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2020-06-09Don't WriteOut to readonly mountsFabricio Voznika
When the file closes, it attempts to write dirty cached attributes to the file. This should not be done when the mount is readonly. PiperOrigin-RevId: 315585058
2020-06-08Combine executable lookup codeFabricio Voznika
Run vs. exec, VFS1 vs. VFS2 were executable lookup were slightly different from each other. Combine them all into the same logic. PiperOrigin-RevId: 315426443
2020-06-03Fix data race on f.offset.Nicolas Lacasse
We must hold f.mu to write f.offset. PiperOrigin-RevId: 314582968
2020-06-02Add some detail to milestone #1Ridwan Sharif
This change adds more information about what needs to be done to implement `/dev/fuse`
2020-05-29Refactor the ResolveExecutablePath logic.Nicolas Lacasse
PiperOrigin-RevId: 313871804
2020-05-28Merge pull request #2792 from avagin:g3doc/fuse/refsgVisor bot
PiperOrigin-RevId: 313600051
2020-05-27g3doc/fuse: add more referencesAndrei Vagin
2020-05-26Merge pull request #2751 from mrahatm:fusegVisor bot
PiperOrigin-RevId: 313300882
2020-05-26Write initial design doc for FUSE.Rahat Mahmood
2020-05-19Implement mmap for host fs in vfs2.Dean Deng
In VFS1, both fs/host and fs/gofer used the same utils for host file mappings. Refactor parts of fsimpl/gofer to create similar utils to share with fsimpl/host (memory accounting code moved to fsutil, page rounding arithmetic moved to usermem). Updates #1476. PiperOrigin-RevId: 312345090
2020-05-13Enable overlayfs_stale_read by default for runsc.Jamie Liu
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
2020-05-12Don't allow rename across different gofer or tmpfs mounts.Nicolas Lacasse
Fixes #2651. PiperOrigin-RevId: 311193661
2020-05-07Update privateunixsocket TODOs.Dean Deng
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
2020-05-06Add maximum memory limit.Nicolas Lacasse
PiperOrigin-RevId: 310179277
2020-05-05Translate p9.NoUID/GID to OverflowUID/GID.Jamie Liu
p9.NoUID/GID (== uint32(-1) == auth.NoID) is not a valid auth.KUID/KGID; in particular, using it for file ownership causes capabilities to be ineffective since file capabilities require that the file's KUID and KGID are mapped into the capability holder's user namespace [1], and auth.NoID is not mapped into any user namespace. Map p9.NoUID/GID to a different, valid KUID/KGID; in the unlikely case that an application actually using the overflow KUID/KGID attempts an operation that is consequently permitted by client permission checks, the remote operation will still fail with EPERM. Since this changes the VFS2 gofer client to no longer ignore the invalid IDs entirely, this CL both permits and requires that we change synthetic mount point creation to use root credentials. [1] See fs.Inode.CheckCapability or vfs.GenericCheckPermissions. PiperOrigin-RevId: 309856455
2020-04-28Support pipes and sockets in VFS2 gofer fs.Dean Deng
Named pipes and sockets can be represented in two ways in gofer fs: 1. As a file on the remote filesystem. In this case, all file operations are passed through 9p. 2. As a synthetic file that is internal to the sandbox. In this case, the dentry stores an endpoint or VFSPipe for sockets and pipes respectively, which replaces interactions with the remote fs through the gofer. In gofer.filesystem.MknodAt, we attempt to call mknod(2) through 9p, and if it fails, fall back to the synthetic version. Updates #1200. PiperOrigin-RevId: 308828161
2020-04-27Import host sockets.Dean Deng
The FileDescription implementation for hostfs sockets uses the standard Unix socket implementation (unix.SocketVFS2), but is also tied to a hostfs dentry. Updates #1672, #1476 PiperOrigin-RevId: 308716426
2020-04-24Port SCM Rights to VFS2.Dean Deng
Fixes #1477. PiperOrigin-RevId: 308317511
2020-04-23Port devpts to VFS2.Nicolas Lacasse
PiperOrigin-RevId: 308164359
2020-04-22Move user home detection to its own library.Nicolas Lacasse
PiperOrigin-RevId: 307977689
2020-04-21Misc VFS2 fixesFabricio Voznika
- Fix defer operation ordering in kernfs.Filesystem.AccessAt() - Add AT_NULL entry in proc/pid/auvx - Fix line padding in /proc/pid/maps - Fix linux_dirent serialization for getdents(2) - Remove file creation flags from vfs.FileDescription.statusFlags() Updates #1193, #1035 PiperOrigin-RevId: 307704159
2020-04-21Sentry metrics updates.Dave Bailey
Sentry metrics with nanoseconds units are labeled as such, and non-cumulative sentry metrics are supported. PiperOrigin-RevId: 307621080
2020-04-13Remove obsolete TODOs for b/38173783Jon Budd
The comments in the ticket indicate that this behavior is fine and that the ticket should be closed, so we shouldn't need pointers to the ticket. PiperOrigin-RevId: 306266071
2020-04-10Use O_CLOEXEC when dup'ing FDsFabricio Voznika
The sentry doesn't allow execve, but it's a good defense in-depth measure. PiperOrigin-RevId: 305958737
2020-04-09Merge pull request #2253 from amscanne:nogogVisor bot
PiperOrigin-RevId: 305807868
2020-04-09Downgrade VFS1-specific FIXME to a NOTE.Jamie Liu
PiperOrigin-RevId: 305794509
2020-04-08Clean up TODOsFabricio Voznika
PiperOrigin-RevId: 305592245
2020-04-08Remove InodeOperations FIXMEs that will be obsoleted by VFS2.Dean Deng
PiperOrigin-RevId: 305588941
2020-04-08Handle utimes correctly for shared gofer filesystems.Dean Deng
Determine system time from within the sentry rather than relying on the remote filesystem to prevent inconsistencies. Resolve related TODOs; the time discrepancies in question don't exist anymore. PiperOrigin-RevId: 305557099
2020-04-08Enable SubprocessExited and SubprocessZombie for gVisorFabricio Voznika
Updates #164 PiperOrigin-RevId: 305544029
2020-04-08Fix all printf formatting errors.Adin Scannell
Updates #2243
2020-04-08Fix all copy locks violations.Adin Scannell
This required minor restructuring of how system call tables were saved and restored, but it makes way more sense this way. Updates #2243
2020-04-02Fix typo in TODO comments.Dean Deng
PiperOrigin-RevId: 304508083
2020-03-31Include original copyUp error in panic if cleanupUpper fails.Nicolas Lacasse
When copyUp fails, we attempt to clean up the upper filesystem by removing any files that have already been copied-up. If the cleanup fails, we panic because the "overlay filesystem is in an inconsistent state". This CL adds the original copy-up error to the panic information, to hopefully make it easier to track down how the overlay filesystem got into the inconsistent state. PiperOrigin-RevId: 304053370
2020-03-26Use host-defined file owner and mode, when possible, for imported fds.Dean Deng
Using the host-defined file owner matches VFS1. It is more correct to use the host-defined mode, since the cached value may become out of date. However, kernfs.Inode.Mode() does not return an error--other filesystems on kernfs are in-memory so retrieving mode should not fail. Therefore, if the host syscall fails, we rely on a cached value instead. Updates #1672. PiperOrigin-RevId: 303220864
2020-03-19Remove the "frozen" bit from dirents.Zach Koopmans
Frozen was to lock down changes to the host filesystem for hostFS. Now that hostFS is gone, it can be removed. PiperOrigin-RevId: 301907923
2020-03-18Port imported TTY fds to vfs2.Dean Deng
Refactor fs/host.TTYFileOperations so that the relevant functionality can be shared with VFS2 (fsimpl/host.ttyFD). Incorporate host.defaultFileFD into the default host.fileDescription. This way, there is no need for a separate default_file.go. As in vfs1, the TTY file implementation can be built on top of this default and override operations as necessary (PRead/Read/PWrite/Write, Release, Ioctl). Note that these changes still need to be plumbed into runsc, which refers to imported TTYs in control/proc.go:ExecAsync. Updates #1672. PiperOrigin-RevId: 301718157
2020-03-17Remove HostFS from Sentry.Zach Koopmans
PiperOrigin-RevId: 301402181
2020-03-14Plumb VFS2 imported fds into virtual filesystem.Dean Deng
- When setting up the virtual filesystem, mount a host.filesystem to contain all files that need to be imported. - Make read/preadv syscalls to the host in cases where preadv2 may not be supported yet (likewise for writing). - Make save/restore functions in kernel/kernel.go return early if vfs2 is enabled. PiperOrigin-RevId: 300922353
2020-03-13Fix oom_score_adj.Jamie Liu
- Make oomScoreAdj a ThreadGroup field (Linux: signal_struct::oom_score_adj). - Avoid deadlock caused by Task.OOMScoreAdj()/SetOOMScoreAdj() locking Task.mu and TaskSet.mu in the wrong order (via Task.ExitState()). PiperOrigin-RevId: 300814698
2020-03-09Move /proc/net to /proc/PID/net, and make /proc/net -> /proc/self/net.Ting-Yu Wang
Issue #1833 PiperOrigin-RevId: 299998105
2020-03-06Add plumbing for importing fds in VFS2, along with non-socket, non-TTY impl.Dean Deng
In VFS2, imported file descriptors are stored in a kernfs-based filesystem. Upon calling ImportFD, the host fd can be accessed in two ways: 1. a FileDescription that can be added to the FDTable, and 2. a Dentry in the host.filesystem mount, which we will want to access through magic symlinks in /proc/[pid]/fd/. An implementation of the kernfs.Inode interface stores a unique host fd. This inode can be inserted into file descriptions as well as dentries. This change also plumbs in three FileDescriptionImpls corresponding to fds for sockets, TTYs, and other files (only the latter is implemented here). These implementations will mostly make corresponding syscalls to the host. Where possible, the logic is ported over from pkg/sentry/fs/host. Updates #1672 PiperOrigin-RevId: 299417263
2020-03-06Prevent memory leaks in ilistTamir Duberstein
When list elements are removed from a list but not discarded, it becomes important to invalidate the references they hold to their former neighbors to prevent memory leaks. PiperOrigin-RevId: 299412421
2020-03-05Stub oom_score_adj and oom_score.Ian Lewis
Adds an oom_score_adj and oom_score proc file stub. oom_score_adj accepts writes of values -1000 to 1000 and persists the value with the task. New tasks inherit the parent's oom_score_adj. oom_score is a read-only stub that always returns the value '0'. Issue #202 PiperOrigin-RevId: 299245355
2020-03-02Take write lock when removing xattrMichael Pratt
PiperOrigin-RevId: 298380654
2020-02-28Hide /dev/net/tun when using hostinet.Ting-Yu Wang
/dev/net/tun does not currently work with hostinet. This has caused some program starts failing because it thinks the feature exists. PiperOrigin-RevId: 297876196
2020-02-25Fix DATA RACE in fs.MayDelete.Adin Scannell
MayDelete must lock the directory also, otherwise concurrent renames may race. Note that this also changes the methods to be aligned with the actual Remove and RemoveDirectory methods to minimize confusion when reading the code. (It was hard to see that resolution was correct.) PiperOrigin-RevId: 297258304
2020-02-25Fix mount refcount issue.Adin Scannell
Each mount is holds a reference on a root Dirent, but the mount itself may live beyond it's own reference. This means that a call to Root() can come after the associated reference has been dropped. Instead of introducing a separate layer of references for mount objects, we simply change the Root() method to use TryIncRef() and allow it to return nil if the mount is already gone. This requires updating a small number of callers and minimizes the change (since VFSv2 will replace this code shortly). PiperOrigin-RevId: 297174230
2020-02-21Implement tap/tun device in vfs.Ting-Yu Wang
PiperOrigin-RevId: 296526279
2020-02-20Initial network namespace support.gVisor bot
TCP/IP will work with netstack networking. hostinet doesn't work, and sockets will have the same behavior as it is now. Before the userspace is able to create device, the default loopback device can be used to test. /proc/net and /sys/net will still be connected to the root network stack; this is the same behavior now. Issue #1833 PiperOrigin-RevId: 296309389
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