diff options
| -rw-r--r-- | linux-user/mmap.c | 106 |
1 files changed, 73 insertions, 33 deletions
diff --git a/linux-user/mmap.c b/linux-user/mmap.c index 0019447892..46c7eeba9b 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -59,64 +59,96 @@ void mmap_fork_end(int child) pthread_mutex_unlock(&mmap_mutex); } +/* + * Validate target prot bitmask. + * Return the prot bitmask for the host in *HOST_PROT. + * Return 0 if the target prot bitmask is invalid, otherwise + * the internal qemu page_flags (which will include PAGE_VALID). + */ +static int validate_prot_to_pageflags(int *host_prot, int prot) +{ + int valid = PROT_READ | PROT_WRITE | PROT_EXEC | TARGET_PROT_SEM; + int page_flags = (prot & PAGE_BITS) | PAGE_VALID; + + /* + * For the host, we need not pass anything except read/write/exec. + * While PROT_SEM is allowed by all hosts, it is also ignored, so + * don't bother transforming guest bit to host bit. Any other + * target-specific prot bits will not be understood by the host + * and will need to be encoded into page_flags for qemu emulation. + */ + *host_prot = prot & (PROT_READ | PROT_WRITE | PROT_EXEC); + + return prot & ~valid ? 0 : page_flags; +} + /* NOTE: all the constants are the HOST ones, but addresses are target. */ -int target_mprotect(abi_ulong start, abi_ulong len, int prot) +int target_mprotect(abi_ulong start, abi_ulong len, int target_prot) { abi_ulong end, host_start, host_end, addr; - int prot1, ret; + int prot1, ret, page_flags, host_prot; - trace_target_mprotect(start, len, prot); + trace_target_mprotect(start, len, target_prot); - if ((start & ~TARGET_PAGE_MASK) != 0) + if ((start & ~TARGET_PAGE_MASK) != 0) { return -TARGET_EINVAL; + } + page_flags = validate_prot_to_pageflags(&host_prot, target_prot); + if (!page_flags) { + return -TARGET_EINVAL; + } len = TARGET_PAGE_ALIGN(len); end = start + len; if (!guest_range_valid(start, len)) { return -TARGET_ENOMEM; } - prot &= PROT_READ | PROT_WRITE | PROT_EXEC; - if (len == 0) + if (len == 0) { return 0; + } mmap_lock(); host_start = start & qemu_host_page_mask; host_end = HOST_PAGE_ALIGN(end); if (start > host_start) { /* handle host page containing start */ - prot1 = prot; - for(addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) { + prot1 = host_prot; + for (addr = host_start; addr < start; addr += TARGET_PAGE_SIZE) { prot1 |= page_get_flags(addr); } if (host_end == host_start + qemu_host_page_size) { - for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { + for (addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { prot1 |= page_get_flags(addr); } end = host_end; } - ret = mprotect(g2h(host_start), qemu_host_page_size, prot1 & PAGE_BITS); - if (ret != 0) + ret = mprotect(g2h(host_start), qemu_host_page_size, + prot1 & PAGE_BITS); + if (ret != 0) { goto error; + } host_start += qemu_host_page_size; } if (end < host_end) { - prot1 = prot; - for(addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { + prot1 = host_prot; + for (addr = end; addr < host_end; addr += TARGET_PAGE_SIZE) { prot1 |= page_get_flags(addr); } - ret = mprotect(g2h(host_end - qemu_host_page_size), qemu_host_page_size, - prot1 & PAGE_BITS); - if (ret != 0) + ret = mprotect(g2h(host_end - qemu_host_page_size), + qemu_host_page_size, prot1 & PAGE_BITS); + if (ret != 0) { goto error; + } host_end -= qemu_host_page_size; } /* handle the pages in the middle */ if (host_start < host_end) { - ret = mprotect(g2h(host_start), host_end - host_start, prot); - if (ret != 0) + ret = mprotect(g2h(host_start), host_end - host_start, host_prot); + if (ret != 0) { goto error; + } } - page_set_flags(start, start + len, prot | PAGE_VALID); + page_set_flags(start, start + len, page_flags); mmap_unlock(); return 0; error: @@ -360,19 +392,26 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size, abi_ulong align) } /* NOTE: all the constants are the HOST ones */ -abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, +abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot, int flags, int fd, abi_ulong offset) { abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len; + int page_flags, host_prot; mmap_lock(); - trace_target_mmap(start, len, prot, flags, fd, offset); + trace_target_mmap(start, len, target_prot, flags, fd, offset); if (!len) { errno = EINVAL; goto fail; } + page_flags = validate_prot_to_pageflags(&host_prot, target_prot); + if (!page_flags) { + errno = EINVAL; + goto fail; + } + /* Also check for overflows... */ len = TARGET_PAGE_ALIGN(len); if (!len) { @@ -438,14 +477,15 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, /* Note: we prefer to control the mapping address. It is especially important if qemu_host_page_size > qemu_real_host_page_size */ - p = mmap(g2h(start), host_len, prot, + p = mmap(g2h(start), host_len, host_prot, flags | MAP_FIXED | MAP_ANONYMOUS, -1, 0); - if (p == MAP_FAILED) + if (p == MAP_FAILED) { goto fail; + } /* update start so that it points to the file position at 'offset' */ host_start = (unsigned long)p; if (!(flags & MAP_ANONYMOUS)) { - p = mmap(g2h(start), len, prot, + p = mmap(g2h(start), len, host_prot, flags | MAP_FIXED, fd, host_offset); if (p == MAP_FAILED) { munmap(g2h(start), host_len); @@ -479,19 +519,19 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, /* msync() won't work here, so we return an error if write is possible while it is a shared mapping */ if ((flags & MAP_TYPE) == MAP_SHARED && - (prot & PROT_WRITE)) { + (host_prot & PROT_WRITE)) { errno = EINVAL; goto fail; } - retaddr = target_mmap(start, len, prot | PROT_WRITE, + retaddr = target_mmap(start, len, target_prot | PROT_WRITE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (retaddr == -1) goto fail; if (pread(fd, g2h(start), len, offset) == -1) goto fail; - if (!(prot & PROT_WRITE)) { - ret = target_mprotect(start, len, prot); + if (!(host_prot & PROT_WRITE)) { + ret = target_mprotect(start, len, target_prot); assert(ret == 0); } goto the_end; @@ -502,13 +542,13 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, if (real_end == real_start + qemu_host_page_size) { /* one single host page */ ret = mmap_frag(real_start, start, end, - prot, flags, fd, offset); + host_prot, flags, fd, offset); if (ret == -1) goto fail; goto the_end1; } ret = mmap_frag(real_start, start, real_start + qemu_host_page_size, - prot, flags, fd, offset); + host_prot, flags, fd, offset); if (ret == -1) goto fail; real_start += qemu_host_page_size; @@ -517,7 +557,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, if (end < real_end) { ret = mmap_frag(real_end - qemu_host_page_size, real_end - qemu_host_page_size, end, - prot, flags, fd, + host_prot, flags, fd, offset + real_end - qemu_host_page_size - start); if (ret == -1) goto fail; @@ -533,13 +573,13 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, else offset1 = offset + real_start - start; p = mmap(g2h(real_start), real_end - real_start, - prot, flags, fd, offset1); + host_prot, flags, fd, offset1); if (p == MAP_FAILED) goto fail; } } the_end1: - page_set_flags(start, start + len, prot | PAGE_VALID); + page_set_flags(start, start + len, page_flags); the_end: trace_target_mmap_complete(start); if (qemu_loglevel_mask(CPU_LOG_PAGE)) { |