A coredump server that uploads to a blob store must redescribe the coredump and fixup the phdr.
A segment is split wherever a hole was left out and everything a segment covers past p_filesz is zeroes anyway. So the blob store ends up with an ordinary ELF core file that is missing nothing but holes. Nothing downstream of the server has to learn a container format. The coredump with its holes still in it is reassembled alongside the object so the two can be compared. Signed-off-by: Christian Brauner (Amutable) <[email protected]> --- .../coredump/coredump_socket_protocol_test.c | 156 +++++ .../selftests/coredump/coredump_test_helpers.c | 765 +++++++++++++++++++++ .../selftests/coredump/coredump_test_helpers.h | 3 + 3 files changed, 924 insertions(+) diff --git a/tools/testing/selftests/coredump/coredump_socket_protocol_test.c b/tools/testing/selftests/coredump/coredump_socket_protocol_test.c index abf6e2c4c354..f33eaf2fa93d 100644 --- a/tools/testing/selftests/coredump/coredump_socket_protocol_test.c +++ b/tools/testing/selftests/coredump/coredump_socket_protocol_test.c @@ -1882,6 +1882,162 @@ TEST_F(coredump, socket_request_records_truncated) ASSERT_GT(received, 0); } +/* + * A coredump server that uploads to a blob store can't upload a sparse + * file. It doesn't have to: it streams the data records into the object + * as they arrive, leaves the holes out, and uploads the corrected + * program header table last. What it ends up with is an ordinary ELF + * core file that describes the same memory as the coredump the records + * came from, minus the holes. + */ +TEST_F(coredump, socket_request_sparse_blob_upload) +{ + int fd_core_file, pidfd, status; + pid_t pid, pid_coredump_server; + struct pidfd_info info = {}; + off_t coredump_size = 0; + ssize_t received = 0; + int ipc_sockets[2]; + int pipefds[2]; + struct stat st; + char c; + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets), 0); + ASSERT_EQ(pipe(pipefds), 0); + ASSERT_TRUE(set_core_pattern("@@/tmp/coredump.socket")); + + pid_coredump_server = fork(); + ASSERT_GE(pid_coredump_server, 0); + if (pid_coredump_server == 0) { + int fd_server = -1, fd_coredump = -1, fd_peer_pidfd = -1; + int fd_object = -1, fd_reference = -1; + int exit_code = EXIT_FAILURE; + struct coredump_req req = {}; + off_t size = 0; + ssize_t ret; + + close(ipc_sockets[0]); + close(pipefds[0]); + + fd_server = create_and_listen_unix_socket("/tmp/coredump.socket"); + if (fd_server < 0) + goto out; + + if (write_nointr(ipc_sockets[1], "1", 1) < 0) + goto out; + + close(ipc_sockets[1]); + + fd_coredump = accept4(fd_server, NULL, NULL, SOCK_CLOEXEC); + if (fd_coredump < 0) + goto out; + + fd_peer_pidfd = get_peer_pidfd(fd_coredump); + if (fd_peer_pidfd < 0) + goto out; + + /* The object is a plain file. It never sees a hole. */ + fd_object = open("/tmp/coredump.file", + O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC, 0600); + if (fd_object < 0) + goto out; + + /* + * The coredump with its holes still in it is bigger than + * the mapping the child made, so keep it on the detached + * tmpfs and sparse. + */ + fd_reference = open_coredump_tmpfile(self->fd_tmpfs_detached); + if (fd_reference < 0) + goto out; + + if (!read_coredump_req(fd_coredump, &req)) + goto out; + + if (!check_coredump_req(&req)) + goto out; + + if (!send_coredump_ack(fd_coredump, &req, + COREDUMP_KERNEL | COREDUMP_RECORDS | + COREDUMP_SPARSE | COREDUMP_WAIT, 0)) + goto out; + + if (!read_marker(fd_coredump, COREDUMP_MARK_REQACK)) + goto out; + + ret = recv_coredump_compact(fd_coredump, fd_object, + fd_reference, &size); + if (ret < 0) + goto out; + + if (check_compact_coredump(fd_object, fd_reference)) + goto out; + + if (write_nointr(pipefds[1], &ret, sizeof(ret)) != sizeof(ret)) + goto out; + if (write_nointr(pipefds[1], &size, sizeof(size)) != sizeof(size)) + goto out; + + exit_code = EXIT_SUCCESS; +out: + close(pipefds[1]); + if (fd_reference >= 0) + close(fd_reference); + if (fd_object >= 0) + close(fd_object); + if (fd_peer_pidfd >= 0) + close(fd_peer_pidfd); + if (fd_coredump >= 0) + close(fd_coredump); + if (fd_server >= 0) + close(fd_server); + _exit(exit_code); + } + self->pid_coredump_server = pid_coredump_server; + + EXPECT_EQ(close(ipc_sockets[1]), 0); + EXPECT_EQ(close(pipefds[1]), 0); + ASSERT_EQ(read_nointr(ipc_sockets[0], &c, 1), 1); + EXPECT_EQ(close(ipc_sockets[0]), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + if (pid == 0) + crashing_child_sparse(SPARSE_MAPPING_SIZE); + + pidfd = sys_pidfd_open(pid, 0); + ASSERT_GE(pidfd, 0); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFSIGNALED(status)); + ASSERT_TRUE(WCOREDUMP(status)); + + ASSERT_EQ(read_nointr(pipefds[0], &received, sizeof(received)), + sizeof(received)); + ASSERT_EQ(read_nointr(pipefds[0], &coredump_size, sizeof(coredump_size)), + sizeof(coredump_size)); + EXPECT_EQ(close(pipefds[0]), 0); + + ASSERT_TRUE(get_pidfd_info(pidfd, &info)); + ASSERT_GT((info.mask & PIDFD_INFO_COREDUMP), 0); + ASSERT_GT((info.coredump_mask & PIDFD_COREDUMPED), 0); + + wait_and_check_coredump_server(pid_coredump_server, _metadata, self); + + /* The mapping is in the coredump, holes included. */ + ASSERT_GT(coredump_size, (off_t)SPARSE_MAPPING_SIZE); + + /* The object isn't sparse and doesn't carry them. */ + ASSERT_EQ(stat("/tmp/coredump.file", &st), 0); + ASSERT_LT(st.st_size, coredump_size / 8); + + /* And a debugger still sees an ordinary ELF core file. */ + fd_core_file = open("/tmp/coredump.file", O_RDONLY | O_CLOEXEC); + ASSERT_GE(fd_core_file, 0); + ASSERT_TRUE(is_elf_core(fd_core_file)); + EXPECT_EQ(close(fd_core_file), 0); +} + /* Ack @ack_mask, expect the kernel to refuse it as conflicting. */ static void check_conflicting_ack(struct __test_metadata *const _metadata, FIXTURE_DATA(coredump) *self, __u64 ack_mask) diff --git a/tools/testing/selftests/coredump/coredump_test_helpers.c b/tools/testing/selftests/coredump/coredump_test_helpers.c index 89f3954c5607..9346b8f688e2 100644 --- a/tools/testing/selftests/coredump/coredump_test_helpers.c +++ b/tools/testing/selftests/coredump/coredump_test_helpers.c @@ -330,6 +330,771 @@ bool is_elf_core(int fd) return true; } +/* + * A coredump server that uploads to a blob store can't upload a sparse + * file and can't seek in the object it is uploading. It streams the data + * records into the object as they arrive, remembers the holes it left + * out, and uploads the program header table that describes the result + * last. What comes out is an ordinary ELF core file without the holes. + */ + +/* A run of the coredump the object doesn't carry. */ +struct compact_hole { + __u64 offset; + __u64 len; +}; + +/* A program header of the object and where its bytes sat in the coredump. */ +struct compact_piece { + ElfW(Phdr) phdr; + __u64 src; +}; + +struct compact_ctx { + int fd_body; /* the object's payload, append only */ + int fd_reference; /* the coredump with its holes, for the test */ + unsigned char *head; /* everything ahead of the segment data */ + size_t head_len; + size_t head_cap; + __u64 data_offset; /* where the segment data starts, 0 while unknown */ + struct compact_hole *holes; + size_t nr_holes; + size_t holes_cap; + __u64 body_len; +}; + +/* Write @len bytes out, short writes and all. */ +static int compact_write(int fd, const void *buf, size_t len) +{ + const unsigned char *pos = buf; + + while (len) { + ssize_t ret = write(fd, pos, len); + + if (ret <= 0) { + fprintf(stderr, "%s: write failed: %m\n", __func__); + return -1; + } + + pos += ret; + len -= ret; + } + + return 0; +} + +/* Keep @len bytes of the head, or @len zeroes if @buf is NULL. */ +static int compact_head_append(struct compact_ctx *ctx, const void *buf, + size_t len) +{ + if (ctx->head_len + len > ctx->head_cap) { + size_t cap = ctx->head_cap ? ctx->head_cap : PAGE_SIZE; + unsigned char *head; + + while (cap < ctx->head_len + len) + cap *= 2; + + head = realloc(ctx->head, cap); + if (!head) { + fprintf(stderr, "%s: out of memory\n", __func__); + return -1; + } + ctx->head = head; + ctx->head_cap = cap; + } + + if (buf) + memcpy(ctx->head + ctx->head_len, buf, len); + else + memset(ctx->head + ctx->head_len, 0, len); + ctx->head_len += len; + + return 0; +} + +/* Remember a hole so the program header table can account for it later. */ +static int compact_keep_hole(struct compact_ctx *ctx, __u64 offset, __u64 len) +{ + if (ctx->nr_holes == ctx->holes_cap) { + size_t cap = ctx->holes_cap ? ctx->holes_cap * 2 : 64; + struct compact_hole *holes; + + holes = realloc(ctx->holes, cap * sizeof(*holes)); + if (!holes) { + fprintf(stderr, "%s: out of memory\n", __func__); + return -1; + } + ctx->holes = holes; + ctx->holes_cap = cap; + } + + ctx->holes[ctx->nr_holes].offset = offset; + ctx->holes[ctx->nr_holes].len = len; + ctx->nr_holes++; + + return 0; +} + +/* The segment data starts where the first PT_LOAD points. */ +static int compact_probe(struct compact_ctx *ctx) +{ + const ElfW(Ehdr) *ehdr = (const ElfW(Ehdr) *)ctx->head; + const ElfW(Phdr) *phdr; + size_t i; + + if (ctx->data_offset || ctx->head_len < sizeof(*ehdr)) + return 0; + + if (!is_core_ehdr(ehdr)) { + fprintf(stderr, "%s: not an ELF core file\n", __func__); + return -1; + } + + if (ehdr->e_phoff != sizeof(*ehdr) || + ehdr->e_phentsize != sizeof(ElfW(Phdr)) || + ehdr->e_phnum == 0 || ehdr->e_phnum == PN_XNUM) { + fprintf(stderr, "%s: unhandled program header table\n", __func__); + return -1; + } + + if (ctx->head_len < ehdr->e_phoff + + (size_t)ehdr->e_phnum * ehdr->e_phentsize) + return 0; + + phdr = (const ElfW(Phdr) *)(ctx->head + ehdr->e_phoff); + for (i = 0; i < ehdr->e_phnum; i++) { + if (phdr[i].p_type != PT_LOAD) + continue; + if (!ctx->data_offset || phdr[i].p_offset < ctx->data_offset) + ctx->data_offset = phdr[i].p_offset; + } + + if (!ctx->data_offset) { + fprintf(stderr, "%s: coredump without a single segment\n", + __func__); + return -1; + } + + return 0; +} + +/* + * Take whatever of [@offset, @offset + @len) still belongs to the head. + * @buf is NULL for a hole. Returns how much was taken. + */ +static ssize_t compact_head_take(struct compact_ctx *ctx, const void *buf, + __u64 offset, __u64 len) +{ + __u64 chunk; + + if (!len || (ctx->data_offset && offset >= ctx->data_offset)) + return 0; + + chunk = len; + if (ctx->data_offset && offset + chunk > ctx->data_offset) + chunk = ctx->data_offset - offset; + + if (offset != ctx->head_len) { + fprintf(stderr, "%s: head has a gap at %llu\n", __func__, + (unsigned long long)offset); + return -1; + } + + if (compact_head_append(ctx, buf, chunk)) + return -1; + + return chunk; +} + +static int compact_data(void *arg, const void *buf, size_t len, __u64 offset) +{ + struct compact_ctx *ctx = arg; + const unsigned char *pos = buf; + ssize_t head; + + /* Only the test needs a coredump with the holes still in it. */ + if (pwrite(ctx->fd_reference, pos, len, offset) != (ssize_t)len) { + fprintf(stderr, "%s: pwrite failed: %m\n", __func__); + return -1; + } + + /* The head has to be rewritten at the end, so hold on to it. */ + head = compact_head_take(ctx, pos, offset, len); + if (head < 0) + return -1; + if (head && compact_probe(ctx)) + return -1; + + pos += head; + len -= head; + if (!len) + return 0; + + /* Everything else goes into the object as it arrives. */ + if (compact_write(ctx->fd_body, pos, len)) + return -1; + ctx->body_len += len; + + return 0; +} + +static int compact_zero(void *arg, __u64 offset, __u64 len) +{ + struct compact_ctx *ctx = arg; + ssize_t head; + + /* A hole in the head is alignment padding. Write it out. */ + head = compact_head_take(ctx, NULL, offset, len); + if (head < 0) + return -1; + + offset += head; + len -= head; + if (!len) + return 0; + + /* This is what the object doesn't have to carry. */ + return compact_keep_hole(ctx, offset, len); +} + +/* Where @offset ends up in the object once the holes ahead of it are gone. */ +static __u64 compact_offset(const struct compact_ctx *ctx, __u64 body_start, + __u64 offset) +{ + __u64 elided = 0; + size_t i; + + for (i = 0; i < ctx->nr_holes; i++) { + __u64 len = ctx->holes[i].len; + + if (ctx->holes[i].offset >= offset) + break; + if (ctx->holes[i].offset + len > offset) + len = offset - ctx->holes[i].offset; + elided += len; + } + + return body_start + (offset - ctx->data_offset) - elided; +} + +/* A run of segment data that made it into the object. */ +static void compact_add_data(struct compact_piece *pieces, size_t *nr, + const ElfW(Phdr) *phdr, __u64 start, __u64 end) +{ + struct compact_piece *piece = &pieces[(*nr)++]; + + piece->phdr = *phdr; + piece->phdr.p_vaddr = phdr->p_vaddr + (start - phdr->p_offset); + piece->phdr.p_paddr = 0; + piece->phdr.p_filesz = end - start; + piece->phdr.p_memsz = end - start; + piece->src = start; +} + +/* + * A run of @len bytes the object doesn't carry. It grows the piece in + * front of it if this segment already has one, because everything a + * segment covers past p_filesz is zeroes anyway. + */ +static void compact_add_zero(struct compact_piece *pieces, size_t *nr, + size_t first, const ElfW(Phdr) *phdr, __u64 vaddr, + __u64 len) +{ + struct compact_piece *piece; + + if (*nr > first) { + pieces[*nr - 1].phdr.p_memsz += len; + return; + } + + piece = &pieces[(*nr)++]; + piece->phdr = *phdr; + piece->phdr.p_vaddr = vaddr; + piece->phdr.p_paddr = 0; + piece->phdr.p_filesz = 0; + piece->phdr.p_memsz = len; + piece->src = 0; +} + +/* Split the segments at the holes and write out what the object became. */ +static int compact_build(struct compact_ctx *ctx, int fd_object) +{ + __u64 note_offset = 0, note_len = 0, note_new; + __u64 align = 0, head_len, body_start, pos; + size_t nr_old, nr_new = 0, note_piece = 0, i; + struct compact_piece *pieces; + char buffer[PAGE_SIZE]; + const ElfW(Phdr) *old; + ElfW(Ehdr) ehdr; + int ret = -1; + + if (!ctx->data_offset) { + fprintf(stderr, "%s: coredump without segment data\n", __func__); + return -1; + } + + memcpy(&ehdr, ctx->head, sizeof(ehdr)); + if (ehdr.e_shoff) { + fprintf(stderr, "%s: section headers are not handled\n", + __func__); + return -1; + } + + old = (const ElfW(Phdr) *)(ctx->head + ehdr.e_phoff); + nr_old = ehdr.e_phnum; + + pieces = calloc(nr_old + 2 * ctx->nr_holes + 1, sizeof(*pieces)); + if (!pieces) { + fprintf(stderr, "%s: out of memory\n", __func__); + return -1; + } + + for (i = 0; i < nr_old; i++) { + ElfW(Phdr) phdr = old[i]; + __u64 end = phdr.p_offset + phdr.p_filesz; + __u64 cur = phdr.p_offset; + size_t first = nr_new, h; + + /* The notes move because the table in front of them grows. */ + if (phdr.p_type == PT_NOTE) { + if (note_len) { + fprintf(stderr, "%s: more than one note segment\n", + __func__); + goto out; + } + note_offset = phdr.p_offset; + note_len = phdr.p_filesz; + note_piece = nr_new; + pieces[nr_new].phdr = phdr; + pieces[nr_new++].src = 0; + continue; + } + + if (phdr.p_type != PT_LOAD) { + if (phdr.p_filesz && phdr.p_offset < ctx->data_offset) { + fprintf(stderr, "%s: segment %zu is in the head\n", + __func__, i); + goto out; + } + pieces[nr_new].phdr = phdr; + pieces[nr_new++].src = phdr.p_offset; + continue; + } + + if (!align) + align = phdr.p_align; + + for (h = 0; h < ctx->nr_holes && cur < end; h++) { + __u64 start = ctx->holes[h].offset; + __u64 stop = start + ctx->holes[h].len; + + if (stop <= cur) + continue; + if (start >= end) + break; + + /* A hole can span more than this one segment. */ + if (start < cur) + start = cur; + if (stop > end) + stop = end; + + if (start > cur) { + compact_add_data(pieces, &nr_new, &phdr, cur, + start); + cur = start; + } + compact_add_zero(pieces, &nr_new, first, &phdr, + phdr.p_vaddr + (cur - phdr.p_offset), + stop - cur); + cur = stop; + } + + if (cur < end) + compact_add_data(pieces, &nr_new, &phdr, cur, end); + + /* Whatever the kernel didn't dump of this mapping. */ + if (phdr.p_memsz > phdr.p_filesz) + compact_add_zero(pieces, &nr_new, first, &phdr, + phdr.p_vaddr + phdr.p_filesz, + phdr.p_memsz - phdr.p_filesz); + } + + if (!note_len || note_offset + note_len > ctx->head_len) { + fprintf(stderr, "%s: notes aren't where they should be\n", + __func__); + goto out; + } + + if (nr_new >= PN_XNUM) { + fprintf(stderr, "%s: %zu program headers don't fit\n", __func__, + nr_new); + goto out; + } + + if (!align || (align & (align - 1))) + align = sysconf(_SC_PAGESIZE); + + note_new = sizeof(ehdr) + (__u64)nr_new * sizeof(ElfW(Phdr)); + head_len = note_new + note_len; + body_start = (head_len + align - 1) & ~(align - 1); + + for (i = 0; i < nr_new; i++) { + struct compact_piece *piece = &pieces[i]; + + if (i == note_piece) + piece->phdr.p_offset = note_new; + else if (piece->phdr.p_filesz) + piece->phdr.p_offset = compact_offset(ctx, body_start, + piece->src); + else + piece->phdr.p_offset = 0; + } + + /* Only now is the head known. That's why it is uploaded last. */ + ehdr.e_phnum = nr_new; + if (compact_write(fd_object, &ehdr, sizeof(ehdr))) + goto out; + + for (i = 0; i < nr_new; i++) + if (compact_write(fd_object, &pieces[i].phdr, + sizeof(pieces[i].phdr))) + goto out; + + if (compact_write(fd_object, ctx->head + note_offset, note_len)) + goto out; + + /* Keep the segments aligned the way a debugger expects them. */ + memset(buffer, 0, sizeof(buffer)); + for (pos = head_len; pos < body_start; ) { + __u64 chunk = body_start - pos; + + if (chunk > sizeof(buffer)) + chunk = sizeof(buffer); + if (compact_write(fd_object, buffer, chunk)) + goto out; + pos += chunk; + } + + /* Putting the parts together is the blob store's job. Do it here. */ + for (pos = 0; pos < ctx->body_len; ) { + ssize_t chunk = pread(ctx->fd_body, buffer, sizeof(buffer), pos); + + if (chunk <= 0) { + fprintf(stderr, "%s: short read %zd: %m\n", __func__, + chunk); + goto out; + } + if (compact_write(fd_object, buffer, chunk)) + goto out; + pos += chunk; + } + + fprintf(stderr, "Object is %llu bytes in %zu program headers, %zu holes left out\n", + (unsigned long long)(body_start + ctx->body_len), nr_new, + ctx->nr_holes); + ret = 0; +out: + free(pieces); + return ret; +} + +/* + * Reassemble a record stream into an ELF core file that has no holes in + * it, the way a coredump server that uploads to a blob store has to. If + * @fd_reference is valid it gets the coredump the records describe, + * holes and all, so the test can compare the two. + */ +ssize_t recv_coredump_compact(int fd_coredump, int fd_object, int fd_reference, + off_t *coredump_size) +{ + struct compact_ctx ctx = { + .fd_body = -1, + .fd_reference = fd_reference, + }; + struct coredump_record_sink sink = { + .data = compact_data, + .zero = compact_zero, + .ctx = &ctx, + }; + ssize_t received; + off_t size = 0; + FILE *body; + + body = tmpfile(); + if (!body) { + fprintf(stderr, "%s: tmpfile failed: %m\n", __func__); + return -1; + } + ctx.fd_body = fileno(body); + + /* An upload is appended to. Make sure nothing here can seek. */ + if (fcntl(ctx.fd_body, F_SETFL, O_APPEND)) { + fprintf(stderr, "%s: F_SETFL failed: %m\n", __func__); + received = -1; + goto out; + } + + received = __recv_coredump_records(fd_coredump, &sink, &size, NULL, -1); + if (received < 0) + goto out; + + /* + * Nothing is written for a hole, so grow the reference to the size + * the records describe in case the coredump ended in one. + */ + if (ftruncate(fd_reference, size) < 0) { + fprintf(stderr, "%s: ftruncate to %llu failed: %m\n", + __func__, (unsigned long long)size); + received = -1; + goto out; + } + + if (compact_build(&ctx, fd_object)) { + received = -1; + goto out; + } + + if (coredump_size) + *coredump_size = size; +out: + fclose(body); + free(ctx.head); + free(ctx.holes); + return received; +} + +/* Read the ELF header and the program header table of @fd. */ +static ElfW(Phdr) *read_phdrs(int fd, size_t *nr) +{ + ElfW(Ehdr) ehdr; + ElfW(Phdr) *phdr; + size_t size; + + if (pread(fd, &ehdr, sizeof(ehdr), 0) != sizeof(ehdr)) { + fprintf(stderr, "%s: no ELF header: %m\n", __func__); + return NULL; + } + + if (!is_core_ehdr(&ehdr) || !ehdr.e_phnum || + ehdr.e_phentsize != sizeof(*phdr)) { + fprintf(stderr, "%s: not an ELF core file\n", __func__); + return NULL; + } + + size = (size_t)ehdr.e_phnum * ehdr.e_phentsize; + phdr = malloc(size); + if (!phdr) { + fprintf(stderr, "%s: out of memory\n", __func__); + return NULL; + } + + if (pread(fd, phdr, size, ehdr.e_phoff) != (ssize_t)size) { + fprintf(stderr, "%s: short program header table: %m\n", __func__); + free(phdr); + return NULL; + } + + *nr = ehdr.e_phnum; + return phdr; +} + +/* The segment @vaddr falls into. */ +static const ElfW(Phdr) *find_segment(const ElfW(Phdr) *phdr, size_t nr, + __u64 vaddr) +{ + size_t i; + + for (i = 0; i < nr; i++) { + if (phdr[i].p_type != PT_LOAD) + continue; + if (vaddr >= phdr[i].p_vaddr && + vaddr < phdr[i].p_vaddr + phdr[i].p_memsz) + return &phdr[i]; + } + + return NULL; +} + +/* The next stretch of memory the segments cover, split ones merged back. */ +static bool next_range(const ElfW(Phdr) *phdr, size_t nr, size_t *i, + __u64 *start, __u64 *end) +{ + while (*i < nr && phdr[*i].p_type != PT_LOAD) + (*i)++; + + if (*i >= nr) + return false; + + *start = phdr[*i].p_vaddr; + *end = phdr[*i].p_vaddr + phdr[*i].p_memsz; + (*i)++; + + while (*i < nr) { + if (phdr[*i].p_type != PT_LOAD) { + (*i)++; + continue; + } + if (phdr[*i].p_vaddr != *end) + break; + *end = phdr[*i].p_vaddr + phdr[*i].p_memsz; + (*i)++; + } + + return true; +} + +/* Compare @len bytes at @offset against @len bytes at @offset_ref. */ +static int compare_range(int fd, __u64 offset, int fd_ref, __u64 offset_ref, + __u64 len) +{ + char buffer[PAGE_SIZE], buffer_ref[PAGE_SIZE]; + + while (len) { + size_t chunk = len < sizeof(buffer) ? len : sizeof(buffer); + + if (pread(fd, buffer, chunk, offset) != (ssize_t)chunk || + pread(fd_ref, buffer_ref, chunk, offset_ref) != (ssize_t)chunk) { + fprintf(stderr, "%s: short read at %llu: %m\n", + __func__, (unsigned long long)offset); + return -1; + } + + if (memcmp(buffer, buffer_ref, chunk)) { + fprintf(stderr, "%s: %llu differs from %llu\n", __func__, + (unsigned long long)offset, + (unsigned long long)offset_ref); + return -1; + } + + offset += chunk; + offset_ref += chunk; + len -= chunk; + } + + return 0; +} + +/* The @len bytes at @offset the object left out have to have been zeroes. */ +static int check_zero_range(int fd, __u64 offset, __u64 len) +{ + static const char zeroes[PAGE_SIZE]; + char buffer[PAGE_SIZE]; + + while (len) { + size_t chunk = len < sizeof(buffer) ? len : sizeof(buffer); + + if (pread(fd, buffer, chunk, offset) != (ssize_t)chunk) { + fprintf(stderr, "%s: short read at %llu: %m\n", + __func__, (unsigned long long)offset); + return -1; + } + + if (memcmp(buffer, zeroes, chunk)) { + fprintf(stderr, "%s: %llu isn't a hole\n", __func__, + (unsigned long long)offset); + return -1; + } + + offset += chunk; + len -= chunk; + } + + return 0; +} + +/* + * The object has to describe the same memory as the coredump it was built + * from, and it has to describe it correctly. + */ +int check_compact_coredump(int fd_object, int fd_reference) +{ + ElfW(Phdr) *object = NULL, *reference = NULL; + size_t nr_object, nr_reference, i; + size_t io = 0, ir = 0; + int ret = -1; + + object = read_phdrs(fd_object, &nr_object); + reference = read_phdrs(fd_reference, &nr_reference); + if (!object || !reference) + goto out; + + /* Nothing may have been dropped and nothing may have been added. */ + for (;;) { + __u64 start = 0, end = 0, start_ref = 0, end_ref = 0; + bool has, has_ref; + + has = next_range(object, nr_object, &io, &start, &end); + has_ref = next_range(reference, nr_reference, &ir, &start_ref, + &end_ref); + if (!has && !has_ref) + break; + + if (has != has_ref || start != start_ref || end != end_ref) { + fprintf(stderr, "%s: object covers 0x%llx-0x%llx, coredump 0x%llx-0x%llx\n", + __func__, (unsigned long long)start, + (unsigned long long)end, + (unsigned long long)start_ref, + (unsigned long long)end_ref); + goto out; + } + } + + for (i = 0; i < nr_object; i++) { + const ElfW(Phdr) *segment; + __u64 offset, dumped; + + if (object[i].p_type != PT_LOAD || !object[i].p_memsz) + continue; + + segment = find_segment(reference, nr_reference, + object[i].p_vaddr); + if (!segment) { + fprintf(stderr, "%s: 0x%llx isn't in the coredump\n", + __func__, + (unsigned long long)object[i].p_vaddr); + goto out; + } + + offset = object[i].p_vaddr - segment->p_vaddr; + dumped = offset < segment->p_filesz ? + segment->p_filesz - offset : 0; + + /* What the object carries is what the coredump had. */ + if (object[i].p_filesz > dumped) { + fprintf(stderr, "%s: object carries %llu bytes the coredump doesn't have\n", + __func__, + (unsigned long long)(object[i].p_filesz - dumped)); + goto out; + } + + if (compare_range(fd_object, object[i].p_offset, fd_reference, + segment->p_offset + offset, + object[i].p_filesz)) + goto out; + + /* And what it left out was a hole. */ + if (object[i].p_memsz > object[i].p_filesz && + dumped > object[i].p_filesz) { + __u64 left_out = dumped - object[i].p_filesz; + + if (left_out > object[i].p_memsz - object[i].p_filesz) + left_out = object[i].p_memsz - object[i].p_filesz; + + if (check_zero_range(fd_reference, + segment->p_offset + offset + + object[i].p_filesz, left_out)) + goto out; + } + } + + ret = 0; +out: + free(object); + free(reference); + return ret; +} + int create_detached_tmpfs(void) { int fd_context, fd_tmpfs; diff --git a/tools/testing/selftests/coredump/coredump_test_helpers.h b/tools/testing/selftests/coredump/coredump_test_helpers.h index fe0a88a71b05..00d695b67b3f 100644 --- a/tools/testing/selftests/coredump/coredump_test_helpers.h +++ b/tools/testing/selftests/coredump/coredump_test_helpers.h @@ -26,6 +26,9 @@ ssize_t recv_coredump_records(int fd_coredump, int fd_core_file, off_t *coredump_size, bool *truncated, int fd_peer_pidfd); bool is_elf_core(int fd); +ssize_t recv_coredump_compact(int fd_coredump, int fd_object, int fd_reference, + off_t *coredump_size); +int check_compact_coredump(int fd_object, int fd_reference); int create_detached_tmpfs(void); int create_and_listen_unix_socket(const char *path); bool set_core_pattern(const char *pattern); -- 2.53.0
