compat: in_compat_syscall() differs on x86
Subsystems (8)
cover compat: in_compat_syscall() differs on x86
Reading xfrm (ipsec) code I've found such code:
: #ifdef CONFIG_COMPAT
: if (in_compat_syscall())
: return -EOPNOTSUPP;
: #endif
While I can read that it's false on native i386, it's a bit misleading and in result it's better to introduce a helper for that. Grepping other code, I've found that there are already such helpers. And the uniq behavior of in_compat_syscall() on x86 is disturbing.
Adjusting it to generic with the following..
Cc Ard Biesheuvel <[email protected]>
Cc "David S. Miller" <[email protected]>
Cc Herbert Xu <[email protected]>
Cc "H. Peter Anvin" <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc John Stultz <[email protected]>
Cc "Kirill A. Shutemov" <[email protected]>
Cc Oleg Nesterov <[email protected]>
Cc Steffen Klassert <[email protected]>
Cc Stephen Boyd <[email protected]>
Cc Steven Rostedt <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc Dmitry Safonov <[email protected]>
Dmitry Safonov (2):
x86/compat: Adjust in_compat_syscall() to generic code under !COMPAT
compat: Cleanup in_compat_syscall() callers
arch/x86/include/asm/compat.h | 9 ++++++++- arch/x86/include/asm/ftrace.h | 4 +--- arch/x86/kernel/process_64.c | 4 ++-- arch/x86/kernel/sys_x86_64.c | 11 ++++++----- arch/x86/mm/hugetlbpage.c | 4 ++-- arch/x86/mm/mmap.c | 2 +- drivers/firmware/efi/efivars.c | 16 ++++------------ include/linux/compat.h | 4 ++-- kernel/time/time.c | 2 +- net/xfrm/xfrm_state.c | 2 -- net/xfrm/xfrm_user.c | 2 -- 11 files changed, 27 insertions(+), 33 deletions(-)
Signature · 1 line
2.13.6
RFC 1/2 x86/compat: Adjust in_compat_syscall() to generic code under !COMPAT
The result of in_compat_syscall() can be pictured as:
x86 platform:
---------------------------------------------------
| Arch\syscall | 64-bit | ia32 | x32 |
|-------------------------------------------------|
| x86_64 | false | true | true |
|-------------------------------------------------|
| i686 | false | <true> | false |
---------------------------------------------------Other platforms:
------------------------------------------------
| Arch\syscall | 64-bit | compat (32?) |
|----------------------------------------------|
| 64-bit | false | true |
|----------------------------------------------|
| 32-bit(?) | false | <false> |
------------------------------------------------As it seen, the result of in_compat_syscall() on generic 32-bit platform differs from i686.
There is no reason for in_compat_syscall() == true on native i686. It also easy to misread code if the result on native 32-bit platform differs between arches.
Because of that non arch-specific code has many places with:
if (IS_ENABLED(CONFIG_COMPAT) && in_compat_syscall())
in different variations.
It looks-like the only non-x86 code which uses in_compat_syscall() not under CONFIG_COMPAT guard is in amd/amdkfd. But according to the commit a18069c132cb ("amdkfd: Disable support for 32-bit user processes"), it actually should be disabled on native i686.
Rename in_compat_syscall() to in_32bit_syscall() for x86-specific code and make in_compat_syscall() false under !CONFIG_COMPAT.
With a following patch I'll clean generic users which were forced to check IS_ENABLED(CONFIG_COMPAT) with in_compat_syscall().
Signed-off-by Dmitry Safonov <[email protected]>
--- arch/x86/include/asm/compat.h | 9 ++++++++- arch/x86/include/asm/ftrace.h | 4 +--- arch/x86/kernel/process_64.c | 4 ++-- arch/x86/kernel/sys_x86_64.c | 11 ++++++----- arch/x86/mm/hugetlbpage.c | 4 ++-- arch/x86/mm/mmap.c | 2 +- include/linux/compat.h | 4 ++-- 7 files changed, 22 insertions(+), 16 deletions(-)
arch/x86/include/asm/compat.h +8 -1
@@ -232,11 +232,18 @@ static inline bool in_x32_syscall(void)return false; } -static inline bool in_compat_syscall (void ) +static inline bool in_32bit_syscall (void ) {return in_ia32_syscall () ||in_x32_syscall (); } + +#ifdef CONFIG_COMPAT +static inline bool in_compat_syscall (void ) +{ +return in_32bit_syscall (); +}#define in_compat_syscall in_compat_syscall/* override the generic impl */ +#endif struct compat_siginfo ; int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
arch/x86/include/asm/ftrace.h +1 -3
@@ -76,9 +76,7 @@ static inline bool arch_syscall_match_sym_name(const char *sym, const char *name#define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS 1static inline bool arch_trace_is_compat_syscall (struct pt_regs *regs) { -if (in_compat_syscall ()) -return true; -return false; +return in_32bit_syscall (); }#endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_IA32_EMULATION */ #endif /* !COMPILE_OFFSETS */
arch/x86/kernel/process_64.c +2 -2
@@ -564,10 +564,10 @@ static void __set_personality_x32(void) current->mm->context.ia32_compat =TIF_X32 ; current->personality &= ~READ_IMPLIES_EXEC ;/* -* in_compat_syscall() uses the presence of the x32 syscall bit +* in_32bit_syscall() uses the presence of the x32 syscall bit * flag to determine compat status. The x86 mmap() code relies on * the syscall bitness so set x32 syscall bit right here to make -* in_compat_syscall() work during exec(). +* in_32bit_syscall() work during exec(). * * Pretend to come from a x32 execve. */
arch/x86/kernel/sys_x86_64.c +6 -5
@@ -105,7 +105,7 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,static void find_start_end (unsigned long addr,unsigned long flags,unsigned long *begin,unsigned long *end) { -if (!in_compat_syscall () && (flags &MAP_32BIT )) { +if (!in_32bit_syscall () && (flags &MAP_32BIT )) {/* This is usually used needed to map code in small model, so it needs to be in the first 31bit. Limit it to that. This means we need to move the
@@ -122,7 +122,7 @@ static void find_start_end(unsigned long addr, unsigned long flags, } *begin =get_mmap_base (1 ); -if (in_compat_syscall ()) +if (in_32bit_syscall ()) *end =task_size_32bit ();else *end =task_size_64bit (addr >DEFAULT_MAP_WINDOW );
@@ -193,7 +193,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,return addr;/* for MAP_32BIT mappings we force the legacy mmap base */ -if (!in_compat_syscall () && (flags &MAP_32BIT )) +if (!in_32bit_syscall () && (flags &MAP_32BIT )) goto bottomup;/* requesting a specific address */
@@ -217,9 +217,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,* If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area * in the full address space. * -* !in_compat_syscall() check to avoid high addresses for x32. +* !in_32bit_syscall() check to avoid high addresses for x32 +* (and make it no op on native i386). */ -if (addr >DEFAULT_MAP_WINDOW && !in_compat_syscall ()) +if (addr >DEFAULT_MAP_WINDOW && !in_32bit_syscall ()) info.high_limit +=TASK_SIZE_MAX -DEFAULT_MAP_WINDOW ; info.align_mask =0 ;
arch/x86/mm/hugetlbpage.c +2 -2
@@ -92,7 +92,7 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,* If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area * in the full address space. */ - info.high_limit =in_compat_syscall () ? + info.high_limit =in_32bit_syscall () ?task_size_32bit () :task_size_64bit (addr >DEFAULT_MAP_WINDOW ); info.align_mask =PAGE_MASK & ~huge_page_mask (h);
@@ -116,7 +116,7 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,* If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area * in the full address space. */ -if (addr >DEFAULT_MAP_WINDOW && !in_compat_syscall ()) +if (addr >DEFAULT_MAP_WINDOW && !in_32bit_syscall ()) info.high_limit +=TASK_SIZE_MAX -DEFAULT_MAP_WINDOW ; info.align_mask =PAGE_MASK & ~huge_page_mask (h);
arch/x86/mm/mmap.c +1 -1
@@ -166,7 +166,7 @@ unsigned long get_mmap_base(int is_legacy)struct mm_struct *mm = current->mm;#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES -if (in_compat_syscall ()) { +if (in_32bit_syscall ()) {return is_legacy ? mm->mmap_compat_legacy_base : mm->mmap_compat_base; }
include/linux/compat.h +2 -2
@@ -1031,9 +1031,9 @@ static inline struct compat_timeval ns_to_compat_timeval(s64 nsec)#else /* !CONFIG_COMPAT */ #define is_compat_task () (0) -#ifndef in_compat_syscall +/* Ensure no one redefines in_compat_syscall() under !CONFIG_COMPAT */ +#define in_compat_syscall in_compat_syscallstatic inline bool in_compat_syscall (void ) {return false; } -#endif #endif /* CONFIG_COMPAT */
Signature · 1 line
2.13.6
RFC 2/2 compat: Cleanup in_compat_syscall() callers
In reply to Dmitry SafonovNow that in_compat_syscall() == false on native i686, it's possible to remove some ifdeffery and no more needed helpers.
Signed-off-by Dmitry Safonov <[email protected]>
--- drivers/firmware/efi/efivars.c | 16 ++++------------ kernel/time/time.c | 2 +- net/xfrm/xfrm_state.c | 2 -- net/xfrm/xfrm_user.c | 2 -- 4 files changed, 5 insertions(+), 17 deletions(-)
drivers/firmware/efi/efivars.c +4 -12
@@ -229,14 +229,6 @@ sanity_check(struct efi_variable *var, efi_char16_t *name, efi_guid_t vendor,return 0 ; } -static inline bool is_compat (void ) -{ -if (IS_ENABLED (CONFIG_COMPAT ) &&in_compat_syscall ()) -return true; - -return false; -} -static void copy_out_compat (struct efi_variable *dst,struct compat_efi_variable *src) {
@@ -263,7 +255,7 @@ efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)u8 *data;int err; -if (is_compat ()) { +if (in_compat_syscall ()) {struct compat_efi_variable *compat;if (count !=sizeof (*compat))
@@ -324,7 +316,7 @@ efivar_show_raw(struct efivar_entry *entry, char *buf) &entry->var.DataSize, entry->var.Data))return -EIO ; -if (is_compat ()) { +if (in_compat_syscall ()) { compat = (struct compat_efi_variable *)buf; size =sizeof (*compat);
@@ -418,7 +410,7 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,struct compat_efi_variable *compat = (struct compat_efi_variable *)buf;struct efi_variable *new_var = (struct efi_variable *)buf;struct efivar_entry *new_entry; -bool need_compat =is_compat (); +bool need_compat =in_compat_syscall ();efi_char16_t *name;unsigned long size;u32 attributes;
@@ -495,7 +487,7 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,if (!capable (CAP_SYS_ADMIN ))return -EACCES ; -if (is_compat ()) { +if (in_compat_syscall ()) {if (count !=sizeof (*compat))return -EINVAL ;
kernel/time/time.c +1 -1
@@ -865,7 +865,7 @@ int get_timespec64(struct timespec64 *ts, ts->tv_sec = kts.tv_sec;/* Zero out the padding for 32 bit systems or in compat mode */ -if (IS_ENABLED (CONFIG_64BIT_TIME ) && (!IS_ENABLED (CONFIG_64BIT ) ||in_compat_syscall ())) +if (IS_ENABLED (CONFIG_64BIT_TIME ) &&in_compat_syscall ()) kts.tv_nsec &=0xFFFFFFFFUL ; ts->tv_nsec = kts.tv_nsec;
net/xfrm/xfrm_state.c +0 -2
@@ -2057,10 +2057,8 @@ int xfrm_user_policy(struct sock *sk, int optname, u8 __user *optval, int optlenstruct xfrm_mgr *km;struct xfrm_policy *pol =NULL ; -#ifdef CONFIG_COMPAT if (in_compat_syscall ())return -EOPNOTSUPP ; -#endif if (!optval && !optlen) {xfrm_sk_policy_insert (sk,XFRM_POLICY_IN ,NULL );
net/xfrm/xfrm_user.c +0 -2
@@ -2546,10 +2546,8 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,const struct xfrm_link *link;int type, err; -#ifdef CONFIG_COMPAT if (in_compat_syscall ())return -EOPNOTSUPP ; -#endif type = nlh->nlmsg_type;if (type >XFRM_MSG_MAX )
Signature · 1 line
2.13.6