From: Kees Cook <keescook@chromium.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: akpm@linux-foundation.org, ccross@google.com,
sumit.semwal@linaro.org, mhocko@suse.com, dave.hansen@intel.com,
willy@infradead.org, kirill.shutemov@linux.intel.com,
vbabka@suse.cz, hannes@cmpxchg.org, corbet@lwn.net,
viro@zeniv.linux.org.uk, rdunlap@infradead.org,
kaleshsingh@google.com, peterx@redhat.com, rppt@kernel.org,
peterz@infradead.org, catalin.marinas@arm.com,
vincenzo.frascino@arm.com, chinwen.chang@mediatek.com,
axelrasmussen@google.com, aarcange@redhat.com, jannh@google.com,
apopple@nvidia.com, jhubbard@nvidia.com, yuzhao@google.com,
will@kernel.org, fenghua.yu@intel.com,
thunder.leizhen@huawei.com, hughd@google.com,
feng.tang@intel.com, jgg@ziepe.ca, guro@fb.com,
tglx@linutronix.de, krisman@collabora.com,
chris.hyser@oracle.com, pcc@google.com, ebiederm@xmission.com,
axboe@kernel.dk, legion@kernel.org, eb@emlix.com,
gorcunov@gmail.com, songmuchun@bytedance.com,
viresh.kumar@linaro.org, thomascedeno@google.com,
sashal@kernel.org, cxfcosmos@gmail.com, linux@rasmusvillemoes.dk,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-doc@vger.kernel.org, linux-mm@kvack.org,
kernel-team@android.com
Subject: Re: [PATCH v9 2/3] mm: add a field to store names for private anonymous memory
Date: Fri, 3 Sep 2021 14:47:01 -0700 [thread overview]
Message-ID: <202109031439.B58932AF0@keescook> (raw)
In-Reply-To: <20210902231813.3597709-2-surenb@google.com>
(Sorry, a few more things jumped out at me when I looked again...)
On Thu, Sep 02, 2021 at 04:18:12PM -0700, Suren Baghdasaryan wrote:
> [...]
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 72c7639e3c98..25118902a376 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -2299,6 +2299,64 @@ int __weak arch_prctl_spec_ctrl_set(struct task_struct *t, unsigned long which,
>
> #define PR_IO_FLUSHER (PF_MEMALLOC_NOIO | PF_LOCAL_THROTTLE)
>
> +#ifdef CONFIG_MMU
> +
> +#define ANON_VMA_NAME_MAX_LEN 256
> +
> +static inline bool is_valid_name_char(char ch)
> +{
> + /* printable ascii characters, except [ \ ] */
> + return (ch > 0x1f && ch < 0x5b) || (ch > 0x5d && ch < 0x7f);
> +}
In the back of my mind, I feel like disallowing backtick would be nice,
but then if $, (, and ) are allowed, it doesn't matter, and that seems
too limiting. :)
> +
> +static int prctl_set_vma(unsigned long opt, unsigned long addr,
> + unsigned long size, unsigned long arg)
> +{
> + struct mm_struct *mm = current->mm;
> + const char __user *uname;
> + char *name, *pch;
> + int error;
> +
> + switch (opt) {
> + case PR_SET_VMA_ANON_NAME:
> + uname = (const char __user *)arg;
> + if (!uname) {
> + /* Reset the name */
> + name = NULL;
> + goto set_name;
> + }
> +
> + name = strndup_user(uname, ANON_VMA_NAME_MAX_LEN);
> +
> + if (IS_ERR(name))
> + return PTR_ERR(name);
> +
> + for (pch = name; *pch != '\0'; pch++) {
> + if (!is_valid_name_char(*pch)) {
> + kfree(name);
> + return -EINVAL;
> + }
> + }
> +set_name:
> + mmap_write_lock(mm);
> + error = madvise_set_anon_name(mm, addr, size, name);
> + mmap_write_unlock(mm);
> + kfree(name);
> + break;
This is a weird construct with a needless goto. Why not:
switch (opt) {
case PR_SET_VMA_ANON_NAME:
uname = (const char __user *)arg;
if (uname) {
name = strndup_user(uname, ANON_VMA_NAME_MAX_LEN);
if (IS_ERR(name))
return PTR_ERR(name);
for (pch = name; *pch != '\0'; pch++) {
if (!is_valid_name_char(*pch)) {
kfree(name);
return -EINVAL;
}
}
} else {
/* Reset the name */
name = NULL;
}
mmap_write_lock(mm);
error = madvise_set_anon_name(mm, addr, size, name);
mmap_write_unlock(mm);
kfree(name);
break;
--
Kees Cook
next prev parent reply other threads:[~2021-09-03 21:47 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-02 23:18 [PATCH v9 1/3] mm: rearrange madvise code to allow for reuse Suren Baghdasaryan
2021-09-02 23:18 ` [PATCH v9 2/3] mm: add a field to store names for private anonymous memory Suren Baghdasaryan
2021-09-03 21:35 ` Kees Cook
2021-09-03 21:51 ` Suren Baghdasaryan
2021-09-05 13:04 ` Pavel Machek
2021-09-06 15:52 ` Suren Baghdasaryan
2021-09-03 21:47 ` Kees Cook [this message]
2021-09-03 21:56 ` Suren Baghdasaryan
2021-09-03 22:28 ` Kees Cook
2021-10-01 3:44 ` Suren Baghdasaryan
2021-10-01 5:19 ` Kees Cook
2021-09-06 16:55 ` Matthew Wilcox
2021-09-09 4:05 ` Suren Baghdasaryan
2021-09-30 18:56 ` Suren Baghdasaryan
2021-09-30 23:25 ` Kees Cook
2021-10-01 7:01 ` Rasmus Villemoes
2021-10-01 16:34 ` Suren Baghdasaryan
2021-09-02 23:18 ` [PATCH v9 3/3] mm: add anonymous vma name refcounting Suren Baghdasaryan
2021-09-03 22:20 ` Kees Cook
2021-09-03 0:28 ` [PATCH v9 1/3] mm: rearrange madvise code to allow for reuse Suren Baghdasaryan
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