Allow run-as to generate filter bytecode.
authorJonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Fri, 29 Nov 2019 21:12:28 +0000 (16:12 -0500)
committerJérémie Galarneau <jeremie.galarneau@efficios.com>
Wed, 9 Sep 2020 18:28:11 +0000 (14:28 -0400)
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I3742bb00b7c753b7d256cdff1889a5e90865608b

src/common/runas.c
src/common/runas.h

index b1a4b4836a63324b246940fb02f2727a1be90c05..3c4c2ae0bb9d360141c3ed5dbb60fbc6a420e8ab 100644 (file)
@@ -27,6 +27,7 @@
 #include <common/common.h>
 #include <common/utils.h>
 #include <common/compat/getenv.h>
+#include <common/compat/string.h>
 #include <common/unix.h>
 #include <common/defaults.h>
 #include <common/lttng-elf.h>
 
 #include <lttng/constant.h>
 
+#include <common/sessiond-comm/sessiond-comm.h>
+#include <common/filter/filter-ast.h>
+#include <common/filter/filter-bytecode.h>
+
 #include "runas.h"
 
 struct run_as_data;
@@ -57,6 +62,7 @@ enum run_as_cmd {
        RUN_AS_RENAMEAT,
        RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET,
        RUN_AS_EXTRACT_SDT_PROBE_OFFSETS,
+       RUN_AS_GENERATE_FILTER_BYTECODE,
 };
 
 struct run_as_mkdir_data {
@@ -80,7 +86,7 @@ struct run_as_unlink_data {
 struct run_as_rmdir_data {
        int dirfd;
        char path[LTTNG_PATH_MAX];
-       int flags; /* enum lttng_directory_handle_rmdir_recursive_flags */
+       int flags; /* enum lttng_directory_handle_rmdir_recursive_flags. */
 } LTTNG_PACKED;
 
 struct run_as_extract_elf_symbol_offset_data {
@@ -94,6 +100,10 @@ struct run_as_extract_sdt_probe_offsets_data {
        char provider_name[LTTNG_SYMBOL_NAME_LEN];
 } LTTNG_PACKED;
 
+struct run_as_generate_filter_bytecode_data {
+       char filter_expression[LTTNG_FILTER_MAX_LEN];
+} LTTNG_PACKED;
+
 struct run_as_rename_data {
        /*
         * [0] = old_dirfd
@@ -117,6 +127,11 @@ struct run_as_extract_sdt_probe_offsets_ret {
        uint64_t offsets[LTTNG_KERNEL_MAX_UPROBE_NUM];
 } LTTNG_PACKED;
 
+struct run_as_generate_filter_bytecode_ret {
+       /* A lttng_bytecode_filter struct with 'dynamic' payload. */
+       char bytecode[LTTNG_FILTER_MAX_LEN];
+} LTTNG_PACKED;
+
 struct run_as_data {
        enum run_as_cmd cmd;
        union {
@@ -127,6 +142,7 @@ struct run_as_data {
                struct run_as_rename_data rename;
                struct run_as_extract_elf_symbol_offset_data extract_elf_symbol_offset;
                struct run_as_extract_sdt_probe_offsets_data extract_sdt_probe_offsets;
+               struct run_as_generate_filter_bytecode_data generate_filter_bytecode;
        } u;
        uid_t uid;
        gid_t gid;
@@ -153,6 +169,7 @@ struct run_as_ret {
                struct run_as_open_ret open;
                struct run_as_extract_elf_symbol_offset_ret extract_elf_symbol_offset;
                struct run_as_extract_sdt_probe_offsets_ret extract_sdt_probe_offsets;
+               struct run_as_generate_filter_bytecode_ret generate_filter_bytecode;
        } u;
        int _errno;
        bool _error;
@@ -306,6 +323,13 @@ static const struct run_as_command_properties command_properties[] = {
                .out_fd_count = 0,
                .use_cwd_fd = false,
        },
+       [RUN_AS_GENERATE_FILTER_BYTECODE] = {
+               .in_fds_offset = -1,
+               .in_fd_count = 0,
+               .out_fds_offset = -1,
+               .out_fd_count = 0,
+               .use_cwd_fd = false,
+       },
 };
 
 struct run_as_worker {
@@ -619,6 +643,48 @@ int _extract_sdt_probe_offsets(struct run_as_data *data,
 }
 #endif
 
+static
+int _generate_filter_bytecode(struct run_as_data *data,
+               struct run_as_ret *ret_value) {
+       int ret = 0;
+       const char *filter_expression = NULL;
+       struct filter_parser_ctx *ctx = NULL;
+
+       ret_value->_error = false;
+
+       filter_expression = data->u.generate_filter_bytecode.filter_expression;
+
+       if (lttng_strnlen(filter_expression, LTTNG_FILTER_MAX_LEN - 1) == LTTNG_FILTER_MAX_LEN - 1) {
+               ret_value->_error = true;
+               ret = -1;
+               goto end;
+       }
+
+       ret = filter_parser_ctx_create_from_filter_expression(filter_expression, &ctx);
+       if (ret < 0) {
+               ret_value->_error = true;
+               ret = -1;
+               goto end;
+       }
+
+       DBG("Size of bytecode generated: %u bytes.",
+                       bytecode_get_len(&ctx->bytecode->b));
+
+       /* Copy the lttng_bytecode_filter object to the return structure. */
+       memcpy(ret_value->u.generate_filter_bytecode.bytecode,
+                       &ctx->bytecode->b,
+                       sizeof(ctx->bytecode->b) +
+                                       bytecode_get_len(&ctx->bytecode->b));
+
+end:
+       if (ctx) {
+               filter_bytecode_free(ctx);
+               filter_ir_free(ctx);
+               filter_parser_ctx_free(ctx);
+       }
+
+       return ret;
+}
 static
 run_as_fct run_as_enum_to_fct(enum run_as_cmd cmd)
 {
@@ -648,6 +714,8 @@ run_as_fct run_as_enum_to_fct(enum run_as_cmd cmd)
                return _extract_elf_symbol_offset;
        case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS:
                return _extract_sdt_probe_offsets;
+       case RUN_AS_GENERATE_FILTER_BYTECODE:
+               return _generate_filter_bytecode;
        default:
                ERR("Unknown command %d", (int) cmd);
                return NULL;
@@ -794,6 +862,10 @@ int recv_fds_from_master(struct run_as_worker *worker, struct run_as_data *data)
                goto end;
        }
 
+       if (COMMAND_IN_FD_COUNT(data) == 0) {
+               goto end;
+       }
+
        ret = do_recv_fds(worker->sockpair[1], COMMAND_IN_FDS(data),
                        COMMAND_IN_FD_COUNT(data));
        if (ret < 0) {
@@ -1725,6 +1797,49 @@ error:
        return ret;
 }
 
+LTTNG_HIDDEN
+int run_as_generate_filter_bytecode(const char *filter_expression,
+               uid_t uid,
+               gid_t gid,
+               struct lttng_filter_bytecode **bytecode)
+{
+       int ret;
+       struct run_as_data data = {};
+       struct run_as_ret run_as_ret = {};
+       const struct lttng_filter_bytecode *view_bytecode = NULL;
+       struct lttng_filter_bytecode *local_bytecode = NULL;
+
+       DBG3("generate_filter_bytecode() from expression=\"%s\" for uid %d and gid %d",
+                       filter_expression, (int) uid, (int) gid);
+
+       ret = lttng_strncpy(data.u.generate_filter_bytecode.filter_expression, filter_expression,
+                       sizeof(data.u.generate_filter_bytecode.filter_expression));
+       if (ret) {
+               goto error;
+       }
+
+       run_as(RUN_AS_GENERATE_FILTER_BYTECODE, &data, &run_as_ret, uid, gid);
+       errno = run_as_ret._errno;
+       if (run_as_ret._error) {
+               ret = -1;
+               goto error;
+       }
+
+       view_bytecode = (const struct lttng_filter_bytecode *) run_as_ret.u.generate_filter_bytecode.bytecode;
+
+       local_bytecode = zmalloc(sizeof(*local_bytecode) + view_bytecode->len);
+       if (!local_bytecode) {
+               ret = -ENOMEM;
+               goto error;
+       }
+
+       memcpy(local_bytecode, run_as_ret.u.generate_filter_bytecode.bytecode,
+                       sizeof(*local_bytecode) + view_bytecode->len);
+       *bytecode = local_bytecode;
+error:
+       return ret;
+}
+
 LTTNG_HIDDEN
 int run_as_create_worker(const char *procname,
                post_fork_cleanup_cb clean_up_func,
index 619d3d0b3620fde2d6b3fafdc687dda4cbc3e77a..398221708e16948dfc62221d7df228cf3fb6f850 100644 (file)
@@ -14,6 +14,7 @@
 #include <unistd.h>
 
 #include <common/macros.h>
+#include <common/sessiond-comm/sessiond-comm.h>
 
 /*
  * The run-as process is launched by forking without an exec*() call. This means
@@ -70,6 +71,11 @@ int run_as_extract_sdt_probe_offsets(int fd, const char *provider_name,
                const char* probe_name, uid_t uid, gid_t gid,
                uint64_t **offsets, uint32_t *num_offset);
 LTTNG_HIDDEN
+int run_as_generate_filter_bytecode(const char *filter_expression,
+               uid_t uid,
+               gid_t gid,
+               struct lttng_filter_bytecode **bytecode);
+LTTNG_HIDDEN
 int run_as_create_worker(const char *procname,
                post_fork_cleanup_cb clean_up_func, void *clean_up_user_data);
 LTTNG_HIDDEN
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