License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 22:07:57 +08:00
|
|
|
/* SPDX-License-Identifier: GPL-2.0 */
|
2005-04-17 06:20:36 +08:00
|
|
|
/*
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
* A security identifier table (sidtab) is a lookup table
|
2005-04-17 06:20:36 +08:00
|
|
|
* of security context structures indexed by SID value.
|
|
|
|
|
*
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
* Original author: Stephen Smalley, <sds@tycho.nsa.gov>
|
|
|
|
|
* Author: Ondrej Mosnacek, <omosnacek@gmail.com>
|
|
|
|
|
*
|
|
|
|
|
* Copyright (C) 2018 Red Hat, Inc.
|
2005-04-17 06:20:36 +08:00
|
|
|
*/
|
|
|
|
|
#ifndef _SS_SIDTAB_H_
|
|
|
|
|
#define _SS_SIDTAB_H_
|
|
|
|
|
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
#include <linux/spinlock_types.h>
|
|
|
|
|
#include <linux/log2.h>
|
2019-11-22 17:33:06 +08:00
|
|
|
#include <linux/hashtable.h>
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
#include "context.h"
|
|
|
|
|
|
2019-11-26 21:57:00 +08:00
|
|
|
struct sidtab_entry {
|
2019-11-22 17:33:06 +08:00
|
|
|
u32 sid;
|
2020-04-17 16:11:57 +08:00
|
|
|
u32 hash;
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
struct context context;
|
2019-11-26 21:57:00 +08:00
|
|
|
#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
|
|
|
|
|
struct sidtab_str_cache __rcu *cache;
|
|
|
|
|
#endif
|
2019-11-22 17:33:06 +08:00
|
|
|
struct hlist_node list;
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
};
|
|
|
|
|
|
|
|
|
|
union sidtab_entry_inner {
|
|
|
|
|
struct sidtab_node_inner *ptr_inner;
|
|
|
|
|
struct sidtab_node_leaf *ptr_leaf;
|
2005-04-17 06:20:36 +08:00
|
|
|
};
|
|
|
|
|
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
/* align node size to page boundary */
|
|
|
|
|
#define SIDTAB_NODE_ALLOC_SHIFT PAGE_SHIFT
|
|
|
|
|
#define SIDTAB_NODE_ALLOC_SIZE PAGE_SIZE
|
|
|
|
|
|
|
|
|
|
#define size_to_shift(size) ((size) == 1 ? 1 : (const_ilog2((size) - 1) + 1))
|
|
|
|
|
|
|
|
|
|
#define SIDTAB_INNER_SHIFT \
|
|
|
|
|
(SIDTAB_NODE_ALLOC_SHIFT - size_to_shift(sizeof(union sidtab_entry_inner)))
|
|
|
|
|
#define SIDTAB_INNER_ENTRIES ((size_t)1 << SIDTAB_INNER_SHIFT)
|
|
|
|
|
#define SIDTAB_LEAF_ENTRIES \
|
2019-11-26 21:57:00 +08:00
|
|
|
(SIDTAB_NODE_ALLOC_SIZE / sizeof(struct sidtab_entry))
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2019-08-14 21:33:20 +08:00
|
|
|
#define SIDTAB_MAX_BITS 32
|
|
|
|
|
#define SIDTAB_MAX U32_MAX
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
/* ensure enough tree levels for SIDTAB_MAX entries */
|
|
|
|
|
#define SIDTAB_MAX_LEVEL \
|
|
|
|
|
DIV_ROUND_UP(SIDTAB_MAX_BITS - size_to_shift(SIDTAB_LEAF_ENTRIES), \
|
|
|
|
|
SIDTAB_INNER_SHIFT)
|
|
|
|
|
|
|
|
|
|
struct sidtab_node_leaf {
|
2019-11-26 21:57:00 +08:00
|
|
|
struct sidtab_entry entries[SIDTAB_LEAF_ENTRIES];
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
};
|
|
|
|
|
|
|
|
|
|
struct sidtab_node_inner {
|
|
|
|
|
union sidtab_entry_inner entries[SIDTAB_INNER_ENTRIES];
|
|
|
|
|
};
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2018-11-30 23:24:07 +08:00
|
|
|
struct sidtab_isid_entry {
|
|
|
|
|
int set;
|
2019-11-26 21:57:00 +08:00
|
|
|
struct sidtab_entry entry;
|
2018-11-30 23:24:07 +08:00
|
|
|
};
|
|
|
|
|
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
struct sidtab_convert_params {
|
selinux: enable use of both GFP_KERNEL and GFP_ATOMIC in convert_context()
The following warning was triggered on a hardware environment:
SELinux: Converting 162 SID table entries...
BUG: sleeping function called from invalid context at
__might_sleep+0x60/0x74 0x0
in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 5943, name: tar
CPU: 7 PID: 5943 Comm: tar Tainted: P O 5.10.0 #1
Call trace:
dump_backtrace+0x0/0x1c8
show_stack+0x18/0x28
dump_stack+0xe8/0x15c
___might_sleep+0x168/0x17c
__might_sleep+0x60/0x74
__kmalloc_track_caller+0xa0/0x7dc
kstrdup+0x54/0xac
convert_context+0x48/0x2e4
sidtab_context_to_sid+0x1c4/0x36c
security_context_to_sid_core+0x168/0x238
security_context_to_sid_default+0x14/0x24
inode_doinit_use_xattr+0x164/0x1e4
inode_doinit_with_dentry+0x1c0/0x488
selinux_d_instantiate+0x20/0x34
security_d_instantiate+0x70/0xbc
d_splice_alias+0x4c/0x3c0
ext4_lookup+0x1d8/0x200 [ext4]
__lookup_slow+0x12c/0x1e4
walk_component+0x100/0x200
path_lookupat+0x88/0x118
filename_lookup+0x98/0x130
user_path_at_empty+0x48/0x60
vfs_statx+0x84/0x140
vfs_fstatat+0x20/0x30
__se_sys_newfstatat+0x30/0x74
__arm64_sys_newfstatat+0x1c/0x2c
el0_svc_common.constprop.0+0x100/0x184
do_el0_svc+0x1c/0x2c
el0_svc+0x20/0x34
el0_sync_handler+0x80/0x17c
el0_sync+0x13c/0x140
SELinux: Context system_u:object_r:pssp_rsyslog_log_t:s0:c0 is
not valid (left unmapped).
It was found that within a critical section of spin_lock_irqsave in
sidtab_context_to_sid(), convert_context() (hooked by
sidtab_convert_params.func) might cause the process to sleep via
allocating memory with GFP_KERNEL, which is problematic.
As Ondrej pointed out [1], convert_context()/sidtab_convert_params.func
has another caller sidtab_convert_tree(), which is okay with GFP_KERNEL.
Therefore, fix this problem by adding a gfp_t argument for
convert_context()/sidtab_convert_params.func and pass GFP_KERNEL/_ATOMIC
properly in individual callers.
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20221018120111.1474581-1-gongruiqi1@huawei.com/ [1]
Reported-by: Tan Ninghao <tanninghao1@huawei.com>
Fixes: ee1a84fdfeed ("selinux: overhaul sidtab to fix bug and improve performance")
Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
[PM: wrap long BUG() output lines, tweak subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-10-19 10:57:10 +08:00
|
|
|
int (*func)(struct context *oldc, struct context *newc, void *args, gfp_t gfp_flags);
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
void *args;
|
|
|
|
|
struct sidtab *target;
|
|
|
|
|
};
|
|
|
|
|
|
2019-11-22 17:33:06 +08:00
|
|
|
#define SIDTAB_HASH_BITS CONFIG_SECURITY_SELINUX_SIDTAB_HASH_BITS
|
|
|
|
|
#define SIDTAB_HASH_BUCKETS (1 << SIDTAB_HASH_BITS)
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
struct sidtab {
|
2019-08-14 21:33:20 +08:00
|
|
|
/*
|
|
|
|
|
* lock-free read access only for as many items as a prior read of
|
|
|
|
|
* 'count'
|
|
|
|
|
*/
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
union sidtab_entry_inner roots[SIDTAB_MAX_LEVEL + 1];
|
2019-08-14 21:33:20 +08:00
|
|
|
/*
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|
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|
* access atomically via {READ|WRITE}_ONCE(); only increment under
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* spinlock
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*/
|
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|
|
|
u32 count;
|
|
|
|
|
/* access only under spinlock */
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
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struct sidtab_convert_params *convert;
|
2021-04-07 15:24:43 +08:00
|
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bool frozen;
|
2005-04-17 06:20:36 +08:00
|
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spinlock_t lock;
|
2018-11-30 23:24:07 +08:00
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2019-11-26 21:57:00 +08:00
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#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
|
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/* SID -> context string cache */
|
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u32 cache_free_slots;
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struct list_head cache_lru_list;
|
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spinlock_t cache_lock;
|
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#endif
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|
2018-11-30 23:24:07 +08:00
|
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/* index == SID - 1 (no entry for SECSID_NULL) */
|
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struct sidtab_isid_entry isids[SECINITSID_NUM];
|
2019-11-22 17:33:06 +08:00
|
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/* Hash table for fast reverse context-to-sid lookups. */
|
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DECLARE_HASHTABLE(context_to_sid, SIDTAB_HASH_BITS);
|
2005-04-17 06:20:36 +08:00
|
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|
};
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int sidtab_init(struct sidtab *s);
|
2018-11-30 23:24:07 +08:00
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int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context);
|
2019-11-26 21:57:00 +08:00
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struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid);
|
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struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid);
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static inline struct context *sidtab_search(struct sidtab *s, u32 sid)
|
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|
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{
|
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|
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struct sidtab_entry *entry = sidtab_search_entry(s, sid);
|
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return entry ? &entry->context : NULL;
|
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}
|
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static inline struct context *sidtab_search_force(struct sidtab *s, u32 sid)
|
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|
|
|
{
|
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|
|
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struct sidtab_entry *entry = sidtab_search_entry_force(s, sid);
|
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|
|
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|
return entry ? &entry->context : NULL;
|
|
|
|
|
}
|
2005-04-17 06:20:36 +08:00
|
|
|
|
selinux: overhaul sidtab to fix bug and improve performance
Before this patch, during a policy reload the sidtab would become frozen
and trying to map a new context to SID would be unable to add a new
entry to sidtab and fail with -ENOMEM.
Such failures are usually propagated into userspace, which has no way of
distignuishing them from actual allocation failures and thus doesn't
handle them gracefully. Such situation can be triggered e.g. by the
following reproducer:
while true; do load_policy; echo -n .; sleep 0.1; done &
for (( i = 0; i < 1024; i++ )); do
runcon -l s0:c$i echo -n x || break
# or:
# chcon -l s0:c$i <some_file> || break
done
This patch overhauls the sidtab so it doesn't need to be frozen during
policy reload, thus solving the above problem.
The new SID table leverages the fact that SIDs are allocated
sequentially and are never invalidated and stores them in linear buckets
indexed by a tree structure. This brings several advantages:
1. Fast SID -> context lookup - this lookup can now be done in
logarithmic time complexity (usually in less than 4 array lookups)
and can still be done safely without locking.
2. No need to re-search the whole table on reverse lookup miss - after
acquiring the spinlock only the newly added entries need to be
searched, which means that reverse lookups that end up inserting a
new entry are now about twice as fast.
3. No need to freeze sidtab during policy reload - it is now possible
to handle insertion of new entries even during sidtab conversion.
The tree structure of the new sidtab is able to grow automatically to up
to about 2^31 entries (at which point it should not have more than about
4 tree levels). The old sidtab had a theoretical capacity of almost 2^32
entries, but half of that is still more than enough since by that point
the reverse table lookups would become unusably slow anyway...
The number of entries per tree node is selected automatically so that
each node fits into a single page, which should be the easiest size for
kmalloc() to handle.
Note that the cache for reverse lookup is preserved with equivalent
logic. The only difference is that instead of storing pointers to the
hash table nodes it stores just the indices of the cached entries.
The new cache ensures that the indices are loaded/stored atomically, but
it still has the drawback that concurrent cache updates may mess up the
contents of the cache. Such situation however only reduces its
effectivity, not the correctness of lookups.
Tested by selinux-testsuite and thoroughly tortured by this simple
stress test:
```
function rand_cat() {
echo $(( $RANDOM % 1024 ))
}
function do_work() {
while true; do
echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \
>/sys/fs/selinux/context 2>/dev/null || true
done
}
do_work >/dev/null &
do_work >/dev/null &
do_work >/dev/null &
while load_policy; do echo -n .; sleep 0.1; done
kill %1
kill %2
kill %3
```
Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
Reported-by: Orion Poplawski <orion@nwra.com>
Reported-by: Li Kun <hw.likun@huawei.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: most of sidtab.c merged by hand due to conflicts]
[PM: checkpatch fixes in mls.c, services.c, sidtab.c]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2018-11-30 23:24:08 +08:00
|
|
|
int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params);
|
2005-04-17 06:20:36 +08:00
|
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|
|
2020-08-07 21:29:34 +08:00
|
|
|
void sidtab_cancel_convert(struct sidtab *s);
|
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|
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|
2021-04-07 15:24:43 +08:00
|
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void sidtab_freeze_begin(struct sidtab *s, unsigned long *flags) __acquires(&s->lock);
|
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|
void sidtab_freeze_end(struct sidtab *s, unsigned long *flags) __releases(&s->lock);
|
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|
2018-11-30 23:24:07 +08:00
|
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int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid);
|
2005-04-17 06:20:36 +08:00
|
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|
void sidtab_destroy(struct sidtab *s);
|
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|
2019-11-22 17:33:06 +08:00
|
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|
int sidtab_hash_stats(struct sidtab *sidtab, char *page);
|
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|
|
|
|
2019-11-26 21:57:00 +08:00
|
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|
#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
|
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|
|
|
void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry,
|
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|
|
|
const char *str, u32 str_len);
|
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|
|
|
int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry,
|
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|
|
|
char **out, u32 *out_len);
|
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|
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|
#else
|
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|
|
|
static inline void sidtab_sid2str_put(struct sidtab *s,
|
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|
|
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struct sidtab_entry *entry,
|
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|
|
|
const char *str, u32 str_len)
|
|
|
|
|
{
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|
}
|
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|
static inline int sidtab_sid2str_get(struct sidtab *s,
|
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struct sidtab_entry *entry,
|
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|
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|
char **out, u32 *out_len)
|
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|
|
|
{
|
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|
return -ENOENT;
|
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|
|
|
}
|
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|
#endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */
|
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|
2005-04-17 06:20:36 +08:00
|
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|
#endif /* _SS_SIDTAB_H_ */
|
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