[release-branch.go1.20] runtime: implement SUID/SGID protections
On Unix platforms, the runtime previously did nothing special when a
program was run with either the SUID or SGID bits set. This can be
dangerous in certain cases, such as when dumping memory state, or
assuming the status of standard i/o file descriptors.
Taking cues from glibc, this change implements a set of protections when
a binary is run with SUID or SGID bits set (or is SUID/SGID-like). On
Linux, whether to enable these protections is determined by whether the
AT_SECURE flag is passed in the auxiliary vector. On platforms which
have the issetugid syscall (the BSDs, darwin, and Solaris/Illumos), that
is used. On the remaining platforms (currently only AIX) we check
!(getuid() == geteuid() && getgid == getegid()).
Currently when we determine a binary is "tainted" (using the glibc
terminology), we implement two specific protections:
1. we check if the file descriptors 0, 1, and 2 are open, and if they
are not, we open them, pointing at /dev/null (or fail).
2. we force GOTRACKBACK=none, and generally prevent dumping of
trackbacks and registers when a program panics/aborts.
In the future we may add additional protections.
This change requires implementing issetugid on the platforms which
support it, and implementing getuid, geteuid, getgid, and getegid on
AIX.
Thanks to Vincent Dehors from Synacktiv for reporting this issue.
Updates #60272
Fixes #60518
Fixes CVE-2023-29403
Change-Id: Icb620f3f8755791d51b02b5c07fb24f40e19cb80
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/
1878434
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Roland Shoemaker <bracewell@google.com>
Reviewed-by: Russ Cox <rsc@google.com>
(cherry picked from commit
87065663ea6d89cd54f65a515d8f2ed0ef285c19)
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/
1902232
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Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/
1904344
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/501227
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