Commit-ID: 91c3dba7dbc199191272f4a9863f86ea3bfd679f Gitweb: http://git.kernel.org/tip/91c3dba7dbc199191272f4a9863f86ea3bfd679f Author: Yu-cheng Yu <[email protected]> AuthorDate: Fri, 17 Jun 2016 13:07:17 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Sun, 10 Jul 2016 17:12:10 +0200
x86/fpu/xstate: Fix PTRACE frames for XSAVES XSAVES uses compacted format and is a kernel instruction. The kernel should use standard-format, non-supervisor state data for PTRACE. Signed-off-by: Yu-cheng Yu <[email protected]> [ Edited away artificial linebreaks. ] Reviewed-by: Dave Hansen <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: Fenghua Yu <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Quentin Casasnovas <[email protected]> Cc: Ravi V. Shankar <[email protected]> Cc: Sai Praneeth Prakhya <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/de3d80949001305fe389799973b675cab055c457.1466179491.git.yu-cheng...@intel.com [ Made various readability edits. ] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/include/asm/fpu/xstate.h | 5 +- arch/x86/kernel/fpu/regset.c | 52 +++++++---- arch/x86/kernel/fpu/xstate.c | 183 ++++++++++++++++++++++++++++++++++++-- 3 files changed, 216 insertions(+), 24 deletions(-) diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 92f376c..ae55a43 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -51,5 +51,8 @@ void fpu__xstate_clear_all_cpu_caps(void); void *get_xsave_addr(struct xregs_state *xsave, int xstate); const void *get_xsave_field_ptr(int xstate_field); int using_compacted_format(void); - +int copyout_from_xsaves(unsigned int pos, unsigned int count, void *kbuf, + void __user *ubuf, struct xregs_state *xsave); +int copyin_to_xsaves(const void *kbuf, const void __user *ubuf, + struct xregs_state *xsave); #endif diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c index 81422df..c114b13 100644 --- a/arch/x86/kernel/fpu/regset.c +++ b/arch/x86/kernel/fpu/regset.c @@ -4,6 +4,7 @@ #include <asm/fpu/internal.h> #include <asm/fpu/signal.h> #include <asm/fpu/regset.h> +#include <asm/fpu/xstate.h> /* * The xstateregs_active() routine is the same as the regset_fpregs_active() routine, @@ -85,21 +86,26 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset, if (!boot_cpu_has(X86_FEATURE_XSAVE)) return -ENODEV; - fpu__activate_fpstate_read(fpu); - xsave = &fpu->state.xsave; - /* - * Copy the 48bytes defined by the software first into the xstate - * memory layout in the thread struct, so that we can copy the entire - * xstateregs to the user using one user_regset_copyout(). - */ - memcpy(&xsave->i387.sw_reserved, - xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes)); - /* - * Copy the xstate memory layout. - */ - ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1); + fpu__activate_fpstate_read(fpu); + + if (using_compacted_format()) { + ret = copyout_from_xsaves(pos, count, kbuf, ubuf, xsave); + } else { + fpstate_sanitize_xstate(fpu); + /* + * Copy the 48 bytes defined by the software into the xsave + * area in the thread struct, so that we can copy the whole + * area to user using one user_regset_copyout(). + */ + memcpy(&xsave->i387.sw_reserved, xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes)); + + /* + * Copy the xstate memory layout. + */ + ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1); + } return ret; } @@ -114,11 +120,27 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset, if (!boot_cpu_has(X86_FEATURE_XSAVE)) return -ENODEV; - fpu__activate_fpstate_write(fpu); + /* + * A whole standard-format XSAVE buffer is needed: + */ + if ((pos != 0) || (count < fpu_user_xstate_size)) + return -EFAULT; xsave = &fpu->state.xsave; - ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1); + fpu__activate_fpstate_write(fpu); + + if (boot_cpu_has(X86_FEATURE_XSAVES)) + ret = copyin_to_xsaves(kbuf, ubuf, xsave); + else + ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1); + + /* + * In case of failure, mark all states as init: + */ + if (ret) + fpstate_init(&fpu->state); + /* * mxcsr reserved bits must be masked to zero for security reasons. */ diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 02786fb..56c0e70 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -11,6 +11,7 @@ #include <asm/fpu/internal.h> #include <asm/fpu/signal.h> #include <asm/fpu/regset.h> +#include <asm/fpu/xstate.h> #include <asm/tlbflush.h> @@ -697,7 +698,12 @@ void __init fpu__init_system_xstate(void) return; } - update_regset_xstate_info(fpu_kernel_xstate_size, xfeatures_mask); + /* + * Update info used for ptrace frames; use standard-format size and no + * supervisor xstates: + */ + update_regset_xstate_info(fpu_user_xstate_size, xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR); + fpu__init_prepare_fx_sw_frame(); setup_init_fpu_buf(); setup_xstate_comp(); @@ -925,16 +931,16 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, if (!boot_cpu_has(X86_FEATURE_OSPKE)) return -EINVAL; - /* Set the bits we need in PKRU */ + /* Set the bits we need in PKRU: */ if (init_val & PKEY_DISABLE_ACCESS) new_pkru_bits |= PKRU_AD_BIT; if (init_val & PKEY_DISABLE_WRITE) new_pkru_bits |= PKRU_WD_BIT; - /* Shift the bits in to the correct place in PKRU for pkey. */ + /* Shift the bits in to the correct place in PKRU for pkey: */ new_pkru_bits <<= pkey_shift; - /* Locate old copy of the state in the xsave buffer */ + /* Locate old copy of the state in the xsave buffer: */ old_pkru_state = get_xsave_addr(xsave, XFEATURE_MASK_PKRU); /* @@ -947,9 +953,10 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, else new_pkru_state.pkru = old_pkru_state->pkru; - /* mask off any old bits in place */ + /* Mask off any old bits in place: */ new_pkru_state.pkru &= ~((PKRU_AD_BIT|PKRU_WD_BIT) << pkey_shift); - /* Set the newly-requested bits */ + + /* Set the newly-requested bits: */ new_pkru_state.pkru |= new_pkru_bits; /* @@ -963,8 +970,168 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, */ new_pkru_state.pad = 0; - fpu__xfeature_set_state(XFEATURE_MASK_PKRU, &new_pkru_state, - sizeof(new_pkru_state)); + fpu__xfeature_set_state(XFEATURE_MASK_PKRU, &new_pkru_state, sizeof(new_pkru_state)); + + return 0; +} + +/* + * This is similar to user_regset_copyout(), but will not add offset to + * the source data pointer or increment pos, count, kbuf, and ubuf. + */ +static inline int xstate_copyout(unsigned int pos, unsigned int count, + void *kbuf, void __user *ubuf, + const void *data, const int start_pos, + const int end_pos) +{ + if ((count == 0) || (pos < start_pos)) + return 0; + + if (end_pos < 0 || pos < end_pos) { + unsigned int copy = (end_pos < 0 ? count : min(count, end_pos - pos)); + + if (kbuf) { + memcpy(kbuf + pos, data, copy); + } else { + if (__copy_to_user(ubuf + pos, data, copy)) + return -EFAULT; + } + } + return 0; +} + +/* + * Convert from kernel XSAVES compacted format to standard format and copy + * to a ptrace buffer. It supports partial copy but pos always starts from + * zero. This is called from xstateregs_get() and there we check the CPU + * has XSAVES. + */ +int copyout_from_xsaves(unsigned int pos, unsigned int count, void *kbuf, + void __user *ubuf, struct xregs_state *xsave) +{ + unsigned int offset, size; + int ret, i; + struct xstate_header header; + + /* + * Currently copy_regset_to_user() starts from pos 0: + */ + if (unlikely(pos != 0)) + return -EFAULT; + + /* + * The destination is a ptrace buffer; we put in only user xstates: + */ + memset(&header, 0, sizeof(header)); + header.xfeatures = xsave->header.xfeatures; + header.xfeatures &= ~XFEATURE_MASK_SUPERVISOR; + + /* + * Copy xregs_state->header: + */ + offset = offsetof(struct xregs_state, header); + size = sizeof(header); + + ret = xstate_copyout(offset, size, kbuf, ubuf, &header, 0, count); + + if (ret) + return ret; + + for (i = 0; i < XFEATURE_MAX; i++) { + /* + * Copy only in-use xstates: + */ + if ((header.xfeatures >> i) & 1) { + void *src = __raw_xsave_addr(xsave, 1 << i); + + offset = xstate_offsets[i]; + size = xstate_sizes[i]; + + ret = xstate_copyout(offset, size, kbuf, ubuf, src, 0, count); + + if (ret) + return ret; + + if (offset + size >= count) + break; + } + + } + + /* + * Fill xsave->i387.sw_reserved value for ptrace frame: + */ + offset = offsetof(struct fxregs_state, sw_reserved); + size = sizeof(xstate_fx_sw_bytes); + + ret = xstate_copyout(offset, size, kbuf, ubuf, xstate_fx_sw_bytes, 0, count); + + if (ret) + return ret; + + return 0; +} + +/* + * Convert from a ptrace standard-format buffer to kernel XSAVES format + * and copy to the target thread. This is called from xstateregs_set() and + * there we check the CPU has XSAVES and a whole standard-sized buffer + * exists. + */ +int copyin_to_xsaves(const void *kbuf, const void __user *ubuf, + struct xregs_state *xsave) +{ + unsigned int offset, size; + int i; + u64 xfeatures; + u64 allowed_features; + + offset = offsetof(struct xregs_state, header); + size = sizeof(xfeatures); + + if (kbuf) { + memcpy(&xfeatures, kbuf + offset, size); + } else { + if (__copy_from_user(&xfeatures, ubuf + offset, size)) + return -EFAULT; + } + + /* + * Reject if the user sets any disabled or supervisor features: + */ + allowed_features = xfeatures_mask & ~XFEATURE_MASK_SUPERVISOR; + + if (xfeatures & ~allowed_features) + return -EINVAL; + + for (i = 0; i < XFEATURE_MAX; i++) { + u64 mask = ((u64)1 << i); + + if (xfeatures & mask) { + void *dst = __raw_xsave_addr(xsave, 1 << i); + + offset = xstate_offsets[i]; + size = xstate_sizes[i]; + + if (kbuf) { + memcpy(dst, kbuf + offset, size); + } else { + if (__copy_from_user(dst, ubuf + offset, size)) + return -EFAULT; + } + } + } + + /* + * The state that came in from userspace was user-state only. + * Mask all the user states out of 'xfeatures': + */ + xsave->header.xfeatures &= XFEATURE_MASK_SUPERVISOR; + + /* + * Add back in the features that came in from userspace: + */ + xsave->header.xfeatures |= xfeatures; return 0; }
