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-rw-r--r--client/mount.cifs.c202
1 files changed, 162 insertions, 40 deletions
diff --git a/client/mount.cifs.c b/client/mount.cifs.c
index 1b94486a1a..f53bcf1607 100644
--- a/client/mount.cifs.c
+++ b/client/mount.cifs.c
@@ -39,10 +39,11 @@
#include <mntent.h>
#include <fcntl.h>
#include <limits.h>
+#include <fstab.h>
#include "mount.h"
#define MOUNT_CIFS_VERSION_MAJOR "1"
-#define MOUNT_CIFS_VERSION_MINOR "12"
+#define MOUNT_CIFS_VERSION_MINOR "13"
#ifndef MOUNT_CIFS_VENDOR_SUFFIX
#ifdef _SAMBA_BUILD_
@@ -69,6 +70,10 @@
#define MS_BIND 4096
#endif
+/* private flags - clear these before passing to kernel */
+#define MS_USERS 0x40000000
+#define MS_USER 0x80000000
+
#define MAX_UNC_LEN 1024
#define CONST_DISCARD(type, ptr) ((type) ((void *) (ptr)))
@@ -83,6 +88,27 @@
/* currently maximum length of IPv6 address string */
#define MAX_ADDRESS_LEN INET6_ADDRSTRLEN
+/*
+ * By default, mount.cifs follows the conventions set forth by /bin/mount
+ * for user mounts. That is, it requires that the mount be listed in
+ * /etc/fstab with the "user" option when run as an unprivileged user and
+ * mount.cifs is setuid root.
+ *
+ * Older versions of mount.cifs however were "looser" in this regard. When
+ * made setuid root, a user could run mount.cifs directly and mount any share
+ * on a directory owned by that user.
+ *
+ * The legacy behavior is now disabled by default. To reenable it, set the
+ * following #define to true.
+ */
+#define CIFS_LEGACY_SETUID_CHECK 0
+
+/*
+ * When an unprivileged user runs a setuid mount.cifs, we set certain mount
+ * flags by default. These defaults can be changed here.
+ */
+#define CIFS_SETUID_FLAGS (MS_NOSUID|MS_NODEV)
+
const char *thisprogram;
int verboseflag = 0;
int fakemnt = 0;
@@ -142,6 +168,99 @@ static size_t strlcat(char *d, const char *s, size_t bufsize)
}
#endif
+/*
+ * If an unprivileged user is doing the mounting then we need to ensure
+ * that the entry is in /etc/fstab.
+ */
+static int
+check_mountpoint(const char *progname, char *mountpoint)
+{
+ int err;
+ struct stat statbuf;
+
+ /* does mountpoint exist and is it a directory? */
+ err = stat(mountpoint, &statbuf);
+ if (err) {
+ fprintf(stderr, "%s: failed to stat %s: %s\n", progname,
+ mountpoint, strerror(errno));
+ return EX_USAGE;
+ }
+
+ if (!S_ISDIR(statbuf.st_mode)) {
+ fprintf(stderr, "%s: %s is not a directory!", progname,
+ mountpoint);
+ return EX_USAGE;
+ }
+
+#if CIFS_LEGACY_SETUID_CHECK
+ /* do extra checks on mountpoint for legacy setuid behavior */
+ if (!getuid() || geteuid())
+ return 0;
+
+ if (statbuf.st_uid != getuid()) {
+ fprintf(stderr, "%s: %s is not owned by user\n", progname,
+ mountpoint);
+ return EX_USAGE;
+ }
+
+ if ((statbuf.st_mode & S_IRWXU) != S_IRWXU) {
+ fprintf(stderr, "%s: invalid permissions on %s\n", progname,
+ mountpoint);
+ return EX_USAGE;
+ }
+#endif /* CIFS_LEGACY_SETUID_CHECK */
+
+ return 0;
+}
+
+#if CIFS_LEGACY_SETUID_CHECK
+static int
+check_fstab(const char *progname, char *mountpoint, char *devname,
+ char **options)
+{
+ return 0;
+}
+#else /* CIFS_LEGACY_SETUID_CHECK */
+static int
+check_fstab(const char *progname, char *mountpoint, char *devname,
+ char **options)
+{
+ FILE *fstab;
+ struct mntent *mnt;
+
+ /* make sure this mount is listed in /etc/fstab */
+ fstab = setmntent(_PATH_FSTAB, "r");
+ if (!fstab) {
+ fprintf(stderr, "Couldn't open %s for reading!\n",
+ _PATH_FSTAB);
+ return EX_FILEIO;
+ }
+
+ while((mnt = getmntent(fstab))) {
+ if (!strcmp(mountpoint, mnt->mnt_dir))
+ break;
+ }
+ endmntent(fstab);
+
+ if (mnt == NULL || strcmp(mnt->mnt_fsname, devname)) {
+ fprintf(stderr, "%s: permission denied: no match for "
+ "%s found in %s\n", progname, mountpoint,
+ _PATH_FSTAB);
+ return EX_USAGE;
+ }
+
+ /*
+ * 'mount' munges the options from fstab before passing them
+ * to us. It is non-trivial to test that we have the correct
+ * set of options. We don't want to trust what the user
+ * gave us, so just take whatever is in /etc/fstab.
+ */
+ free(*options);
+ *options = strdup(mnt->mnt_opts);
+ return 0;
+}
+#endif /* CIFS_LEGACY_SETUID_CHECK */
+
/* BB finish BB
cifs_umount
@@ -362,7 +481,7 @@ static int get_password_from_file(int file_descript, char * filename)
return rc;
}
-static int parse_options(char ** optionsp, int * filesys_flags)
+static int parse_options(char ** optionsp, unsigned long * filesys_flags)
{
const char * data;
char * percent_char = NULL;
@@ -415,6 +534,7 @@ static int parse_options(char ** optionsp, int * filesys_flags)
if (strncmp(data, "users",5) == 0) {
if(!value || !*value) {
+ *filesys_flags |= MS_USERS;
goto nocopy;
}
} else if (strncmp(data, "user_xattr",10) == 0) {
@@ -423,10 +543,7 @@ static int parse_options(char ** optionsp, int * filesys_flags)
if (!value || !*value) {
if(data[4] == '\0') {
- if(verboseflag)
- printf("\nskipping empty user mount parameter\n");
- /* remove the parm since it would otherwise be confusing
- to the kernel code which would think it was a real username */
+ *filesys_flags |= MS_USER;
goto nocopy;
} else {
printf("username specified with no parameter\n");
@@ -1029,7 +1146,7 @@ static void print_cifs_mount_version(void)
int main(int argc, char ** argv)
{
int c;
- int flags = MS_MANDLOCK; /* no need to set legacy MS_MGC_VAL */
+ unsigned long flags = MS_MANDLOCK;
char * orgoptions = NULL;
char * share_name = NULL;
const char * ipaddr = NULL;
@@ -1052,7 +1169,6 @@ int main(int argc, char ** argv)
size_t current_len;
int retry = 0; /* set when we have to retry mount with uppercase */
struct addrinfo *addrhead = NULL, *addr;
- struct stat statbuf;
struct utsname sysinfo;
struct mntent mountent;
struct sockaddr_in *addr4;
@@ -1110,8 +1226,8 @@ int main(int argc, char ** argv)
exit(EX_USAGE);
}
- /* add sharename in opts string as unc= parm */
+ /* add sharename in opts string as unc= parm */
while ((c = getopt_long (argc, argv, "afFhilL:no:O:rsSU:vVwt:",
longopts, NULL)) != -1) {
switch (c) {
@@ -1249,6 +1365,22 @@ int main(int argc, char ** argv)
exit(EX_USAGE);
}
+ /* make sure mountpoint is legit */
+ rc = check_mountpoint(thisprogram, mountpoint);
+ if (rc)
+ goto mount_exit;
+
+ /* sanity check for unprivileged mounts */
+ if (getuid()) {
+ rc = check_fstab(thisprogram, mountpoint, dev_name,
+ &orgoptions);
+ if (rc)
+ goto mount_exit;
+
+ /* enable any default user mount flags */
+ flags |= CIFS_SETUID_FLAGS;
+ }
+
if (getenv("PASSWD")) {
if(mountpassword == NULL)
mountpassword = (char *)calloc(MOUNT_PASSWD_SIZE+1,1);
@@ -1266,6 +1398,27 @@ int main(int argc, char ** argv)
rc = EX_USAGE;
goto mount_exit;
}
+
+ if (getuid()) {
+#if !CIFS_LEGACY_SETUID_CHECK
+ if (!(flags & (MS_USERS|MS_USER))) {
+ fprintf(stderr, "%s: permission denied\n", thisprogram);
+ rc = EX_USAGE;
+ goto mount_exit;
+ }
+#endif /* !CIFS_LEGACY_SETUID_CHECK */
+
+ if (geteuid()) {
+ fprintf(stderr, "%s: not installed setuid - \"user\" "
+ "CIFS mounts not supported.",
+ thisprogram);
+ rc = EX_FAIL;
+ goto mount_exit;
+ }
+ }
+
+ flags &= ~(MS_USERS|MS_USER);
+
addrhead = addr = parse_server(&share_name);
if((addrhead == NULL) && (got_ip == 0)) {
printf("No ip address specified and hostname not found\n");
@@ -1282,37 +1435,6 @@ int main(int argc, char ** argv)
mountpoint = resolved_path;
}
}
- if(chdir(mountpoint)) {
- printf("mount error: can not change directory into mount target %s\n",mountpoint);
- rc = EX_USAGE;
- goto mount_exit;
- }
-
- if(stat (".", &statbuf)) {
- printf("mount error: mount point %s does not exist\n",mountpoint);
- rc = EX_USAGE;
- goto mount_exit;
- }
-
- if (S_ISDIR(statbuf.st_mode) == 0) {
- printf("mount error: mount point %s is not a directory\n",mountpoint);
- rc = EX_USAGE;
- goto mount_exit;
- }
-
- if((getuid() != 0) && (geteuid() == 0)) {
- if((statbuf.st_uid == getuid()) && (S_IRWXU == (statbuf.st_mode & S_IRWXU))) {
-#ifndef CIFS_ALLOW_USR_SUID
- /* Do not allow user mounts to control suid flag
- for mount unless explicitly built that way */
- flags |= MS_NOSUID | MS_NODEV;
-#endif
- } else {
- printf("mount error: permission denied or not superuser and mount.cifs not installed SUID\n");
- exit(EX_USAGE);
- }
- }
-
if(got_user == 0) {
/* Note that the password will not be retrieved from the
USER env variable (ie user%password form) as there is
generated by cgit (git 2.34.1) at 2024-11-25 23:47:46 +0000