From 7dcd79c295fb1f4bcdda5ead43739acf34100ef8 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Tue, 9 Dec 2014 18:07:46 +0100 Subject: [PATCH] sd-bus: properly support passing memfds around with offset/size parameters --- src/libsystemd/sd-bus/bus-message.c | 94 ++++++++++++++-------- src/libsystemd/sd-bus/bus-message.h | 3 +- src/libsystemd/sd-bus/test-bus-zero-copy.c | 14 +++- src/systemd/sd-bus.h | 4 +- 4 files changed, 75 insertions(+), 40 deletions(-) diff --git a/src/libsystemd/sd-bus/bus-message.c b/src/libsystemd/sd-bus/bus-message.c index ad417c0f1..06d8d770f 100644 --- a/src/libsystemd/sd-bus/bus-message.c +++ b/src/libsystemd/sd-bus/bus-message.c @@ -69,13 +69,13 @@ static void message_free_part(sd_bus_message *m, struct bus_body_part *part) { bus_kernel_push_memfd(m->bus, part->memfd, part->data, part->mapped, part->allocated); else { if (part->mapped > 0) - assert_se(munmap(part->data, part->mapped) == 0); + assert_se(munmap(part->mmap_begin, part->mapped) == 0); safe_close(part->memfd); } } else if (part->munmap_this) - munmap(part->data, part->mapped); + munmap(part->mmap_begin, part->mapped); else if (part->free_this) free(part->data); @@ -1126,17 +1126,18 @@ static int part_make_space( psz = PAGE_ALIGN(sz > 0 ? sz : 1); if (part->mapped <= 0) - n = mmap(NULL, psz, PROT_READ|PROT_WRITE, MAP_SHARED, part->memfd, part->memfd_offset); + n = mmap(NULL, psz, PROT_READ|PROT_WRITE, MAP_SHARED, part->memfd, 0); else - n = mremap(part->data, part->mapped, psz, MREMAP_MAYMOVE); + n = mremap(part->mmap_begin, part->mapped, psz, MREMAP_MAYMOVE); if (n == MAP_FAILED) { m->poisoned = true; return -errno; } + part->mmap_begin = part->data = n; part->mapped = psz; - part->data = n; + part->memfd_offset = 0; } part->munmap_this = true; @@ -2503,10 +2504,11 @@ _public_ int sd_bus_message_append_array_space( return 0; } -_public_ int sd_bus_message_append_array(sd_bus_message *m, - char type, - const void *ptr, - size_t size) { +_public_ int sd_bus_message_append_array( + sd_bus_message *m, + char type, + const void *ptr, + size_t size) { int r; void *p; @@ -2562,26 +2564,26 @@ _public_ int sd_bus_message_append_array_iovec( return 0; } -_public_ int sd_bus_message_append_array_memfd(sd_bus_message *m, - char type, - int memfd) { +_public_ int sd_bus_message_append_array_memfd( + sd_bus_message *m, + char type, + int memfd, + uint64_t offset, + uint64_t size) { + _cleanup_close_ int copy_fd = -1; struct bus_body_part *part; ssize_t align, sz; - uint64_t size; + uint64_t real_size; void *a; int r; - if (!m) - return -EINVAL; - if (memfd < 0) - return -EINVAL; - if (m->sealed) - return -EPERM; - if (!bus_type_is_trivial(type)) - return -EINVAL; - if (m->poisoned) - return -ESTALE; + assert_return(m, -EINVAL); + assert_return(memfd >= 0, -EINVAL); + assert_return(bus_type_is_trivial(type), -EINVAL); + assert_return(size > 0, -EINVAL); + assert_return(!m->sealed, -EPERM); + assert_return(!m->poisoned, -ESTALE); r = memfd_set_sealed(memfd); if (r < 0) @@ -2591,16 +2593,24 @@ _public_ int sd_bus_message_append_array_memfd(sd_bus_message *m, if (copy_fd < 0) return copy_fd; - r = memfd_get_size(memfd, &size); + r = memfd_get_size(memfd, &real_size); if (r < 0) return r; + if (offset == 0 && size == (uint64_t) -1) + size = real_size; + else if (offset + size > real_size) + return -EMSGSIZE; + align = bus_type_get_alignment(type); sz = bus_type_get_size(type); assert_se(align > 0); assert_se(sz > 0); + if (offset % align != 0) + return -EINVAL; + if (size % sz != 0) return -EINVAL; @@ -2620,7 +2630,7 @@ _public_ int sd_bus_message_append_array_memfd(sd_bus_message *m, return -ENOMEM; part->memfd = copy_fd; - part->memfd_offset = 0; + part->memfd_offset = offset; part->sealed = true; part->size = size; copy_fd = -1; @@ -2631,16 +2641,22 @@ _public_ int sd_bus_message_append_array_memfd(sd_bus_message *m, return sd_bus_message_close_container(m); } -_public_ int sd_bus_message_append_string_memfd(sd_bus_message *m, int memfd) { +_public_ int sd_bus_message_append_string_memfd( + sd_bus_message *m, + int memfd, + uint64_t offset, + uint64_t size) { + _cleanup_close_ int copy_fd = -1; struct bus_body_part *part; struct bus_container *c; - uint64_t size; + uint64_t real_size; void *a; int r; assert_return(m, -EINVAL); assert_return(memfd >= 0, -EINVAL); + assert_return(size > 0, -EINVAL); assert_return(!m->sealed, -EPERM); assert_return(!m->poisoned, -ESTALE); @@ -2652,10 +2668,15 @@ _public_ int sd_bus_message_append_string_memfd(sd_bus_message *m, int memfd) { if (copy_fd < 0) return copy_fd; - r = memfd_get_size(memfd, &size); + r = memfd_get_size(memfd, &real_size); if (r < 0) return r; + if (offset == 0 && size == (uint64_t) -1) + size = real_size; + else if (offset + size > real_size) + return -EMSGSIZE; + /* We require this to be NUL terminated */ if (size == 0) return -EINVAL; @@ -2696,7 +2717,7 @@ _public_ int sd_bus_message_append_string_memfd(sd_bus_message *m, int memfd) { return -ENOMEM; part->memfd = copy_fd; - part->memfd_offset = 0; + part->memfd_offset = offset; part->sealed = true; part->size = size; copy_fd = -1; @@ -2860,7 +2881,7 @@ int bus_message_seal(sd_bus_message *m, uint64_t cookie, usec_t timeout) { int bus_body_part_map(struct bus_body_part *part) { void *p; - size_t psz; + size_t psz, shift; assert_se(part); @@ -2877,10 +2898,11 @@ int bus_body_part_map(struct bus_body_part *part) { return 0; } - psz = PAGE_ALIGN(part->size); + shift = part->memfd_offset - ((part->memfd_offset / page_size()) * page_size()); + psz = PAGE_ALIGN(part->size + shift); if (part->memfd >= 0) - p = mmap(NULL, psz, PROT_READ, MAP_PRIVATE, part->memfd, part->memfd_offset); + p = mmap(NULL, psz, PROT_READ, MAP_PRIVATE, part->memfd, part->memfd_offset - shift); else if (part->is_zero) p = mmap(NULL, psz, PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); else @@ -2890,7 +2912,8 @@ int bus_body_part_map(struct bus_body_part *part) { return -errno; part->mapped = psz; - part->data = p; + part->mmap_begin = p; + part->data = (uint8_t*) p + shift; part->munmap_this = true; return 0; @@ -2903,14 +2926,15 @@ void bus_body_part_unmap(struct bus_body_part *part) { if (part->memfd < 0) return; - if (!part->data) + if (!part->mmap_begin) return; if (!part->munmap_this) return; - assert_se(munmap(part->data, part->mapped) == 0); + assert_se(munmap(part->mmap_begin, part->mapped) == 0); + part->mmap_begin = NULL; part->data = NULL; part->mapped = 0; part->munmap_this = false; diff --git a/src/libsystemd/sd-bus/bus-message.h b/src/libsystemd/sd-bus/bus-message.h index db5f90c5d..4dd280dcf 100644 --- a/src/libsystemd/sd-bus/bus-message.h +++ b/src/libsystemd/sd-bus/bus-message.h @@ -55,10 +55,11 @@ struct bus_container { struct bus_body_part { struct bus_body_part *next; void *data; + void *mmap_begin; size_t size; size_t mapped; size_t allocated; - size_t memfd_offset; + uint64_t memfd_offset; int memfd; bool free_this:1; bool munmap_this:1; diff --git a/src/libsystemd/sd-bus/test-bus-zero-copy.c b/src/libsystemd/sd-bus/test-bus-zero-copy.c index 2cc671b16..a054f74bf 100644 --- a/src/libsystemd/sd-bus/test-bus-zero-copy.c +++ b/src/libsystemd/sd-bus/test-bus-zero-copy.c @@ -48,6 +48,7 @@ int main(int argc, char *argv[]) { uint32_t u32; size_t i, l; char *s; + _cleanup_close_ int sfd = -1; log_set_max_level(LOG_DEBUG); @@ -107,7 +108,7 @@ int main(int argc, char *argv[]) { assert_se(r >= 0); assert_se(sz == STRING_SIZE); - r = sd_bus_message_append_string_memfd(m, f); + r = sd_bus_message_append_string_memfd(m, f, 0, (uint64_t) -1); assert_se(r >= 0); close(f); @@ -124,7 +125,7 @@ int main(int argc, char *argv[]) { assert_se(r >= 0); assert_se(sz == SECOND_ARRAY); - r = sd_bus_message_append_array_memfd(m, 'y', f); + r = sd_bus_message_append_array_memfd(m, 'y', f, 0, (uint64_t) -1); assert_se(r >= 0); close(f); @@ -135,6 +136,11 @@ int main(int argc, char *argv[]) { r = sd_bus_message_append(m, "u", 4711); assert_se(r >= 0); + assert_se((sfd = memfd_new_and_map(NULL, 6, (void**) &p)) >= 0); + memcpy(p, "abcd\0", 6); + munmap(p, 6); + assert_se(sd_bus_message_append_string_memfd(m, sfd, 1, 4) >= 0); + r = bus_message_seal(m, 55, 99*USEC_PER_SEC); assert_se(r >= 0); @@ -188,6 +194,10 @@ int main(int argc, char *argv[]) { assert_se(r > 0); assert_se(u32 == 4711); + r = sd_bus_message_read(m, "s", &s); + assert_se(r > 0); + assert_se(streq_ptr(s, "bcd")); + sd_bus_message_unref(m); sd_bus_unref(a); diff --git a/src/systemd/sd-bus.h b/src/systemd/sd-bus.h index f5fd37a66..3636d66fb 100644 --- a/src/systemd/sd-bus.h +++ b/src/systemd/sd-bus.h @@ -261,10 +261,10 @@ int sd_bus_message_append_basic(sd_bus_message *m, char type, const void *p); int sd_bus_message_append_array(sd_bus_message *m, char type, const void *ptr, size_t size); int sd_bus_message_append_array_space(sd_bus_message *m, char type, size_t size, void **ptr); int sd_bus_message_append_array_iovec(sd_bus_message *m, char type, const struct iovec *iov, unsigned n); -int sd_bus_message_append_array_memfd(sd_bus_message *m, char type, int memfd); +int sd_bus_message_append_array_memfd(sd_bus_message *m, char type, int memfd, uint64_t offset, uint64_t size); int sd_bus_message_append_string_space(sd_bus_message *m, size_t size, char **s); int sd_bus_message_append_string_iovec(sd_bus_message *m, const struct iovec *iov, unsigned n); -int sd_bus_message_append_string_memfd(sd_bus_message *m, int memfd); +int sd_bus_message_append_string_memfd(sd_bus_message *m, int memfd, uint64_t offset, uint64_t size); int sd_bus_message_append_strv(sd_bus_message *m, char **l); int sd_bus_message_open_container(sd_bus_message *m, char type, const char *contents); int sd_bus_message_close_container(sd_bus_message *m); -- 2.30.2