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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

23 lines
501 B
Python

load("//tools:defs.bzl", "go_library")
package(default_applicable_licenses = ["//:license"])
licenses(["notice"])
go_library(
name = "timerfd",
srcs = ["timerfd.go"],
visibility = ["//pkg/sentry:internal"],
deps = [
"//pkg/atomicbitops",
"//pkg/context",
"//pkg/errors/linuxerr",
"//pkg/hostarch",
"//pkg/sentry/kernel/auth",
"//pkg/sentry/ktime",
"//pkg/sentry/vfs",
"//pkg/usermem",
"//pkg/waiter",
],
)