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newuidmap,newgidmap: New suid helpers for using subordinate uids and gids

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Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
This commit is contained in:
Eric W. Biederman
2013-01-22 01:20:07 -08:00
committed by Serge Hallyn
parent 2cffa14105
commit 673c2a6f9a
9 changed files with 856 additions and 2 deletions
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126
libmisc/idmapping.c Normal file
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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 <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.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 * 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; idx < ranges; idx++, argidx += 3, mapping++) {
if (!getulong(argv[argidx + 0], &mapping->upper))
return NULL;
if (!getulong(argv[argidx + 1], &mapping->lower))
return NULL;
if (!getulong(argv[argidx + 2], &mapping->count))
return NULL;
}
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);
}