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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id du14-20020a056a002b4e00b00690fe1c928esm10256201pfb.91.2023.09.28.20.24.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 Sep 2023 20:24:36 -0700 (PDT) From: Kees Cook To: Eric Biederman Cc: Kees Cook , Alexander Viro , Christian Brauner , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Pedro Falcato , Sebastian Ott , =?utf-8?q?Thomas_Wei=C3=9Fschuh?= , Andrew Morton , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v4 3/6] binfmt_elf: Use elf_load() for interpreter Date: Thu, 28 Sep 2023 20:24:31 -0700 Message-Id: <20230929032435.2391507-3-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230929031716.it.155-kees@kernel.org> References: <20230929031716.it.155-kees@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2936; i=keescook@chromium.org; h=from:subject; bh=8mN64ZnApkL7mlS3J3j8M/PeeHjiU24xpvEFIwO52Sc=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlFkNyQ5p5E4Tg789OjEFFGvDw6hy8O/CboaqJO +gn/YtsP02JAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZRZDcgAKCRCJcvTf3G3A JlfrD/0UmFIiwvqM26CPsRIStoMfmoWWLE+1T0+B6VIpoHHYl6fxgrYIk1GMjuaGbD0RwF9QP+t BqcWROGSbE7jtsk5rW33lmv5P4kATjv1E8P0xTh6YLwy/qmxm1iBcqH7A7aIp5rT/ZZxmRWS7z/ KaumFG9s9XzIzz7vNtyCpYAslNBn7Ct0D760d/KdyUyF0tRcwUZGbbqsCSJ3qDlqi9Oh48d8rqr zVrOdBbcoN0GFz2NFhwg1g0iypiVC72gYNSKuCVuYoSflzMWmk+MWWz+KoGHh8QQyufk09tUrRt 7e7QzVJPtxRfKGiVSBnbT7mPxw87BCa7B1z+sX5Sj7D4++z7rbKsnwJGiOeSn9hRsn3zwU/bHKg 2VugFFQ+5/llgN3z58QGPu56dO6ydWYCZeneBcrQoNc1xhZyz8M2IpA5m0iJS719hxg22R2fW1p xaQITu1kMm0y6BxdReD/XHhw3eM0HzXWV9ltG8nLrJXOVz5Ve3z1wcEusMGPOh07NsX6dEfXDJv XYtMF21/+UxnZ3eYxaWMHimE+Qo2DtB694DxSqJhwRK4FB4KUShHOAsbSQTcGSzXCx13gP3vhF0 S8eSoWkYBz90zkFWSPCcyq4F9jfXjVmVgHQgU/leUKWz2vDzeEVdmX04CQNaCQPS6MFWyGJaKml bTMeDeMtwCCfvfQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Handle arbitrary memsz>filesz in interpreter ELF segments, instead of only supporting it in the last segment (which is expected to be the BSS). Cc: Eric Biederman Cc: Alexander Viro Cc: Christian Brauner Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Reported-by: Pedro Falcato Closes: https://lore.kernel.org/lkml/20221106021657.1145519-1-pedro.falcato@gmail.com/ Signed-off-by: Kees Cook --- fs/binfmt_elf.c | 46 +--------------------------------------------- 1 file changed, 1 insertion(+), 45 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 0214d5a949fc..db47cb802f89 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -622,8 +622,6 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, struct elf_phdr *eppnt; unsigned long load_addr = 0; int load_addr_set = 0; - unsigned long last_bss = 0, elf_bss = 0; - int bss_prot = 0; unsigned long error = ~0UL; unsigned long total_size; int i; @@ -660,7 +658,7 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, else if (no_base && interp_elf_ex->e_type == ET_DYN) load_addr = -vaddr; - map_addr = elf_map(interpreter, load_addr + vaddr, + map_addr = elf_load(interpreter, load_addr + vaddr, eppnt, elf_prot, elf_type, total_size); total_size = 0; error = map_addr; @@ -686,51 +684,9 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, error = -ENOMEM; goto out; } - - /* - * Find the end of the file mapping for this phdr, and - * keep track of the largest address we see for this. - */ - k = load_addr + eppnt->p_vaddr + eppnt->p_filesz; - if (k > elf_bss) - elf_bss = k; - - /* - * Do the same thing for the memory mapping - between - * elf_bss and last_bss is the bss section. - */ - k = load_addr + eppnt->p_vaddr + eppnt->p_memsz; - if (k > last_bss) { - last_bss = k; - bss_prot = elf_prot; - } } } - /* - * Now fill out the bss section: first pad the last page from - * the file up to the page boundary, and zero it from elf_bss - * up to the end of the page. - */ - if (padzero(elf_bss)) { - error = -EFAULT; - goto out; - } - /* - * Next, align both the file and mem bss up to the page size, - * since this is where elf_bss was just zeroed up to, and where - * last_bss will end after the vm_brk_flags() below. - */ - elf_bss = ELF_PAGEALIGN(elf_bss); - last_bss = ELF_PAGEALIGN(last_bss); - /* Finally, if there is still more bss to allocate, do it. */ - if (last_bss > elf_bss) { - error = vm_brk_flags(elf_bss, last_bss - elf_bss, - bss_prot & PROT_EXEC ? VM_EXEC : 0); - if (error) - goto out; - } - error = load_addr; out: return error;