linux.git/security/keys/key.c, branch v5.2

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

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 license as published by
  the free software foundation either version 2 of the license 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 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

keys: Timestamp new keys

2019-02-15T22:12:09+00:00

Set the timestamp on new keys rather than leaving it unset.

Fixes: 31d5a79d7f3d ("KEYS: Do LRU discard in full keyrings")
Signed-off-by: David Howells 
Signed-off-by: James Morris

KEYS: allow reaching the keys quotas exactly

2019-02-15T22:12:08+00:00

If the sysctl 'kernel.keys.maxkeys' is set to some number n, then
actually users can only add up to 'n - 1' keys.  Likewise for
'kernel.keys.maxbytes' and the root_* versions of these sysctls.  But
these sysctls are apparently supposed to be *maximums*, as per their
names and all documentation I could find -- the keyrings(7) man page,
Documentation/security/keys/core.rst, and all the mentions of EDQUOT
meaning that the key quota was *exceeded* (as opposed to reached).

Thus, fix the code to allow reaching the quotas exactly.

Fixes: 0b77f5bfb45c ("keys: make the keyring quotas controllable through /proc/sys")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers 
Signed-off-by: David Howells 
Signed-off-by: James Morris

security: audit and remove any unnecessary uses of module.h

2018-12-12T22:58:51+00:00

Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends.  That changed
when we forked out support for the latter into the export.h file.
This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig.

The advantage in removing such instances is that module.h itself
sources about 15 other headers; adding significantly to what we feed
cpp, and it can obscure what headers we are effectively using.

Since module.h might have been the implicit source for init.h
(for __init) and for export.h (for EXPORT_SYMBOL) we consider each
instance for the presence of either and replace as needed.

Cc: James Morris 
Cc: "Serge E. Hallyn" 
Cc: John Johansen 
Cc: Mimi Zohar 
Cc: Dmitry Kasatkin 
Cc: David Howells 
Cc: linux-security-module@vger.kernel.org
Cc: linux-integrity@vger.kernel.org
Cc: keyrings@vger.kernel.org
Signed-off-by: Paul Gortmaker 
Signed-off-by: James Morris

security: keys: remove redundant assignment to key_ref

2017-12-08T15:13:29+00:00

Variable key_ref is being assigned a value that is never read;
key_ref is being re-assigned a few statements later.  Hence this
assignment is redundant and can be removed.

Signed-off-by: Colin Ian King 
Signed-off-by: David Howells 
Reviewed-by: James Morris

security: keys: Replace time_t with time64_t for struct key_preparsed_payload

2017-11-15T16:38:45+00:00

The 'struct key_preparsed_payload' will use 'time_t' which we will
try to remove in the kernel, since 'time_t' is not year 2038 safe on
32bits systems.

Thus this patch replaces 'time_t' with 'time64_t' which is year 2038
safe on 32 bits system for 'struct key_preparsed_payload', moreover
we should use the 'TIME64_MAX' macro to initialize the 'time64_t'
type variable.

Signed-off-by: Baolin Wang 
Reviewed-by: Arnd Bergmann 
Signed-off-by: David Howells 
Reviewed-by: James Morris

security: keys: Replace time_t/timespec with time64_t

2017-11-15T16:38:45+00:00

The 'struct key' will use 'time_t' which we try to remove in the
kernel, since 'time_t' is not year 2038 safe on 32bit systems.
Also the 'struct keyring_search_context' will use 'timespec' type
to record current time, which is also not year 2038 safe on 32bit
systems.

Thus this patch replaces 'time_t' with 'time64_t' which is year 2038
safe for 'struct key', and replace 'timespec' with 'time64_t' for the
'struct keyring_search_context', since we only look at the the seconds
part of 'timespec' variable. Moreover we also change the codes where
using the 'time_t' and 'timespec', and we can get current time by
ktime_get_real_seconds() instead of current_kernel_time(), and use
'TIME64_MAX' macro to initialize the 'time64_t' type variable.

Especially in proc.c file, we have replaced 'unsigned long' and 'timespec'
type with 'u64' and 'time64_t' type to save the timeout value, which means
user will get one 'u64' type timeout value by issuing proc_keys_show()
function.

Signed-off-by: Baolin Wang 
Reviewed-by: Arnd Bergmann 
Signed-off-by: David Howells 
Reviewed-by: James Morris

KEYS: don't let add_key() update an uninstantiated key

2017-10-18T08:12:40+00:00

Currently, when passed a key that already exists, add_key() will call the
key's ->update() method if such exists.  But this is heavily broken in the
case where the key is uninstantiated because it doesn't call
__key_instantiate_and_link().  Consequently, it doesn't do most of the
things that are supposed to happen when the key is instantiated, such as
setting the instantiation state, clearing KEY_FLAG_USER_CONSTRUCT and
awakening tasks waiting on it, and incrementing key->user->nikeys.

It also never takes key_construction_mutex, which means that
->instantiate() can run concurrently with ->update() on the same key.  In
the case of the "user" and "logon" key types this causes a memory leak, at
best.  Maybe even worse, the ->update() methods of the "encrypted" and
"trusted" key types actually just dereference a NULL pointer when passed an
uninstantiated key.

Change key_create_or_update() to wait interruptibly for the key to finish
construction before continuing.

This patch only affects *uninstantiated* keys.  For now we still allow a
negatively instantiated key to be updated (thereby positively
instantiating it), although that's broken too (the next patch fixes it)
and I'm not sure that anyone actually uses that functionality either.

Here is a simple reproducer for the bug using the "encrypted" key type
(requires CONFIG_ENCRYPTED_KEYS=y), though as noted above the bug
pertained to more than just the "encrypted" key type:

    #include 
    #include 
    #include 

    int main(void)
    {
        int ringid = keyctl_join_session_keyring(NULL);

        if (fork()) {
            for (;;) {
                const char payload[] = "update user:foo 32";

                usleep(rand() % 10000);
                add_key("encrypted", "desc", payload, sizeof(payload), ringid);
                keyctl_clear(ringid);
            }
        } else {
            for (;;)
                request_key("encrypted", "desc", "callout_info", ringid);
        }
    }

It causes:

    BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
    IP: encrypted_update+0xb0/0x170
    PGD 7a178067 P4D 7a178067 PUD 77269067 PMD 0
    PREEMPT SMP
    CPU: 0 PID: 340 Comm: reproduce Tainted: G      D         4.14.0-rc1-00025-g428490e38b2e #796
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
    task: ffff8a467a39a340 task.stack: ffffb15c40770000
    RIP: 0010:encrypted_update+0xb0/0x170
    RSP: 0018:ffffb15c40773de8 EFLAGS: 00010246
    RAX: 0000000000000000 RBX: ffff8a467a275b00 RCX: 0000000000000000
    RDX: 0000000000000005 RSI: ffff8a467a275b14 RDI: ffffffffb742f303
    RBP: ffffb15c40773e20 R08: 0000000000000000 R09: ffff8a467a275b17
    R10: 0000000000000020 R11: 0000000000000000 R12: 0000000000000000
    R13: 0000000000000000 R14: ffff8a4677057180 R15: ffff8a467a275b0f
    FS:  00007f5d7fb08700(0000) GS:ffff8a467f200000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000000000000018 CR3: 0000000077262005 CR4: 00000000001606f0
    Call Trace:
     key_create_or_update+0x2bc/0x460
     SyS_add_key+0x10c/0x1d0
     entry_SYSCALL_64_fastpath+0x1f/0xbe
    RIP: 0033:0x7f5d7f211259
    RSP: 002b:00007ffed03904c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000f8
    RAX: ffffffffffffffda RBX: 000000003b2a7955 RCX: 00007f5d7f211259
    RDX: 00000000004009e4 RSI: 00000000004009ff RDI: 0000000000400a04
    RBP: 0000000068db8bad R08: 000000003b2a7955 R09: 0000000000000004
    R10: 000000000000001a R11: 0000000000000246 R12: 0000000000400868
    R13: 00007ffed03905d0 R14: 0000000000000000 R15: 0000000000000000
    Code: 77 28 e8 64 34 1f 00 45 31 c0 31 c9 48 8d 55 c8 48 89 df 48 8d 75 d0 e8 ff f9 ff ff 85 c0 41 89 c4 0f 88 84 00 00 00 4c 8b 7d c8 <49> 8b 75 18 4c 89 ff e8 24 f8 ff ff 85 c0 41 89 c4 78 6d 49 8b
    RIP: encrypted_update+0xb0/0x170 RSP: ffffb15c40773de8
    CR2: 0000000000000018

Cc:  # v2.6.12+
Reported-by: Eric Biggers 
Signed-off-by: David Howells 
cc: Eric Biggers

KEYS: Fix race between updating and finding a negative key

2017-10-18T08:12:40+00:00

Consolidate KEY_FLAG_INSTANTIATED, KEY_FLAG_NEGATIVE and the rejection
error into one field such that:

 (1) The instantiation state can be modified/read atomically.

 (2) The error can be accessed atomically with the state.

 (3) The error isn't stored unioned with the payload pointers.

This deals with the problem that the state is spread over three different
objects (two bits and a separate variable) and reading or updating them
atomically isn't practical, given that not only can uninstantiated keys
change into instantiated or rejected keys, but rejected keys can also turn
into instantiated keys - and someone accessing the key might not be using
any locking.

The main side effect of this problem is that what was held in the payload
may change, depending on the state.  For instance, you might observe the
key to be in the rejected state.  You then read the cached error, but if
the key semaphore wasn't locked, the key might've become instantiated
between the two reads - and you might now have something in hand that isn't
actually an error code.

The state is now KEY_IS_UNINSTANTIATED, KEY_IS_POSITIVE or a negative error
code if the key is negatively instantiated.  The key_is_instantiated()
function is replaced with key_is_positive() to avoid confusion as negative
keys are also 'instantiated'.

Additionally, barriering is included:

 (1) Order payload-set before state-set during instantiation.

 (2) Order state-read before payload-read when using the key.

Further separate barriering is necessary if RCU is being used to access the
payload content after reading the payload pointers.

Fixes: 146aa8b1453b ("KEYS: Merge the type-specific data with the payload data")
Cc: stable@vger.kernel.org # v4.4+
Reported-by: Eric Biggers 
Signed-off-by: David Howells 
Reviewed-by: Eric Biggers

KEYS: reset parent each time before searching key_user_tree

2017-09-25T14:19:57+00:00

In key_user_lookup(), if there is no key_user for the given uid, we drop
key_user_lock, allocate a new key_user, and search the tree again.  But
we failed to set 'parent' to NULL at the beginning of the second search.
If the tree were to be empty for the second search, the insertion would
be done with an invalid 'parent', scribbling over freed memory.

Fortunately this can't actually happen currently because the tree always
contains at least the root_key_user.  But it still should be fixed to
make the code more robust.

Signed-off-by: Eric Biggers 
Signed-off-by: David Howells