[3/3] quota: simplify the quotactl compat handling
diff mbox series

Message ID 20200731122202.213333-4-hch@lst.de
State New
Headers show
Series
  • [1/3] compat: lift compat_s64 and compat_u64 to <asm-generic/compat.h>
Related show

Commit Message

Christoph Hellwig July 31, 2020, 12:22 p.m. UTC
Fold the misaligned u64 workarounds into the main quotactl flow instead
of implementing a separate compat syscall handler.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jan Kara <jack@suse.cz>
---
 arch/x86/entry/syscalls/syscall_32.tbl |   2 +-
 fs/quota/Kconfig                       |   5 --
 fs/quota/Makefile                      |   1 -
 fs/quota/compat.c                      | 120 -------------------------
 fs/quota/compat.h                      |  34 +++++++
 fs/quota/quota.c                       |  73 ++++++++++++---
 include/linux/quotaops.h               |   3 -
 kernel/sys_ni.c                        |   1 -
 8 files changed, 94 insertions(+), 145 deletions(-)
 delete mode 100644 fs/quota/compat.c
 create mode 100644 fs/quota/compat.h

Comments

David Laight Aug. 7, 2020, 9:07 a.m. UTC | #1
From: Christoph Hellwig
> Sent: 31 July 2020 13:22
>
> Fold the misaligned u64 workarounds into the main quotactl flow instead
> of implementing a separate compat syscall handler.
> 
...
> diff --git a/fs/quota/compat.h b/fs/quota/compat.h
> new file mode 100644
> index 00000000000000..ef7d1e12d650b3
> --- /dev/null
> +++ b/fs/quota/compat.h
> @@ -0,0 +1,34 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/compat.h>
> +
> +struct compat_if_dqblk {
> +	compat_u64			dqb_bhardlimit;
> +	compat_u64			dqb_bsoftlimit;
> +	compat_u64			dqb_curspace;
> +	compat_u64			dqb_ihardlimit;
> +	compat_u64			dqb_isoftlimit;
> +	compat_u64			dqb_curinodes;
> +	compat_u64			dqb_btime;
> +	compat_u64			dqb_itime;
> +	compat_uint_t			dqb_valid;
> +};
> +
> +struct compat_fs_qfilestat {
> +	compat_u64			dqb_bhardlimit;
> +	compat_u64			qfs_nblks;
> +	compat_uint_t			qfs_nextents;
> +};
> +
> +struct compat_fs_quota_stat {
> +	__s8				qs_version;
> +	__u16				qs_flags;
> +	__s8				qs_pad;
> +	struct compat_fs_qfilestat	qs_uquota;
> +	struct compat_fs_qfilestat	qs_gquota;
> +	compat_uint_t			qs_incoredqs;
> +	compat_int_t			qs_btimelimit;
> +	compat_int_t			qs_itimelimit;
> +	compat_int_t			qs_rtbtimelimit;
> +	__u16				qs_bwarnlimit;
> +	__u16				qs_iwarnlimit;
> +};
> diff --git a/fs/quota/quota.c b/fs/quota/quota.c
> index 5444d3c4d93f37..e1e9d05a14c3e4 100644
> --- a/fs/quota/quota.c
> +++ b/fs/quota/quota.c
> @@ -19,6 +19,7 @@
>  #include <linux/types.h>
>  #include <linux/writeback.h>
>  #include <linux/nospec.h>
> +#include "compat.h"
> 
>  static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
>  				     qid_t id)
> @@ -211,8 +212,18 @@ static int quota_getquota(struct super_block *sb, int type, qid_t id,
>  	if (ret)
>  		return ret;
>  	copy_to_if_dqblk(&idq, &fdq);
> -	if (copy_to_user(addr, &idq, sizeof(idq)))
> -		return -EFAULT;
> +
> +	if (compat_need_64bit_alignment_fixup()) {
> +		struct compat_if_dqblk __user *compat_dqblk = addr;
> +
> +		if (copy_to_user(compat_dqblk, &idq, sizeof(*compat_dqblk)))
> +			return -EFAULT;
> +		if (put_user(idq.dqb_valid, &compat_dqblk->dqb_valid))
> +			return -EFAULT;

Isn't this always copying the same value again?
I don't think Linux has any 64 bit systems with a 32bit compat
layer that have 64bit 'int'.
Since the only difference in the structures is the 'end padding'
isn't it enough to just copy the size of the 'compat' structure
in a compat system call?
It might even be that gcc will optimise the condition away
when the structure sizes match.

The same is true for a lot of the rest of this file.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
David Laight Aug. 7, 2020, 9:38 a.m. UTC | #2
From: Christoph Hellwig
> Sent: 31 July 2020 13:22
> 
> Fold the misaligned u64 workarounds into the main quotactl flow instead
> of implementing a separate compat syscall handler.
> 
...
> +static int compat_copy_fs_quota_stat(struct compat_fs_quota_stat __user *to,
> +		struct fs_quota_stat *from)
> +{
> +	if (put_user(from->qs_version, &to->qs_version) ||
> +	    put_user(from->qs_flags, &to->qs_flags) ||
> +	    put_user(from->qs_pad, &to->qs_pad) ||
> +	    compat_copy_fs_qfilestat(&to->qs_uquota, &from->qs_uquota) ||
> +	    compat_copy_fs_qfilestat(&to->qs_gquota, &from->qs_gquota) ||
> +	    put_user(from->qs_incoredqs, &to->qs_incoredqs) ||
> +	    put_user(from->qs_btimelimit, &to->qs_btimelimit) ||
> +	    put_user(from->qs_itimelimit, &to->qs_itimelimit) ||
> +	    put_user(from->qs_rtbtimelimit, &to->qs_rtbtimelimit) ||
> +	    put_user(from->qs_bwarnlimit, &to->qs_bwarnlimit) ||
> +	    put_user(from->qs_iwarnlimit, &to->qs_iwarnlimit))
> +		return -EFAULT;
> +	return 0;
> +}

That might look better as a 'noinline' function that copied
all the fields into an on-stack struct compat_fs_quota_stat
and then did a single copy_to_user().

(I do 'like' qs_pad - I wonder what the person who added
it was smoking.)

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

Patch
diff mbox series

diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index d8f8a1a69ed11f..41d442d7c2db67 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -142,7 +142,7 @@ 
 128	i386	init_module		sys_init_module
 129	i386	delete_module		sys_delete_module
 130	i386	get_kernel_syms
-131	i386	quotactl		sys_quotactl			compat_sys_quotactl32
+131	i386	quotactl		sys_quotactl
 132	i386	getpgid			sys_getpgid
 133	i386	fchdir			sys_fchdir
 134	i386	bdflush			sys_bdflush
diff --git a/fs/quota/Kconfig b/fs/quota/Kconfig
index 7218314ca13f00..4f5bb85099a904 100644
--- a/fs/quota/Kconfig
+++ b/fs/quota/Kconfig
@@ -70,8 +70,3 @@  config QFMT_V2
 config QUOTACTL
 	bool
 	default n
-
-config QUOTACTL_COMPAT
-	bool
-	depends on QUOTACTL && COMPAT_FOR_U64_ALIGNMENT
-	default y
diff --git a/fs/quota/Makefile b/fs/quota/Makefile
index f2b49d0f0287c9..9160639daffa75 100644
--- a/fs/quota/Makefile
+++ b/fs/quota/Makefile
@@ -4,5 +4,4 @@  obj-$(CONFIG_QFMT_V1)		+= quota_v1.o
 obj-$(CONFIG_QFMT_V2)		+= quota_v2.o
 obj-$(CONFIG_QUOTA_TREE)	+= quota_tree.o
 obj-$(CONFIG_QUOTACTL)		+= quota.o kqid.o
-obj-$(CONFIG_QUOTACTL_COMPAT)	+= compat.o
 obj-$(CONFIG_QUOTA_NETLINK_INTERFACE)	+= netlink.o
diff --git a/fs/quota/compat.c b/fs/quota/compat.c
deleted file mode 100644
index c305728576193d..00000000000000
--- a/fs/quota/compat.c
+++ /dev/null
@@ -1,120 +0,0 @@ 
-// SPDX-License-Identifier: GPL-2.0
-
-#include <linux/syscalls.h>
-#include <linux/compat.h>
-#include <linux/quotaops.h>
-
-/*
- * This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
- * and is necessary due to alignment problems.
- */
-struct compat_if_dqblk {
-	compat_u64 dqb_bhardlimit;
-	compat_u64 dqb_bsoftlimit;
-	compat_u64 dqb_curspace;
-	compat_u64 dqb_ihardlimit;
-	compat_u64 dqb_isoftlimit;
-	compat_u64 dqb_curinodes;
-	compat_u64 dqb_btime;
-	compat_u64 dqb_itime;
-	compat_uint_t dqb_valid;
-};
-
-/* XFS structures */
-struct compat_fs_qfilestat {
-	compat_u64 dqb_bhardlimit;
-	compat_u64 qfs_nblks;
-	compat_uint_t qfs_nextents;
-};
-
-struct compat_fs_quota_stat {
-	__s8		qs_version;
-	__u16		qs_flags;
-	__s8		qs_pad;
-	struct compat_fs_qfilestat	qs_uquota;
-	struct compat_fs_qfilestat	qs_gquota;
-	compat_uint_t	qs_incoredqs;
-	compat_int_t	qs_btimelimit;
-	compat_int_t	qs_itimelimit;
-	compat_int_t	qs_rtbtimelimit;
-	__u16		qs_bwarnlimit;
-	__u16		qs_iwarnlimit;
-};
-
-COMPAT_SYSCALL_DEFINE4(quotactl32, unsigned int, cmd,
-		       const char __user *, special, qid_t, id,
-		       void __user *, addr)
-{
-	unsigned int cmds;
-	struct if_dqblk __user *dqblk;
-	struct compat_if_dqblk __user *compat_dqblk;
-	struct fs_quota_stat __user *fsqstat;
-	struct compat_fs_quota_stat __user *compat_fsqstat;
-	compat_uint_t data;
-	u16 xdata;
-	long ret;
-
-	cmds = cmd >> SUBCMDSHIFT;
-
-	switch (cmds) {
-	case Q_GETQUOTA:
-		dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
-		compat_dqblk = addr;
-		ret = kernel_quotactl(cmd, special, id, dqblk);
-		if (ret)
-			break;
-		if (copy_in_user(compat_dqblk, dqblk, sizeof(*compat_dqblk)) ||
-			get_user(data, &dqblk->dqb_valid) ||
-			put_user(data, &compat_dqblk->dqb_valid))
-			ret = -EFAULT;
-		break;
-	case Q_SETQUOTA:
-		dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
-		compat_dqblk = addr;
-		ret = -EFAULT;
-		if (copy_in_user(dqblk, compat_dqblk, sizeof(*compat_dqblk)) ||
-			get_user(data, &compat_dqblk->dqb_valid) ||
-			put_user(data, &dqblk->dqb_valid))
-			break;
-		ret = kernel_quotactl(cmd, special, id, dqblk);
-		break;
-	case Q_XGETQSTAT:
-		fsqstat = compat_alloc_user_space(sizeof(struct fs_quota_stat));
-		compat_fsqstat = addr;
-		ret = kernel_quotactl(cmd, special, id, fsqstat);
-		if (ret)
-			break;
-		ret = -EFAULT;
-		/* Copying qs_version, qs_flags, qs_pad */
-		if (copy_in_user(compat_fsqstat, fsqstat,
-			offsetof(struct compat_fs_quota_stat, qs_uquota)))
-			break;
-		/* Copying qs_uquota */
-		if (copy_in_user(&compat_fsqstat->qs_uquota,
-			&fsqstat->qs_uquota,
-			sizeof(compat_fsqstat->qs_uquota)) ||
-			get_user(data, &fsqstat->qs_uquota.qfs_nextents) ||
-			put_user(data, &compat_fsqstat->qs_uquota.qfs_nextents))
-			break;
-		/* Copying qs_gquota */
-		if (copy_in_user(&compat_fsqstat->qs_gquota,
-			&fsqstat->qs_gquota,
-			sizeof(compat_fsqstat->qs_gquota)) ||
-			get_user(data, &fsqstat->qs_gquota.qfs_nextents) ||
-			put_user(data, &compat_fsqstat->qs_gquota.qfs_nextents))
-			break;
-		/* Copying the rest */
-		if (copy_in_user(&compat_fsqstat->qs_incoredqs,
-			&fsqstat->qs_incoredqs,
-			sizeof(struct compat_fs_quota_stat) -
-			offsetof(struct compat_fs_quota_stat, qs_incoredqs)) ||
-			get_user(xdata, &fsqstat->qs_iwarnlimit) ||
-			put_user(xdata, &compat_fsqstat->qs_iwarnlimit))
-			break;
-		ret = 0;
-		break;
-	default:
-		ret = kernel_quotactl(cmd, special, id, addr);
-	}
-	return ret;
-}
diff --git a/fs/quota/compat.h b/fs/quota/compat.h
new file mode 100644
index 00000000000000..ef7d1e12d650b3
--- /dev/null
+++ b/fs/quota/compat.h
@@ -0,0 +1,34 @@ 
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/compat.h>
+
+struct compat_if_dqblk {
+	compat_u64			dqb_bhardlimit;
+	compat_u64			dqb_bsoftlimit;
+	compat_u64			dqb_curspace;
+	compat_u64			dqb_ihardlimit;
+	compat_u64			dqb_isoftlimit;
+	compat_u64			dqb_curinodes;
+	compat_u64			dqb_btime;
+	compat_u64			dqb_itime;
+	compat_uint_t			dqb_valid;
+};
+
+struct compat_fs_qfilestat {
+	compat_u64			dqb_bhardlimit;
+	compat_u64			qfs_nblks;
+	compat_uint_t			qfs_nextents;
+};
+
+struct compat_fs_quota_stat {
+	__s8				qs_version;
+	__u16				qs_flags;
+	__s8				qs_pad;
+	struct compat_fs_qfilestat	qs_uquota;
+	struct compat_fs_qfilestat	qs_gquota;
+	compat_uint_t			qs_incoredqs;
+	compat_int_t			qs_btimelimit;
+	compat_int_t			qs_itimelimit;
+	compat_int_t			qs_rtbtimelimit;
+	__u16				qs_bwarnlimit;
+	__u16				qs_iwarnlimit;
+};
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index 5444d3c4d93f37..e1e9d05a14c3e4 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -19,6 +19,7 @@ 
 #include <linux/types.h>
 #include <linux/writeback.h>
 #include <linux/nospec.h>
+#include "compat.h"
 
 static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
 				     qid_t id)
@@ -211,8 +212,18 @@  static int quota_getquota(struct super_block *sb, int type, qid_t id,
 	if (ret)
 		return ret;
 	copy_to_if_dqblk(&idq, &fdq);
-	if (copy_to_user(addr, &idq, sizeof(idq)))
-		return -EFAULT;
+
+	if (compat_need_64bit_alignment_fixup()) {
+		struct compat_if_dqblk __user *compat_dqblk = addr;
+
+		if (copy_to_user(compat_dqblk, &idq, sizeof(*compat_dqblk)))
+			return -EFAULT;
+		if (put_user(idq.dqb_valid, &compat_dqblk->dqb_valid))
+			return -EFAULT;
+	} else {
+		if (copy_to_user(addr, &idq, sizeof(idq)))
+			return -EFAULT;
+	}
 	return 0;
 }
 
@@ -277,8 +288,16 @@  static int quota_setquota(struct super_block *sb, int type, qid_t id,
 	struct if_dqblk idq;
 	struct kqid qid;
 
-	if (copy_from_user(&idq, addr, sizeof(idq)))
-		return -EFAULT;
+	if (compat_need_64bit_alignment_fixup()) {
+		struct compat_if_dqblk __user *compat_dqblk = addr;
+
+		if (copy_from_user(&idq, compat_dqblk, sizeof(*compat_dqblk)) ||
+		    get_user(idq.dqb_valid, &compat_dqblk->dqb_valid))
+			return -EFAULT;
+	} else {
+		if (copy_from_user(&idq, addr, sizeof(idq)))
+			return -EFAULT;
+	}
 	if (!sb->s_qcop->set_dqblk)
 		return -ENOSYS;
 	qid = make_kqid(current_user_ns(), type, id);
@@ -382,6 +401,33 @@  static int quota_getstate(struct super_block *sb, int type,
 	return 0;
 }
 
+static int compat_copy_fs_qfilestat(struct compat_fs_qfilestat __user *to,
+		struct fs_qfilestat *from)
+{
+	if (copy_to_user(to, from, sizeof(*to)) ||
+	    put_user(from->qfs_nextents, &to->qfs_nextents))
+		return -EFAULT;
+	return 0;
+}
+
+static int compat_copy_fs_quota_stat(struct compat_fs_quota_stat __user *to,
+		struct fs_quota_stat *from)
+{
+	if (put_user(from->qs_version, &to->qs_version) ||
+	    put_user(from->qs_flags, &to->qs_flags) ||
+	    put_user(from->qs_pad, &to->qs_pad) ||
+	    compat_copy_fs_qfilestat(&to->qs_uquota, &from->qs_uquota) ||
+	    compat_copy_fs_qfilestat(&to->qs_gquota, &from->qs_gquota) ||
+	    put_user(from->qs_incoredqs, &to->qs_incoredqs) ||
+	    put_user(from->qs_btimelimit, &to->qs_btimelimit) ||
+	    put_user(from->qs_itimelimit, &to->qs_itimelimit) ||
+	    put_user(from->qs_rtbtimelimit, &to->qs_rtbtimelimit) ||
+	    put_user(from->qs_bwarnlimit, &to->qs_bwarnlimit) ||
+	    put_user(from->qs_iwarnlimit, &to->qs_iwarnlimit))
+		return -EFAULT;
+	return 0;
+}
+
 static int quota_getxstate(struct super_block *sb, int type, void __user *addr)
 {
 	struct fs_quota_stat fqs;
@@ -390,9 +436,14 @@  static int quota_getxstate(struct super_block *sb, int type, void __user *addr)
 	if (!sb->s_qcop->get_state)
 		return -ENOSYS;
 	ret = quota_getstate(sb, type, &fqs);
-	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
+	if (ret)
+		return ret;
+
+	if (compat_need_64bit_alignment_fixup())
+		return compat_copy_fs_quota_stat(addr, &fqs);
+	if (copy_to_user(addr, &fqs, sizeof(fqs)))
 		return -EFAULT;
-	return ret;
+	return 0;
 }
 
 static int quota_getstatev(struct super_block *sb, int type,
@@ -816,8 +867,8 @@  static struct super_block *quotactl_block(const char __user *special, int cmd)
  * calls. Maybe we need to add the process quotas etc. in the future,
  * but we probably should use rlimits for that.
  */
-int kernel_quotactl(unsigned int cmd, const char __user *special,
-		    qid_t id, void __user *addr)
+SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
+		qid_t, id, void __user *, addr)
 {
 	uint cmds, type;
 	struct super_block *sb = NULL;
@@ -871,9 +922,3 @@  int kernel_quotactl(unsigned int cmd, const char __user *special,
 		path_put(pathp);
 	return ret;
 }
-
-SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
-		qid_t, id, void __user *, addr)
-{
-	return kernel_quotactl(cmd, special, id, addr);
-}
diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index 9cf0cd3dc88c68..a0f6668924d3ef 100644
--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -27,9 +27,6 @@  static inline bool is_quota_modification(struct inode *inode, struct iattr *ia)
 		(ia->ia_valid & ATTR_GID && !gid_eq(ia->ia_gid, inode->i_gid));
 }
 
-int kernel_quotactl(unsigned int cmd, const char __user *special,
-		    qid_t id, void __user *addr);
-
 #if defined(CONFIG_QUOTA)
 
 #define quota_error(sb, fmt, args...) \
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 3b69a560a7ac56..f01b91cc57fa00 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -370,7 +370,6 @@  COND_SYSCALL_COMPAT(fanotify_mark);
 /* x86 */
 COND_SYSCALL(vm86old);
 COND_SYSCALL(modify_ldt);
-COND_SYSCALL_COMPAT(quotactl32);
 COND_SYSCALL(vm86);
 COND_SYSCALL(kexec_file_load);