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tftpd: Verify world-writability for WRQ when using relative paths

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tftpd(8) says that files may only be written if they already exist and are
publicly writable.  tftpd.c verifies that a file is publicly writable if it
uses an absolute pathname.  However, if the pathname is relative, that check
is skipped.  Fix it.

Note that this is not a security vulnerability, because the transfer
ultimately doesn't work unless the file already exists and is owned by user
nobody.  Also, this bug does not affect the default configuration, because
the default uses the "-s" option which makes all pathnames absolute.

PR:		226004
MFC after:	3 weeks
This commit is contained in:
asomers 2018-03-10 01:35:26 +00:00
parent 9ab6695f02
commit 26f5519e21
2 changed files with 17 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
libexec/tftpd/tests/functional.c
View File

@ -350,6 +350,10 @@ setup(struct sockaddr_storage *to, uint16_t idx)
ATF_REQUIRE((client_s = socket(protocol, SOCK_DGRAM, 0)) > 0);
break;
}
/* Clear the client's umask. Test cases will specify exact modes */
umask(0000);
return (client_s);
}
@ -714,7 +718,7 @@ TFTPD_TC_DEFINE(wrq_dropped_ack,)
for (i = 0; i < nitems(contents); i++)
contents[i] = i;
fd = open("medium.txt", O_RDWR | O_CREAT, 0644);
fd = open("medium.txt", O_RDWR | O_CREAT, 0666);
ATF_REQUIRE(fd >= 0);
close(fd);
@ -747,7 +751,7 @@ TFTPD_TC_DEFINE(wrq_dropped_data,)
size_t contents_len;
char buffer[1024];
fd = open("small.txt", O_RDWR | O_CREAT, 0644);
fd = open("small.txt", O_RDWR | O_CREAT, 0666);
ATF_REQUIRE(fd >= 0);
close(fd);
contents_len = strlen(contents) + 1;
@ -782,7 +786,7 @@ TFTPD_TC_DEFINE(wrq_duped_data,)
for (i = 0; i < nitems(contents); i++)
contents[i] = i;
fd = open("medium.txt", O_RDWR | O_CREAT, 0644);
fd = open("medium.txt", O_RDWR | O_CREAT, 0666);
ATF_REQUIRE(fd >= 0);
close(fd);
@ -831,7 +835,8 @@ TFTPD_TC_DEFINE(wrq_eaccess_world_readable,)
close(fd);
SEND_WRQ("empty.txt", "octet");
atf_tc_expect_fail("PR 226004 with relative pathnames, tftpd doesn't validate world writability");
atf_tc_expect_fail("PR 225996 tftpd doesn't abort on a WRQ access "
"violation");
RECV_ERROR(2, "Access violation");
}

8
libexec/tftpd/tftpd.c
View File

@ -743,7 +743,11 @@ validate_access(int peer, char **filep, int mode)
dirp->name, filename);
if (stat(pathname, &stbuf) == 0 &&
(stbuf.st_mode & S_IFMT) == S_IFREG) {
if ((stbuf.st_mode & S_IROTH) != 0) {
if (mode == RRQ) {
if ((stbuf.st_mode & S_IROTH) != 0)
break;
} else {
if ((stbuf.st_mode & S_IWOTH) != 0)
break;
}
err = EACCESS;
@ -753,6 +757,8 @@ validate_access(int peer, char **filep, int mode)
*filep = filename = pathname;
else if (mode == RRQ)
return (err);
else if (err != ENOTFOUND || !create_new)
return (err);
}
/*