This is a note to let you know that I've just added the patch titled ptrace: Set PF_SUPERPRIV when checking capability to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ptrace-set-pf_superpriv-when-checking-capability.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From cf23705244c947151179f929774fabf71e239eee Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= <mic@xxxxxxxxxxxxxxxxxxx> Date: Fri, 30 Oct 2020 13:38:48 +0100 Subject: ptrace: Set PF_SUPERPRIV when checking capability MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx> commit cf23705244c947151179f929774fabf71e239eee upstream. Commit 69f594a38967 ("ptrace: do not audit capability check when outputing /proc/pid/stat") replaced the use of ns_capable() with has_ns_capability{,_noaudit}() which doesn't set PF_SUPERPRIV. Commit 6b3ad6649a4c ("ptrace: reintroduce usage of subjective credentials in ptrace_has_cap()") replaced has_ns_capability{,_noaudit}() with security_capable(), which doesn't set PF_SUPERPRIV neither. Since commit 98f368e9e263 ("kernel: Add noaudit variant of ns_capable()"), a new ns_capable_noaudit() helper is available. Let's use it! As a result, the signature of ptrace_has_cap() is restored to its original one. Cc: Christian Brauner <christian.brauner@xxxxxxxxxx> Cc: Eric Paris <eparis@xxxxxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Serge E. Hallyn <serge@xxxxxxxxxx> Cc: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Fixes: 6b3ad6649a4c ("ptrace: reintroduce usage of subjective credentials in ptrace_has_cap()") Fixes: 69f594a38967 ("ptrace: do not audit capability check when outputing /proc/pid/stat") Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxxxxxxxxxx> Reviewed-by: Jann Horn <jannh@xxxxxxxxxx> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20201030123849.770769-2-mic@xxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/ptrace.c | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-) --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -264,17 +264,11 @@ static int ptrace_check_attach(struct ta return ret; } -static bool ptrace_has_cap(const struct cred *cred, struct user_namespace *ns, - unsigned int mode) +static bool ptrace_has_cap(struct user_namespace *ns, unsigned int mode) { - int ret; - if (mode & PTRACE_MODE_NOAUDIT) - ret = security_capable(cred, ns, CAP_SYS_PTRACE, CAP_OPT_NOAUDIT); - else - ret = security_capable(cred, ns, CAP_SYS_PTRACE, CAP_OPT_NONE); - - return ret == 0; + return ns_capable_noaudit(ns, CAP_SYS_PTRACE); + return ns_capable(ns, CAP_SYS_PTRACE); } /* Returns 0 on success, -errno on denial. */ @@ -326,7 +320,7 @@ static int __ptrace_may_access(struct ta gid_eq(caller_gid, tcred->sgid) && gid_eq(caller_gid, tcred->gid)) goto ok; - if (ptrace_has_cap(cred, tcred->user_ns, mode)) + if (ptrace_has_cap(tcred->user_ns, mode)) goto ok; rcu_read_unlock(); return -EPERM; @@ -345,7 +339,7 @@ ok: mm = task->mm; if (mm && ((get_dumpable(mm) != SUID_DUMP_USER) && - !ptrace_has_cap(cred, mm->user_ns, mode))) + !ptrace_has_cap(mm->user_ns, mode))) return -EPERM; return security_ptrace_access_check(task, mode); Patches currently in stable-queue which might be from mic@xxxxxxxxxxxxxxxxxxx are queue-5.4/ptrace-set-pf_superpriv-when-checking-capability.patch queue-5.4/seccomp-set-pf_superpriv-when-checking-capability.patch