This patch allows users to provide a custom template format through the new kernel command line parameter 'ima_template_fmt'. If the supplied format is not valid, IMA uses the default template descriptor.
Signed-off-by: Roberto Sassu <roberto.sa...@polito.it> --- Documentation/kernel-parameters.txt | 4 +++ Documentation/security/IMA-templates.txt | 29 +++++++++--------- security/integrity/ima/ima_template.c | 50 ++++++++++++++++++++++++++++++++ 3 files changed, 68 insertions(+), 15 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 1e8761c..27b14b2 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1199,6 +1199,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Formats: { "ima" | "ima-ng" } Default: "ima-ng" + ima_template_fmt= + [IMA] Define a custom template format. + Format: { "field1|...|fieldN" } + init= [KNL] Format: <full_path> Run specified binary instead of /sbin/init as init diff --git a/Documentation/security/IMA-templates.txt b/Documentation/security/IMA-templates.txt index a777e5f..08ea2da 100644 --- a/Documentation/security/IMA-templates.txt +++ b/Documentation/security/IMA-templates.txt @@ -27,25 +27,22 @@ Managing templates with these structures is very simple. To support a new data type, developers define the field identifier and implement two functions, init() and show(), respectively to generate and display measurement entries. Defining a new template descriptor requires -specifying the template format, a string of field identifiers separated -by the '|' character. While in the current implementation it is possible -to define new template descriptors only by adding their definition in the -template specific code (ima_template.c), in a future version it will be -possible to register a new template on a running kernel by supplying to IMA -the desired format string. In this version, IMA initializes at boot time -all defined template descriptors by translating the format into an array -of template fields structures taken from the set of the supported ones. +specifying the template format (a string of field identifiers separated +by the '|' character) through the 'ima_template_fmt' kernel command line +parameter. At boot time, IMA initializes all defined template descriptors +by translating the format into an array of template fields structures taken +from the set of the supported ones. After the initialization step, IMA will call ima_alloc_init_template() (new function defined within the patches for the new template management mechanism) to generate a new measurement entry by using the template descriptor chosen through the kernel configuration or through the newly -introduced 'ima_template=' kernel command line parameter. It is during this -phase that the advantages of the new architecture are clearly shown: -the latter function will not contain specific code to handle a given template -but, instead, it simply calls the init() method of the template fields -associated to the chosen template descriptor and store the result (pointer -to allocated data and data length) in the measurement entry structure. +introduced 'ima_template' and 'ima_template_fmt' kernel command line parameters. +It is during this phase that the advantages of the new architecture are +clearly shown: the latter function will not contain specific code to handle +a given template but, instead, it simply calls the init() method of the template +fields associated to the chosen template descriptor and store the result +(pointer to allocated data and data length) in the measurement entry structure. The same mechanism is employed to display measurements entries. The functions ima[_ascii]_measurements_show() retrieve, for each entry, @@ -84,4 +81,6 @@ currently the following methods are supported: - select a template descriptor among those supported in the kernel configuration ('ima-ng' is the default choice); - specify a template descriptor name from the kernel command line through - the 'ima_template=' parameter. + the 'ima_template=' parameter; + - register a new template descriptor with custom format through the kernel + command line parameter 'ima_template_fmt='. diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c index bb33576..5a95d06 100644 --- a/security/integrity/ima/ima_template.c +++ b/security/integrity/ima/ima_template.c @@ -21,6 +21,7 @@ static struct ima_template_desc defined_templates[] = { {.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT}, {.name = "ima-ng",.fmt = "d-ng|n-ng"}, {.name = "ima-sig",.fmt = "d-ng|n-ng|sig"}, + {.name = "",.fmt = ""}, /* placeholder for a custom format */ }; static struct ima_template_field supported_fields[] = { @@ -38,12 +39,16 @@ static struct ima_template_field supported_fields[] = { static struct ima_template_desc *ima_template; static struct ima_template_desc *lookup_template_desc(const char *name); +static struct ima_template_field *lookup_template_field(const char *field_id); static int __init ima_template_setup(char *str) { struct ima_template_desc *template_desc; int template_len = strlen(str); + if (ima_template) + return 1; + /* * Verify that a template with the supplied name exists. * If not, use CONFIG_IMA_DEFAULT_TEMPLATE. @@ -70,6 +75,48 @@ static int __init ima_template_setup(char *str) } __setup("ima_template=", ima_template_setup); +static int __init ima_template_fmt_setup(char *str) +{ + int num_templates = ARRAY_SIZE(defined_templates); + char *str_ptr_start = str; + char *str_ptr_end = str_ptr_start; + + if (ima_template) + return 1; + + while (str_ptr_start != NULL) { + char field_id[IMA_TEMPLATE_FIELD_ID_MAX_LEN]; + int len; + + str_ptr_end = strpbrk(str_ptr_start, "|"); + if (str_ptr_end == NULL) + len = str + strlen(str) - str_ptr_start; + else + len = str_ptr_end++ - str_ptr_start; + + if (len >= IMA_TEMPLATE_FIELD_ID_MAX_LEN) { + pr_err("IMA: field too long, using template %s\n", + CONFIG_IMA_DEFAULT_TEMPLATE); + return 1; + } + + memcpy(field_id, str_ptr_start, len); + field_id[len] = '\0'; + if (lookup_template_field(field_id) == NULL) { + pr_err("IMA: field '%s' not found, using template %s\n", + field_id, CONFIG_IMA_DEFAULT_TEMPLATE); + return 1; + } + + str_ptr_start = str_ptr_end; + } + + defined_templates[num_templates - 1].fmt = str; + ima_template = defined_templates + num_templates - 1; + return 1; +} +__setup("ima_template_fmt=", ima_template_fmt_setup); + static struct ima_template_desc *lookup_template_desc(const char *name) { int i; @@ -160,6 +207,9 @@ static int init_defined_templates(void) for (i = 0; i < ARRAY_SIZE(defined_templates); i++) { struct ima_template_desc *template = &defined_templates[i]; + if (strlen(template->fmt) == 0) + continue; + result = template_desc_init_fields(template->fmt, &(template->fields), &(template->num_fields)); -- 1.8.1.4
smime.p7s
Description: S/MIME cryptographic signature