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Refactor the sudoedit code to copy files so it can be shared.

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The SELinux sudoedit code now extends the destination file the
same way the non-SELinux version does.
This commit is contained in:
Todd C. Miller
2020-04-21 11:05:32 -06:00
parent 0bd39701b4
commit 009876bf36
6 changed files with 193 additions and 119 deletions
Download Patch File Download Diff File Expand all files Collapse all files

116
src/sudo_edit.c
View File

@@ -42,7 +42,6 @@
#include <grp.h>
#include <pwd.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include "sudo.h"
@@ -532,8 +531,6 @@ sudo_edit_create_tfiles(struct command_details *command_details,
struct tempfile *tf, char *files[], int nfiles)
{
int i, j, tfd, ofd, rc;
char buf[BUFSIZ];
ssize_t nwritten, nread;
struct timespec times[2];
struct stat sb;
debug_decl(sudo_edit_create_tfiles, SUDO_DEBUG_EDIT);
@@ -610,18 +607,7 @@ sudo_edit_create_tfiles(struct command_details *command_details,
debug_return_int(-1);
}
if (ofd != -1) {
while ((nread = read(ofd, buf, sizeof(buf))) > 0) {
if ((nwritten = write(tfd, buf, nread)) != nread) {
if (nwritten == -1)
sudo_warn("%s", tf[j].tfile);
else
sudo_warnx(U_("%s: short write"), tf[j].tfile);
break;
}
}
if (nread != 0) {
if (nread < 0)
sudo_warn("%s", files[i]);
if (sudo_copy_file(tf[j].ofile, ofd, tf[j].osize, tf[j].tfile, tfd, -1) == -1) {
close(ofd);
close(tfd);
debug_return_int(-1);
@@ -650,51 +636,6 @@ sudo_edit_create_tfiles(struct command_details *command_details,
debug_return_int(j);
}
/*
* Extend the given fd to the specified size in bytes.
* We do this to allocate disk space up-front before overwriting
* the original file with the temporary. Otherwise, we could
* we run out of disk space after truncating the original file.
*/
static int
sudo_edit_extend_file(int fd, off_t new_size)
{
off_t old_size, size;
ssize_t nwritten;
char zeroes[1024] = { '\0' };
debug_decl(sudo_edit_extend_file, SUDO_DEBUG_EDIT);
if ((old_size = lseek(fd, 0, SEEK_END)) == -1) {
sudo_warn("lseek");
debug_return_int(-1);
}
sudo_debug_printf(SUDO_DEBUG_INFO, "%s: extending file from %lld to %lld",
__func__, (long long)old_size, (long long)new_size);
for (size = old_size; size < new_size; size += nwritten) {
size_t len = new_size - size;
if (len > sizeof(zeroes))
len = sizeof(zeroes);
nwritten = write(fd, zeroes, len);
if (nwritten == -1) {
int serrno = errno;
if (ftruncate(fd, old_size) == -1) {
sudo_debug_printf(
SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO|SUDO_DEBUG_ERRNO,
"unable to truncate to %lld", (long long)old_size);
}
errno = serrno;
debug_return_int(-1);
}
}
if (lseek(fd, 0, SEEK_SET) == -1) {
sudo_warn("lseek");
debug_return_int(-1);
}
debug_return_int(0);
}
/*
* Copy the temporary files specified in tf to the originals.
* Returns the number of copy errors or 0 if completely successful.
@@ -703,9 +644,7 @@ static int
sudo_edit_copy_tfiles(struct command_details *command_details,
struct tempfile *tf, int nfiles, struct timespec *times)
{
int i, tfd, ofd, rc, errors = 0;
char buf[BUFSIZ];
ssize_t nwritten, nread;
int i, tfd, ofd, errors = 0;
struct timespec ts;
struct stat sb;
mode_t oldmask;
@@ -713,7 +652,7 @@ sudo_edit_copy_tfiles(struct command_details *command_details,
/* Copy contents of temp files to real ones. */
for (i = 0; i < nfiles; i++) {
rc = -1;
int rc = -1;
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"seteuid(%u)", (unsigned int)user_details.uid);
if (seteuid(user_details.uid) != 0)
@@ -726,8 +665,8 @@ sudo_edit_copy_tfiles(struct command_details *command_details,
"seteuid(%u)", ROOT_UID);
if (seteuid(ROOT_UID) != 0)
sudo_fatal("seteuid(ROOT_UID)");
if (rc || !S_ISREG(sb.st_mode)) {
if (rc)
if (rc == -1 || !S_ISREG(sb.st_mode)) {
if (rc == -1)
sudo_warn("%s", tf[i].tfile);
else
sudo_warnx(U_("%s: not a regular file"), tf[i].tfile);
@@ -758,46 +697,19 @@ sudo_edit_copy_tfiles(struct command_details *command_details,
umask(oldmask);
switch_user(ROOT_UID, user_details.egid,
user_details.ngroups, user_details.groups);
if (ofd == -1)
goto write_error;
/* Extend the file to the new size if larger before copying. */
if (tf[i].osize > 0 && sb.st_size > tf[i].osize) {
if (sudo_edit_extend_file(ofd, sb.st_size) == -1)
goto write_error;
}
/* Overwrite the old file with the new contents. */
while ((nread = read(tfd, buf, sizeof(buf))) > 0) {
ssize_t off = 0;
do {
nwritten = write(ofd, buf + off, nread - off);
if (nwritten == -1)
goto write_error;
off += nwritten;
} while (nread > off);
}
if (nread == 0) {
/* success, read to EOF */
if (tf[i].osize > 0 && sb.st_size < tf[i].osize) {
/* We don't open with O_TRUNC so must truncate manually. */
if (ftruncate(ofd, sb.st_size) == -1) {
sudo_debug_printf(
SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO|SUDO_DEBUG_ERRNO,
"unable to truncate %s to %lld", tf[i].ofile,
(long long)sb.st_size);
goto write_error;
}
}
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);
errors++;
} else {
write_error:
if (ofd == -1) {
sudo_warn(U_("unable to write to %s"), tf[i].ofile);
goto bad;
}
/* Overwrite the old file with the new contents. */
if (sudo_copy_file(tf[i].tfile, tfd, sb.st_size, tf[i].ofile, ofd,
tf[i].osize) == -1) {
bad:
sudo_warnx(U_("contents of edit session left in %s"), tf[i].tfile);
errors++;
}
if (ofd != -1)
close(ofd);
close(tfd);