X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Frunas.c;h=930c973ff956ec2c13aeed57d2d2d69b8995775f;hp=1147296ad3357e21d4fd169ef54f73c78f13512f;hb=f895927f329180ca1e6f4426e9d3c6250ae698ba;hpb=58daac01d91347336f24e1fc1cacd4e7a3101e93

diff --git a/src/common/runas.c b/src/common/runas.c
index 1147296ad..930c973ff 100644
--- a/src/common/runas.c
+++ b/src/common/runas.c
@@ -8,20 +8,21 @@
  */
 
 #define _LGPL_SOURCE
+#include <fcntl.h>
+#include <grp.h>
 #include <limits.h>
+#include <pwd.h>
+#include <sched.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/wait.h>
-#include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 #include <unistd.h>
-#include <fcntl.h>
-#include <sched.h>
-#include <signal.h>
-#include <assert.h>
-#include <signal.h>
 
+#include <common/bytecode/bytecode.h>
 #include <common/lttng-kernel.h>
 #include <common/common.h>
 #include <common/utils.h>
@@ -37,10 +38,11 @@
 
 #include <common/sessiond-comm/sessiond-comm.h>
 #include <common/filter/filter-ast.h>
-#include <common/filter/filter-bytecode.h>
 
 #include "runas.h"
 
+#define GETPW_BUFFER_FALLBACK_SIZE 4096
+
 struct run_as_data;
 struct run_as_ret;
 typedef int (*run_as_fct)(struct run_as_data *data, struct run_as_ret *ret_value);
@@ -124,7 +126,7 @@ struct run_as_extract_elf_symbol_offset_ret {
 
 struct run_as_extract_sdt_probe_offsets_ret {
 	uint32_t num_offset;
-	uint64_t offsets[LTTNG_KERNEL_MAX_UPROBE_NUM];
+	uint64_t offsets[LTTNG_KERNEL_ABI_MAX_UPROBE_NUM];
 } LTTNG_PACKED;
 
 struct run_as_generate_filter_bytecode_ret {
@@ -607,7 +609,7 @@ int _extract_sdt_probe_offsets(struct run_as_data *data,
 		goto end;
 	}
 
-	if (num_offset <= 0 || num_offset > LTTNG_KERNEL_MAX_UPROBE_NUM) {
+	if (num_offset <= 0 || num_offset > LTTNG_KERNEL_ABI_MAX_UPROBE_NUM) {
 		DBG("Wrong number of probes.");
 		ret = -1;
 		ret_value->_error = true;
@@ -730,7 +732,7 @@ int do_send_fds(int sock, const int *fds, unsigned int fd_count)
 
 	for (i = 0; i < fd_count; i++) {
 		if (fds[i] < 0) {
-			ERR("Attempt to send invalid file descriptor to master (fd = %i)",
+			DBG("Attempt to send invalid file descriptor (fd = %i)",
 					fds[i]);
 			/* Return 0 as this is not a fatal error. */
 			return 0;
@@ -818,10 +820,14 @@ int send_fds_to_master(struct run_as_worker *worker, enum run_as_cmd cmd,
 	}
 
 	for (i = 0; i < COMMAND_OUT_FD_COUNT(cmd); i++) {
-		int ret_close = close(COMMAND_OUT_FDS(cmd, run_as_ret)[i]);
+		int fd = COMMAND_OUT_FDS(cmd, run_as_ret)[i];
+		if (fd >= 0) {
+			int ret_close = close(fd);
 
-		if (ret_close < 0) {
-			PERROR("Failed to close result file descriptor");
+			if (ret_close < 0) {
+				PERROR("Failed to close result file descriptor (fd = %i)",
+						fd);
+			}
 		}
 	}
 end:
@@ -895,18 +901,210 @@ end:
 	return ret;
 }
 
+static int get_user_infos_from_uid(
+		uid_t uid, char **username, gid_t *primary_gid)
+{
+	int ret;
+	char *buf = NULL;
+	long raw_get_pw_buf_size;
+	size_t get_pw_buf_size;
+	struct passwd pwd;
+	struct passwd *result = NULL;
+
+	/* Fetch the max size for the temporary buffer. */
+	errno = 0;
+	raw_get_pw_buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
+	if (raw_get_pw_buf_size < 0) {
+		if (errno != 0) {
+			PERROR("Failed to query _SC_GETPW_R_SIZE_MAX");
+			goto error;
+		}
+
+		/* Limit is indeterminate. */
+		WARN("Failed to query _SC_GETPW_R_SIZE_MAX as it is "
+			"indeterminate; falling back to default buffer size");
+		raw_get_pw_buf_size = GETPW_BUFFER_FALLBACK_SIZE;
+	}
+
+	get_pw_buf_size = (size_t) raw_get_pw_buf_size;
+
+	buf = zmalloc(get_pw_buf_size);
+	if (buf == NULL) {
+		PERROR("Failed to allocate buffer to get password file entries");
+		goto error;
+	}
+
+	ret = getpwuid_r(uid, &pwd, buf, get_pw_buf_size, &result);
+	if (ret < 0) {
+		PERROR("Failed to get user information for user:  uid = %d",
+				(int) uid);
+		goto error;
+	}
+
+	if (result == NULL) {
+		ERR("Failed to find user information in password entries: uid = %d",
+				(int) uid);
+		ret = -1;
+		goto error;
+	}
+
+	*username = strdup(result->pw_name);
+	if (*username == NULL) {
+		PERROR("Failed to copy user name");
+		goto error;
+	}
+
+	*primary_gid = result->pw_gid;
+
+end:
+	free(buf);
+	return ret;
+error:
+	*username = NULL;
+	*primary_gid = -1;
+	ret = -1;
+	goto end;
+}
+
+static int demote_creds(
+		uid_t prev_uid, gid_t prev_gid, uid_t new_uid, gid_t new_gid)
+{
+	int ret = 0;
+	gid_t primary_gid;
+	char *username = NULL;
+
+	/* Change the group id. */
+	if (prev_gid != new_gid) {
+		ret = setegid(new_gid);
+		if (ret < 0) {
+			PERROR("Failed to set effective group id: new_gid = %d",
+					(int) new_gid);
+			goto end;
+		}
+	}
+
+	/* Change the user id. */
+	if (prev_uid != new_uid) {
+		ret = get_user_infos_from_uid(new_uid, &username, &primary_gid);
+		if (ret < 0) {
+			goto end;
+		}
+
+		/*
+		 * Initialize the supplementary group access list.
+		 *
+		 * This is needed to handle cases where the supplementary groups
+		 * of the user the process is demoting-to would give it access
+		 * to a given file/folder, but not it's primary group.
+		 *
+		 * e.g
+		 *   username: User1
+		 *   Primary Group: User1
+		 *   Secondary group: Disk, Network
+		 *
+		 *   mkdir inside the following directory must work since User1
+		 *   is part of the Network group.
+		 *
+		 *   drwxrwx--- 2 root Network 4096 Jul 23 17:17 /tmp/my_folder/
+		 *
+		 *
+		 * The order of the following initgroups and seteuid calls is
+		 * important here;
+		 * Only a root process or one with CAP_SETGID capability can
+		 * call the the initgroups() function. We must initialize the
+		 * supplementary groups before we change the effective
+		 * UID to a less-privileged user.
+		 */
+		ret = initgroups(username, primary_gid);
+		if (ret < 0) {
+			PERROR("Failed to init the supplementary group access list: "
+					"username = `%s`, primary gid = %d", username,
+					(int) primary_gid);
+			goto end;
+		}
+
+		ret = seteuid(new_uid);
+		if (ret < 0) {
+			PERROR("Failed to set effective user id: new_uid = %d",
+					(int) new_uid);
+			goto end;
+		}
+	}
+end:
+	free(username);
+	return ret;
+}
+
+static int promote_creds(
+		uid_t prev_uid, gid_t prev_gid, uid_t new_uid, gid_t new_gid)
+{
+	int ret = 0;
+	gid_t primary_gid;
+	char *username = NULL;
+
+	/* Change the group id. */
+	if (prev_gid != new_gid) {
+		ret = setegid(new_gid);
+		if (ret < 0) {
+			PERROR("Failed to set effective group id: new_gid = %d",
+					(int) new_gid);
+			goto end;
+		}
+	}
+
+	/* Change the user id. */
+	if (prev_uid != new_uid) {
+		ret = get_user_infos_from_uid(new_uid, &username, &primary_gid);
+		if (ret < 0) {
+			goto end;
+		}
+
+		/*
+		 * seteuid call must be done before the initgroups call because
+		 * we need to be privileged (CAP_SETGID) to call initgroups().
+		 */
+		ret = seteuid(new_uid);
+		if (ret < 0) {
+			PERROR("Failed to set effective user id: new_uid = %d",
+					(int) new_uid);
+			goto end;
+		}
+
+		/*
+		 * Initialize the supplementary group access list.
+		 *
+		 * There is a possibility the groups we set in the following
+		 * initgroups() call are not exactly the same as the ones we
+		 * had when we originally demoted. This can happen if the
+		 * /etc/group file is modified after the runas process is
+		 * forked. This is very unlikely.
+		 */
+		ret = initgroups(username, primary_gid);
+		if (ret < 0) {
+			PERROR("Failed to init the supplementary group access "
+					"list: username = `%s`, primary gid = %d",
+					username, (int) primary_gid)
+			goto end;
+		}
+	}
+end:
+	free(username);
+	return ret;
+}
+
 /*
  * Return < 0 on error, 0 if OK, 1 on hangup.
  */
 static
 int handle_one_cmd(struct run_as_worker *worker)
 {
-	int ret = 0;
+	int ret = 0, promote_ret;
 	struct run_as_data data = {};
 	ssize_t readlen, writelen;
 	struct run_as_ret sendret = {};
 	run_as_fct cmd;
-	uid_t prev_euid;
+	const uid_t prev_ruid = getuid();
+	const gid_t prev_rgid = getgid();
 
 	/*
 	 * Stage 1: Receive run_as_data struct from the master.
@@ -944,24 +1142,9 @@ int handle_one_cmd(struct run_as_worker *worker)
 		goto end;
 	}
 
-	prev_euid = getuid();
-	if (data.gid != getegid()) {
-		ret = setegid(data.gid);
-		if (ret < 0) {
-			sendret._error = true;
-			sendret._errno = errno;
-			PERROR("setegid");
-			goto write_return;
-		}
-	}
-	if (data.uid != prev_euid) {
-		ret = seteuid(data.uid);
-		if (ret < 0) {
-			sendret._error = true;
-			sendret._errno = errno;
-			PERROR("seteuid");
-			goto write_return;
-		}
+	ret = demote_creds(prev_ruid, prev_rgid, data.uid, data.gid);
+	if (ret < 0) {
+		goto write_return;
 	}
 
 	/*
@@ -981,7 +1164,7 @@ write_return:
 	ret = cleanup_received_fds(&data);
 	if (ret < 0) {
 		ERR("Error cleaning up FD");
-		goto end;
+		goto promote_back;
 	}
 
 	/*
@@ -993,7 +1176,7 @@ write_return:
 	if (writelen < sizeof(sendret)) {
 		PERROR("lttcomm_send_unix_sock error");
 		ret = -1;
-		goto end;
+		goto promote_back;
 	}
 
 	/*
@@ -1002,15 +1185,17 @@ write_return:
 	ret = send_fds_to_master(worker, data.cmd, &sendret);
 	if (ret < 0) {
 		DBG("Sending FD to master returned an error");
-		goto end;
 	}
 
-	if (seteuid(prev_euid) < 0) {
-		PERROR("seteuid");
-		ret = -1;
-		goto end;
-	}
 	ret = 0;
+
+promote_back:
+	/* Return to previous uid/gid. */
+	promote_ret = promote_creds(data.uid, data.gid, prev_ruid, prev_rgid);
+	if (promote_ret < 0) {
+		ERR("Failed to promote back to the initial credentials");
+	}
+
 end:
 	return ret;
 }
@@ -1262,7 +1447,7 @@ int run_as_create_worker_no_lock(const char *procname,
 	struct run_as_ret recvret;
 	struct run_as_worker *worker;
 
-	assert(!global_worker);
+	LTTNG_ASSERT(!global_worker);
 	if (!use_clone()) {
 		/*
 		 * Don't initialize a worker, all run_as tasks will be performed
@@ -1299,6 +1484,9 @@ int run_as_create_worker_no_lock(const char *procname,
 		reset_sighandler();
 
 		set_worker_sighandlers();
+
+		logger_set_thread_name("Run-as worker", true);
+
 		if (clean_up_func) {
 			if (clean_up_func(clean_up_user_data) < 0) {
 				ERR("Run-as post-fork clean-up failed, exiting.");
@@ -1453,7 +1641,7 @@ int run_as(enum run_as_cmd cmd, struct run_as_data *data,
 	if (use_clone()) {
 		DBG("Using run_as worker");
 
-		assert(global_worker);
+		LTTNG_ASSERT(global_worker);
 
 		ret = run_as_cmd(global_worker, cmd, data, ret_value, uid, gid);
 		saved_errno = ret_value->_errno;
@@ -1480,13 +1668,11 @@ err:
 	return ret;
 }
 
-LTTNG_HIDDEN
 int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid)
 {
 	return run_as_mkdirat_recursive(AT_FDCWD, path, mode, uid, gid);
 }
 
-LTTNG_HIDDEN
 int run_as_mkdirat_recursive(int dirfd, const char *path, mode_t mode,
 		uid_t uid, gid_t gid)
 {
@@ -1514,13 +1700,11 @@ error:
 	return ret;
 }
 
-LTTNG_HIDDEN
 int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid)
 {
 	return run_as_mkdirat(AT_FDCWD, path, mode, uid, gid);
 }
 
-LTTNG_HIDDEN
 int run_as_mkdirat(int dirfd, const char *path, mode_t mode,
 		uid_t uid, gid_t gid)
 {
@@ -1548,14 +1732,12 @@ error:
 	return ret;
 }
 
-LTTNG_HIDDEN
 int run_as_open(const char *path, int flags, mode_t mode, uid_t uid,
 		gid_t gid)
 {
 	return run_as_openat(AT_FDCWD, path, flags, mode, uid, gid);
 }
 
-LTTNG_HIDDEN
 int run_as_openat(int dirfd, const char *path, int flags, mode_t mode,
 		uid_t uid, gid_t gid)
 {
@@ -1583,13 +1765,11 @@ error:
 	return ret;
 }
 
-LTTNG_HIDDEN
 int run_as_unlink(const char *path, uid_t uid, gid_t gid)
 {
 	return run_as_unlinkat(AT_FDCWD, path, uid, gid);
 }
 
-LTTNG_HIDDEN
 int run_as_unlinkat(int dirfd, const char *path, uid_t uid, gid_t gid)
 {
 	int ret;
@@ -1613,13 +1793,11 @@ error:
 	return ret;
 }
 
-LTTNG_HIDDEN
 int run_as_rmdir(const char *path, uid_t uid, gid_t gid)
 {
 	return run_as_rmdirat(AT_FDCWD, path, uid, gid);
 }
 
-LTTNG_HIDDEN
 int run_as_rmdirat(int dirfd, const char *path, uid_t uid, gid_t gid)
 {
 	int ret;
@@ -1643,13 +1821,11 @@ error:
 	return ret;
 }
 
-LTTNG_HIDDEN
 int run_as_rmdir_recursive(const char *path, uid_t uid, gid_t gid, int flags)
 {
 	return run_as_rmdirat_recursive(AT_FDCWD, path, uid, gid, flags);
 }
 
-LTTNG_HIDDEN
 int run_as_rmdirat_recursive(int dirfd, const char *path, uid_t uid, gid_t gid, int flags)
 {
 	int ret;
@@ -1674,13 +1850,11 @@ error:
 	return ret;
 }
 
-LTTNG_HIDDEN
 int run_as_rename(const char *old, const char *new, uid_t uid, gid_t gid)
 {
 	return run_as_renameat(AT_FDCWD, old, AT_FDCWD, new, uid, gid);
 }
 
-LTTNG_HIDDEN
 int run_as_renameat(int old_dirfd, const char *old_name,
 		int new_dirfd, const char *new_name, uid_t uid, gid_t gid)
 {
@@ -1715,7 +1889,6 @@ error:
 	return ret;
 }
 
-LTTNG_HIDDEN
 int run_as_extract_elf_symbol_offset(int fd, const char* function,
 		uid_t uid, gid_t gid, uint64_t *offset)
 {
@@ -1750,7 +1923,6 @@ error:
 	return ret;
 }
 
-LTTNG_HIDDEN
 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)
@@ -1797,16 +1969,15 @@ error:
 	return ret;
 }
 
-LTTNG_HIDDEN
 int run_as_generate_filter_bytecode(const char *filter_expression,
 		const struct lttng_credentials *creds,
-		struct lttng_filter_bytecode **bytecode)
+		struct lttng_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;
+	const struct lttng_bytecode *view_bytecode = NULL;
+	struct lttng_bytecode *local_bytecode = NULL;
 	const uid_t uid = lttng_credentials_get_uid(creds);
 	const gid_t gid = lttng_credentials_get_gid(creds);
 
@@ -1826,7 +1997,7 @@ int run_as_generate_filter_bytecode(const char *filter_expression,
 		goto error;
 	}
 
-	view_bytecode = (const struct lttng_filter_bytecode *) run_as_ret.u.generate_filter_bytecode.bytecode;
+	view_bytecode = (const struct lttng_bytecode *) run_as_ret.u.generate_filter_bytecode.bytecode;
 
 	local_bytecode = zmalloc(sizeof(*local_bytecode) + view_bytecode->len);
 	if (!local_bytecode) {
@@ -1841,7 +2012,6 @@ error:
 	return ret;
 }
 
-LTTNG_HIDDEN
 int run_as_create_worker(const char *procname,
 		post_fork_cleanup_cb clean_up_func,
 		void *clean_up_user_data)
@@ -1855,7 +2025,6 @@ int run_as_create_worker(const char *procname,
 	return ret;
 }
 
-LTTNG_HIDDEN
 void run_as_destroy_worker(void)
 {
 	pthread_mutex_lock(&worker_lock);