Files
Shailend ChandandgVisor bot e428bbea51 Fix creds check in linkat(AT_EMPTY_PATH)
linkat(AT_EMPTY_PATH) needs to check for CAP_DAC_READ_SEARCH in the userns in
which the fd was opened, not the userns of the task running linkat().

To get at that userns, vfs.FileDescription now saves a pointer to the creds
at the time of its creation: plumbing these creds in accounts for much of the
diff. This is similar to how `struct file` stores creds in `f_cred` in Linux.

Moreover, since the Linux patch "vfs: relax linkat() AT_EMPTY_PATH..." [1], the
need for this cap is excused if the creds of the calling task are literally
the same as the one stored in the fd.

[1] https://github.com/torvalds/linux/commit/42bd2af5950456d

PiperOrigin-RevId: 853374474
2026-01-07 12:48:17 -08:00

80 lines
1.6 KiB
Python

load("//pkg/sync/locking:locking.bzl", "declare_mutex")
load("//tools:defs.bzl", "go_library", "go_test")
package(
default_applicable_licenses = ["//:license"],
licenses = ["notice"],
)
declare_mutex(
name = "vfs_mutex",
out = "vfs_mutex.go",
package = "pipe",
prefix = "vfs",
)
declare_mutex(
name = "pipe_mutex",
out = "pipe_mutex.go",
nested_lock_names = ["pipe"],
package = "pipe",
prefix = "pipe",
)
declare_mutex(
name = "inode_mutex",
out = "inode_mutex.go",
package = "pipe",
prefix = "inode",
)
go_library(
name = "pipe",
srcs = [
"inode_mutex.go",
"pipe.go",
"pipe_mutex.go",
"pipe_unsafe.go",
"pipe_util.go",
"save_restore.go",
"vfs.go",
],
visibility = ["//pkg/sentry:internal"],
deps = [
"//pkg/abi/linux",
"//pkg/atomicbitops",
"//pkg/context",
"//pkg/errors/linuxerr",
"//pkg/hostarch",
"//pkg/log",
"//pkg/marshal/primitive",
"//pkg/safemem",
"//pkg/sentry/arch",
"//pkg/sentry/fsutil",
"//pkg/sentry/kernel/auth",
"//pkg/sentry/vfs",
"//pkg/sync",
"//pkg/sync/locking",
"//pkg/usermem",
"//pkg/waiter",
"@org_golang_x_sys//unix:go_default_library",
],
)
go_test(
name = "pipe_test",
size = "small",
srcs = [
"pipe_test.go",
],
library = ":pipe",
deps = [
"//pkg/context",
"//pkg/errors/linuxerr",
"//pkg/sentry/contexttest",
"//pkg/sentry/vfs",
"//pkg/usermem",
"//pkg/waiter",
],
)