upload-pack.con commit upload-pack: tighten request validation. (565ebbf)
   1#include "cache.h"
   2#include "refs.h"
   3#include "pkt-line.h"
   4#include "tag.h"
   5#include "object.h"
   6
   7static const char upload_pack_usage[] = "git-upload-pack [--strict] [--timeout=nn] <dir>";
   8
   9#define OUR_REF (1U << 1)
  10#define WANTED (1U << 2)
  11#define MAX_HAS 256
  12#define MAX_NEEDS 256
  13static int nr_has = 0, nr_needs = 0, nr_our_refs = 0;
  14static unsigned char has_sha1[MAX_HAS][20];
  15static unsigned char needs_sha1[MAX_NEEDS][20];
  16static unsigned int timeout = 0;
  17
  18static void reset_timeout(void)
  19{
  20        alarm(timeout);
  21}
  22
  23static int strip(char *line, int len)
  24{
  25        if (len && line[len-1] == '\n')
  26                line[--len] = 0;
  27        return len;
  28}
  29
  30static void create_pack_file(void)
  31{
  32        int fd[2];
  33        pid_t pid;
  34        int create_full_pack = (nr_our_refs == nr_needs && !nr_has);
  35
  36        if (pipe(fd) < 0)
  37                die("git-upload-pack: unable to create pipe");
  38        pid = fork();
  39        if (pid < 0)
  40                die("git-upload-pack: unable to fork git-rev-list");
  41
  42        if (!pid) {
  43                int i;
  44                int args;
  45                char **argv;
  46                char *buf;
  47                char **p;
  48
  49                if (create_full_pack)
  50                        args = 10;
  51                else
  52                        args = nr_has + nr_needs + 5;
  53                argv = xmalloc(args * sizeof(char *));
  54                buf = xmalloc(args * 45);
  55                p = argv;
  56
  57                dup2(fd[1], 1);
  58                close(0);
  59                close(fd[0]);
  60                close(fd[1]);
  61                *p++ = "git-rev-list";
  62                *p++ = "--objects";
  63                if (MAX_NEEDS <= nr_needs)
  64                        *p++ = "--all";
  65                else {
  66                        for (i = 0; i < nr_needs; i++) {
  67                                *p++ = buf;
  68                                memcpy(buf, sha1_to_hex(needs_sha1[i]), 41);
  69                                buf += 41;
  70                        }
  71                }
  72                for (i = 0; i < nr_has; i++) {
  73                        *p++ = buf;
  74                        *buf++ = '^';
  75                        memcpy(buf, sha1_to_hex(has_sha1[i]), 41);
  76                        buf += 41;
  77                }
  78                *p++ = NULL;
  79                execvp("git-rev-list", argv);
  80                die("git-upload-pack: unable to exec git-rev-list");
  81        }
  82        dup2(fd[0], 0);
  83        close(fd[0]);
  84        close(fd[1]);
  85        execlp("git-pack-objects", "git-pack-objects", "--stdout", NULL);
  86        die("git-upload-pack: unable to exec git-pack-objects");
  87}
  88
  89static int got_sha1(char *hex, unsigned char *sha1)
  90{
  91        int nr;
  92        if (get_sha1_hex(hex, sha1))
  93                die("git-upload-pack: expected SHA1 object, got '%s'", hex);
  94        if (!has_sha1_file(sha1))
  95                return 0;
  96        nr = nr_has;
  97        if (nr < MAX_HAS) {
  98                memcpy(has_sha1[nr], sha1, 20);
  99                nr_has = nr+1;
 100        }
 101        return 1;
 102}
 103
 104static int get_common_commits(void)
 105{
 106        static char line[1000];
 107        unsigned char sha1[20];
 108        int len;
 109
 110        for(;;) {
 111                len = packet_read_line(0, line, sizeof(line));
 112                reset_timeout();
 113
 114                if (!len) {
 115                        packet_write(1, "NAK\n");
 116                        continue;
 117                }
 118                len = strip(line, len);
 119                if (!strncmp(line, "have ", 5)) {
 120                        if (got_sha1(line+5, sha1)) {
 121                                packet_write(1, "ACK %s\n", sha1_to_hex(sha1));
 122                                break;
 123                        }
 124                        continue;
 125                }
 126                if (!strcmp(line, "done")) {
 127                        packet_write(1, "NAK\n");
 128                        return -1;
 129                }
 130                die("git-upload-pack: expected SHA1 list, got '%s'", line);
 131        }
 132
 133        for (;;) {
 134                len = packet_read_line(0, line, sizeof(line));
 135                reset_timeout();
 136                if (!len)
 137                        continue;
 138                len = strip(line, len);
 139                if (!strncmp(line, "have ", 5)) {
 140                        got_sha1(line+5, sha1);
 141                        continue;
 142                }
 143                if (!strcmp(line, "done"))
 144                        break;
 145                die("git-upload-pack: expected SHA1 list, got '%s'", line);
 146        }
 147        return 0;
 148}
 149
 150static int receive_needs(void)
 151{
 152        static char line[1000];
 153        int len, needs;
 154
 155        needs = 0;
 156        for (;;) {
 157                struct object *o;
 158                unsigned char dummy[20], *sha1_buf;
 159                len = packet_read_line(0, line, sizeof(line));
 160                reset_timeout();
 161                if (!len)
 162                        return needs;
 163
 164                sha1_buf = dummy;
 165                if (needs == MAX_NEEDS) {
 166                        fprintf(stderr,
 167                                "warning: supporting only a max of %d requests. "
 168                                "sending everything instead.\n",
 169                                MAX_NEEDS);
 170                }
 171                else if (needs < MAX_NEEDS)
 172                        sha1_buf = needs_sha1[needs];
 173
 174                if (strncmp("want ", line, 5) || get_sha1_hex(line+5, sha1_buf))
 175                        die("git-upload-pack: protocol error, "
 176                            "expected to get sha, not '%s'", line);
 177
 178                /* We have sent all our refs already, and the other end
 179                 * should have chosen out of them; otherwise they are
 180                 * asking for nonsense.
 181                 *
 182                 * Hmph.  We may later want to allow "want" line that
 183                 * asks for something like "master~10" (symbolic)...
 184                 * would it make sense?  I don't know.
 185                 */
 186                o = lookup_object(sha1_buf);
 187                if (!o || !(o->flags & OUR_REF))
 188                        die("git-upload-pack: not our ref %s", line+5);
 189                if (!(o->flags & WANTED)) {
 190                        o->flags |= WANTED;
 191                        needs++;
 192                }
 193        }
 194}
 195
 196static int send_ref(const char *refname, const unsigned char *sha1)
 197{
 198        struct object *o = parse_object(sha1);
 199
 200        packet_write(1, "%s %s\n", sha1_to_hex(sha1), refname);
 201        if (!(o->flags & OUR_REF)) {
 202                o->flags |= OUR_REF;
 203                nr_our_refs++;
 204        }
 205        if (o->type == tag_type) {
 206                o = deref_tag(o);
 207                packet_write(1, "%s %s^{}\n", sha1_to_hex(o->sha1), refname);
 208        }
 209        return 0;
 210}
 211
 212static int upload_pack(void)
 213{
 214        reset_timeout();
 215        head_ref(send_ref);
 216        for_each_ref(send_ref);
 217        packet_flush(1);
 218        nr_needs = receive_needs();
 219        if (!nr_needs)
 220                return 0;
 221        get_common_commits();
 222        create_pack_file();
 223        return 0;
 224}
 225
 226int main(int argc, char **argv)
 227{
 228        const char *dir;
 229        int i;
 230        int strict = 0;
 231
 232        for (i = 1; i < argc; i++) {
 233                char *arg = argv[i];
 234
 235                if (arg[0] != '-')
 236                        break;
 237                if (!strcmp(arg, "--strict")) {
 238                        strict = 1;
 239                        continue;
 240                }
 241                if (!strncmp(arg, "--timeout=", 10)) {
 242                        timeout = atoi(arg+10);
 243                        continue;
 244                }
 245                if (!strcmp(arg, "--")) {
 246                        i++;
 247                        break;
 248                }
 249        }
 250        
 251        if (i != argc-1)
 252                usage(upload_pack_usage);
 253        dir = argv[i];
 254
 255        /* chdir to the directory. If that fails, try appending ".git" */
 256        if (chdir(dir) < 0) {
 257                if (strict || chdir(mkpath("%s.git", dir)) < 0)
 258                        die("git-upload-pack unable to chdir to %s", dir);
 259        }
 260        if (!strict)
 261                chdir(".git");
 262
 263        if (access("objects", X_OK) || access("refs", X_OK))
 264                die("git-upload-pack: %s doesn't seem to be a git archive", dir);
 265
 266        putenv("GIT_DIR=.");
 267        upload_pack();
 268        return 0;
 269}