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Diffstat (limited to 'src/newgidmap.c')
| -rw-r--r-- | src/newgidmap.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/src/newgidmap.c b/src/newgidmap.c new file mode 100644 index 0000000..b1e3351 --- /dev/null +++ b/src/newgidmap.c @@ -0,0 +1,186 @@ +/* + * 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/subgid */ + if (have_sub_gids(pw->pw_name, range->lower, range->count)) + return true; + + /* Allow a process to map its own gid */ + if ((range->count == 1) && (pw->pw_gid == 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: gid range [%lu-%lu) -> [%lu-%lu) not allowed\n"), + Prog, + mapping->upper, + mapping->upper + mapping->count, + mapping->lower, + mapping->lower + mapping->count); + exit(EXIT_FAILURE); + } + } +} + +static void usage(void) +{ + fprintf(stderr, _("usage: %s <pid> <gid> <lowergid> <count> [ <gid> <lowergid> <count> ] ... \n"), Prog); + exit(EXIT_FAILURE); +} + +/* + * newgidmap - Set the gid_map for the specified process + */ +int main(int argc, char **argv) +{ + char proc_dir_name[32]; + char *target_str; + pid_t target, parent; + 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 + * newgidmap target_pid + */ + if (argc < 2) + usage(); + + /* Find the process that needs its user namespace + * gid 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 %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_gid_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, "gid_map"); + sub_gid_close(); + + return EXIT_SUCCESS; +} |