From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1944) id 172363851503; Thu, 27 Oct 2022 13:53:58 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 172363851503 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1666878838; bh=xXwlVCUigz1Wum2Kp5fz1w97LJxz6ysqsaGxpKZEico=; h=From:To:Subject:Date:From; b=YdTE4++Ch+UuiHlCr3eQiollGxz/FzeNfsm6GufGPb3ssyttcw2yUTRCho5EzX3dN laGTgeBEhEjfIkg9umYcuxJkX5/IB/73sQsOQTIEh6Oe+/irQ5jLE3oI0o0W3NtKoE pBOzfThAIpqOkP6qI2/Dihyxti0tDI2RTkq2VBo0= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Szabolcs Nagy To: glibc-cvs@sourceware.org Subject: [glibc/arm/morello/main] TODO(uapi): narrow capability in mmap and mremap X-Act-Checkin: glibc X-Git-Author: Szabolcs Nagy X-Git-Refname: refs/heads/arm/morello/main X-Git-Oldrev: ab15a586a0d679878bc3034bc1db5540cda63911 X-Git-Newrev: 1635be334baa886f7576b078c05e529742828ca8 Message-Id: <20221027135358.172363851503@sourceware.org> Date: Thu, 27 Oct 2022 13:53:58 +0000 (GMT) List-Id: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=1635be334baa886f7576b078c05e529742828ca8 commit 1635be334baa886f7576b078c05e529742828ca8 Author: Szabolcs Nagy Date: Fri Aug 5 11:44:57 2022 +0100 TODO(uapi): narrow capability in mmap and mremap This is a temporary workaround. length is rounded up to pagesize and don't use exact bound (bounds will be larger if exact value is not representable). capability permissions are roughly emulated too. TODO: kernel should do this Diff: --- sysdeps/unix/sysv/linux/mmap64.c | 31 +++++++++++++++++++++++++++++-- sysdeps/unix/sysv/linux/mremap.c | 12 +++++++++++- 2 files changed, 40 insertions(+), 3 deletions(-) diff --git a/sysdeps/unix/sysv/linux/mmap64.c b/sysdeps/unix/sysv/linux/mmap64.c index 659dadadaf..a7bd396880 100644 --- a/sysdeps/unix/sysv/linux/mmap64.c +++ b/sysdeps/unix/sysv/linux/mmap64.c @@ -20,7 +20,11 @@ #include #include #include +#include #include +#ifdef __CHERI_PURE_CAPABILITY__ +# include +#endif #ifdef __NR_mmap2 /* To avoid silent truncation of offset when using mmap2, do not accept @@ -51,12 +55,35 @@ __mmap64 (void *addr, size_t len, int prot, int flags, int fd, off64_t offset) return (void *) INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL); MMAP_PREPARE (addr, len, prot, flags, fd, offset); + void *ret; #ifdef __NR_mmap2 - return (void *) MMAP_CALL (mmap2, addr, len, prot, flags, fd, + ret = (void *) MMAP_CALL (mmap2, addr, len, prot, flags, fd, (off_t) (offset / MMAP2_PAGE_UNIT)); #else - return (void *) MMAP_CALL (mmap, addr, len, prot, flags, fd, offset); + ret = (void *) MMAP_CALL (mmap, addr, len, prot, flags, fd, offset); +#endif +#ifdef __CHERI_PURE_CAPABILITY__ + if (ret != MAP_FAILED) + { + size_t ps = GLRO(dl_pagesize); + ret = __builtin_cheri_bounds_set (ret, (len + ps - 1) & -ps); + unsigned long mask = CAP_PERM_MASK_BASE; + if (prot & PROT_READ) + mask |= CAP_PERM_MASK_R; + if (prot & PROT_WRITE) + mask |= CAP_PERM_MASK_RW; + if (prot & PROT_EXEC) + mask |= CAP_PERM_MASK_RX; + if (prot & PROT_MAX (PROT_READ)) + mask |= CAP_PERM_MASK_R; + if (prot & PROT_MAX (PROT_WRITE)) + mask |= CAP_PERM_MASK_RW; + if (prot & PROT_MAX (PROT_EXEC)) + mask |= CAP_PERM_MASK_RX; + ret = __builtin_cheri_perms_and (ret, mask); + } #endif + return ret; } weak_alias (__mmap64, mmap64) libc_hidden_def (__mmap64) diff --git a/sysdeps/unix/sysv/linux/mremap.c b/sysdeps/unix/sysv/linux/mremap.c index e829a29dbd..2e89f43faa 100644 --- a/sysdeps/unix/sysv/linux/mremap.c +++ b/sysdeps/unix/sysv/linux/mremap.c @@ -20,6 +20,7 @@ #include #include #include +#include void * __mremap (void *addr, size_t old_len, size_t new_len, int flags, ...) @@ -34,8 +35,17 @@ __mremap (void *addr, size_t old_len, size_t new_len, int flags, ...) va_end (va); } - return (void *) INLINE_SYSCALL_CALL (mremap, addr, old_len, new_len, flags, + void *ret; + ret = (void *) INLINE_SYSCALL_CALL (mremap, addr, old_len, new_len, flags, new_addr); +#ifdef __CHERI_PURE_CAPABILITY__ + if (ret != MAP_FAILED) + { + size_t ps = GLRO(dl_pagesize); + ret = __builtin_cheri_bounds_set (ret, (new_len + ps - 1) & -ps); + } +#endif + return ret; } libc_hidden_def (__mremap) weak_alias (__mremap, mremap)