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Message-Id: <20201121135736.295705-5-alx.manpages@gmail.com>
Date: Sat, 21 Nov 2020 14:57:36 +0100
From: Alejandro Colomar <alx.manpages@...il.com>
To: Alexander Viro <viro@...iv.linux.org.uk>,
linux-fsdevel@...r.kernel.org
Cc: Alejandro Colomar <alx.manpages@...il.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] fs/binfmt_elf.c: Cosmetic
Non-trivial changes:
Invert 'if's to simplify logic.
Use 'goto' in conjunction with the above, when appropriate.
Signed-off-by: Alejandro Colomar <alx.manpages@...il.com>
---
fs/binfmt_elf.c | 115 +++++++++++++++++++++++++-----------------------
1 file changed, 59 insertions(+), 56 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index b5e1e0a0917a..dbd50b5bf238 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1079,65 +1079,68 @@ static int load_elf_binary(struct linux_binprm *bprm)
*/
if (elf_ex->e_type == ET_EXEC || load_addr_set) {
elf_flags |= MAP_FIXED;
- } else if (elf_ex->e_type == ET_DYN) {
- /*
- * This logic is run once for the first LOAD Program
- * Header for ET_DYN binaries to calculate the
- * randomization (load_bias) for all the LOAD
- * Program Headers, and to calculate the entire
- * size of the ELF mapping (total_size). (Note that
- * load_addr_set is set to true later once the
- * initial mapping is performed.)
- *
- * There are effectively two types of ET_DYN
- * binaries: programs (i.e. PIE: ET_DYN with INTERP)
- * and loaders (ET_DYN without INTERP, since they
- * _are_ the ELF interpreter). The loaders must
- * be loaded away from programs since the program
- * may otherwise collide with the loader (especially
- * for ET_EXEC which does not have a randomized
- * position). For example to handle invocations of
- * "./ld.so someprog" to test out a new version of
- * the loader, the subsequent program that the
- * loader loads must avoid the loader itself, so
- * they cannot share the same load range. Sufficient
- * room for the brk must be allocated with the
- * loader as well, since brk must be available with
- * the loader.
- *
- * Therefore, programs are loaded offset from
- * ELF_ET_DYN_BASE and loaders are loaded into the
- * independently randomized mmap region (0 load_bias
- * without MAP_FIXED).
- */
- if (interpreter) {
- load_bias = ELF_ET_DYN_BASE;
- if (current->flags & PF_RANDOMIZE)
- load_bias += arch_mmap_rnd();
- alignment = maximum_alignment(elf_phdata, elf_ex->e_phnum);
- if (alignment)
- load_bias &= ~(alignment - 1);
- elf_flags |= MAP_FIXED;
- } else
- load_bias = 0;
+ goto proceed_normally;
+ }
+ if (elf_ex->e_type != ET_DYN)
+ goto proceed_normally;
+ /*
+ * This logic is run once for the first LOAD Program
+ * Header for ET_DYN binaries to calculate the
+ * randomization (load_bias) for all the LOAD
+ * Program Headers, and to calculate the entire
+ * size of the ELF mapping (total_size). (Note that
+ * load_addr_set is set to true later once the
+ * initial mapping is performed.)
+ *
+ * There are effectively two types of ET_DYN
+ * binaries: programs (i.e. PIE: ET_DYN with INTERP)
+ * and loaders (ET_DYN without INTERP, since they
+ * _are_ the ELF interpreter). The loaders must
+ * be loaded away from programs since the program
+ * may otherwise collide with the loader (especially
+ * for ET_EXEC which does not have a randomized
+ * position). For example to handle invocations of
+ * "./ld.so someprog" to test out a new version of
+ * the loader, the subsequent program that the
+ * loader loads must avoid the loader itself, so
+ * they cannot share the same load range. Sufficient
+ * room for the brk must be allocated with the
+ * loader as well, since brk must be available with
+ * the loader.
+ *
+ * Therefore, programs are loaded offset from
+ * ELF_ET_DYN_BASE and loaders are loaded into the
+ * independently randomized mmap region (0 load_bias
+ * without MAP_FIXED).
+ */
+ if (interpreter) {
+ load_bias = ELF_ET_DYN_BASE;
+ if (current->flags & PF_RANDOMIZE)
+ load_bias += arch_mmap_rnd();
+ alignment = maximum_alignment(elf_phdata, elf_ex->e_phnum);
+ if (alignment)
+ load_bias &= ~(alignment - 1);
+ elf_flags |= MAP_FIXED;
+ } else {
+ load_bias = 0;
+ }
- /*
- * Since load_bias is used for all subsequent loading
- * calculations, we must lower it by the first vaddr
- * so that the remaining calculations based on the
- * ELF vaddrs will be correctly offset. The result
- * is then page aligned.
- */
- load_bias = ELF_PAGESTART(load_bias - vaddr);
+ /*
+ * Since load_bias is used for all subsequent loading
+ * calculations, we must lower it by the first vaddr
+ * so that the remaining calculations based on the
+ * ELF vaddrs will be correctly offset. The result
+ * is then page aligned.
+ */
+ load_bias = ELF_PAGESTART(load_bias - vaddr);
- total_size = total_mapping_size(elf_phdata,
- elf_ex->e_phnum);
- if (!total_size) {
- retval = -EINVAL;
- goto out_free_dentry;
- }
+ total_size = total_mapping_size(elf_phdata,
+ elf_ex->e_phnum);
+ if (!total_size) {
+ retval = -EINVAL;
+ goto out_free_dentry;
}
-
+proceed_normally: /* FIXME: a better label name? */
error = elf_map(bprm->file, load_bias + vaddr, elf_ppnt,
elf_prot, elf_flags, total_size);
if (BAD_ADDR(error)) {
--
2.28.0
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