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AJvYcCUbikWwxNM2T7HadXLXr5rnxyUP2RFr63R+hRXVyHVngFSYdtrx2IFysmflJyhat6PSxVY89wr/rV5eGuM=@vger.kernel.org X-Gm-Message-State: AOJu0YxFVrGW3rFvU+lFI1xTyI8D4WUG7FfpiXBMe0TaYLe1BkVp1SDI ovprxPtPbtBdqB2E6+EY2BvDCkZYVCaHaV5TASzIYSkYpiuRtVQ+cp+BhTIY0C09P5FCwvpt9mA lre93UQ== X-Google-Smtp-Source: AGHT+IGx+nve+AoQTJhC0039Mrm5L1Mmot8nzzFqz6EcNfCPXpgrANZ2tGjsmltzJQkDur51XUIFhuHCnZ0h X-Received: from anyblade.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:1791]) (user=mmaurer job=sendgmr) by 2002:a25:780e:0:b0:e16:6e0a:bb0b with SMTP id 3f1490d57ef6-e24d44cad51mr4787276.0.1727307572609; Wed, 25 Sep 2024 16:39:32 -0700 (PDT) Date: Wed, 25 Sep 2024 23:38:20 +0000 In-Reply-To: <20240925233854.90072-1-mmaurer@google.com> Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240925233854.90072-1-mmaurer@google.com> X-Mailer: git-send-email 2.46.1.824.gd892dcdcdd-goog Message-ID: <20240925233854.90072-6-mmaurer@google.com> Subject: [PATCH v5 05/16] module: Factor out elf_validity_cache_index_info From: Matthew Maurer To: masahiroy@kernel.org, ndesaulniers@google.com, ojeda@kernel.org, gary@garyguo.net, mcgrof@kernel.org, Alex Gaynor Cc: rust-for-linux@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, neal@gompa.dev, marcan@marcan.st, j@jannau.net, asahi@lists.linux.dev, linux-modules@vger.kernel.org, Matthew Maurer , Petr Pavlu , Sami Tolvanen , Daniel Gomez , Boqun Feng , " =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= " , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross Centralize .modinfo detection and property validation. Signed-off-by: Matthew Maurer --- kernel/module/main.c | 82 ++++++++++++++++++++++++++++++++++++-------- 1 file changed, 68 insertions(+), 14 deletions(-) diff --git a/kernel/module/main.c b/kernel/module/main.c index 6a9159afca02..511d645ac577 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -195,6 +195,38 @@ static unsigned int find_sec(const struct load_info *info, const char *name) return 0; } +/** + * find_any_unique_sec() - Find a unique section index by name + * @info: Load info for the module to scan + * @name: Name of the section we're looking for + * + * Locates a unique section by name. Ignores SHF_ALLOC. + * + * Return: Section index if found uniquely, zero if absent, negative count + * of total instances if multiple were found. + */ +static int find_any_unique_sec(const struct load_info *info, const char *name) +{ + unsigned int idx; + unsigned int count = 0; + int i; + + for (i = 1; i < info->hdr->e_shnum; i++) { + if (strcmp(info->secstrings + info->sechdrs[i].sh_name, + name) == 0) { + count++; + idx = i; + } + } + if (count == 1) { + return idx; + } else if (count == 0) { + return 0; + } else { + return -count; + } +} + /* Find a module section, or NULL. */ static void *section_addr(const struct load_info *info, const char *name) { @@ -1854,6 +1886,39 @@ static int elf_validity_cache_secstrings(struct load_info *info) return 0; } +/** + * elf_validity_cache_index_info() - Validate and cache modinfo section + * @info: Load info to populate the modinfo index on. + * Must have &load_info->sechdrs and &load_info->secstrings populated + * + * Checks that if there is a .modinfo section, it is unique. + * Then, it caches its index in &load_info->index.info. + * Finally, it tries to populate the name to improve error messages. + * + * Return: %0 if valid, %-ENOEXEC if multiple modinfo sections were found. + */ +static int elf_validity_cache_index_info(struct load_info *info) +{ + int info_idx; + + info_idx = find_any_unique_sec(info, ".modinfo"); + + if (info_idx == 0) + /* Early return, no .modinfo */ + return 0; + + if (info_idx < 0) { + pr_err("Only one .modinfo section must exist.\n"); + return -ENOEXEC; + } + + info->index.info = info_idx; + /* Try to find a name early so we can log errors with a module name */ + info->name = get_modinfo(info, "name"); + + return 0; +} + /* * Check userspace passed ELF module against our expectations, and cache * useful variables for further processing as we go. @@ -1880,13 +1945,15 @@ static int elf_validity_cache_copy(struct load_info *info, int flags) Elf_Shdr *shdr; int err; unsigned int num_mod_secs = 0, mod_idx; - unsigned int num_info_secs = 0, info_idx; unsigned int num_sym_secs = 0, sym_idx; err = elf_validity_cache_sechdrs(info); if (err < 0) return err; err = elf_validity_cache_secstrings(info); + if (err < 0) + return err; + err = elf_validity_cache_index_info(info); if (err < 0) return err; @@ -1912,24 +1979,11 @@ static int elf_validity_cache_copy(struct load_info *info, int flags) ".gnu.linkonce.this_module") == 0) { num_mod_secs++; mod_idx = i; - } else if (strcmp(info->secstrings + shdr->sh_name, - ".modinfo") == 0) { - num_info_secs++; - info_idx = i; } break; } } - if (num_info_secs > 1) { - pr_err("Only one .modinfo section must exist.\n"); - goto no_exec; - } else if (num_info_secs == 1) { - /* Try to find a name early so we can log errors with a module name */ - info->index.info = info_idx; - info->name = get_modinfo(info, "name"); - } - if (num_sym_secs != 1) { pr_warn("%s: module has no symbols (stripped?)\n", info->name ?: "(missing .modinfo section or name field)");