From: Al Viro <viro@zeniv•linux.org.uk>
To: Aleksa Sarai <cyphar@cyphar•com>
Cc: linux-ia64@vger•kernel.org, linux-sh@vger•kernel.org,
Peter Zijlstra <peterz@infradead•org>,
Rasmus Villemoes <linux@rasmusvillemoes•dk>,
Alexei Starovoitov <ast@kernel•org>,
linux-kernel@vger•kernel.org, David Howells <dhowells@redhat•com>,
linux-kselftest@vger•kernel.org, sparclinux@vger•kernel.org,
Christian Brauner <christian.brauner@ubuntu•com>,
Shuah Khan <shuah@kernel•org>,
linux-arch@vger•kernel.org, linux-s390@vger•kernel.org,
Tycho Andersen <tycho@tycho•ws>, Aleksa Sarai <asarai@suse•de>,
Jiri Olsa <jolsa@redhat•com>,
Alexander Shishkin <alexander.shishkin@linux•intel.com>,
Ingo Molnar <mingo@redhat•com>,
linux-arm-kernel@lists•infradead.org, linux-mips@vger•kernel.org,
linux-xtensa@linux-xtensa•org, Kees Cook <keescook@chromium•org>,
Arnd Bergmann <arnd@arndb•de>, Jann Horn <jannh@google•com>,
linuxppc-dev@lists•ozlabs.org, linux-m68k@lists•linux-m68k.org,
Andy Lutomirski <luto@kernel•org>,
Shuah Khan <skhan@linuxfoundation•org>,
Namhyung Kim <namhyung@kernel•org>,
David Drysdale <drysdale@google•com>,
Christian Brauner <christian@brauner•io>,
"J. Bruce Fields" <bfields@fieldses•org>,
libc-alpha@sourceware•org, linux-parisc@vger•kernel.org,
linux-api@vger•kernel.org, Chanho Min <chanho.min@lge•com>,
Jeff Layton <jlayton@kernel•org>, Oleg Nesterov <oleg@redhat•com>,
Eric Biederman <ebiederm@xmission•com>,
linux-alpha@vger•kernel.org, linux-fsdevel@vger•kernel.org,
Andrew Morton <akpm@linux-foundation•org>,
Linus Torvalds <torvalds@linux-foundation•org>,
containers@lists•linux-foundation.org
Subject: Re: [PATCH v15 2/9] namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution
Date: Wed, 13 Nov 2019 01:24:26 +0000 [thread overview]
Message-ID: <20191113012426.GY26530@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20191105090553.6350-3-cyphar@cyphar.com>
On Tue, Nov 05, 2019 at 08:05:46PM +1100, Aleksa Sarai wrote:
> @@ -1078,6 +1079,10 @@ const char *get_link(struct nameidata *nd)
> } else {
> res = get(dentry, inode, &last->done);
> }
> + if (nd->flags & LOOKUP_MAGICLINK_JUMPED) {
> + if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS))
> + return ERR_PTR(-ELOOP);
> + }
Minor nit - the first check probably wants unlikely() more than the
second one; it's probably noise anyway, but most of the symlinks
traversed are not going to be procfs ones, so you get test + branch
taken most of the time.
OTOH, that just might compile into
fetch nd->flags
and with LOOKUP_MAGICLINK_JUMPED | LOOKUP_NO_MAGICLINKS
compare with the same constant
unlikely branch when equal
Anyway, that's no more than a minor nit and can be dealt with later (if
at all)
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists•infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@zeniv•linux.org.uk>
To: Aleksa Sarai <cyphar@cyphar•com>
Cc: Jeff Layton <jlayton@kernel•org>,
"J. Bruce Fields" <bfields@fieldses•org>,
Arnd Bergmann <arnd@arndb•de>,
David Howells <dhowells@redhat•com>,
Shuah Khan <shuah@kernel•org>,
Shuah Khan <skhan@linuxfoundation•org>,
Ingo Molnar <mingo@redhat•com>,
Peter Zijlstra <peterz@infradead•org>,
Christian Brauner <christian.brauner@ubuntu•com>,
David Drysdale <drysdale@google•com>,
Andy Lutomirski <luto@kernel•org>,
Linus Torvalds <torvalds@linux-foundation•org>,
Eric Biederman <ebiederm@xmission•com>,
Andrew Morton <akpm@linux-foundation•org>,
Alexei Starovoitov <ast@kernel•org>,
Kees Cook <keescook@chromium•org>, Jann Horn <jannh@google•com>,
Tycho Andersen <tycho@tycho•ws>, Chanho Min <chanho.min@lge•com>,
Oleg Nesterov <oleg@redhat•com>,
Rasmus Villemoes <linux@rasmusvillemoes•dk>,
Alexander Shishkin <alexander.shishkin@linux•intel.com>,
Jiri Olsa <jolsa@redhat•com>, Namhyung Kim <namhyung@kernel•org>,
Christian Brauner <christian@brauner•io>,
Aleksa Sarai <asarai@suse•de>,
containers@lists•linux-foundation.org,
linux-alpha@vger•kernel.org, linux-api@vger•kernel.org,
libc-alpha@sourceware•org, linux-arch@vger•kernel.org,
linux-arm-kernel@lists•infradead.org,
linux-fsdevel@vger•kernel.org, linux-ia64@vger•kernel.org,
linux-kernel@vger•kernel.org, linux-kselftest@vger•kernel.org,
linux-m68k@lists•linux-m68k.org, linux-mips@vger•kernel.org,
linux-parisc@vger•kernel.org, linuxppc-dev@lists•ozlabs.org,
linux-s390@vger•kernel.org, linux-sh@vger•kernel.org,
linux-xtensa@linux-xtensa•org, sparclinux@vger•kernel.org
Subject: Re: [PATCH v15 2/9] namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution
Date: Wed, 13 Nov 2019 01:24:26 +0000 [thread overview]
Message-ID: <20191113012426.GY26530@ZenIV.linux.org.uk> (raw)
Message-ID: <20191113012426.GE-P-Q8SLa6YfJUufwRabxnKApThmoNn64PAgHAcet8@z> (raw)
In-Reply-To: <20191105090553.6350-3-cyphar@cyphar.com>
On Tue, Nov 05, 2019 at 08:05:46PM +1100, Aleksa Sarai wrote:
> @@ -1078,6 +1079,10 @@ const char *get_link(struct nameidata *nd)
> } else {
> res = get(dentry, inode, &last->done);
> }
> + if (nd->flags & LOOKUP_MAGICLINK_JUMPED) {
> + if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS))
> + return ERR_PTR(-ELOOP);
> + }
Minor nit - the first check probably wants unlikely() more than the
second one; it's probably noise anyway, but most of the symlinks
traversed are not going to be procfs ones, so you get test + branch
taken most of the time.
OTOH, that just might compile into
fetch nd->flags
and with LOOKUP_MAGICLINK_JUMPED | LOOKUP_NO_MAGICLINKS
compare with the same constant
unlikely branch when equal
Anyway, that's no more than a minor nit and can be dealt with later (if
at all)
next prev parent reply other threads:[~2019-11-13 1:29 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-05 9:05 [PATCH v15 0/9] open: introduce openat2(2) syscall Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 1/9] namei: LOOKUP_NO_SYMLINKS: block symlink resolution Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 2/9] namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution Aleksa Sarai
2019-11-13 1:24 ` Al Viro [this message]
2019-11-13 1:24 ` Al Viro
2019-11-05 9:05 ` [PATCH v15 3/9] namei: LOOKUP_NO_XDEV: block mountpoint crossing Aleksa Sarai
2019-11-13 1:36 ` Al Viro
2019-11-13 1:36 ` Al Viro
2019-11-14 4:49 ` Aleksa Sarai
2019-11-14 4:49 ` Aleksa Sarai
2019-11-14 5:43 ` Al Viro
2019-11-14 5:43 ` Al Viro
2019-11-14 13:33 ` Aleksa Sarai
2019-11-14 13:33 ` Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 4/9] namei: LOOKUP_BENEATH: O_BENEATH-like scoped resolution Aleksa Sarai
2019-11-13 1:55 ` Al Viro
2019-11-13 1:55 ` Al Viro
2019-11-13 7:47 ` Aleksa Sarai
2019-11-13 7:47 ` Aleksa Sarai
2019-11-14 4:57 ` Aleksa Sarai
2019-11-14 4:57 ` Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 5/9] namei: LOOKUP_IN_ROOT: chroot-like " Aleksa Sarai
2019-11-13 2:03 ` Al Viro
2019-11-13 2:03 ` Al Viro
2019-11-13 2:44 ` Aleksa Sarai
2019-11-13 2:44 ` Aleksa Sarai
2019-11-13 2:59 ` Al Viro
2019-11-13 2:59 ` Al Viro
2019-11-13 3:55 ` Aleksa Sarai
2019-11-13 3:55 ` Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 6/9] namei: LOOKUP_{IN_ROOT, BENEATH}: permit limited ".." resolution Aleksa Sarai
2019-11-13 2:09 ` [PATCH v15 6/9] namei: LOOKUP_{IN_ROOT,BENEATH}: " Al Viro
2019-11-13 2:09 ` Al Viro
2019-11-13 7:52 ` Aleksa Sarai
2019-11-13 7:52 ` Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 7/9] open: introduce openat2(2) syscall Aleksa Sarai
2019-11-13 2:29 ` Al Viro
2019-11-13 2:29 ` Al Viro
2019-11-13 2:35 ` Aleksa Sarai
2019-11-13 2:35 ` Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 8/9] selftests: add openat2(2) selftests Aleksa Sarai
2019-11-05 9:05 ` [PATCH v15 9/9] Documentation: path-lookup: mention LOOKUP_MAGICLINK_JUMPED Aleksa Sarai
2019-11-11 13:24 ` [PATCH v15 0/9] open: introduce openat2(2) syscall Aleksa Sarai
2019-11-12 23:01 ` Kees Cook
2019-11-12 23:01 ` Kees Cook
2019-11-12 23:06 ` Christian Brauner
2019-11-12 23:06 ` Christian Brauner
2019-11-13 0:46 ` Aleksa Sarai
2019-11-13 0:46 ` Aleksa Sarai
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