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-rw-r--r--src/newuidmap.c186
1 files changed, 186 insertions, 0 deletions
diff --git a/src/newuidmap.c b/src/newuidmap.c
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+++ b/src/newuidmap.c
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+/*
+ * Copyright (c) 2013 Eric Biederman
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. The name of the copyright holders or contributors may not be used to
+ * endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include "defines.h"
+#include "prototypes.h"
+#include "subordinateio.h"
+#include "idmapping.h"
+
+/*
+ * Global variables
+ */
+const char *Prog;
+
+static bool verify_range(struct passwd *pw, struct map_range *range)
+{
+ /* An empty range is invalid */
+ if (range->count == 0)
+ return false;
+
+ /* Test /etc/subuid */
+ if (have_sub_uids(pw->pw_name, range->lower, range->count))
+ return true;
+
+ /* Allow a process to map its own uid */
+ if ((range->count == 1) && (pw->pw_uid == range->lower))
+ return true;
+
+ return false;
+}
+
+static void verify_ranges(struct passwd *pw, int ranges,
+ struct map_range *mappings)
+{
+ struct map_range *mapping;
+ int idx;
+
+ mapping = mappings;
+ for (idx = 0; idx < ranges; idx++, mapping++) {
+ if (!verify_range(pw, mapping)) {
+ fprintf(stderr, _( "%s: uid range [%lu-%lu) -> [%lu-%lu) not allowed\n"),
+ Prog,
+ mapping->upper,
+ mapping->upper + mapping->count,
+ mapping->lower,
+ mapping->lower + mapping->count);
+ exit(EXIT_FAILURE);
+ }
+ }
+}
+
+void usage(void)
+{
+ fprintf(stderr, _("usage: %s <pid> <uid> <loweruid> <count> [ <uid> <loweruid> <count> ] ... \n"), Prog);
+ exit(EXIT_FAILURE);
+}
+
+/*
+ * newuidmap - Set the uid_map for the specified process
+ */
+int main(int argc, char **argv)
+{
+ char proc_dir_name[32];
+ char *target_str;
+ pid_t target;
+ int proc_dir_fd;
+ int ranges;
+ struct map_range *mappings;
+ struct stat st;
+ struct passwd *pw;
+ int written;
+
+ Prog = Basename (argv[0]);
+
+ /*
+ * The valid syntax are
+ * newuidmap target_pid
+ */
+ if (argc < 2)
+ usage();
+
+ /* Find the process that needs its user namespace
+ * uid mapping set.
+ */
+ target_str = argv[1];
+ if (!get_pid(target_str, &target))
+ usage();
+
+ /* max string length is 6 + 10 + 1 + 1 = 18, allocate 32 bytes */
+ written = snprintf(proc_dir_name, sizeof(proc_dir_name), "/proc/%u/",
+ target);
+ if ((written <= 0) || (written >= sizeof(proc_dir_name))) {
+ fprintf(stderr, "%s: snprintf of proc path failed: %s\n",
+ Prog, strerror(errno));
+ }
+
+ proc_dir_fd = open(proc_dir_name, O_DIRECTORY);
+ if (proc_dir_fd < 0) {
+ fprintf(stderr, _("%s: Could not open proc directory for target %u\n"),
+ Prog, target);
+ return EXIT_FAILURE;
+ }
+
+ /* Who am i? */
+ pw = get_my_pwent ();
+ if (NULL == pw) {
+ fprintf (stderr,
+ _("%s: Cannot determine your user name.\n"),
+ Prog);
+ SYSLOG ((LOG_WARN, "Cannot determine the user name of the caller (UID %lu)",
+ (unsigned long) getuid ()));
+ return EXIT_FAILURE;
+ }
+
+ /* Get the effective uid and effective gid of the target process */
+ if (fstat(proc_dir_fd, &st) < 0) {
+ fprintf(stderr, _("%s: Could not stat directory for target %u\n"),
+ Prog, target);
+ return EXIT_FAILURE;
+ }
+
+ /* Verify real user and real group matches the password entry
+ * and the effective user and group of the program whose
+ * mappings we have been asked to set.
+ */
+ if ((getuid() != pw->pw_uid) ||
+ (getgid() != pw->pw_gid) ||
+ (pw->pw_uid != st.st_uid) ||
+ (pw->pw_gid != st.st_gid)) {
+ fprintf(stderr, _( "%s: Target process %u is owned by a different user: uid:%lu pw_uid:%lu st_uid:%lu, gid:%lu pw_gid:%lu st_gid:%lu\n" ),
+ Prog, target,
+ (unsigned long int)getuid(), (unsigned long int)pw->pw_uid, (unsigned long int)st.st_uid,
+ (unsigned long int)getgid(), (unsigned long int)pw->pw_gid, (unsigned long int)st.st_gid);
+ return EXIT_FAILURE;
+ }
+
+ if (!sub_uid_open(O_RDONLY)) {
+ return EXIT_FAILURE;
+ }
+
+ ranges = ((argc - 2) + 2) / 3;
+ mappings = get_map_ranges(ranges, argc - 2, argv + 2);
+ if (!mappings)
+ usage();
+
+ verify_ranges(pw, ranges, mappings);
+
+ write_mapping(proc_dir_fd, ranges, mappings, "uid_map", pw->pw_uid);
+ sub_uid_close();
+
+ return EXIT_SUCCESS;
+}