git: 3299277af825 - stable/14 - bhyveload: hold /boot and do relative lookups for the loader
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Date: Mon, 22 Jan 2024 17:30:00 UTC
The branch stable/14 has been updated by kevans: URL: https://cgit.FreeBSD.org/src/commit/?id=3299277af8257c4a1cd59b3d813fcacbbe358ca9 commit 3299277af8257c4a1cd59b3d813fcacbbe358ca9 Author: Kyle Evans <kevans@FreeBSD.org> AuthorDate: 2024-01-03 22:17:59 +0000 Commit: Kyle Evans <kevans@FreeBSD.org> CommitDate: 2024-01-22 17:18:37 +0000 bhyveload: hold /boot and do relative lookups for the loader The next change will push bhyveload into capability mode right after we allocate vcpu state, before we've setup or entered the loader, to limit the surface area that a rogue loader script can touch. With an explicit -l loader, we don't need to preopen /boot because changing interpreters isn't allowed. We'll just dlopen() entirely in advance in that case to eliminate some complexity. Reviewed by: allanjude (earlier version), markj (cherry picked from commit bf7c4fcbbb05ff99afde0744d013feeb35d77191) (cherry picked from commit 67082f077f39d9c7b7bd561c14622e6f3ef23681) --- usr.sbin/bhyveload/bhyveload.c | 73 +++++++++++++++++++++++++++++------------- 1 file changed, 51 insertions(+), 22 deletions(-) diff --git a/usr.sbin/bhyveload/bhyveload.c b/usr.sbin/bhyveload/bhyveload.c index 4c1dbd583e1f..7503598ba94b 100644 --- a/usr.sbin/bhyveload/bhyveload.c +++ b/usr.sbin/bhyveload/bhyveload.c @@ -94,11 +94,9 @@ static int ndisks; static int consin_fd, consout_fd; static int hostbase_fd = -1; -static int need_reinit; - static void *loader_hdl; static char *loader; -static int explicit_loader; +static int explicit_loader_fd = -1; static jmp_buf jb; static char *vmname, *progname; @@ -618,7 +616,7 @@ cb_swap_interpreter(void *arg __unused, const char *interp_req) * not try to pivot to a different loader on them. */ free(loader); - if (explicit_loader == 1) { + if (explicit_loader_fd != -1) { perror("requested loader interpreter does not match guest userboot"); cb_exit(NULL, 1); } @@ -627,9 +625,8 @@ cb_swap_interpreter(void *arg __unused, const char *interp_req) cb_exit(NULL, 1); } - if (asprintf(&loader, "/boot/userboot_%s.so", interp_req) == -1) + if (asprintf(&loader, "userboot_%s.so", interp_req) == -1) err(EX_OSERR, "malloc"); - need_reinit = 1; longjmp(jb, 1); } @@ -744,13 +741,38 @@ hostbase_open(const char *base) err(EX_OSERR, "open"); } +static void +loader_open(int bootfd) +{ + int fd; + + if (loader == NULL) { + loader = strdup("userboot.so"); + if (loader == NULL) + err(EX_OSERR, "malloc"); + } + + assert(bootfd >= 0 || explicit_loader_fd >= 0); + if (explicit_loader_fd >= 0) + fd = explicit_loader_fd; + else + fd = openat(bootfd, loader, O_RDONLY | O_RESOLVE_BENEATH); + if (fd == -1) + err(EX_OSERR, "openat"); + + loader_hdl = fdlopen(fd, RTLD_LOCAL); + if (!loader_hdl) + errx(EX_OSERR, "dlopen: %s", dlerror()); +} + int main(int argc, char** argv) { void (*func)(struct loader_callbacks *, void *, int, int); uint64_t mem_size; - int opt, error, memflags; + int bootfd, opt, error, memflags, need_reinit; + bootfd = -1; progname = basename(argv[0]); memflags = 0; @@ -787,7 +809,9 @@ main(int argc, char** argv) loader = strdup(optarg); if (loader == NULL) err(EX_OSERR, "malloc"); - explicit_loader = 1; + explicit_loader_fd = open(loader, O_RDONLY); + if (explicit_loader_fd == -1) + err(EX_OSERR, "%s", loader); break; case 'm': @@ -830,6 +854,18 @@ main(int argc, char** argv) exit(1); } + /* + * If we weren't given an explicit loader to use, we need to support the + * guest requesting a different one. + */ + if (explicit_loader_fd == -1) { + bootfd = open("/boot", O_DIRECTORY | O_PATH); + if (bootfd == -1) { + perror("open"); + exit(1); + } + } + vcpu = vm_vcpu_open(ctx, BSP); /* @@ -837,7 +873,12 @@ main(int argc, char** argv) * cb_swap_interpreter will swap out loader as appropriate and set * need_reinit so that we end up in a clean state once again. */ - setjmp(jb); + if (setjmp(jb) != 0) { + dlclose(loader_hdl); + loader_hdl = NULL; + + need_reinit = 1; + } if (need_reinit) { error = vm_reinit(ctx); @@ -854,19 +895,7 @@ main(int argc, char** argv) exit(1); } - if (loader == NULL) { - loader = strdup("/boot/userboot.so"); - if (loader == NULL) - err(EX_OSERR, "malloc"); - } - if (loader_hdl != NULL) - dlclose(loader_hdl); - loader_hdl = dlopen(loader, RTLD_LOCAL); - if (!loader_hdl) { - printf("%s\n", dlerror()); - free(loader); - return (1); - } + loader_open(bootfd); func = dlsym(loader_hdl, "loader_main"); if (!func) { printf("%s\n", dlerror());