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Diffstat (limited to 'libmisc/idmapping.c')
| -rw-r--r-- | libmisc/idmapping.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/libmisc/idmapping.c b/libmisc/idmapping.c new file mode 100644 index 0000000..db254fc --- /dev/null +++ b/libmisc/idmapping.c @@ -0,0 +1,164 @@ +/* + * 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 <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <limits.h> +#include <stdlib.h> +#include <stdio.h> +#include "prototypes.h" +#include "idmapping.h" + +struct map_range *get_map_ranges(int ranges, int argc, char **argv) +{ + struct map_range *mappings, *mapping; + int idx, argidx; + + if (ranges < 0 || argc < 0) { + fprintf(stderr, "%s: error calculating number of arguments\n", Prog); + return NULL; + } + + if (ranges != ((argc + 2) / 3)) { + fprintf(stderr, "%s: ranges: %u is wrong for argc: %d\n", Prog, ranges, argc); + return NULL; + } + + if ((ranges * 3) > argc) { + fprintf(stderr, "ranges: %u argc: %d\n", + ranges, argc); + fprintf(stderr, + _( "%s: Not enough arguments to form %u mappings\n"), + Prog, ranges); + return NULL; + } + + mappings = calloc(ranges, sizeof(*mappings)); + if (!mappings) { + fprintf(stderr, _( "%s: Memory allocation failure\n"), + Prog); + exit(EXIT_FAILURE); + } + + /* Gather up the ranges from the command line */ + mapping = mappings; + for (idx = 0, argidx = 0; idx < ranges; idx++, argidx += 3, mapping++) { + if (!getulong(argv[argidx + 0], &mapping->upper)) { + free(mappings); + return NULL; + } + if (!getulong(argv[argidx + 1], &mapping->lower)) { + free(mappings); + return NULL; + } + if (!getulong(argv[argidx + 2], &mapping->count)) { + free(mappings); + return NULL; + } + if (ULONG_MAX - mapping->upper <= mapping->count || ULONG_MAX - mapping->lower <= mapping->count) { + fprintf(stderr, _( "%s: subuid overflow detected.\n"), Prog); + exit(EXIT_FAILURE); + } + if (mapping->upper > UINT_MAX || + mapping->lower > UINT_MAX || + mapping->count > UINT_MAX) { + fprintf(stderr, _( "%s: subuid overflow detected.\n"), Prog); + exit(EXIT_FAILURE); + } + if (mapping->lower + mapping->count > UINT_MAX || + mapping->upper + mapping->count > UINT_MAX) { + fprintf(stderr, _( "%s: subuid overflow detected.\n"), Prog); + exit(EXIT_FAILURE); + } + if (mapping->lower + mapping->count < mapping->lower || + mapping->upper + mapping->count < mapping->upper) { + /* this one really shouldn't be possible given previous checks */ + fprintf(stderr, _( "%s: subuid overflow detected.\n"), Prog); + exit(EXIT_FAILURE); + } + } + return mappings; +} + +/* Number of ascii digits needed to print any unsigned long in decimal. + * There are approximately 10 bits for every 3 decimal digits. + * So from bits to digits the formula is roundup((Number of bits)/10) * 3. + * For common sizes of integers this works out to: + * 2bytes --> 6 ascii estimate -> 65536 (5 real) + * 4bytes --> 12 ascii estimated -> 4294967296 (10 real) + * 8bytes --> 21 ascii estimated -> 18446744073709551616 (20 real) + * 16bytes --> 39 ascii estimated -> 340282366920938463463374607431768211456 (39 real) + */ +#define ULONG_DIGITS ((((sizeof(unsigned long) * CHAR_BIT) + 9)/10)*3) + + +void write_mapping(int proc_dir_fd, int ranges, struct map_range *mappings, + const char *map_file) +{ + int idx; + struct map_range *mapping; + size_t bufsize; + char *buf, *pos; + int fd; + + bufsize = ranges * ((ULONG_DIGITS + 1) * 3); + pos = buf = xmalloc(bufsize); + + /* Build the mapping command */ + mapping = mappings; + for (idx = 0; idx < ranges; idx++, mapping++) { + /* Append this range to the string that will be written */ + int written = snprintf(pos, bufsize - (pos - buf), + "%lu %lu %lu\n", + mapping->upper, + mapping->lower, + mapping->count); + if ((written <= 0) || (written >= (bufsize - (pos - buf)))) { + fprintf(stderr, _("%s: snprintf failed!\n"), Prog); + exit(EXIT_FAILURE); + } + pos += written; + } + + /* Write the mapping to the maping file */ + fd = openat(proc_dir_fd, map_file, O_WRONLY); + if (fd < 0) { + fprintf(stderr, _("%s: open of %s failed: %s\n"), + Prog, map_file, strerror(errno)); + exit(EXIT_FAILURE); + } + if (write(fd, buf, pos - buf) != (pos - buf)) { + fprintf(stderr, _("%s: write to %s failed: %s\n"), + Prog, map_file, strerror(errno)); + exit(EXIT_FAILURE); + } + close(fd); +} |