From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Linus Torvalds <torvalds@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH v3 1/7] fs/readdir: Fix filldir() and filldir64() use of user_access_begin()
Date: Thu, 23 Jan 2020 12:59:52 +0000 (UTC) [thread overview]
Message-ID: <fed4f49349913cb6739dac647ba6a61d56b989d2.1579783936.git.christophe.leroy@c-s.fr> (raw)
Some architectures grant full access to userspace regardless of the
address/len passed to user_access_begin(), but other architectures
only grant access to the requested area.
For example, on 32 bits powerpc (book3s/32), access is granted by
segments of 256 Mbytes.
Modify filldir() and filldir64() to request the real area they need
to get access to, i.e. the area covering the parent dirent (if any)
and the contiguous current dirent.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: 9f79b78ef744 ("Convert filldir[64]() from __put_user() to unsafe_put_user()")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v2: have user_access_begin() cover both parent dirent (if any) and current dirent
v3: replaced by patch from Linus
---
fs/readdir.c | 70 +++++++++++++++++++++++++---------------------------
1 file changed, 34 insertions(+), 36 deletions(-)
diff --git a/fs/readdir.c b/fs/readdir.c
index d26d5ea4de7b..4b466cbb0f3a 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -206,7 +206,7 @@ struct linux_dirent {
struct getdents_callback {
struct dir_context ctx;
struct linux_dirent __user * current_dir;
- struct linux_dirent __user * previous;
+ int prev_reclen;
int count;
int error;
};
@@ -214,12 +214,13 @@ struct getdents_callback {
static int filldir(struct dir_context *ctx, const char *name, int namlen,
loff_t offset, u64 ino, unsigned int d_type)
{
- struct linux_dirent __user * dirent;
+ struct linux_dirent __user *dirent, *prev;
struct getdents_callback *buf =
container_of(ctx, struct getdents_callback, ctx);
unsigned long d_ino;
int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
sizeof(long));
+ int prev_reclen;
buf->error = verify_dirent_name(name, namlen);
if (unlikely(buf->error))
@@ -232,28 +233,24 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen,
buf->error = -EOVERFLOW;
return -EOVERFLOW;
}
- dirent = buf->previous;
- if (dirent && signal_pending(current))
+ prev_reclen = buf->prev_reclen;
+ if (prev_reclen && signal_pending(current))
return -EINTR;
-
- /*
- * Note! This range-checks 'previous' (which may be NULL).
- * The real range was checked in getdents
- */
- if (!user_access_begin(dirent, sizeof(*dirent)))
- goto efault;
- if (dirent)
- unsafe_put_user(offset, &dirent->d_off, efault_end);
dirent = buf->current_dir;
+ prev = (void __user *)dirent - prev_reclen;
+ if (!user_access_begin(prev, reclen + prev_reclen))
+ goto efault;
+
+ /* This might be 'dirent->d_off', but if so it will get overwritten */
+ unsafe_put_user(offset, &prev->d_off, efault_end);
unsafe_put_user(d_ino, &dirent->d_ino, efault_end);
unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end);
unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
user_access_end();
- buf->previous = dirent;
- dirent = (void __user *)dirent + reclen;
- buf->current_dir = dirent;
+ buf->current_dir = (void __user *)dirent + reclen;
+ buf->prev_reclen = reclen;
buf->count -= reclen;
return 0;
efault_end:
@@ -267,7 +264,6 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
struct linux_dirent __user *, dirent, unsigned int, count)
{
struct fd f;
- struct linux_dirent __user * lastdirent;
struct getdents_callback buf = {
.ctx.actor = filldir,
.count = count,
@@ -285,8 +281,10 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
error = iterate_dir(f.file, &buf.ctx);
if (error >= 0)
error = buf.error;
- lastdirent = buf.previous;
- if (lastdirent) {
+ if (buf.prev_reclen) {
+ struct linux_dirent __user *lastdirent;
+ lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;
+
if (put_user(buf.ctx.pos, &lastdirent->d_off))
error = -EFAULT;
else
@@ -299,7 +297,7 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
struct getdents_callback64 {
struct dir_context ctx;
struct linux_dirent64 __user * current_dir;
- struct linux_dirent64 __user * previous;
+ int prev_reclen;
int count;
int error;
};
@@ -307,11 +305,12 @@ struct getdents_callback64 {
static int filldir64(struct dir_context *ctx, const char *name, int namlen,
loff_t offset, u64 ino, unsigned int d_type)
{
- struct linux_dirent64 __user *dirent;
+ struct linux_dirent64 __user *dirent, *prev;
struct getdents_callback64 *buf =
container_of(ctx, struct getdents_callback64, ctx);
int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
sizeof(u64));
+ int prev_reclen;
buf->error = verify_dirent_name(name, namlen);
if (unlikely(buf->error))
@@ -319,30 +318,28 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen,
buf->error = -EINVAL; /* only used if we fail.. */
if (reclen > buf->count)
return -EINVAL;
- dirent = buf->previous;
- if (dirent && signal_pending(current))
+ prev_reclen = buf->prev_reclen;
+ if (prev_reclen && signal_pending(current))
return -EINTR;
-
- /*
- * Note! This range-checks 'previous' (which may be NULL).
- * The real range was checked in getdents
- */
- if (!user_access_begin(dirent, sizeof(*dirent)))
- goto efault;
- if (dirent)
- unsafe_put_user(offset, &dirent->d_off, efault_end);
dirent = buf->current_dir;
+ prev = (void __user *)dirent - prev_reclen;
+ if (!user_access_begin(prev, reclen + prev_reclen))
+ goto efault;
+
+ /* This might be 'dirent->d_off', but if so it will get overwritten */
+ unsafe_put_user(offset, &prev->d_off, efault_end);
unsafe_put_user(ino, &dirent->d_ino, efault_end);
unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
unsafe_put_user(d_type, &dirent->d_type, efault_end);
unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
user_access_end();
- buf->previous = dirent;
+ buf->prev_reclen = reclen;
dirent = (void __user *)dirent + reclen;
buf->current_dir = dirent;
buf->count -= reclen;
return 0;
+
efault_end:
user_access_end();
efault:
@@ -354,7 +351,6 @@ int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
unsigned int count)
{
struct fd f;
- struct linux_dirent64 __user * lastdirent;
struct getdents_callback64 buf = {
.ctx.actor = filldir64,
.count = count,
@@ -372,9 +368,11 @@ int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
error = iterate_dir(f.file, &buf.ctx);
if (error >= 0)
error = buf.error;
- lastdirent = buf.previous;
- if (lastdirent) {
+ if (buf.prev_reclen) {
+ struct linux_dirent64 __user *lastdirent;
typeof(lastdirent->d_off) d_off = buf.ctx.pos;
+
+ lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;
if (__put_user(d_off, &lastdirent->d_off))
error = -EFAULT;
else
--
2.25.0
next reply other threads:[~2020-01-23 12:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 12:59 Christophe Leroy [this message]
2020-01-23 12:59 ` [PATCH v3 2/7] uaccess: Tell user_access_begin() if it's for a write or not Christophe Leroy
2020-01-23 13:11 ` Jani Nikula
2020-01-23 18:02 ` Linus Torvalds
2020-01-23 19:47 ` christophe leroy
2020-01-23 19:57 ` Linus Torvalds
2020-01-24 2:03 ` hpa
2020-01-25 6:17 ` Tony Luck
2020-01-25 14:40 ` kbuild test robot
2020-01-23 12:59 ` [PATCH v3 3/7] powerpc/32s: Fix bad_kuap_fault() Christophe Leroy
2020-01-23 12:59 ` [PATCH v3 4/7] powerpc/kuap: Fix set direction in allow/prevent_user_access() Christophe Leroy
2020-01-23 12:59 ` [PATCH v3 5/7] powerpc/32s: Drop NULL addr verification Christophe Leroy
2020-01-23 12:59 ` [PATCH v3 6/7] powerpc/32s: Prepare allow_user_access() for user_access_begin() Christophe Leroy
2020-01-23 12:59 ` [PATCH v3 7/7] powerpc: Implement user_access_begin and friends Christophe Leroy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=fed4f49349913cb6739dac647ba6a61d56b989d2.1579783936.git.christophe.leroy@c-s.fr \
--to=christophe.leroy@c-s.fr \
--cc=akpm@linux-foundation.org \
--cc=benh@kernel.crashing.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=paulus@samba.org \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).