead is mostly benign, but because credentials can be accessed under the RCU read lock, the freeing involves a RCU grace period. Which is not a huge deal normally, but if you have a lot of access() calls, this causes a fair amount of seconday damage: instead of having a nice alloc/free patterns that hits in hot per-CPU slab caches, you have all those delayed free's, and on big machines with hundreds of cores, the RCU overhead can end up being enormous. But it turns out that all of this is entirely unnecessary. Exactly because access() only installs the credential as the thread-local subjective credential, the temporary cred pointer doesn't actually need to be RCU free'd at all. Once we're done using it, we can just free it synchronously and avoid all the RCU overhead. So add a 'non_rcu' flag to 'struct cred', which can be set by users that know they only use it in non-RCU context (there are other potential users for this). We can make it a union with the rcu freeing list head that we need for the RCU case, so this doesn't need any extra storage. Note that this also makes 'get_current_cred()' clear the new non_rcu flag, in case we have filesystems that take a long-term reference to the cred and then expect the RCU delayed freeing afterwards. It's not entirely clear that this is required, but it makes for clear semantics: the subjective cred remains non-RCU as long as you only access it synchronously using the thread-local accessors, but you _can_ use it as a generic cred if you want to. It is possible that we should just remove the whole RCU markings for ->cred entirely. Only ->real_cred is really supposed to be accessed through RCU, and the long-term cred copies that nfs uses might want to explicitly re-enable RCU freeing if required, rather than have get_current_cred() do it implicitly. But this is a "minimal semantic changes" change for the immediate problem. Acked-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by:
Eric Dumazet <edumazet@google.com> Acked-by:
Paul E. McKenney <paulmck@linux.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Jan Glauber <jglauber@marvell.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: Jayachandran Chandrasekharan Nair <jnair@marvell.com> Cc: Greg KH <greg@kroah.com> Cc: Kees Cook <keescook@chromium.org> Cc: David Howells <dhowells@redhat.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:
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- 19 Jun, 2019 1 commit
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David Howells authored
If a filesystem uses keys to hold authentication tokens, then it needs a token for each VFS operation that might perform an authentication check - either by passing it to the server, or using to perform a check based on authentication data cached locally. For open files this isn't a problem, since the key should be cached in the file struct since it represents the subject performing operations on that file descriptor. During pathwalk, however, there isn't anywhere to cache the key, except perhaps in the nameidata struct - but that isn't exposed to the filesystems. Further, a pathwalk can incur a lot of operations, calling one or more of the following, for instance: ->lookup() ->permission() ->d_revalidate() ->d_automount() ->get_acl() ->getxattr() on each dentry/inode it encounters - and each one may need to call request_key(). And then, at the end of pathwalk, it will call the actual operation: ->mkdir() ->mknod() ->getattr() ->open() ... which may need to go and get the token again. However, it is very likely that all of the operations on a single dentry/inode - and quite possibly a sequence of them - will all want to use the same authentication token, which suggests that caching it would be a good idea. To this end: (1) Make it so that a positive result of request_key() and co. that didn't require upcalling to userspace is cached temporarily in task_struct. (2) The cache is 1 deep, so a new result displaces the old one. (3) The key is released by exit and by notify-resume. (4) The cache is cleared in a newly forked process. Signed-off-by:
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- 11 Jun, 2019 1 commit
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Jann Horn authored
Restore the read memory barrier in __ptrace_may_access() that was deleted a couple years ago. Also add comments on this barrier and the one it pairs with to explain why they're there (as far as I understand). Fixes: bfedb589 ("mm: Add a user_ns owner to mm_struct and fix ptrace permission checks") Cc: stable@vger.kernel.org Acked-by:
Oleg Nesterov <oleg@redhat.com> Signed-off-by:
Jann Horn <jannh@google.com> Signed-off-by:
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- 24 May, 2019 1 commit
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Thomas Gleixner authored
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public licence as published by the free software foundation either version 2 of the licence or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 114 file(s). Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Reviewed-by:
Allison Randal <allison@lohutok.net> Reviewed-by:
Kate Stewart <kstewart@linuxfoundation.org> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190520170857.552531963@linutronix.de Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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- 22 May, 2019 1 commit
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David Howells authored
Sparse warnings are incurred by key_fs[ug]id_changed() due to unprotected accesses of tsk->cred, which is marked __rcu. Fix this by passing the new cred struct to these functions from commit_creds() rather than the task pointer. Signed-off-by:
James Morris <jamorris@linux.microsoft.com>
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- 08 Jan, 2019 1 commit
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Casey Schaufler authored
The SELinux specific credential poisioning only makes sense if SELinux is managing the credentials. As the intent of this patch set is to move the blob management out of the modules and into the infrastructure, the SELinux specific code has to go. The poisioning could be introduced into the infrastructure at some later date. Signed-off-by:
Casey Schaufler <casey@schaufler-ca.com> Reviewed-by:
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- 19 Dec, 2018 3 commits
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NeilBrown authored
There is no reason that modules should not be able to use this, and NFS will need it when converted to use 'struct cred'. Signed-off-by:
NeilBrown <neilb@suse.com> Signed-off-by:
Anna Schumaker <Anna.Schumaker@Netapp.com>
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NeilBrown authored
Sometimes we want to opportunistically get a ref to a cred in an rcu_read_lock protected section. get_task_cred() does this, and NFS does as similar thing with its own credential structures. To prepare for NFS converting to use 'struct cred' more uniformly, define get_cred_rcu(), and use it in get_task_cred(). Signed-off-by:
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NeilBrown authored
NFS needs to compare to credentials, to see if they can be treated the same w.r.t. filesystem access. Sometimes an ordering is needed when credentials are used as a key to an rbtree. NFS currently has its own private credential management from before 'struct cred' existed. To move it over to more consistent use of 'struct cred' we need a comparison function. This patch adds that function. Signed-off-by:
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- 18 May, 2017 1 commit
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Kees Cook authored
This updates the credentials API documentation to ReST markup and moves it under the security subsection of kernel API documentation. Cc: David Howells <dhowells@redhat.com> Signed-off-by:
Jonathan Corbet <corbet@lwn.net>
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- 02 Mar, 2017 1 commit
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Ingo Molnar authored
We are going to split <linux/sched/coredump.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/coredump.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by:
Ingo Molnar <mingo@kernel.org>
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- 30 Jun, 2016 1 commit
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Seth Forshee authored
Using INVALID_[UG]ID for the LSM file creation context doesn't make sense, so return an error if the inode passed to set_create_file_as() has an invalid id. Signed-off-by:
Seth Forshee <seth.forshee@canonical.com> Acked-by:
Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by:
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- 15 Jan, 2016 1 commit
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Vladimir Davydov authored
Mark those kmem allocations that are known to be easily triggered from userspace as __GFP_ACCOUNT/SLAB_ACCOUNT, which makes them accounted to memcg. For the list, see below: - threadinfo - task_struct - task_delay_info - pid - cred - mm_struct - vm_area_struct and vm_region (nommu) - anon_vma and anon_vma_chain - signal_struct - sighand_struct - fs_struct - files_struct - fdtable and fdtable->full_fds_bits - dentry and external_name - inode for all filesystems. This is the most tedious part, because most filesystems overwrite the alloc_inode method. The list is far from complete, so feel free to add more objects. Nevertheless, it should be close to "account everything" approach and keep most workloads within bounds. Malevolent users will be able to breach the limit, but this was possible even with the former "account everything" approach (simply because it did not account everything in fact). [akpm@linux-foundation.org: coding-style fixes] Signed-off-by:
Vladimir Davydov <vdavydov@virtuozzo.com> Acked-by:
Johannes Weiner <hannes@cmpxchg.org> Acked-by:
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- 10 Sep, 2015 1 commit
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Joe Perches authored
Commit e0e81739 ("CRED: Add some configurable debugging [try #6]") added the kdebug mechanism to this file back in 2009. The kdebug macro calls no_printk which always evaluates arguments. Most of the kdebug uses have an unnecessary call of atomic_read(&cred->usage) Make the kdebug macro do nothing by defining it with do { if (0) no_printk(...); } while (0) when not enabled. $ size kernel/cred.o* (defconfig x86-64) text data bss dec hex filename 2748 336 8 3092 c14 kernel/cred.o.new 2788 336 8 3132 c3c kernel/cred.o.old Miscellanea: o Neaten the #define kdebug macros while there Signed-off-by:
Joe Perches <joe@perches.com> Cc: David Howells <dhowells@redhat.com> Cc: James Morris <jmorris@namei.org> Signed-off-by:
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- 15 Apr, 2015 1 commit
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Iulia Manda authored
There are a lot of embedded systems that run most or all of their functionality in init, running as root:root. For these systems, supporting multiple users is not necessary. This patch adds a new symbol, CONFIG_MULTIUSER, that makes support for non-root users, non-root groups, and capabilities optional. It is enabled under CONFIG_EXPERT menu. When this symbol is not defined, UID and GID are zero in any possible case and processes always have all capabilities. The following syscalls are compiled out: setuid, setregid, setgid, setreuid, setresuid, getresuid, setresgid, getresgid, setgroups, getgroups, setfsuid, setfsgid, capget, capset. Also, groups.c is compiled out completely. In kernel/capability.c, capable function was moved in order to avoid adding two ifdef blocks. This change saves about 25 KB on a defconfig build. The most minimal kernels have total text sizes in the high hundreds of kB rather than low MB. (The 25k goes down a bit with allnoconfig, but not that much. The kernel was booted in Qemu. All the common functionalities work. Adding users/groups is not possible, failing with -ENOSYS. Bloat-o-meter output: add/remove: 7/87 grow/shrink: 19/397 up/down: 1675/-26325 (-24650) [akpm@linux-foundation.org: coding-style fixes] Signed-off-by:
Iulia Manda <iulia.manda21@gmail.com> Reviewed-by:
Josh Triplett <josh@joshtriplett.org> Acked-by:
Geert Uytterhoeven <geert@linux-m68k.org> Tested-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by:
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- 15 Dec, 2012 1 commit
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Eric W. Biederman authored
When unsharing a user namespace we reduce our credentials to just what can be done in that user namespace. This is a subset of the credentials we previously had. Teach commit_creds to recognize this is a subset of the credentials we have had before and don't clear the dumpability flag. This allows an unprivileged program to do: unshare(CLONE_NEWUSER); fd = open("/proc/self/uid_map", O_RDWR); Where previously opening the uid_map writable would fail because the the task had been made non-dumpable. Acked-by:
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- 02 Oct, 2012 1 commit
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David Howells authored
Make the session keyring per-thread rather than per-process, but still inherited from the parent thread to solve a problem with PAM and gdm. The problem is that join_session_keyring() will reject attempts to change the session keyring of a multithreaded program but gdm is now multithreaded before it gets to the point of starting PAM and running pam_keyinit to create the session keyring. See: https://bugs.freedesktop.org/show_bug.cgi?id=49211 The reason that join_session_keyring() will only change the session keyring under a single-threaded environment is that it's hard to alter the other thread's credentials to effect the change in a multi-threaded program. The problems are such as: (1) How to prevent two threads both running join_session_keyring() from racing. (2) Another thread's credentials may not be modified directly by this process. (3) The number of threads is uncertain whilst we're not holding the appropriate spinlock, making preallocation slightly tricky. (4) We could use TIF_NOTIFY_RESUME and key_replace_session_keyring() to get another thread to replace its keyring, but that means preallocating for each thread. A reasonable way around this is to make the session keyring per-thread rather than per-process and just document that if you want a common session keyring, you must get it before you spawn any threads - which is the current situation anyway. Whilst we're at it, we can the process keyring behave in the same way. This means we can clean up some of the ickyness in the creds code. Basically, after this patch, the session, process and thread keyrings are about inheritance rules only and not about sharing changes of keyring. Reported-by:
Mantas M. <grawity@gmail.com> Signed-off-by:
Ray Strode <rstrode@redhat.com>
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- 24 Aug, 2012 1 commit
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Eric W. Biederman authored
Cc: David Howells <dhowells@redhat.com> Acked-by:
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- 24 May, 2012 1 commit
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Oleg Nesterov authored
Kill the no longer used task_struct->replacement_session_keyring, update copy_creds() and exit_creds(). Signed-off-by:
Al Viro <viro@zeniv.linux.org.uk>
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- 03 May, 2012 1 commit
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Eric W. Biederman authored
cred.h and a few trivial users of struct cred are changed. The rest of the users of struct cred are left for other patches as there are too many changes to make in one go and leave the change reviewable. If the user namespace is disabled and CONFIG_UIDGID_STRICT_TYPE_CHECKS are disabled the code will contiue to compile and behave correctly. Acked-by:
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- 11 Apr, 2012 1 commit
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Oleg Nesterov authored
keyctl_session_to_parent(task) sets ->replacement_session_keyring, it should be processed and cleared by key_replace_session_keyring(). However, this task can fork before it notices TIF_NOTIFY_RESUME and the new child gets the bogus ->replacement_session_keyring copied by dup_task_struct(). This is obviously wrong and, if nothing else, this leads to put_cred(already_freed_cred). change copy_creds() to clear this member. If copy_process() fails before this point the wrong ->replacement_session_keyring doesn't matter, exit_creds() won't be called. Cc: <stable@vger.kernel.org> Signed-off-by:
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- 07 Apr, 2012 1 commit
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Eric W. Biederman authored
struct user_struct will shortly loose it's user_ns reference so make the cred user_ns reference a proper reference complete with reference counting. Acked-by:
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- 13 Feb, 2012 1 commit
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Al Viro authored
Trim security.h Signed-off-by:
James Morris <jmorris@namei.org>
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- 31 Oct, 2011 1 commit
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Paul Gortmaker authored
The changed files were only including linux/module.h for the EXPORT_SYMBOL infrastructure, and nothing else. Revector them onto the isolated export header for faster compile times. Nothing to see here but a whole lot of instances of: -#include <linux/module.h> +#include <linux/export.h> This commit is only changing the kernel dir; next targets will probably be mm, fs, the arch dirs, etc. Signed-off-by:Paul Gortmaker <paul.gortmaker@windriver.com>
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- 23 Aug, 2011 1 commit
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Axel Lin authored
This patch adds CONFIG_KEYS guard for tgcred to fix below build error if CONFIG_KEYS is not configured. CC kernel/cred.o kernel/cred.c: In function 'prepare_kernel_cred': kernel/cred.c:657: error: 'tgcred' undeclared (first use in this function) kernel/cred.c:657: error: (Each undeclared identifier is reported only once kernel/cred.c:657: error: for each function it appears in.) make[1]: *** [kernel/cred.o] Error 1 make: *** [kernel] Error 2 Signed-off-by:
Axel Lin <axel.lin@gmail.com> Acked-by:
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- 22 Aug, 2011 1 commit
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David Howells authored
Fix prepare_kernel_cred() to provide a new, separate thread_group_cred struct otherwise when using request_key() ____call_usermodehelper() calls umh_keys_init() with the new creds pointing to init_tgcred, which umh_keys_init() then blithely alters. The problem can be demonstrated by: # keyctl request2 user a debug:a @s 249681132 # grep req /proc/keys 079906a5 I--Q-- 1 perm 1f3f0000 0 0 keyring _req.249681132: 1/4 38ef1626 IR---- 1 expd 0b010000 0 0 .request_ key:ee1d4ec pid:4371 ci:1 The keyring _req.XXXX should have gone away, but something (init_tgcred) is pinning it. That key actually requested can then be removed and a new one created: # keyctl unlink 249681132 1 links removed [root@andromeda ~]# grep req /proc/keys 116cecac IR---- 1 expd 0b010000 0 0 .request_ key:eeb4911 pid:4379 ci:1 36d1cbf8 I--Q-- 1 perm 1f3f0000 0 0 keyring _req.250300689: 1/4 which causes the old _req keyring to go away and a new one to take its place. This is a consequence of the changes in: commit 87966996 Author: David Howells <dhowells@redhat.com> Date: Fri Jun 17 11:25:59 2011 +0100 KEYS/DNS: Fix ____call_usermodehelper() to not lose the session keyring and: commit 17f60a7d Author: Eric Paris <eparis@redhat.com> Date: Fri Apr 1 17:07:50 2011 -0400 capabilites: allow the application of capability limits to usermode helpers After this patch is applied, the _req keyring and the .request_key key are cleaned up. Signed-off-by:
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