/** * mnt_context_do_mount * @cxt: context * * Call mount(2) or mount.type helper. Unnecessary for mnt_context_mount(). * * Note that this function could be called only once. If you want to mount * another source or target than you have to call mnt_reset_context(). * * If you want to call mount(2) for the same source and target with a diffrent * mount flags or fstype then call mnt_context_reset_status() and then try * again mnt_context_do_mount(). * * WARNING: non-zero return code does not mean that mount(2) syscall or * mount.type helper wasn't successfully called. * * Check mnt_context_get_status() after error! * * Returns: 0 on success; * >0 in case of mount(2) error (returns syscall errno), * <0 in case of other errors. */ int mnt_context_do_mount(struct libmnt_context *cxt) { const char *type; int res; assert(cxt); assert(cxt->fs); assert(cxt->helper_exec_status == 1); assert(cxt->syscall_status == 1); assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED)); assert((cxt->flags & MNT_FL_PREPARED)); assert((cxt->action == MNT_ACT_MOUNT)); DBG(CXT, mnt_debug_h(cxt, "mount: do mount")); if (!(cxt->flags & MNT_FL_MOUNTDATA)) cxt->mountdata = (char *) mnt_fs_get_fs_options(cxt->fs); type = mnt_fs_get_fstype(cxt->fs); if (type) res = do_mount(cxt, NULL); else res = do_mount_by_pattern(cxt, cxt->fstype_pattern); if (mnt_context_get_status(cxt) && !mnt_context_is_fake(cxt) && !cxt->helper) { /* * Mounted by mount(2), do some post-mount checks * * Kernel allows to use MS_RDONLY for bind mounts, but the * read-only request could be silently ignored. Check it to * avoid 'ro' in mtab and 'rw' in /proc/mounts. */ if ((cxt->mountflags & MS_BIND) && (cxt->mountflags & MS_RDONLY) && !mnt_is_readonly(mnt_context_get_target(cxt))) mnt_context_set_mflags(cxt, cxt->mountflags & ~MS_RDONLY); /* Kernel can silently add MS_RDONLY flag when mounting file * system that does not have write support. Check this to avoid * 'ro' in /proc/mounts and 'rw' in mtab. */ if (!(cxt->mountflags & (MS_RDONLY | MS_PROPAGATION | MS_MOVE)) && mnt_is_readonly(mnt_context_get_target(cxt))) mnt_context_set_mflags(cxt, cxt->mountflags | MS_RDONLY); } return res; }
static int try_mount(struct libmnt_context *cxt, int bg) { struct libmnt_fs *fs; const char *p; char *src = NULL, *tgt = NULL, *type = NULL, *opts = NULL; unsigned long flags = 0; int fake, ret = 0; fs = mnt_context_get_fs(cxt); /* libmount returns read-only pointers (const char) * so, reallocate for nfsmount() functions. */ if ((p = mnt_fs_get_source(fs))) /* spec */ src = strdup(p); if ((p = mnt_fs_get_target(fs))) /* mountpoint */ tgt = strdup(p); if ((p = mnt_fs_get_fstype(fs))) /* FS type */ type = strdup(p); if ((p = mnt_fs_get_fs_options(fs))) /* mount options */ opts = strdup(p); mnt_context_get_mflags(cxt, &flags); /* mount(2) flags */ fake = mnt_context_is_fake(cxt); if (string) ret = nfsmount_string(src, tgt, type, flags, &opts, fake, bg); else if (strcmp(type, "nfs4") == 0) ret = nfs4mount(src, tgt, flags, &opts, fake, bg); else ret = nfsmount(src, tgt, flags, &opts, fake, bg); /* Store mount options if not called with mount --no-mtab */ if (!ret && !mnt_context_is_nomtab(cxt)) store_mount_options(fs, opts); free(src); free(tgt); free(type); free(opts); return ret; }
/** * mnt_context_do_umount: * @cxt: mount context * * Umount filesystem by umount(2) or fork()+exec(/sbin/umount.type). * Unnecessary for mnt_context_umount(). * * See also mnt_context_disable_helpers(). * * WARNING: non-zero return code does not mean that umount(2) syscall or * umount.type helper wasn't successfully called. * * Check mnt_context_get_status() after error! * * Returns: 0 on success; * >0 in case of umount(2) error (returns syscall errno), * <0 in case of other errors. */ int mnt_context_do_umount(struct libmnt_context *cxt) { int rc; assert(cxt); assert(cxt->fs); assert(cxt->helper_exec_status == 1); assert(cxt->syscall_status == 1); assert((cxt->flags & MNT_FL_PREPARED)); assert((cxt->action == MNT_ACT_UMOUNT)); assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED)); rc = do_umount(cxt); if (rc) return rc; if (mnt_context_get_status(cxt) && !mnt_context_is_fake(cxt)) { /* * Umounted, do some post-umount operations * - remove loopdev * - refresh in-memory mtab stuff if remount rather than * umount has been performed */ if (mnt_context_is_loopdel(cxt) && !(cxt->mountflags & MS_REMOUNT)) rc = mnt_context_delete_loopdev(cxt); if (!mnt_context_is_nomtab(cxt) && mnt_context_get_status(cxt) && !cxt->helper && mnt_context_is_rdonly_umount(cxt) && (cxt->mountflags & MS_REMOUNT)) { /* use "remount" instead of "umount" in /etc/mtab */ if (!rc && cxt->update && cxt->mtab_writable) rc = mnt_update_set_fs(cxt->update, cxt->mountflags, NULL, cxt->fs); } } return rc; }
static int do_umount(struct libmnt_context *cxt) { int rc = 0, flags = 0; const char *src, *target; char *tgtbuf = NULL; assert(cxt); assert(cxt->fs); assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED)); assert(cxt->syscall_status == 1); if (cxt->helper) return exec_helper(cxt); src = mnt_fs_get_srcpath(cxt->fs); target = mnt_fs_get_target(cxt->fs); if (!target) return -EINVAL; DBG(CXT, mnt_debug_h(cxt, "do umount")); if (cxt->restricted && !mnt_context_is_fake(cxt)) { /* * extra paranoia for non-root users * -- chdir to the parent of the mountpoint and use NOFOLLOW * flag to avoid races and symlink attacks. */ if (umount_nofollow_support()) flags |= UMOUNT_NOFOLLOW; rc = mnt_chdir_to_parent(target, &tgtbuf); if (rc) return rc; target = tgtbuf; } if (mnt_context_is_lazy(cxt)) flags |= MNT_DETACH; else if (mnt_context_is_force(cxt)) flags |= MNT_FORCE; DBG(CXT, mnt_debug_h(cxt, "umount(2) [target='%s', flags=0x%08x]%s", target, flags, mnt_context_is_fake(cxt) ? " (FAKE)" : "")); if (mnt_context_is_fake(cxt)) rc = 0; else { rc = flags ? umount2(target, flags) : umount(target); if (rc < 0) cxt->syscall_status = -errno; free(tgtbuf); } /* * try remount read-only */ if (rc < 0 && cxt->syscall_status == -EBUSY && mnt_context_is_rdonly_umount(cxt) && src) { mnt_context_set_mflags(cxt, (cxt->mountflags | MS_REMOUNT | MS_RDONLY)); mnt_context_enable_loopdel(cxt, FALSE); DBG(CXT, mnt_debug_h(cxt, "umount(2) failed [errno=%d] -- trying to remount read-only", -cxt->syscall_status)); rc = mount(src, mnt_fs_get_target(cxt->fs), NULL, MS_MGC_VAL | MS_REMOUNT | MS_RDONLY, NULL); if (rc < 0) { cxt->syscall_status = -errno; DBG(CXT, mnt_debug_h(cxt, "read-only re-mount(2) failed [errno=%d]", -cxt->syscall_status)); return -cxt->syscall_status; } cxt->syscall_status = 0; DBG(CXT, mnt_debug_h(cxt, "read-only re-mount(2) success")); return 0; } if (rc < 0) { DBG(CXT, mnt_debug_h(cxt, "umount(2) failed [errno=%d]", -cxt->syscall_status)); return -cxt->syscall_status; } cxt->syscall_status = 0; DBG(CXT, mnt_debug_h(cxt, "umount(2) success")); return 0; }
static int exec_helper(struct libmnt_context *cxt) { int rc; assert(cxt); assert(cxt->fs); assert(cxt->helper); assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED)); assert(cxt->helper_exec_status == 1); if (mnt_context_is_fake(cxt)) { DBG(CXT, ul_debugobj(cxt, "fake mode: does not execute helper")); cxt->helper_exec_status = rc = 0; return rc; } DBG_FLUSH; switch (fork()) { case 0: { const char *args[10], *type; int i = 0; if (setgid(getgid()) < 0) exit(EXIT_FAILURE); if (setuid(getuid()) < 0) exit(EXIT_FAILURE); type = mnt_fs_get_fstype(cxt->fs); args[i++] = cxt->helper; /* 1 */ args[i++] = mnt_fs_get_target(cxt->fs); /* 2 */ if (mnt_context_is_nomtab(cxt)) args[i++] = "-n"; /* 3 */ if (mnt_context_is_lazy(cxt)) args[i++] = "-l"; /* 4 */ if (mnt_context_is_force(cxt)) args[i++] = "-f"; /* 5 */ if (mnt_context_is_verbose(cxt)) args[i++] = "-v"; /* 6 */ if (mnt_context_is_rdonly_umount(cxt)) args[i++] = "-r"; /* 7 */ if (type && strchr(type, '.') && !endswith(cxt->helper, type)) { args[i++] = "-t"; /* 8 */ args[i++] = (char *) type; /* 9 */ } args[i] = NULL; /* 10 */ for (i = 0; args[i]; i++) DBG(CXT, ul_debugobj(cxt, "argv[%d] = \"%s\"", i, args[i])); DBG_FLUSH; execv(cxt->helper, (char * const *) args); exit(EXIT_FAILURE); } default: { int st; wait(&st); cxt->helper_status = WIFEXITED(st) ? WEXITSTATUS(st) : -1; DBG(CXT, ul_debugobj(cxt, "%s executed [status=%d]", cxt->helper, cxt->helper_status)); cxt->helper_exec_status = rc = 0; break; } case -1: cxt->helper_exec_status = rc = -errno; DBG(CXT, ul_debugobj(cxt, "fork() failed")); break; } return rc; }
/* * The default is to use fstype from cxt->fs, this could be overwritten by * @try_type argument. * * Returns: 0 on success, * >0 in case of mount(2) error (returns syscall errno), * <0 in case of other errors. */ static int do_mount(struct libmnt_context *cxt, const char *try_type) { int rc = 0; const char *src, *target, *type; unsigned long flags; assert(cxt); assert(cxt->fs); assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED)); if (try_type && !cxt->helper) { rc = mnt_context_prepare_helper(cxt, "mount", try_type); if (rc) return rc; } if (cxt->helper) return exec_helper(cxt); flags = cxt->mountflags; src = mnt_fs_get_srcpath(cxt->fs); target = mnt_fs_get_target(cxt->fs); if (!target) return -EINVAL; if (!src) { /* unnecessary, should be already resolved in * mnt_context_prepare_srcpath(), but for sure... */ DBG(CXT, mnt_debug_h(cxt, "WARNING: source is NULL -- using \"none\"!")); src = "none"; } type = try_type ? : mnt_fs_get_fstype(cxt->fs); if (!(flags & MS_MGC_MSK)) flags |= MS_MGC_VAL; DBG(CXT, mnt_debug_h(cxt, "%smount(2) " "[source=%s, target=%s, type=%s, " " mountflags=0x%08lx, mountdata=%s]", mnt_context_is_fake(cxt) ? "(FAKE) " : "", src, target, type, flags, cxt->mountdata ? "yes" : "<none>")); if (mnt_context_is_fake(cxt)) cxt->syscall_status = 0; else { if (mount(src, target, type, flags, cxt->mountdata)) { cxt->syscall_status = -errno; DBG(CXT, mnt_debug_h(cxt, "mount(2) failed [errno=%d %m]", -cxt->syscall_status)); return -cxt->syscall_status; } DBG(CXT, mnt_debug_h(cxt, "mount(2) success")); cxt->syscall_status = 0; } if (try_type && cxt->update) { struct libmnt_fs *fs = mnt_update_get_fs(cxt->update); if (fs) rc = mnt_fs_set_fstype(fs, try_type); } return rc; }
static int exec_helper(struct libmnt_context *cxt) { char *o = NULL; int rc; assert(cxt); assert(cxt->fs); assert(cxt->helper); assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED)); DBG(CXT, mnt_debug_h(cxt, "mount: executing helper %s", cxt->helper)); rc = generate_helper_optstr(cxt, &o); if (rc) return -EINVAL; DBG_FLUSH; switch (fork()) { case 0: { const char *args[12], *type; int i = 0; if (setgid(getgid()) < 0) exit(EXIT_FAILURE); if (setuid(getuid()) < 0) exit(EXIT_FAILURE); type = mnt_fs_get_fstype(cxt->fs); args[i++] = cxt->helper; /* 1 */ args[i++] = mnt_fs_get_srcpath(cxt->fs);/* 2 */ args[i++] = mnt_fs_get_target(cxt->fs); /* 3 */ /* * TODO: remove the exception for "nfs", -s is documented * for years should be usable everywhere. */ if (mnt_context_is_sloppy(cxt) && type && startswith(type, "nfs")) args[i++] = "-s"; /* 4 */ if (mnt_context_is_fake(cxt)) args[i++] = "-f"; /* 5 */ if (mnt_context_is_nomtab(cxt)) args[i++] = "-n"; /* 6 */ if (mnt_context_is_verbose(cxt)) args[i++] = "-v"; /* 7 */ if (o) { args[i++] = "-o"; /* 8 */ args[i++] = o; /* 9 */ } if (type && !endswith(cxt->helper, type)) { args[i++] = "-t"; /* 10 */ args[i++] = type; /* 11 */ } args[i] = NULL; /* 12 */ #ifdef CONFIG_LIBMOUNT_DEBUG for (i = 0; args[i]; i++) DBG(CXT, mnt_debug_h(cxt, "argv[%d] = \"%s\"", i, args[i])); #endif DBG_FLUSH; execv(cxt->helper, (char * const *) args); exit(EXIT_FAILURE); } default: { int st; wait(&st); cxt->helper_status = WIFEXITED(st) ? WEXITSTATUS(st) : -1; DBG(CXT, mnt_debug_h(cxt, "%s executed [status=%d]", cxt->helper, cxt->helper_status)); cxt->helper_exec_status = rc = 0; break; } case -1: cxt->helper_exec_status = rc = -errno; DBG(CXT, mnt_debug_h(cxt, "fork() failed")); break; } return rc; }