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Refactor code that copies temp files into separate functions.

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This commit is contained in:
Todd C. Miller
2014-08-21 15:28:35 -06:00
parent ffbc003b7c
commit a147330f3f
1 changed files with 224 additions and 139 deletions
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365
src/sudo_edit.c
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@@ -53,6 +53,52 @@
#if defined(HAVE_SETRESUID) || defined(HAVE_SETREUID) || defined(HAVE_SETEUID) #if defined(HAVE_SETRESUID) || defined(HAVE_SETREUID) || defined(HAVE_SETEUID)
/*
* Editor temporary file name along with original name, mtime and size.
*/
struct tempfile {
char *tfile;
char *ofile;
struct timeval omtim;
off_t osize;
};
static char edit_tmpdir[MAX(sizeof(_PATH_VARTMP), sizeof(_PATH_TMP))];
/*
* Find our temporary directory, one of /var/tmp, /usr/tmp, or /tmp
* Returns true on success, else false;
*/
static bool
set_tmpdir(void)
{
const char *tdir;
struct stat sb;
size_t len;
debug_decl(set_tmpdir, SUDO_DEBUG_EDIT)
if (stat(_PATH_VARTMP, &sb) == 0 && S_ISDIR(sb.st_mode)) {
tdir = _PATH_VARTMP;
}
#ifdef _PATH_USRTMP
else if (stat(_PATH_USRTMP, &sb) == 0 && S_ISDIR(sb.st_mode)) {
tdir = _PATH_USRTMP;
}
#endif
else {
tdir = _PATH_TMP;
}
len = strlcpy(edit_tmpdir, tdir, sizeof(edit_tmpdir));
if (len >= sizeof(edit_tmpdir)) {
errno = ENAMETOOLONG;
sudo_warn("%s", tdir);
debug_return_bool(false);
}
while (len > 0 && edit_tmpdir[--len] == '/')
edit_tmpdir[len] = '\0';
debug_return_bool(true);
}
static void static void
switch_user(uid_t euid, gid_t egid, int ngroups, GETGROUPS_T *groups) switch_user(uid_t euid, gid_t egid, int ngroups, GETGROUPS_T *groups)
{ {
@@ -80,75 +126,51 @@ switch_user(uid_t euid, gid_t egid, int ngroups, GETGROUPS_T *groups)
} }
/* /*
* Wrapper to allow users to edit privileged files with their own uid. * Construct a temporary file name for file and return an
* open file descriptor. The temporary file name is stored
* in tfile which the caller is responsible for freeing.
*/ */
int static int
sudo_edit(struct command_details *command_details) sudo_edit_mktemp(const char *ofile, char **tfile)
{ {
struct command_details saved_command_details; const char *cp, *suff;
ssize_t nread, nwritten; debug_decl(sudo_edit_mktemp, SUDO_DEBUG_EDIT)
const char *tmpdir;
char *cp, *suff, **nargv = NULL, **ap, **files = NULL; if ((cp = strrchr(ofile, '/')) != NULL)
cp++;
else
cp = ofile;
suff = strrchr(cp, '.');
if (suff != NULL) {
sudo_easprintf(tfile, "%s/%.*sXXXXXXXX%s", edit_tmpdir,
(int)(size_t)(suff - cp), cp, suff);
} else {
sudo_easprintf(tfile, "%s/%s.XXXXXXXX", edit_tmpdir, cp);
}
debug_return_int(mkstemps(*tfile, suff ? strlen(suff) : 0));
}
/*
* Create temporary copies of files[] and store the temporary path name
* along with the original name, size and mtime in tf.
* Returns the number of files copied (which may be less than nfiles)
* or -1 if a fatal error occurred.
*/
static int
sudo_edit_create_tfiles(struct command_details *command_details,
struct tempfile *tf, char * const files[], int nfiles)
{
int i, j, tfd, ofd, rc;
char buf[BUFSIZ]; char buf[BUFSIZ];
int rc, i, j, ac, ofd, tfd, nargc, rval, tmplen; ssize_t nwritten, nread;
int editor_argc = 0, nfiles = 0; struct timeval times[2];
struct stat sb; struct stat sb;
struct timeval tv, times[2]; debug_decl(sudo_edit_create_tfiles, SUDO_DEBUG_EDIT)
struct tempfile {
char *tfile;
char *ofile;
struct timeval omtim;
off_t osize;
} *tf = NULL;
debug_decl(sudo_edit, SUDO_DEBUG_EDIT)
/*
* Set real, effective and saved uids to root.
* We will change the euid as needed below.
*/
if (setuid(ROOT_UID) != 0) {
sudo_warn(U_("unable to change uid to root (%u)"), ROOT_UID);
goto cleanup;
}
/*
* Find our temporary directory, one of /var/tmp, /usr/tmp, or /tmp
*/
if (stat(_PATH_VARTMP, &sb) == 0 && S_ISDIR(sb.st_mode))
tmpdir = _PATH_VARTMP;
#ifdef _PATH_USRTMP
else if (stat(_PATH_USRTMP, &sb) == 0 && S_ISDIR(sb.st_mode))
tmpdir = _PATH_USRTMP;
#endif
else
tmpdir = _PATH_TMP;
tmplen = strlen(tmpdir);
while (tmplen > 0 && tmpdir[tmplen - 1] == '/')
tmplen--;
/*
* The user's editor must be separated from the files to be
* edited by a "--" option.
*/
for (ap = command_details->argv; *ap != NULL; ap++) {
if (files)
nfiles++;
else if (strcmp(*ap, "--") == 0)
files = ap + 1;
else
editor_argc++;
}
if (nfiles == 0) {
sudo_warnx(U_("plugin error: missing file list for sudoedit"));
goto cleanup;
}
/* /*
* For each file specified by the user, make a temporary version * For each file specified by the user, make a temporary version
* and copy the contents of the original to it. * and copy the contents of the original to it.
*/ */
tf = sudo_emallocarray(nfiles, sizeof(*tf));
memset(tf, 0, nfiles * sizeof(*tf));
for (i = 0, j = 0; i < nfiles; i++) { for (i = 0, j = 0; i < nfiles; i++) {
rc = -1; rc = -1;
switch_user(command_details->euid, command_details->egid, switch_user(command_details->euid, command_details->egid,
@@ -175,25 +197,14 @@ sudo_edit(struct command_details *command_details)
tf[j].ofile = files[i]; tf[j].ofile = files[i];
tf[j].osize = sb.st_size; tf[j].osize = sb.st_size;
mtim_get(&sb, &tf[j].omtim); mtim_get(&sb, &tf[j].omtim);
if ((cp = strrchr(tf[j].ofile, '/')) != NULL)
cp++;
else
cp = tf[j].ofile;
suff = strrchr(cp, '.');
if (suff != NULL) {
sudo_easprintf(&tf[j].tfile, "%.*s/%.*sXXXXXXXX%s", tmplen, tmpdir,
(int)(size_t)(suff - cp), cp, suff);
} else {
sudo_easprintf(&tf[j].tfile, "%.*s/%s.XXXXXXXX", tmplen, tmpdir, cp);
}
if (seteuid(user_details.uid) != 0) if (seteuid(user_details.uid) != 0)
sudo_fatal("seteuid(%d)", (int)user_details.uid); sudo_fatal("seteuid(%d)", (int)user_details.uid);
tfd = mkstemps(tf[j].tfile, suff ? strlen(suff) : 0); tfd = sudo_edit_mktemp(tf[j].ofile, &tf[j].tfile);
if (seteuid(ROOT_UID) != 0) if (seteuid(ROOT_UID) != 0)
sudo_fatal("seteuid(ROOT_UID)"); sudo_fatal("seteuid(ROOT_UID)");
if (tfd == -1) { if (tfd == -1) {
sudo_warn("mkstemps"); sudo_warn("mkstemps");
goto cleanup; debug_return_int(-1);
} }
if (ofd != -1) { if (ofd != -1) {
while ((nread = read(ofd, buf, sizeof(buf))) != 0) { while ((nread = read(ofd, buf, sizeof(buf))) != 0) {
@@ -202,7 +213,7 @@ sudo_edit(struct command_details *command_details)
sudo_warn("%s", tf[j].tfile); sudo_warn("%s", tf[j].tfile);
else else
sudo_warnx(U_("%s: short write"), tf[j].tfile); sudo_warnx(U_("%s: short write"), tf[j].tfile);
goto cleanup; debug_return_int(-1);
} }
} }
close(ofd); close(ofd);
@@ -227,8 +238,143 @@ sudo_edit(struct command_details *command_details)
close(tfd); close(tfd);
j++; j++;
} }
if ((nfiles = j) == 0) debug_return_int(j);
goto cleanup; /* no files readable, you lose */ }
/*
* Copy the temporary files specified in tf to the originals.
* Returns the number of copy errors or 0 if completely successful.
*/
static int
sudo_edit_copy_tfiles(struct command_details *command_details,
struct tempfile *tf, int nfiles, struct timeval *times)
{
int i, tfd, ofd, rc, errors = 0;
char buf[BUFSIZ];
ssize_t nwritten, nread;
struct timeval tv;
struct stat sb;
debug_decl(sudo_edit_copy_tfiles, SUDO_DEBUG_EDIT)
/* Copy contents of temp files to real ones. */
for (i = 0; i < nfiles; i++) {
rc = -1;
if (seteuid(user_details.uid) != 0)
sudo_fatal("seteuid(%d)", (int)user_details.uid);
if ((tfd = open(tf[i].tfile, O_RDONLY, 0644)) != -1) {
rc = fstat(tfd, &sb);
}
if (seteuid(ROOT_UID) != 0)
sudo_fatal("seteuid(ROOT_UID)");
if (rc || !S_ISREG(sb.st_mode)) {
if (rc)
sudo_warn("%s", tf[i].tfile);
else
sudo_warnx(U_("%s: not a regular file"), tf[i].tfile);
sudo_warnx(U_("%s left unmodified"), tf[i].ofile);
if (tfd != -1)
close(tfd);
errors++;
continue;
}
mtim_get(&sb, &tv);
if (tf[i].osize == sb.st_size && sudo_timevalcmp(&tf[i].omtim, &tv, ==)) {
/*
* If mtime and size match but the user spent no measurable
* time in the editor we can't tell if the file was changed.
*/
if (sudo_timevalcmp(&times[0], &times[1], !=)) {
sudo_warnx(U_("%s unchanged"), tf[i].ofile);
unlink(tf[i].tfile);
close(tfd);
errors++;
continue;
}
}
switch_user(command_details->euid, command_details->egid,
command_details->ngroups, command_details->groups);
ofd = open(tf[i].ofile, O_WRONLY|O_TRUNC|O_CREAT, 0644);
switch_user(ROOT_UID, user_details.egid,
user_details.ngroups, user_details.groups);
if (ofd == -1) {
sudo_warn(U_("unable to write to %s"), tf[i].ofile);
sudo_warnx(U_("contents of edit session left in %s"), tf[i].tfile);
close(tfd);
errors++;
continue;
}
while ((nread = read(tfd, buf, sizeof(buf))) > 0) {
if ((nwritten = write(ofd, buf, nread)) != nread) {
if (nwritten == -1)
sudo_warn("%s", tf[i].ofile);
else
sudo_warnx(U_("%s: short write"), tf[i].ofile);
break;
}
}
if (nread == 0) {
/* success, got EOF */
unlink(tf[i].tfile);
} else if (nread < 0) {
sudo_warn(U_("unable to read temporary file"));
sudo_warnx(U_("contents of edit session left in %s"), tf[i].tfile);
} else {
sudo_warn(U_("unable to write to %s"), tf[i].ofile);
sudo_warnx(U_("contents of edit session left in %s"), tf[i].tfile);
}
close(ofd);
}
debug_return_int(errors);
}
/*
* Wrapper to allow users to edit privileged files with their own uid.
*/
int
sudo_edit(struct command_details *command_details)
{
struct command_details saved_command_details;
char **nargv = NULL, **ap, **files = NULL;
int i, ac, nargc, rval;
int editor_argc = 0, nfiles = 0;
struct timeval times[2];
struct tempfile *tf = NULL;
debug_decl(sudo_edit, SUDO_DEBUG_EDIT)
if (!set_tmpdir())
goto cleanup;
/*
* Set real, effective and saved uids to root.
* We will change the euid as needed below.
*/
if (setuid(ROOT_UID) != 0) {
sudo_warn(U_("unable to change uid to root (%u)"), ROOT_UID);
goto cleanup;
}
/*
* The user's editor must be separated from the files to be
* edited by a "--" option.
*/
for (ap = command_details->argv; *ap != NULL; ap++) {
if (files)
nfiles++;
else if (strcmp(*ap, "--") == 0)
files = ap + 1;
else
editor_argc++;
}
if (nfiles == 0) {
sudo_warnx(U_("plugin error: missing file list for sudoedit"));
goto cleanup;
}
/* Copy editor files to temporaries. */
tf = sudo_ecalloc(nfiles, sizeof(*tf));
nfiles = sudo_edit_create_tfiles(command_details, tf, files, nfiles);
if (nfiles <= 0)
goto cleanup;
/* /*
* Allocate space for the new argument vector and fill it in. * Allocate space for the new argument vector and fill it in.
@@ -269,70 +415,9 @@ sudo_edit(struct command_details *command_details)
command_details->argv = saved_command_details.argv; command_details->argv = saved_command_details.argv;
/* Copy contents of temp files to real ones. */ /* Copy contents of temp files to real ones. */
for (i = 0; i < nfiles; i++) { if (sudo_edit_copy_tfiles(command_details, tf, nfiles, times) != 0)
rc = -1; rval = 1;
if (seteuid(user_details.uid) != 0)
sudo_fatal("seteuid(%d)", (int)user_details.uid);
if ((tfd = open(tf[i].tfile, O_RDONLY, 0644)) != -1) {
rc = fstat(tfd, &sb);
}
if (seteuid(ROOT_UID) != 0)
sudo_fatal("seteuid(ROOT_UID)");
if (rc || !S_ISREG(sb.st_mode)) {
if (rc)
sudo_warn("%s", tf[i].tfile);
else
sudo_warnx(U_("%s: not a regular file"), tf[i].tfile);
sudo_warnx(U_("%s left unmodified"), tf[i].ofile);
if (tfd != -1)
close(tfd);
continue;
}
mtim_get(&sb, &tv);
if (tf[i].osize == sb.st_size && sudo_timevalcmp(&tf[i].omtim, &tv, ==)) {
/*
* If mtime and size match but the user spent no measurable
* time in the editor we can't tell if the file was changed.
*/
if (sudo_timevalcmp(&times[0], &times[1], !=)) {
sudo_warnx(U_("%s unchanged"), tf[i].ofile);
unlink(tf[i].tfile);
close(tfd);
continue;
}
}
switch_user(command_details->euid, command_details->egid,
command_details->ngroups, command_details->groups);
ofd = open(tf[i].ofile, O_WRONLY|O_TRUNC|O_CREAT, 0644);
switch_user(ROOT_UID, user_details.egid,
user_details.ngroups, user_details.groups);
if (ofd == -1) {
sudo_warn(U_("unable to write to %s"), tf[i].ofile);
sudo_warnx(U_("contents of edit session left in %s"), tf[i].tfile);
close(tfd);
continue;
}
while ((nread = read(tfd, buf, sizeof(buf))) > 0) {
if ((nwritten = write(ofd, buf, nread)) != nread) {
if (nwritten == -1)
sudo_warn("%s", tf[i].ofile);
else
sudo_warnx(U_("%s: short write"), tf[i].ofile);
break;
}
}
if (nread == 0) {
/* success, got EOF */
unlink(tf[i].tfile);
} else if (nread < 0) {
sudo_warn(U_("unable to read temporary file"));
sudo_warnx(U_("contents of edit session left in %s"), tf[i].tfile);
} else {
sudo_warn(U_("unable to write to %s"), tf[i].ofile);
sudo_warnx(U_("contents of edit session left in %s"), tf[i].tfile);
}
close(ofd);
}
sudo_efree(tf); sudo_efree(tf);
sudo_efree(nargv); sudo_efree(nargv);
debug_return_int(rval); debug_return_int(rval);