From 522e92743b35351bda1b6a9136560f833a9c2490 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 23 Jun 2021 14:01:58 +0200 Subject: [PATCH] x86/fpu: Deduplicate copy_uabi_from_user/kernel_to_xstate() copy_uabi_from_user_to_xstate() and copy_uabi_from_kernel_to_xstate() are almost identical except for the copy function. Unify them. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Borislav Petkov Acked-by: Andy Lutomirski Link: https://lkml.kernel.org/r/20210623121454.414215896@linutronix.de --- arch/x86/kernel/fpu/xstate.c | 137 +++++++++++++++---------------------------- 1 file changed, 47 insertions(+), 90 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 57674f8c2..0eb42a1 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -953,23 +953,6 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, } #endif /* ! CONFIG_ARCH_HAS_PKEYS */ -/* - * Weird legacy quirk: SSE and YMM states store information in the - * MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP - * area is marked as unused in the xfeatures header, we need to copy - * MXCSR and MXCSR_FLAGS if either SSE or YMM are in use. - */ -static inline bool xfeatures_mxcsr_quirk(u64 xfeatures) -{ - if (!(xfeatures & (XFEATURE_MASK_SSE|XFEATURE_MASK_YMM))) - return false; - - if (xfeatures & XFEATURE_MASK_FP) - return false; - - return true; -} - static void copy_feature(bool from_xstate, struct membuf *to, void *xstate, void *init_xstate, unsigned int size) { @@ -1082,39 +1065,53 @@ out: membuf_zero(&to, to.left); } -static inline bool mxcsr_valid(struct xstate_header *hdr, const u32 *mxcsr) +static int copy_from_buffer(void *dst, unsigned int offset, unsigned int size, + const void *kbuf, const void __user *ubuf) { - u64 mask = XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM; - - /* Only check if it is in use */ - if (hdr->xfeatures & mask) { - /* Reserved bits in MXCSR must be zero. */ - if (*mxcsr & ~mxcsr_feature_mask) - return false; + if (kbuf) { + memcpy(dst, kbuf + offset, size); + } else { + if (copy_from_user(dst, ubuf + offset, size)) + return -EFAULT; } - return true; + return 0; } -/* - * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S] format - * and copy to the target thread. This is called from xstateregs_set(). - */ -int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) + +static int copy_uabi_to_xstate(struct xregs_state *xsave, const void *kbuf, + const void __user *ubuf) { unsigned int offset, size; - int i; struct xstate_header hdr; + u64 mask; + int i; offset = offsetof(struct xregs_state, header); - size = sizeof(hdr); - - memcpy(&hdr, kbuf + offset, size); + if (copy_from_buffer(&hdr, offset, sizeof(hdr), kbuf, ubuf)) + return -EFAULT; if (validate_user_xstate_header(&hdr)) return -EINVAL; - if (!mxcsr_valid(&hdr, kbuf + offsetof(struct fxregs_state, mxcsr))) - return -EINVAL; + /* Validate MXCSR when any of the related features is in use */ + mask = XFEATURE_MASK_FP | XFEATURE_MASK_SSE | XFEATURE_MASK_YMM; + if (hdr.xfeatures & mask) { + u32 mxcsr[2]; + + offset = offsetof(struct fxregs_state, mxcsr); + if (copy_from_buffer(mxcsr, offset, sizeof(mxcsr), kbuf, ubuf)) + return -EFAULT; + + /* Reserved bits in MXCSR must be zero. */ + if (mxcsr[0] & ~mxcsr_feature_mask) + return -EINVAL; + + /* SSE and YMM require MXCSR even when FP is not in use. */ + if (!(hdr.xfeatures & XFEATURE_MASK_FP)) { + xsave->i387.mxcsr = mxcsr[0]; + xsave->i387.mxcsr_mask = mxcsr[1]; + } + } for (i = 0; i < XFEATURE_MAX; i++) { u64 mask = ((u64)1 << i); @@ -1125,16 +1122,11 @@ int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) offset = xstate_offsets[i]; size = xstate_sizes[i]; - memcpy(dst, kbuf + offset, size); + if (copy_from_buffer(dst, offset, size, kbuf, ubuf)) + return -EFAULT; } } - if (xfeatures_mxcsr_quirk(hdr.xfeatures)) { - offset = offsetof(struct fxregs_state, mxcsr); - size = MXCSR_AND_FLAGS_SIZE; - memcpy(&xsave->i387.mxcsr, kbuf + offset, size); - } - /* * The state that came in from userspace was user-state only. * Mask all the user states out of 'xfeatures': @@ -1150,6 +1142,16 @@ int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) } /* + * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S] + * format and copy to the target thread. This is called from + * xstateregs_set(). + */ +int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) +{ + return copy_uabi_to_xstate(xsave, kbuf, NULL); +} + +/* * Convert from a sigreturn standard-format user-space buffer to kernel * XSAVE[S] format and copy to the target thread. This is called from the * sigreturn() and rt_sigreturn() system calls. @@ -1157,52 +1159,7 @@ int copy_uabi_from_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf) int copy_sigframe_from_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf) { - unsigned int offset, size; - int i; - struct xstate_header hdr; - - offset = offsetof(struct xregs_state, header); - size = sizeof(hdr); - - if (copy_from_user(&hdr, ubuf + offset, size)) - return -EFAULT; - - if (validate_user_xstate_header(&hdr)) - return -EINVAL; - - for (i = 0; i < XFEATURE_MAX; i++) { - u64 mask = ((u64)1 << i); - - if (hdr.xfeatures & mask) { - void *dst = __raw_xsave_addr(xsave, i); - - offset = xstate_offsets[i]; - size = xstate_sizes[i]; - - if (copy_from_user(dst, ubuf + offset, size)) - return -EFAULT; - } - } - - if (xfeatures_mxcsr_quirk(hdr.xfeatures)) { - offset = offsetof(struct fxregs_state, mxcsr); - size = MXCSR_AND_FLAGS_SIZE; - if (copy_from_user(&xsave->i387.mxcsr, 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_ALL; - - /* - * Add back in the features that came in from userspace: - */ - xsave->header.xfeatures |= hdr.xfeatures; - - return 0; + return copy_uabi_to_xstate(xsave, NULL, ubuf); } /** -- 2.7.4