Age | Commit message (Collapse) | Author |
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Linux 4.18 and later make reads and writes coherent between pre-copy-up and
post-copy-up FDs representing the same file on an overlay filesystem. However,
memory mappings remain incoherent:
- Documentation/filesystems/overlayfs.rst, "Non-standard behavior": "If a file
residing on a lower layer is opened for read-only and then memory mapped with
MAP_SHARED, then subsequent changes to the file are not reflected in the
memory mapping."
- fs/overlay/file.c:ovl_mmap() passes through to the underlying FD without any
management of coherence in the overlay.
- Experimentally on Linux 5.2:
```
$ cat mmap_cat_page.c
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
int main(int argc, char **argv) {
if (argc < 2) {
errx(1, "syntax: %s [FILE]", argv[0]);
}
const int fd = open(argv[1], O_RDONLY);
if (fd < 0) {
err(1, "open(%s)", argv[1]);
}
const size_t page_size = sysconf(_SC_PAGE_SIZE);
void* page = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
if (page == MAP_FAILED) {
err(1, "mmap");
}
for (;;) {
write(1, page, strnlen(page, page_size));
if (getc(stdin) == EOF) {
break;
}
}
return 0;
}
$ gcc -O2 -o mmap_cat_page mmap_cat_page.c
$ mkdir lowerdir upperdir workdir overlaydir
$ echo old > lowerdir/file
$ sudo mount -t overlay -o "lowerdir=lowerdir,upperdir=upperdir,workdir=workdir" none overlaydir
$ ./mmap_cat_page overlaydir/file
old
^Z
[1]+ Stopped ./mmap_cat_page overlaydir/file
$ echo new > overlaydir/file
$ cat overlaydir/file
new
$ fg
./mmap_cat_page overlaydir/file
old
```
Therefore, while the VFS1 gofer client's behavior of reopening read FDs is only
necessary pre-4.18, replacing existing memory mappings (in both sentry and
application address spaces) with mappings of the new FD is required regardless
of kernel version, and this latter behavior is common to both VFS1 and VFS2.
Re-document accordingly, and change the runsc flag to enabled by default.
New test:
- Before this CL: https://source.cloud.google.com/results/invocations/5b222d2c-e918-4bae-afc4-407f5bac509b
- After this CL: https://source.cloud.google.com/results/invocations/f28c747e-d89c-4d8c-a461-602b33e71aab
PiperOrigin-RevId: 311361267
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PiperOrigin-RevId: 311203776
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Fixes #2651.
PiperOrigin-RevId: 311193661
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PiperOrigin-RevId: 311181084
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kernel.Task.Block() requires that the caller is running on the task goroutine.
netstack.SocketOperations.Write() uses kernel.TaskFromContext() to call
kernel.Task.Block() even if it's not running on the task goroutine. Stop doing
that.
PiperOrigin-RevId: 311178335
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- Added support for matching gid owner and invert flag for uid
and gid.
$ iptables -A OUTPUT -p tcp -m owner --gid-owner root -j ACCEPT
$ iptables -A OUTPUT -p tcp -m owner ! --uid-owner root -j ACCEPT
$ iptables -A OUTPUT -p tcp -m owner ! --gid-owner root -j DROP
- Added tests for uid, gid and invert flags.
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PiperOrigin-RevId: 311153824
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PiperOrigin-RevId: 311046755
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We weren't properly checking whether the inserted default rule was
unconditional.
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Signed-off-by: Bin Lu <bin.lu@arm.com>
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PiperOrigin-RevId: 311014995
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Some code paths needed these syscalls anyways, so they should be included in
the filters. Given that we depend on these syscalls in some cases, there's no
real reason to avoid them any more.
PiperOrigin-RevId: 310829126
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Enables commands with -o (--out-interface) for iptables rules.
$ iptables -A OUTPUT -o eth0 -j ACCEPT
PiperOrigin-RevId: 310642286
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This has two effects: It makes flags passed to open("/proc/[pid]/fd/[hostfd]")
effective, and it prevents imported pipes/sockets/character devices from being
opened with O_NONBLOCK unconditionally (because the underlying host FD was set
to non-blocking in ImportFD()).
PiperOrigin-RevId: 310596062
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The common syscall definitions mean that ARM64-exclusive files need stubs in
the ARM64 build.
PiperOrigin-RevId: 310446698
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Updates #1197, #1198, #1672
PiperOrigin-RevId: 310432006
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They don't depend on anything in VFS2, so they should be their own packages.
PiperOrigin-RevId: 310416807
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PiperOrigin-RevId: 310404113
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Synthetic sockets do not have the race condition issue in VFS2, and we will
get rid of privateunixsocket as well.
Fixes #1200.
PiperOrigin-RevId: 310386474
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Fixes #1965.
PiperOrigin-RevId: 310380433
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PiperOrigin-RevId: 310259686
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Compare:
https://elixir.bootlin.com/linux/v5.6/source/fs/timerfd.c#L431
PiperOrigin-RevId: 310246908
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We can register any number of tables with any number of architectures, and
need not limit the definitions to the architecture in question. This allows
runsc to generate documentation for all architectures simultaneously.
Similarly, this simplifies the VFSv2 patching process.
PiperOrigin-RevId: 310224827
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PiperOrigin-RevId: 310179277
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PiperOrigin-RevId: 310057834
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Three updates:
- Mark all vfs2 socket syscalls as supported.
- Use the same dev number and ino number generator for all types of sockets,
unlike in VFS1.
- Do not use host fd for hostinet metadata.
Fixes #1476, #1478, #1484, 1485, #2017.
PiperOrigin-RevId: 309994579
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