From ae5ec51e0ddc99dc5552e51bd5c095084dbb61aa Mon Sep 17 00:00:00 2001 From: Neil Brown Date: Fri, 16 Mar 2007 18:07:41 +1100 Subject: [PATCH] Correctly handle "user" and "users" mount options. If "user" or "users" is given, then allow mount.nfs to be run by a non-root user providing that the mountpoint, filesystem, and options exactly match what is found in fstab. For "user", record the user name in mtab so they can unmount the filesystem later. Also alwasys ignore auto, owner, group and their negations as well as "_netdev", "comment" and "loop". --- support/include/fstab.h | 7 +++++ support/nfs/fstab.c | 58 +++++++++++++++++++++++++++++++++++++ utils/mount/mount.c | 63 +++++++++++++++++++++++++++++++++++++---- 3 files changed, 122 insertions(+), 6 deletions(-) diff --git a/support/include/fstab.h b/support/include/fstab.h index 8053066..ab30c5a 100644 --- a/support/include/fstab.h +++ b/support/include/fstab.h @@ -3,6 +3,10 @@ #include "nfs_mntent.h" +#ifndef _PATH_FSTAB +#define _PATH_FSTAB "/etc/fstab" +#endif + int mtab_is_writable(void); int mtab_does_not_exist(void); @@ -15,6 +19,9 @@ struct mntentchn *getmntoptfile (const char *file); struct mntentchn *getmntdirbackward (const char *dir, struct mntentchn *mc); struct mntentchn *getmntdevbackward (const char *dev, struct mntentchn *mc); +struct mntentchn *getfsfile (const char *file); +struct mntentchn *getfsspec (const char *spec); + void lock_mtab (void); void unlock_mtab (void); void update_mtab (const char *special, nfs_mntent_t *with); diff --git a/support/nfs/fstab.c b/support/nfs/fstab.c index 23ea927..ba7e580 100644 --- a/support/nfs/fstab.c +++ b/support/nfs/fstab.c @@ -80,8 +80,11 @@ mtab_is_writable() { struct mntentchn mounttable; static int got_mtab = 0; +struct mntentchn fstab; +static int got_fstab = 0; static void read_mounttable(void); +static void read_fstab(void); static struct mntentchn * mtab_head() { @@ -90,6 +93,14 @@ mtab_head() { return &mounttable; } +static struct mntentchn * +fstab_head() +{ + if (!got_fstab) + read_fstab(); + return &fstab; +} + static void my_free(const void *s) { if (s) @@ -167,6 +178,27 @@ read_mounttable() { read_mntentchn(mfp, fnam, mc); } +static void +read_fstab() +{ + mntFILE *mfp = NULL; + const char *fnam; + struct mntentchn *mc = &fstab; + + got_fstab = 1; + mc->nxt = mc->prev = NULL; + + fnam = _PATH_FSTAB; + mfp = nfs_setmntent (fnam, "r"); + if (mfp == NULL || mfp->mntent_fp == NULL) { + int errsv = errno; + error(_("warning: can't open %s: %s"), + _PATH_FSTAB, strerror (errsv)); + return; + } + read_mntentchn(mfp, fnam, mc); +} + /* * Given the directory name NAME, and the place MCPREV we found it last time, * try to find more occurrences. @@ -201,6 +233,32 @@ getmntdevbackward (const char *name, struct mntentchn *mcprev) { return NULL; } +/* Find the dir FILE in fstab. */ +struct mntentchn * +getfsfile (const char *file) +{ + struct mntentchn *mc, *mc0; + + mc0 = fstab_head(); + for (mc = mc0->nxt; mc && mc != mc0; mc = mc->nxt) + if (streq(mc->m.mnt_dir, file)) + return mc; + return NULL; +} + +/* Find the device SPEC in fstab. */ +struct mntentchn * +getfsspec (const char *spec) +{ + struct mntentchn *mc, *mc0; + + mc0 = fstab_head(); + for (mc = mc0->nxt; mc && mc != mc0; mc = mc->nxt) + if (streq(mc->m.mnt_fsname, spec)) + return mc; + return NULL; +} + /* Updating mtab ----------------------------------------------*/ /* Flag for already existing lock file. */ diff --git a/utils/mount/mount.c b/utils/mount/mount.c index 0edcc1a..cdccfe8 100644 --- a/utils/mount/mount.c +++ b/utils/mount/mount.c @@ -28,6 +28,7 @@ #include #include #include +#include #include "fstab.h" #include "xcommon.h" @@ -75,6 +76,11 @@ struct opt_map { int mask; /* flag mask value */ }; +/* Custom mount options for our own purposes. */ +#define MS_DUMMY 0x00000000 +#define MS_USERS 0x40000000 +#define MS_USER 0x80000000 + static const struct opt_map opt_map[] = { { "defaults", 0, 0, 0 }, /* default options */ { "ro", 1, 0, MS_RDONLY }, /* read-only */ @@ -91,6 +97,20 @@ static const struct opt_map opt_map[] = { { "remount", 0, 0, MS_REMOUNT}, /* Alter flags of mounted FS */ { "bind", 0, 0, MS_BIND }, /* Remount part of tree elsewhere */ { "rbind", 0, 0, MS_BIND|MS_REC }, /* Idem, plus mounted subtrees */ + { "auto", 0, 0, MS_DUMMY }, /* Can be mounted using -a */ + { "noauto", 0, 0, MS_DUMMY }, /* Can only be mounted explicitly */ + { "users", 1, 0, MS_USERS|MS_NOEXEC|MS_NOSUID|MS_NODEV }, + /* Allow ordinary user to mount */ + { "nousers", 0, 1, MS_DUMMY }, /* Forbid ordinary user to mount */ + { "user", 1, 0, MS_USER|MS_NOEXEC|MS_NOSUID|MS_NODEV }, + /* Allow ordinary user to mount */ + { "nouser", 0, 1, MS_DUMMY }, /* Forbid ordinary user to mount */ + { "owner", 0, 0, MS_DUMMY }, /* Let the owner of the device mount */ + { "noowner", 0, 0, MS_DUMMY }, /* Device owner has no special privs */ + { "group", 0, 0, MS_DUMMY }, /* Let the group of the device mount */ + { "nogroup", 0, 0, MS_DUMMY }, /* Device group has no special privs */ + { "_netdev", 0, 0, MS_DUMMY}, /* Device requires network */ + { "comment", 0, 0, MS_DUMMY}, /* fstab comment only (kudzu,_netdev)*/ /* add new options here */ #ifdef MS_NOSUB @@ -105,6 +125,7 @@ static const struct opt_map opt_map[] = { { "mand", 0, 0, MS_MANDLOCK }, /* Allow mandatory locks on this FS */ { "nomand", 0, 1, MS_MANDLOCK }, /* Forbid mandatory locks on this FS */ #endif + { "loop", 1, 0, MS_DUMMY }, /* use a loop device */ #ifdef MS_NOATIME { "atime", 0, 1, MS_NOATIME }, /* Update access time */ { "noatime", 0, 0, MS_NOATIME }, /* Do not update access time */ @@ -122,6 +143,15 @@ static char * fix_opts_string (int flags, const char *extra_opts) { char *new_opts; new_opts = xstrdup((flags & MS_RDONLY) ? "ro" : "rw"); + if (flags & MS_USER) { + /* record who mounted this so they can unmount */ + struct passwd *pw = getpwuid(getuid()); + if(pw) + new_opts = xstrconcat3(new_opts, ",user=", pw->pw_name); + } + if (flags & MS_USERS) + new_opts = xstrconcat3(new_opts, ",users", ""); + for (om = opt_map; om->opt != NULL; om++) { if (om->skip) continue; @@ -282,16 +312,12 @@ int main(int argc, char *argv[]) int c, flags = 0, nfs_mount_vers = 0, mnt_err = 1, fake = 0; char *spec, *mount_point, *extra_opts = NULL; char *mount_opts = NULL, *p; + uid_t uid = getuid(); progname = argv[0]; if ((p = strrchr(progname, '/')) != NULL) progname = p+1; - if (getuid() != 0) { - printf("%s: only root can do that.\n", progname); - exit(1); - } - if(!strncmp(progname, "umount", strlen("umount"))) { if(argc < 2) { umount_usage(); @@ -375,10 +401,35 @@ int main(int argc, char *argv[]) } spec = argv[1]; - mount_point = canonicalize(argv[2]); + mount_point = argv[2]; + + if (uid != 0) { + /* don't even think about it unless options exactly + * make fstab + */ + struct mntentchn *mc; + + if ((mc = getfsfile(mount_point)) == NULL || + strcmp(mc->m.mnt_fsname, spec) != 0 || + strcmp(mc->m.mnt_opts, mount_opts) != 0) { + fprintf(stderr, "%s: permission died - no match for fstab\n", + progname); + exit(1); + } + mounttype = 0; + } + + mount_point = canonicalize(mount_point); parse_opts(mount_opts, &flags, &extra_opts); + if (uid != 0) { + if (! (flags & (MS_USERS | MS_USER))) { + fprintf(stderr, "%s: permission denied\n", progname); + exit(1); + } + } + if (!strcmp(progname, "mount.nfs4") || nfs_mount_vers == 4) { nfs_mount_vers = 4; mnt_err = nfs4mount(spec, mount_point, &flags, &extra_opts, &mount_opts, 0); -- 2.39.5