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In commit c628c2296392ed3bf2cb8d8470668e64fe53389f (elf: Remove
ldconfig kernel version check), the layout of auxcache entries
changed because the osversion field was removed from
struct aux_cache_file_entry. However, AUX_CACHEMAGIC was not
changed, so existing files are still used, potentially leading
to unintended ldconfig behavior. This commit changes AUX_CACHEMAGIC,
so that the file is regenerated.
Reported-by: DJ Delorie <dj@redhat.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit 0a536f6e2f76e3ef581b3fd9af1e5cf4ddc7a5a2)
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_wide_data and _mode are not available in legacy code, so do not attempt
to free the wide backup buffer in legacy code.
Resolves: BZ #32137 and BZ #27821
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
(cherry picked from commit ae4d44b1d501421ad9a3af95279b8f4d1546f1ce)
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Rename the identifier sz to __sz everywhere.
Fixes: a643f60c53 ("Make sure that the fortified function conditionals are constant")
(cherry picked from commit 39ca997ab378990d5ac1aadbaa52aaf1db6d526f)
(redone from scratch because of many conflicts)
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Update the mremap C implementation to support the optional argument for
MREMAP_DONTUNMAP added in Linux 5.7 since it may not always be correct
to implement a variadic function as a non-variadic function on all Linux
targets. Return MAP_FAILED and set errno to EINVAL for unknown flag bits.
This fixes BZ #31968.
Note: A test must be added when a new flag bit is introduced.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit 6c40cb0e9f893d49dc7caee580a055de53562206)
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This avoids changing _res.options, which inteferes with change
detection as part of automatic reloading of /etc/resolv.conf.
Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit 868ab8923a2ec977faafec97ecafac0c3159c1b2)
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In single-request mode, there is no second response after an error
because the second query has not been sent yet. Waiting for it
introduces an unnecessary timeout.
Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit af625987d619388a100b153520d3ee308bda9889)
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Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit 691a3b2e9bfaba842e46a5ccb7f5e6ea144c3ade)
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The __rseq_size value is now the active area of struct rseq
(so 20 initially), not the full struct size including padding
at the end (32 initially).
Update misc/tst-rseq to print some additional diagnostics.
Reviewed-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
(cherry picked from commit 2e456ccf0c34a056e3ccafac4a0c7effef14d918)
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The multibyte character needs to fit into the remaining buffer space,
not the already-written buffer space. Without the fix, we were never
moving the write pointer from the start of the buffer, always using
the single-character fallback buffer.
Fixes commit 04b76b5aa8b2d1d19066e42dd1 ("Don't error out writing
a multibyte character to an unbuffered stream (bug 17522)").
(cherry picked from commit ecc7c3deb9f347649c2078fcc0f94d4cedf92d60)
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_dl_tlsdesc_undefweak and _dl_tlsdesc_dynamic access the thread pointer
via the tcb field in TCB:
_dl_tlsdesc_undefweak:
_CET_ENDBR
movq 8(%rax), %rax
subq %fs:0, %rax
ret
_dl_tlsdesc_dynamic:
...
subq %fs:0, %rax
movq -8(%rsp), %rdi
ret
Since the tcb field in TCB is a pointer, %fs:0 is a 32-bit location,
not 64-bit. It should use "sub %fs:0, %RAX_LP" instead. Since
_dl_tlsdesc_undefweak returns ptrdiff_t and _dl_make_tlsdesc_dynamic
returns void *, RAX_LP is appropriate here for x32 and x86-64. This
fixes BZ #31185.
(cherry picked from commit 81be2a61dafc168327c1639e97b6dae128c7ccf3)
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On x32, I got
FAIL: elf/tst-tlsgap
$ gdb elf/tst-tlsgap
...
open tst-tlsgap-mod1.so
Thread 2 "tst-tlsgap" received signal SIGSEGV, Segmentation fault.
[Switching to LWP 2268754]
_dl_tlsdesc_dynamic () at ../sysdeps/x86_64/dl-tlsdesc.S:108
108 movq (%rsi), %rax
(gdb) p/x $rsi
$4 = 0xf7dbf9005655fb18
(gdb)
This is caused by
_dl_tlsdesc_dynamic:
_CET_ENDBR
/* Preserve call-clobbered registers that we modify.
We need two scratch regs anyway. */
movq %rsi, -16(%rsp)
movq %fs:DTV_OFFSET, %rsi
Since the dtv field in TCB is a pointer, %fs:DTV_OFFSET is a 32-bit
location, not 64-bit. Load the dtv field to RSI_LP instead of rsi.
This fixes BZ #31184.
(cherry picked from commit 3502440397bbb840e2f7223734aa5cc2cc0e29b6)
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This reverts commit a7e34a667585f675143563569688756f4f4a6e47.
Reason for revert: Incompatibility with existing applications.
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The string parsing routine may end up writing beyond bounds of tunestr
if the input tunable string is malformed, of the form name=name=val.
This gets processed twice, first as name=name=val and next as name=val,
resulting in tunestr being name=name=val:name=val, thus overflowing
tunestr.
Terminate the parsing loop at the first instance itself so that tunestr
does not overflow.
This also fixes up tst-env-setuid-tunables to actually handle failures
correct and add new tests to validate the fix for this CVE.
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit 1056e5b4c3f2d90ed2b4a55f96add28da2f4c8fa)
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These are tracked in BZ #30884 and BZ #30843.
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
(cherry picked from commit fd134feba35fa839018965733b34d28a09a075dd)
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Some legacy AMD CPUs and hypervisors have the _cpuid_ '0x8000_001D'
set to Zero, thus resulting in zeroed-out computed cache values.
This patch reintroduces the old way of cache computation as a
fail-safe option to handle these exceptions.
Fixed 'level4_cache_size' value through handle_amd().
Reviewed-by: Premachandra Mallappa <premachandra.mallappa@amd.com>
Tested-by: Florian Weimer <fweimer@redhat.com>
(cherry picked from commit dcad5c8578130dec7f35fd5b0885304b59f9f543)
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Without passing alt_dns_packet_buffer, __res_context_search can only
store 2048 bytes (what fits into dns_packet_buffer). However,
the function returns the total packet size, and the subsequent
DNS parsing code in _nss_dns_gethostbyname4_r reads beyond the end
of the stack-allocated buffer.
Fixes commit f282cdbe7f436c75864e5640a4 ("resolv: Implement no-aaaa
stub resolver option") and bug 30842.
(cherry picked from commit bd77dd7e73e3530203be1c52c8a29d08270cb25d)
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The current implementation of dlclose (and process exit) re-sorts the
link maps before calling ELF destructors. Destructor order is not the
reverse of the constructor order as a result: The second sort takes
relocation dependencies into account, and other differences can result
from ambiguous inputs, such as cycles. (The force_first handling in
_dl_sort_maps is not effective for dlclose.) After the changes in
this commit, there is still a required difference due to
dlopen/dlclose ordering by the application, but the previous
discrepancies went beyond that.
A new global (namespace-spanning) list of link maps,
_dl_init_called_list, is updated right before ELF constructors are
called from _dl_init.
In dl_close_worker, the maps variable, an on-stack variable length
array, is eliminated. (VLAs are problematic, and dlclose should not
call malloc because it cannot readily deal with malloc failure.)
Marking still-used objects uses the namespace list directly, with
next and next_idx replacing the done_index variable.
After marking, _dl_init_called_list is used to call the destructors
of now-unused maps in reverse destructor order. These destructors
can call dlopen. Previously, new objects do not have l_map_used set.
This had to change: There is no copy of the link map list anymore,
so processing would cover newly opened (and unmarked) mappings,
unloading them. Now, _dl_init (indirectly) sets l_map_used, too.
(dlclose is handled by the existing reentrancy guard.)
After _dl_init_called_list traversal, two more loops follow. The
processing order changes to the original link map order in the
namespace. Previously, dependency order was used. The difference
should not matter because relocation dependencies could already
reorder link maps in the old code.
The changes to _dl_fini remove the sorting step and replace it with
a traversal of _dl_init_called_list. The l_direct_opencount
decrement outside the loader lock is removed because it appears
incorrect: the counter manipulation could race with other dynamic
loader operations.
tst-audit23 needs adjustments to the changes in LA_ACT_DELETE
notifications. The new approach for checking la_activity should
make it clearer that la_activty calls come in pairs around namespace
updates.
The dependency sorting test cases need updates because the destructor
order is always the opposite order of constructor order, even with
relocation dependencies or cycles present.
There is a future cleanup opportunity to remove the now-constant
force_first and for_fini arguments from the _dl_sort_maps function.
Fixes commit 1df71d32fe5f5905ffd5d100e5e9ca8ad62 ("elf: Implement
force_first handling in _dl_sort_maps_dfs (bug 28937)").
Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit 6985865bc3ad5b23147ee73466583dd7fdf65892)
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Commit 5f828ff824e3b7cd1 ("io: Fix F_GETLK, F_SETLK, and F_SETLKW for
powerpc64") fixed an issue with the value of the lock constants on
powerpc64 when not using __USE_FILE_OFFSET64, but it ended-up also
changing the value when using __USE_FILE_OFFSET64 causing an API change.
Fix that by also checking that define, restoring the pre
4d0fe291aed3a476a commit values:
Default values:
- F_GETLK: 5
- F_SETLK: 6
- F_SETLKW: 7
With -D_FILE_OFFSET_BITS=64:
- F_GETLK: 12
- F_SETLK: 13
- F_SETLKW: 14
At the same time, it has been noticed that there was no test for io lock
with __USE_FILE_OFFSET64, so just add one.
Tested on x86_64-linux-gnu, i686-linux-gnu and
powerpc64le-unknown-linux-gnu.
Resolves: BZ #30804.
Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
(cherry picked from commit 434bf72a94de68f0cc7fbf3c44bf38c1911b70cb)
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Success is reported with a 0 return value, and failure is -1.
Enhance the kitchen sink test elf/tst-audit28 to cover
_dl_find_object as well.
Fixes commit 5d28a8962dcb ("elf: Add _dl_find_object function")
and bug 30515.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit 1bcfe0f732066ae5336b252295591ebe7e51c301)
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(BZ#30477)
For architecture with default 64 bit time_t support, the kernel
does not provide LFS and non-LFS values for F_GETLK, F_GETLK, and
F_GETLK (the default value used for 64 bit architecture are used).
This is might be considered an ABI break, but the currenct exported
values is bogus anyway.
The POSIX lockf is not affected since it is aliased to lockf64,
which already uses the LFS values.
Checked on i686-linux-gnu and the new tests on a riscv32.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit 4d0fe291aed3a476a3b59c4ecfae9d35ac0f15e8)
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V2 of this patch fixes an issue in V1, where the state was changed to ON not
OFF at end of _mcleanup. I hadn't noticed that (counterintuitively) ON=0 and
OFF=3, hence zeroing the buffer turned it back on. So set the state to OFF
after the memset.
1. Prevent double free, and reads from unallocated memory, when
_mcleanup is (incorrectly) called two or more times in a row,
without an intervening call to __monstartup; with this patch, the
second and subsequent calls effectively become no-ops instead.
While setting tos=NULL is minimal fix, safest action is to zero the
whole gmonparam buffer.
2. Prevent memory leak when __monstartup is (incorrectly) called two
or more times in a row, without an intervening call to _mcleanup;
with this patch, the second and subsequent calls effectively become
no-ops instead.
3. After _mcleanup, treat __moncontrol(1) as __moncontrol(0) instead.
With zeroing of gmonparam buffer in _mcleanup, this stops the
state incorrectly being changed to GMON_PROF_ON despite profiling
actually being off. If we'd just done the minimal fix to _mcleanup
of setting tos=NULL, there is risk of far worse memory corruption:
kcount would point to deallocated memory, and the __profil syscall
would make the kernel write profiling data into that memory,
which could have since been reallocated to something unrelated.
4. Ensure __moncontrol(0) still turns off profiling even in error
state. Otherwise, if mcount overflows and sets state to
GMON_PROF_ERROR, when _mcleanup calls __moncontrol(0), the __profil
syscall to disable profiling will not be invoked. _mcleanup will
free the buffer, but the kernel will still be writing profiling
data into it, potentially corrupted arbitrary memory.
Also adds a test case for (1). Issues (2)-(4) are not feasible to test.
Signed-off-by: Simon Kissane <skissane@gmail.com>
Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit bde121872001d8f3224eeafa5b7effb871c3fbca)
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When mcount overflows, no gmon.out file is generated, but no message is printed
to the user, leaving the user with no idea why, and thinking maybe there is
some bug - which is how BZ 27576 ended up being logged. Print a message to
stderr in this case so the user knows what is going on.
As a comment in sys/gmon.h acknowledges, the hardcoded MAXARCS value is too
small for some large applications, including the test case in that BZ. Rather
than increase it, add tunables to enable MINARCS and MAXARCS to be overridden
at runtime (glibc.gmon.minarcs and glibc.gmon.maxarcs). So if a user gets the
mcount overflow error, they can try increasing maxarcs (they might need to
increase minarcs too if the heuristic is wrong in their case.)
Note setting minarcs/maxarcs too large can cause monstartup to fail with an
out of memory error. If you set them large enough, it can cause an integer
overflow in calculating the buffer size. I haven't done anything to defend
against that - it would not generally be a security vulnerability, since these
tunables will be ignored in suid/sgid programs (due to the SXID_ERASE default),
and if you can set GLIBC_TUNABLES in the environment of a process, you can take
it over anyway (LD_PRELOAD, LD_LIBRARY_PATH, etc). I thought about modifying
the code of monstartup to defend against integer overflows, but doing so is
complicated, and I realise the existing code is susceptible to them even prior
to this change (e.g. try passing a pathologically large highpc argument to
monstartup), so I decided just to leave that possibility in-place.
Add a test case which demonstrates mcount overflow and the tunables.
Document the new tunables in the manual.
Signed-off-by: Simon Kissane <skissane@gmail.com>
Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit 31be941e4367c001b2009308839db5c67bf9dcbc)
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The `__monstartup()` allocates a buffer used to store all the data
accumulated by the monitor.
The size of this buffer depends on the size of the internal structures
used and the address range for which the monitor is activated, as well
as on the maximum density of call instructions and/or callable functions
that could be potentially on a segment of executable code.
In particular a hash table of arcs is placed at the end of this buffer.
The size of this hash table is calculated in bytes as
p->fromssize = p->textsize / HASHFRACTION;
but actually should be
p->fromssize = ROUNDUP(p->textsize / HASHFRACTION, sizeof(*p->froms));
This results in writing beyond the end of the allocated buffer when an
added arc corresponds to a call near from the end of the monitored
address range, since `_mcount()` check the incoming caller address for
monitored range but not the intermediate result hash-like index that
uses to write into the table.
It should be noted that when the results are output to `gmon.out`, the
table is read to the last element calculated from the allocated size in
bytes, so the arcs stored outside the buffer boundary did not fall into
`gprof` for analysis. Thus this "feature" help me to found this bug
during working with https://sourceware.org/bugzilla/show_bug.cgi?id=29438
Just in case, I will explicitly note that the problem breaks the
`make test t=gmon/tst-gmon-dso` added for Bug 29438.
There, the arc of the `f3()` call disappears from the output, since in
the DSO case, the call to `f3` is located close to the end of the
monitored range.
Signed-off-by: Леонид Юрьев (Leonid Yuriev) <leo@yuriev.ru>
Another minor error seems a related typo in the calculation of
`kcountsize`, but since kcounts are smaller than froms, this is
actually to align the p->froms data.
Co-authored-by: DJ Delorie <dj@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit 801af9fafd4689337ebf27260aa115335a0cb2bc)
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Fix bug that SIGCHLD is erroneously blocked forever in the following
scenario:
1. Thread A calls system but hasn't returned yet
2. Thread B calls another system but returns
SIGCHLD would be blocked forever in thread B after its system() returns,
even after the system() in thread A returns.
Although POSIX does not require, glibc system implementation aims to be
thread and cancellation safe. This bug was introduced in
5fb7fc96350575c9adb1316833e48ca11553be49 when we moved reverting signal
mask to happen when the last concurrently running system returns,
despite that signal mask is per thread. This commit reverts this logic
and adds a test.
Signed-off-by: Adam Yi <ayi@janestreet.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit 436a604b7dc741fc76b5a6704c6cd8bb178518e7)
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The divss instruction clobbers its first argument, and the constraints
need to reflect that. Fortunately, with GCC 12, generated code does
not actually change, so there is no externally visible bug.
Suggested-by: Jakub Jelinek <jakub@redhat.com>
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
(cherry picked from commit 5d1ccdda7b0c625751661d50977f3dfbc73f8eae)
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Before this change, sgetsgent_r did not set errno to ERANGE, but
sgetsgent only check errno, not the return value from sgetsgent_r.
Consequently, sgetsgent did not detect any error, and reported
success to the caller, without initializing the struct sgrp object
whose address was returned.
This commit changes sgetsgent_r to set errno as well. This avoids
similar issues in applications which only change errno.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
(cherry picked from commit 969e9733c7d17edf1e239a73fa172f357561f440)
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While cleaning up old libc version support, the deprecated libc4 code was
accidentally kept in `implicit_soname`, instead of the libc6 code.
This causes additional symlinks to be created by `ldconfig` for libraries
without a soname, e.g. a library `libsomething.123.456.789` without a soname
will create a `libsomething.123` -> `libsomething.123.456.789` symlink.
As the libc6 version of the `implicit_soname` code is a trivial `xstrdup`,
just inline it and remove `implicit_soname` altogether.
Some further simplification looks possible (e.g. the call to `create_links`
looks like a no-op if `soname == NULL`, other than the verbose printfs), but
logic is kept as-is for now.
Fixes: BZ #30125
Fixes: 8ee878592c4a ("Assume only FLAG_ELF_LIBC6 suport")
Signed-off-by: Joan Bruguera <joanbrugueram@gmail.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit 1b0ea8c5d886fedabd611a569b5ec58a6f5153e6)
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Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
(cherry picked from commit 67c37737ed474d25fd4dc535dfd822c426e6b971)
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Both functions use time_t only internally, so the ABI is not affected.
(cherry picked from commit 41349f6f67c83e7bafe49f985b56493d2c4c9c77)
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Add a NEWS entry noting the removal of the legacy hwcaps search
mechanism for shared objects.
Signed-off-by: Javier Pello <devel@otheo.eu>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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The ahosts, ahostsv4, ahostsv6 commands unconditionally pass
AI_ADDRCONFIG to getaddrinfo, which is not always desired.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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This reverts commit 6f85dbf102ad7982409ba0fe96886caeb6389fef.
Once this change hits the release branches, it will require relinking
of all statically linked applications before static dlopen works
again, for the majority of updates on release branches: The NEWS file
is regularly updated with bug references, so the __libc_early_init
suffix changes, and static dlopen cannot find the function anymore.
While this ABI check is still technically correct (we do require
rebuilding & relinking after glibc updates to keep static dlopen
working), it is too drastic for stable release branches.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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The files NEWS, include/link.h, and sysdeps/generic/ldsodefs.h
contribute to the version fingerprint used for detection. The
fingerprint can be further refined using the --with-extra-version-id
configure argument.
_dl_call_libc_early_init is replaced with _dl_lookup_libc_early_init.
The new function is used store a pointer to libc.so's
__libc_early_init function in the libc_map_early_init member of the
ld.so namespace structure. This function pointer can then be called
directly, so the separate invocation function is no longer needed.
The versioned symbol lookup needs the symbol versioning data
structures, so the initialization of libc_map and libc_map_early_init
is now done from _dl_check_map_versions, after this information
becomes available. (_dl_map_object_from_fd does not set this up
in time, so the initialization code had to be moved from there.)
This means that the separate initialization code can be removed from
dl_main because _dl_check_map_versions covers all maps, including
the initial executable loaded by the kernel. The lookup still happens
before relocation and the invocation of IFUNC resolvers, so IFUNC
resolvers are protected from ABI mismatch.
The __libc_early_init function pointer is not protected because
so little code runs between the pointer write and the invocation
(only dynamic linker code and IFUNC resolvers).
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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Rather than buffering 16 MiB of entropy in userspace (by way of
chacha20), simply call getrandom() every time.
This approach is doubtlessly slower, for now, but trying to prematurely
optimize arc4random appears to be leading toward all sorts of nasty
properties and gotchas. Instead, this patch takes a much more
conservative approach. The interface is added as a basic loop wrapper
around getrandom(), and then later, the kernel and libc together can
work together on optimizing that.
This prevents numerous issues in which userspace is unaware of when it
really must throw away its buffer, since we avoid buffering all
together. Future improvements may include userspace learning more from
the kernel about when to do that, which might make these sorts of
chacha20-based optimizations more possible. The current heuristic of 16
MiB is meaningless garbage that doesn't correspond to anything the
kernel might know about. So for now, let's just do something
conservative that we know is correct and won't lead to cryptographic
issues for users of this function.
This patch might be considered along the lines of, "optimization is the
root of all evil," in that the much more complex implementation it
replaces moves too fast without considering security implications,
whereas the incremental approach done here is a much safer way of going
about things. Once this lands, we can take our time in optimizing this
properly using new interplay between the kernel and userspace.
getrandom(0) is used, since that's the one that ensures the bytes
returned are cryptographically secure. But on systems without it, we
fallback to using /dev/urandom. This is unfortunate because it means
opening a file descriptor, but there's not much of a choice. Secondly,
as part of the fallback, in order to get more or less the same
properties of getrandom(0), we poll on /dev/random, and if the poll
succeeds at least once, then we assume the RNG is initialized. This is a
rough approximation, as the ancient "non-blocking pool" initialized
after the "blocking pool", not before, and it may not port back to all
ancient kernels, though it does to all kernels supported by glibc
(≥3.2), so generally it's the best approximation we can do.
The motivation for including arc4random, in the first place, is to have
source-level compatibility with existing code. That means this patch
doesn't attempt to litigate the interface itself. It does, however,
choose a conservative approach for implementing it.
Cc: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Cristian Rodríguez <crrodriguez@opensuse.org>
Cc: Paul Eggert <eggert@cs.ucla.edu>
Cc: Mark Harris <mark.hsj@gmail.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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The implementation is based on scalar Chacha20 with per-thread cache.
It uses getrandom or /dev/urandom as fallback to get the initial entropy,
and reseeds the internal state on every 16MB of consumed buffer.
To improve performance and lower memory consumption the per-thread cache
is allocated lazily on first arc4random functions call, and if the
memory allocation fails getentropy or /dev/urandom is used as fallback.
The cache is also cleared on thread exit iff it was initialized (so if
arc4random is not called it is not touched).
Although it is lock-free, arc4random is still not async-signal-safe
(the per thread state is not updated atomically).
The ChaCha20 implementation is based on RFC8439 [1], omitting the final
XOR of the keystream with the plaintext because the plaintext is a
stream of zeros. This strategy is similar to what OpenBSD arc4random
does.
The arc4random_uniform is based on previous work by Florian Weimer,
where the algorithm is based on Jérémie Lumbroso paper Optimal Discrete
Uniform Generation from Coin Flips, and Applications (2013) [2], who
credits Donald E. Knuth and Andrew C. Yao, The complexity of nonuniform
random number generation (1976), for solving the general case.
The main advantage of this method is the that the unit of randomness is not
the uniform random variable (uint32_t), but a random bit. It optimizes the
internal buffer sampling by initially consuming a 32-bit random variable
and then sampling byte per byte. Depending of the upper bound requested,
it might lead to better CPU utilization.
Checked on x86_64-linux-gnu, aarch64-linux, and powerpc64le-linux-gnu.
Co-authored-by: Florian Weimer <fweimer@redhat.com>
Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>
[1] https://datatracker.ietf.org/doc/html/rfc8439
[2] https://arxiv.org/pdf/1304.1916.pdf
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This change provides implementations for the mbrtoc8 and c8rtomb
functions adopted for C++20 via WG21 P0482R6 and for C2X via WG14
N2653. It also provides the char8_t typedef from WG14 N2653.
The mbrtoc8 and c8rtomb functions are declared in uchar.h in C2X
mode or when the _GNU_SOURCE macro or C++20 __cpp_char8_t feature
test macro is defined.
The char8_t typedef is declared in uchar.h in C2X mode or when the
_GNU_SOURCE macro is defined and the C++20 __cpp_char8_t feature
test macro is not defined (if __cpp_char8_t is defined, then char8_t
is a builtin type).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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It was added on Linux 5.12 (2a1867219c7b27f928e2545782b86daaf9ad50bd)
to allow change the properties of a mount or a mount tree using file
descriptors which the new mount api is based on.
Checked on x86_64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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It was added on Linux 5.2 (a07b20004793d8926f78d63eb5980559f7813404)
to return a O_PATH-opened file descriptor to an existing mountpoint.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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It was added on Linux 5.2 (cf3cba4a429be43e5527a3f78859b1bfd9ebc5fb)
that can be used to pick an existing mountpoint into an filesystem
context which can thereafter be used to reconfigure a superblock
with fsconfig syscall.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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It was added on Linux 5.2 (ecdab150fddb42fe6a739335257949220033b782)
as a way to a configure filesystem creation context and trigger
actions upon it, to be used in conjunction with fsopen, fspick and
fsmount.
The fsconfig_command commands are currently only defined as an enum,
so they can't be checked on tst-mount-consts.py with current test
support.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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Previously, they were assumed to be in ISO-8859-1, and that the output
charset overlapped with ISO-8859-1 for the characters actually used.
However, this did not work as intended on many architectures even for
an ISO-8859-1 output encoding because of the char signedness bug in
lr_getc. Therefore, this commit switches to UTF-8 without making
provisions for backwards compatibility.
The following Elisp code can be used to convert locale definition files
to UTF-8:
(defun glibc/convert-localedef (from to)
(interactive "r")
(save-excursion
(save-restriction
(narrow-to-region from to)
(goto-char (point-min))
(save-match-data
(while (re-search-forward "<U\\([0-9a-fA-F]+\\)>" nil t)
(let* ((codepoint (string-to-number (match-string 1) 16))
(converted
(cond
((memq codepoint '(?/ ?\ ?< ?>))
(string ?/ codepoint))
((= codepoint ?\") "<U0022>")
(t (string codepoint)))))
(replace-match converted t)))))))
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
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