Add user facing errors for exceeding process memory limits

Previously the process terminating with SIGABRT at startup was the
only notification.

PR:		200617
Reviewed by:	kib
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D2731

1 files changed, 24 insertions, 10 deletions

diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index a98a15d..c3953fe 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -732,7 +732,7 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
 	u_long addr, baddr, et_dyn_addr, entry = 0, proghdr = 0;
 	int32_t osrel = 0;
 	int error = 0, i, n, interp_name_len = 0;
-	const char *interp = NULL, *newinterp = NULL;
+	const char *err_str = NULL, *interp = NULL, *newinterp = NULL;
 	Elf_Brandinfo *brand_info;
 	char *path;
 	struct sysentvec *sv;
@@ -755,11 +755,14 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
 	if ((hdr->e_phoff > PAGE_SIZE) ||
 	    (u_int)hdr->e_phentsize * hdr->e_phnum > PAGE_SIZE - hdr->e_phoff) {
 		/* Only support headers in first page for now */
+		uprintf("Program headers not in the first page\n");
 		return (ENOEXEC);
 	}
-	phdr = (const Elf_Phdr *)(imgp->image_header + hdr->e_phoff);
-	if (!aligned(phdr, Elf_Addr))
+	phdr = (const Elf_Phdr *)(imgp->image_header + hdr->e_phoff); 
+	if (!aligned(phdr, Elf_Addr)) {
+		uprintf("Unaligned program headers\n");
 		return (ENOEXEC);
+	}
 	n = 0;
 	baddr = 0;
 	for (i = 0; i < hdr->e_phnum; i++) {
@@ -773,8 +776,10 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
 			/* Path to interpreter */
 			if (phdr[i].p_filesz > MAXPATHLEN ||
 			    phdr[i].p_offset > PAGE_SIZE ||
-			    phdr[i].p_filesz > PAGE_SIZE - phdr[i].p_offset)
+			    phdr[i].p_filesz > PAGE_SIZE - phdr[i].p_offset) {
+				uprintf("Invalid PT_INTERP\n");
 				return (ENOEXEC);
+			}
 			interp = imgp->image_header + phdr[i].p_offset;
 			interp_name_len = phdr[i].p_filesz;
 			break;
@@ -795,8 +800,10 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
 		return (ENOEXEC);
 	}
 	if (hdr->e_type == ET_DYN) {
-		if ((brand_info->flags & BI_CAN_EXEC_DYN) == 0)
+		if ((brand_info->flags & BI_CAN_EXEC_DYN) == 0) {
+			uprintf("Cannot execute shared object\n");
 			return (ENOEXEC);
+		}
 		/*
 		 * Honour the base load address from the dso if it is
 		 * non-zero for some reason.
@@ -901,12 +908,19 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
 	 * not actually fault in all the segments pages.
 	 */
 	PROC_LOCK(imgp->proc);
-	if (data_size > lim_cur(imgp->proc, RLIMIT_DATA) ||
-	    text_size > maxtsiz ||
-	    total_size > lim_cur(imgp->proc, RLIMIT_VMEM) ||
-	    racct_set(imgp->proc, RACCT_DATA, data_size) != 0 ||
-	    racct_set(imgp->proc, RACCT_VMEM, total_size) != 0) {
+	if (data_size > lim_cur(imgp->proc, RLIMIT_DATA))
+		err_str = "Data segment size exceeds process limit";
+	else if (text_size > maxtsiz)
+		err_str = "Text segment size exceeds system limit";
+	else if (total_size > lim_cur(imgp->proc, RLIMIT_VMEM))
+		err_str = "Total segment size exceeds process limit";
+	else if (racct_set(imgp->proc, RACCT_DATA, data_size) != 0)
+		err_str = "Data segment size exceeds resource limit";
+	else if (racct_set(imgp->proc, RACCT_VMEM, total_size) != 0)
+		err_str = "Total segment size exceeds resource limit";
+	if (err_str != NULL) {
 		PROC_UNLOCK(imgp->proc);
+		uprintf("%s\n", err_str);
 		return (ENOMEM);
 	}