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author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-26 14:11:54 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-26 14:11:54 -0800 |
commit | 02fc87b117a9b9ec325089d098fce86ed11966bd (patch) | |
tree | 537176c1c32b25c781bf8974af854a4ee4dbc77a /arch/x86/kernel/umip.c | |
parent | Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/k... (diff) | |
parent | x86/decoder: Add new TEST instruction pattern (diff) | |
download | linux-02fc87b117a9b9ec325089d098fce86ed11966bd.tar.gz linux-02fc87b117a9b9ec325089d098fce86ed11966bd.tar.bz2 linux-02fc87b117a9b9ec325089d098fce86ed11966bd.zip |
Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 fixes from Ingo Molnar:
- topology enumeration fixes
- KASAN fix
- two entry fixes (not yet the big series related to KASLR)
- remove obsolete code
- instruction decoder fix
- better /dev/mem sanity checks, hopefully working better this time
- pkeys fixes
- two ACPI fixes
- 5-level paging related fixes
- UMIP fixes that should make application visible faults more debuggable
- boot fix for weird virtualization environment
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
x86/decoder: Add new TEST instruction pattern
x86/PCI: Remove unused HyperTransport interrupt support
x86/umip: Fix insn_get_code_seg_params()'s return value
x86/boot/KASLR: Remove unused variable
x86/entry/64: Add missing irqflags tracing to native_load_gs_index()
x86/mm/kasan: Don't use vmemmap_populate() to initialize shadow
x86/entry/64: Fix entry_SYSCALL_64_after_hwframe() IRQ tracing
x86/pkeys/selftests: Fix protection keys write() warning
x86/pkeys/selftests: Rename 'si_pkey' to 'siginfo_pkey'
x86/mpx/selftests: Fix up weird arrays
x86/pkeys: Update documentation about availability
x86/umip: Print a warning into the syslog if UMIP-protected instructions are used
x86/smpboot: Fix __max_logical_packages estimate
x86/topology: Avoid wasting 128k for package id array
perf/x86/intel/uncore: Cache logical pkg id in uncore driver
x86/acpi: Reduce code duplication in mp_override_legacy_irq()
x86/acpi: Handle SCI interrupts above legacy space gracefully
x86/boot: Fix boot failure when SMP MP-table is based at 0
x86/mm: Limit mmap() of /dev/mem to valid physical addresses
x86/selftests: Add test for mapping placement for 5-level paging
...
Diffstat (limited to 'arch/x86/kernel/umip.c')
-rw-r--r-- | arch/x86/kernel/umip.c | 88 |
1 files changed, 75 insertions, 13 deletions
diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c index 6ba82be68cff..f44ce0fb3583 100644 --- a/arch/x86/kernel/umip.c +++ b/arch/x86/kernel/umip.c @@ -78,7 +78,60 @@ #define UMIP_INST_SGDT 0 /* 0F 01 /0 */ #define UMIP_INST_SIDT 1 /* 0F 01 /1 */ -#define UMIP_INST_SMSW 3 /* 0F 01 /4 */ +#define UMIP_INST_SMSW 2 /* 0F 01 /4 */ +#define UMIP_INST_SLDT 3 /* 0F 00 /0 */ +#define UMIP_INST_STR 4 /* 0F 00 /1 */ + +const char * const umip_insns[5] = { + [UMIP_INST_SGDT] = "SGDT", + [UMIP_INST_SIDT] = "SIDT", + [UMIP_INST_SMSW] = "SMSW", + [UMIP_INST_SLDT] = "SLDT", + [UMIP_INST_STR] = "STR", +}; + +#define umip_pr_err(regs, fmt, ...) \ + umip_printk(regs, KERN_ERR, fmt, ##__VA_ARGS__) +#define umip_pr_warning(regs, fmt, ...) \ + umip_printk(regs, KERN_WARNING, fmt, ##__VA_ARGS__) + +/** + * umip_printk() - Print a rate-limited message + * @regs: Register set with the context in which the warning is printed + * @log_level: Kernel log level to print the message + * @fmt: The text string to print + * + * Print the text contained in @fmt. The print rate is limited to bursts of 5 + * messages every two minutes. The purpose of this customized version of + * printk() is to print messages when user space processes use any of the + * UMIP-protected instructions. Thus, the printed text is prepended with the + * task name and process ID number of the current task as well as the + * instruction and stack pointers in @regs as seen when entering kernel mode. + * + * Returns: + * + * None. + */ +static __printf(3, 4) +void umip_printk(const struct pt_regs *regs, const char *log_level, + const char *fmt, ...) +{ + /* Bursts of 5 messages every two minutes */ + static DEFINE_RATELIMIT_STATE(ratelimit, 2 * 60 * HZ, 5); + struct task_struct *tsk = current; + struct va_format vaf; + va_list args; + + if (!__ratelimit(&ratelimit)) + return; + + va_start(args, fmt); + vaf.fmt = fmt; + vaf.va = &args; + printk("%s" pr_fmt("%s[%d] ip:%lx sp:%lx: %pV"), log_level, tsk->comm, + task_pid_nr(tsk), regs->ip, regs->sp, &vaf); + va_end(args); +} /** * identify_insn() - Identify a UMIP-protected instruction @@ -118,10 +171,16 @@ static int identify_insn(struct insn *insn) default: return -EINVAL; } + } else if (insn->opcode.bytes[1] == 0x0) { + if (X86_MODRM_REG(insn->modrm.value) == 0) + return UMIP_INST_SLDT; + else if (X86_MODRM_REG(insn->modrm.value) == 1) + return UMIP_INST_STR; + else + return -EINVAL; + } else { + return -EINVAL; } - - /* SLDT AND STR are not emulated */ - return -EINVAL; } /** @@ -228,10 +287,8 @@ static void force_sig_info_umip_fault(void __user *addr, struct pt_regs *regs) if (!(show_unhandled_signals && unhandled_signal(tsk, SIGSEGV))) return; - pr_err_ratelimited("%s[%d] umip emulation segfault ip:%lx sp:%lx error:%x in %lx\n", - tsk->comm, task_pid_nr(tsk), regs->ip, - regs->sp, X86_PF_USER | X86_PF_WRITE, - regs->ip); + umip_pr_err(regs, "segfault in emulation. error%x\n", + X86_PF_USER | X86_PF_WRITE); } /** @@ -262,15 +319,11 @@ bool fixup_umip_exception(struct pt_regs *regs) unsigned char buf[MAX_INSN_SIZE]; void __user *uaddr; struct insn insn; - char seg_defs; + int seg_defs; if (!regs) return false; - /* Do not emulate 64-bit processes. */ - if (user_64bit_mode(regs)) - return false; - /* * If not in user-space long mode, a custom code segment could be in * use. This is true in protected mode (if the process defined a local @@ -322,6 +375,15 @@ bool fixup_umip_exception(struct pt_regs *regs) if (umip_inst < 0) return false; + umip_pr_warning(regs, "%s instruction cannot be used by applications.\n", + umip_insns[umip_inst]); + + /* Do not emulate SLDT, STR or user long mode processes. */ + if (umip_inst == UMIP_INST_STR || umip_inst == UMIP_INST_SLDT || user_64bit_mode(regs)) + return false; + + umip_pr_warning(regs, "For now, expensive software emulation returns the result.\n"); + if (emulate_umip_insn(&insn, umip_inst, dummy_data, &dummy_data_size)) return false; |