Date: Tue, 28 Nov 2017 11:06:18 +0000 (UTC) From: Andrew Turner <andrew@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r326313 - in stable/11/sys: arm/arm arm64/arm64 arm64/include Message-ID: <201711281106.vASB6I5F025046@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: andrew Date: Tue Nov 28 11:06:17 2017 New Revision: 326313 URL: https://svnweb.freebsd.org/changeset/base/326313 Log: MFC r326137: Ensure we check the program state set in the trap frame on arm and arm64. This value may be set by userspace so we need to check it before using it. If this is not done correctly on exception return the kernel may continue in kernel mode with all registers set to a userspace controlled value. Fix this by moving the check into set_mcontext, and also add the missing sanitisation from the arm64 set_regs. Discussed with: security-officer@ Sponsored by: DARPA, AFRL Modified: stable/11/sys/arm/arm/machdep.c stable/11/sys/arm64/arm64/machdep.c stable/11/sys/arm64/include/armreg.h Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/arm/arm/machdep.c ============================================================================== --- stable/11/sys/arm/arm/machdep.c Tue Nov 28 11:04:47 2017 (r326312) +++ stable/11/sys/arm/arm/machdep.c Tue Nov 28 11:06:17 2017 (r326313) @@ -507,7 +507,17 @@ set_mcontext(struct thread *td, mcontext_t *mcp) mcontext_vfp_t mc_vfp, *vfp; struct trapframe *tf = td->td_frame; const __greg_t *gr = mcp->__gregs; + int spsr; + /* + * Make sure the processor mode has not been tampered with and + * interrupts have not been disabled. + */ + spsr = gr[_REG_CPSR]; + if ((spsr & PSR_MODE) != PSR_USR32_MODE || + (spsr & (PSR_I | PSR_F)) != 0) + return (EINVAL); + #ifdef WITNESS if (mcp->mc_vfp_size != 0 && mcp->mc_vfp_size != sizeof(mc_vfp)) { printf("%s: %s: Malformed mc_vfp_size: %d (0x%08X)\n", @@ -666,22 +676,16 @@ sys_sigreturn(td, uap) } */ *uap; { ucontext_t uc; - int spsr; + int error; if (uap == NULL) return (EFAULT); if (copyin(uap->sigcntxp, &uc, sizeof(uc))) return (EFAULT); - /* - * Make sure the processor mode has not been tampered with and - * interrupts have not been disabled. - */ - spsr = uc.uc_mcontext.__gregs[_REG_CPSR]; - if ((spsr & PSR_MODE) != PSR_USR32_MODE || - (spsr & (PSR_I | PSR_F)) != 0) - return (EINVAL); /* Restore register context. */ - set_mcontext(td, &uc.uc_mcontext); + error = set_mcontext(td, &uc.uc_mcontext); + if (error != 0) + return (error); /* Restore signal mask. */ kern_sigprocmask(td, SIG_SETMASK, &uc.uc_sigmask, NULL, 0); Modified: stable/11/sys/arm64/arm64/machdep.c ============================================================================== --- stable/11/sys/arm64/arm64/machdep.c Tue Nov 28 11:04:47 2017 (r326312) +++ stable/11/sys/arm64/arm64/machdep.c Tue Nov 28 11:06:17 2017 (r326313) @@ -194,7 +194,8 @@ set_regs(struct thread *td, struct reg *regs) frame->tf_sp = regs->sp; frame->tf_lr = regs->lr; frame->tf_elr = regs->elr; - frame->tf_spsr = regs->spsr; + frame->tf_spsr &= ~PSR_FLAGS; + frame->tf_spsr |= regs->spsr & PSR_FLAGS; memcpy(frame->tf_x, regs->x, sizeof(frame->tf_x)); @@ -332,7 +333,13 @@ int set_mcontext(struct thread *td, mcontext_t *mcp) { struct trapframe *tf = td->td_frame; + uint32_t spsr; + spsr = mcp->mc_gpregs.gp_spsr; + if ((spsr & PSR_M_MASK) != PSR_M_EL0t || + (spsr & (PSR_F | PSR_I | PSR_A | PSR_D)) != 0) + return (EINVAL); + memcpy(tf->tf_x, mcp->mc_gpregs.gp_x, sizeof(tf->tf_x)); tf->tf_sp = mcp->mc_gpregs.gp_sp; @@ -502,19 +509,16 @@ int sys_sigreturn(struct thread *td, struct sigreturn_args *uap) { ucontext_t uc; - uint32_t spsr; + int error; if (uap == NULL) return (EFAULT); if (copyin(uap->sigcntxp, &uc, sizeof(uc))) return (EFAULT); - spsr = uc.uc_mcontext.mc_gpregs.gp_spsr; - if ((spsr & PSR_M_MASK) != PSR_M_EL0t || - (spsr & (PSR_F | PSR_I | PSR_A | PSR_D)) != 0) - return (EINVAL); - - set_mcontext(td, &uc.uc_mcontext); + error = set_mcontext(td, &uc.uc_mcontext); + if (error != 0) + return (error); set_fpcontext(td, &uc.uc_mcontext); /* Restore signal mask. */ Modified: stable/11/sys/arm64/include/armreg.h ============================================================================== --- stable/11/sys/arm64/include/armreg.h Tue Nov 28 11:04:47 2017 (r326312) +++ stable/11/sys/arm64/include/armreg.h Tue Nov 28 11:06:17 2017 (r326313) @@ -439,6 +439,7 @@ #define PSR_C 0x20000000 #define PSR_Z 0x40000000 #define PSR_N 0x80000000 +#define PSR_FLAGS 0xf0000000 /* TCR_EL1 - Translation Control Register */ #define TCR_ASID_16 (1 << 36)
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201711281106.vASB6I5F025046>