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mount: sanitize paths from non-root users 

$ mount /root/.ssh/../../dev/sda2
 mount: only root can mount UUID=17bc65ec-4125-4e7c-8a7d-e2795064c736 on /boot

this is too promiscuous. It seems better to ignore on command line
specified paths which are not resolve-able for non-root users.

Fixed version:

  $ mount /root/.ssh/../../dev/sda2
  mount: /root/.ssh/../../dev/sda2: Permission denied

  $ mount /dev/sda2
  mount: only root can mount UUID=17bc65ec-4125-4e7c-8a7d-e2795064c736 on /boot

Note that this bug has no relation to mount(2) permissions evaluation
in suid mode. The way how non-root user specifies paths on command
line is completely irrelevant for comparison with fstab entries.

Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2012-11-26 14:30:22 +01:00
parent 33c5fd0c5a
commit 5ebbc3865d
1 changed files with 35 additions and 0 deletions
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35
sys-utils/mount.c
View File

@ -39,6 +39,7 @@
#include "exitcodes.h"
#include "xalloc.h"
#include "closestream.h"
#include "canonicalize.h"
#define OPTUTILS_EXIT_CODE MOUNT_EX_USAGE
#include "optutils.h"
@ -603,6 +604,37 @@ static struct libmnt_table *append_fstab(struct libmnt_context *cxt,
return fstab;
}
/*
* Check source and target paths -- non-root user should not be able to
* resolve paths which are unreadable for him.
*/
static void sanitize_paths(struct libmnt_context *cxt)
{
const char *p;
struct libmnt_fs *fs = mnt_context_get_fs(cxt);
if (!fs)
return;
p = mnt_fs_get_target(fs);
if (p) {
char *np = canonicalize_path_restricted(p);
if (!np)
err(MOUNT_EX_USAGE, "%s", p);
mnt_fs_set_target(fs, np);
free(np);
}
p = mnt_fs_get_srcpath(fs);
if (p) {
char *np = canonicalize_path_restricted(p);
if (!np)
err(MOUNT_EX_USAGE, "%s", p);
mnt_fs_set_source(fs, np);
free(np);
}
}
static void __attribute__((__noreturn__)) usage(FILE *out)
{
fputs(USAGE_HEADER, out);
@ -970,6 +1002,9 @@ int main(int argc, char **argv)
} else
usage(stderr);
if (mnt_context_is_restricted(cxt))
sanitize_paths(cxt);
if (oper) {
/* MS_PROPAGATION operations, let's set the mount flags */
mnt_context_set_mflags(cxt, oper);