libexec: detect short files
if an exec() fails partway through reading in the sections, the target process is already gone and a defunct process remains. sanity checking the binary beforehand helps that. test10 mutilates binaries and exec()s them on purpose; making an exec() fail cleanly in such cases seems like acceptable behaviour. fixes test10 on ARM. Change-Id: I1ed9bb200ce469d4d349073cadccad5503b2fcb0
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57bab02d57
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298b41b523
8 changed files with 20 additions and 4 deletions
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@ -131,7 +131,7 @@ void arch_boot_proc(struct boot_image *ip, struct proc *rp)
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execi.stack_size = 32 * 1024; /* not too crazy as it must be preallocated */
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execi.proc_e = ip->endpoint;
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execi.hdr = (char *) mod->mod_start; /* phys mem direct */
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execi.hdr_len = mod->mod_end - mod->mod_start;
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execi.filesize = execi.hdr_len = mod->mod_end - mod->mod_start;
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strcpy(execi.progname, ip->proc_name);
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execi.frame_len = 0;
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@ -407,7 +407,7 @@ void arch_boot_proc(struct boot_image *ip, struct proc *rp)
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execi.stack_size = 16 * 1024; /* not too crazy as it must be preallocated */
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execi.proc_e = ip->endpoint;
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execi.hdr = (char *) mod->mod_start; /* phys mem direct */
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execi.hdr_len = mod->mod_end - mod->mod_start;
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execi.filesize = execi.hdr_len = mod->mod_end - mod->mod_start;
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strlcpy(execi.progname, ip->proc_name, sizeof(execi.progname));
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execi.frame_len = 0;
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@ -156,6 +156,15 @@ int libexec_load_elf(struct exec_info *execi)
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assert(execi->allocmem_prealloc);
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assert(execi->allocmem_ondemand);
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for (i = 0; i < hdr->e_phnum; i++) {
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Elf_Phdr *ph = &phdr[i];
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off_t file_limit = ph->p_offset + ph->p_filesz;
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/* sanity check binary before wiping out the target process */
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if(execi->filesize < file_limit) {
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return ENOEXEC;
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}
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}
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if(execi->clearproc) execi->clearproc(execi);
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for (i = 0; i < hdr->e_phnum; i++) {
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@ -28,6 +28,7 @@ struct exec_info {
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int allow_setuid; /* Allow set{u,g}id execution? */
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vir_bytes stack_size; /* Desired stack size */
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vir_bytes load_offset; /* Desired load offset */
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off_t filesize; /* How big is the file */
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/* Callback pointers for use by libexec */
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libexec_loadfunc_t copymem; /* Copy callback */
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@ -124,7 +124,7 @@ static int do_exec(int proc_e, char *exec, size_t exec_len, char *progname,
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execi.stack_size = DEFAULT_STACK_LIMIT;
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execi.proc_e = proc_e;
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execi.hdr = exec;
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execi.hdr_len = exec_len;
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execi.filesize = execi.hdr_len = exec_len;
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strncpy(execi.progname, progname, PROC_NAME_LEN-1);
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execi.progname[PROC_NAME_LEN-1] = '\0';
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execi.frame_len = frame_len;
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@ -312,6 +312,7 @@ int pm_exec(endpoint_t proc_e, vir_bytes path, size_t path_len,
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execi.args.proc_e = proc_e;
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execi.args.frame_len = frame_len;
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execi.args.filesize = execi.vp->v_size;
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for (i = 0; exec_loaders[i].load_object != NULL; i++) {
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r = (*exec_loaders[i].load_object)(&execi.args);
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@ -276,6 +276,7 @@ void exec_bootproc(struct vmproc *vmp, struct boot_image *ip)
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strlcpy(execi->progname, ip->proc_name, sizeof(execi->progname));
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execi->frame_len = 0;
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execi->opaque = &vmexeci;
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execi->filesize = ip->len;
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vmexeci.ip = ip;
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vmexeci.vmp = vmp;
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@ -77,7 +77,11 @@ int n;
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if ((pid = fork()) != 0) {
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wait(&n); /* wait for some child (any one) */
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} else {
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execl(name[n], name[n], (char *) 0);
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/* a successful exec or a successful detection of a broken executable
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* is ok
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*/
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if(execl(name[n], name[n], (char *) 0) < 0 && errno == ENOEXEC)
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exit(0);
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errct++;
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printf("Child execl didn't take. file=%s errno=%d\n", name[n], errno);
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rmfiles();
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