tor/changes/ticket40382

  o Minor features (compatibility, Linux seccomp sandbox):
    - Add a workaround to enable the Linux sandbox to work correctly
      on systems running Glibc 2.33.  These versions have started
      using the fstatat() system call, which previously our sandbox did not
      allow.
      Closes ticket 40382; see the ticket for a discussion of tradeoffs.
Add a sandbox workaround for Glibc 2.33 This change permits the newfstatat() system call, and fixes issues 40382 (and 40381). This isn't a free change. From the commit: // Libc 2.33 uses this syscall to implement both fstat() and stat(). // // The trouble is that to implement fstat(fd, &st), it calls: // newfstatat(fs, "", &st, AT_EMPTY_PATH) // We can't detect this usage in particular, because "" is a pointer // we don't control. And we can't just look for AT_EMPTY_PATH, since // AT_EMPTY_PATH only has effect when the path string is empty. // // So our only solution seems to be allowing all fstatat calls, which // means that an attacker can stat() anything on the filesystem. That's // not a great solution, but I can't find a better one. 2021-05-07 18:09:41 +02:00			`o Minor features (compatibility, Linux seccomp sandbox):`
			`- Add a workaround to enable the Linux sandbox to work correctly`
			`on systems running Glibc 2.33. These versions have started`
			`using the fstatat() system call, which previously our sandbox did not`
			`allow.`
			`Closes ticket 40382; see the ticket for a discussion of tradeoffs.`